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Rashedi N, Sun Y, Vaze V, Shah P, Halter R, Elliott JT, Paradis NA. Prediction of Occult Hemorrhage in the Lower Body Negative Pressure Model: Initial Validation of Machine Learning Approaches. Mil Med 2024; 189:e1629-e1636. [PMID: 38537150 DOI: 10.1093/milmed/usae061] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2023] [Revised: 10/09/2023] [Accepted: 02/12/2024] [Indexed: 07/05/2024] Open
Abstract
INTRODUCTION Detection of occult hemorrhage (OH) before progression to clinically apparent changes in vital signs remains an important clinical problem in managing trauma patients. The resource-intensiveness associated with continuous clinical patient monitoring and rescue from frank shock makes accurate early detection and prediction with noninvasive measurement technology a desirable innovation. Despite significant efforts directed toward the development of innovative noninvasive diagnostics, the implementation and performance of the newest bedside technologies remain inadequate. This poor performance may reflect the limitations of univariate systems based on one sensor in one anatomic location. It is possible that when signals are measured with multiple modalities in multiple locations, the resulting multivariate anatomic and temporal patterns of measured signals may provide additional discriminative power over single technology univariate measurements. We evaluated the potential superiority of multivariate methods over univariate methods. Additionally, we utilized machine learning-based models to compare the performance of noninvasive-only to noninvasive-plus-invasive measurements in predicting the onset of OH. MATERIALS AND METHODS We applied machine learning methods to preexisting datasets derived using the lower body negative pressure human model of simulated hemorrhage. Employing multivariate measured physiological signals, we investigated the extent to which machine learning methods can effectively predict the onset of OH. In particular, we applied 2 ensemble learning methods, namely, random forest and gradient boosting. RESULTS Analysis of precision, recall, and area under the receiver operating characteristic curve showed a superior performance of multivariate approach to that of the univariate ones. In addition, when using both invasive and noninvasive features, random forest classifier had a recall 95% confidence interval (CI) of 0.81 to 0.86 with a precision 95% CI of 0.65 to 0.72. Interestingly, when only noninvasive features were employed, the results worsened only slightly to a recall 95% CI of 0.80 to 0.85 and a precision 95% CI of 0.61 to 0.73. CONCLUSIONS Multivariate ensemble machine learning-based approaches for the prediction of hemodynamic instability appear to hold promise for the development of effective solutions. In the lower body negative pressure multivariate hemorrhage model, predictions based only on noninvasive measurements performed comparably to those using both invasive and noninvasive measurements.
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Affiliation(s)
- Navid Rashedi
- Department of Engineering Sciences, Thayer School of Engineering, Dartmouth College, Hanover, NH 03755, USA
| | - Yifei Sun
- Department of Engineering Sciences, Thayer School of Engineering, Dartmouth College, Hanover, NH 03755, USA
| | - Vikrant Vaze
- Department of Engineering Sciences, Thayer School of Engineering, Dartmouth College, Hanover, NH 03755, USA
| | - Parikshit Shah
- Department of Electrical Engineering and Computer Science, Insight Research, Emerald Hills, CA 94065, USA
| | - Ryan Halter
- Department of Engineering Sciences, Thayer School of Engineering, Dartmouth College, Hanover, NH 03755, USA
| | - Jonathan T Elliott
- Department of Emergency Medicine, Geisel School of Medicine, Dartmouth College, Hanover, NH 03755, USA
| | - Norman A Paradis
- Department of Emergency Medicine, Geisel School of Medicine, Dartmouth College, Hanover, NH 03755, USA
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Hall EA, Whittle RS, Diaz-Artiles A. Ocular perfusion pressure is not reduced in response to lower body negative pressure. NPJ Microgravity 2024; 10:67. [PMID: 38851800 PMCID: PMC11162494 DOI: 10.1038/s41526-024-00404-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2023] [Accepted: 05/16/2024] [Indexed: 06/10/2024] Open
Abstract
Lower body negative pressure (LBNP) has been proposed as a countermeasure to mitigate the cephalad fluid shift occurring during spaceflight, which may be associated with the development of Spaceflight Associated Neuro-ocular Syndrome (SANS). This study quantifies the effect of LBNP on intraocular pressure (IOP), mean arterial pressure at eye level (MAPeye), and ocular perfusion pressure (OPP). Twenty-four subjects (12 male, 12 female) were subjected to graded LBNP in 0° supine and 15° head-down tilt (HDT) postures from 0 mmHg to -50 mmHg in 10 mmHg increments. IOP decreased significantly with LBNP pressure in 0° supine (by 0.7 ± 0.09 mmHg per 10 mmHg LBNP pressure, p < 0.001) and in 15° HDT (by 1.0 ± 0.095 mmHg per 10 mmHg of LBNP pressure, p < 0.001). MAPeye significantly decreased by 0.9 ± 0.4 mmHg per 10 mmHg of LBNP pressure in 0° supine (p = 0.016) but did not significantly change with LBNP in 15° HDT (p = 0.895). OPP did not significantly change with LBNP in 0° supine (p = 0.539) but it significantly increased in 15° HDT at 1.0 ± 0.3 mmHg per 10 mmHg of LBNP pressure (p = 0.010). Sex did not have a significant effect on OPP, MAPeye, or IOP in any condition. In 15° HDT, the reduction in IOP during increasing negative pressure, combined with the relatively constant MAPeye, led to the increase in OPP. Furthermore, results suggest that LBNP, while effective in reducing IOP, is not effective in reducing OPP across all postures investigated.
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Affiliation(s)
- Eric A Hall
- Department of Biomedical Engineering, Texas A&M University, College Station, TX, USA
- School of Engineering Medicine (EnMed), Texas A&M University, Houston, TX, USA
| | - Richard S Whittle
- Department of Mechanical and Aerospace Engineering, University of California Davis, Davis, CA, USA
- Department of Aerospace Engineering, Texas A&M University, College Station, TX, USA
| | - Ana Diaz-Artiles
- Department of Aerospace Engineering, Texas A&M University, College Station, TX, USA.
- Department of Kinesiology and Sport Management, Texas A&M University, College Station, TX, USA.
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Jarrard CP, Watso JC, Atkins WC, McKenna ZJ, Foster J, Huang M, Belval LN, Crandall CG. Sex Differences in Sympathetic Responses to Lower-Body Negative Pressure. Med Sci Sports Exerc 2024; 56:1056-1065. [PMID: 38233995 PMCID: PMC11187698 DOI: 10.1249/mss.0000000000003392] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2024]
Abstract
INTRODUCTION Trauma-induced hemorrhage is a leading cause of death in prehospital settings. Experimental data demonstrate that females have a lower tolerance to simulated hemorrhage (i.e., central hypovolemia). However, the mechanism(s) underpinning these responses are unknown. Therefore, this study aimed to compare autonomic cardiovascular responses during central hypovolemia between the sexes. We hypothesized that females would have a lower tolerance and smaller increase in muscle sympathetic nerve activity (MSNA) to simulated hemorrhage. METHODS Data from 17 females and 19 males, aged 19-45 yr, were retrospectively analyzed. Participants completed a progressive lower-body negative pressure (LBNP) protocol to presyncope to simulate hemorrhagic tolerance with continuous measures of MSNA and beat-to-beat hemodynamic variables. We compared responses at baseline, at two LBNP stages (-40 and -50 mmHg), and at immediately before presyncope. In addition, we compared responses at relative percentages (33%, 66%, and 100%) of hemorrhagic tolerance, calculated via the cumulative stress index (i.e., the sum of the product of time and pressure at each LBNP stage). RESULTS Females had lower tolerance to central hypovolemia (female: 561 ± 309 vs male: 894 ± 304 min·mmHg [time·LBNP]; P = 0.003). At LBNP -40 and -50 mmHg, females had lower diastolic blood pressures (main effect of sex: P = 0.010). For the relative LBNP analysis, females exhibited lower MSNA burst frequency (main effect of sex: P = 0.016) accompanied by a lower total vascular conductance (sex: P = 0.028; main effect of sex). CONCLUSIONS Females have a lower tolerance to central hypovolemia, which was accompanied by lower diastolic blood pressure at -40 and -50 mmHg LBNP. Notably, females had attenuated MSNA responses when assessed as relative LBNP tolerance time.
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Affiliation(s)
- Caitlin P. Jarrard
- Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas, Dallas, TX
- Applied Clinical Research Department, University of Texas Southwestern Medical Center, Dallas TX
| | - Joseph C. Watso
- Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas, Dallas, TX
- Applied Clinical Research Department, University of Texas Southwestern Medical Center, Dallas TX
- College of Health and Human Sciences, Florida State University, Tallahassee, FL
| | - Whitley C. Atkins
- Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas, Dallas, TX
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, TX
| | - Zachary J. McKenna
- Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas, Dallas, TX
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, TX
| | - Josh Foster
- Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas, Dallas, TX
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, TX
- Centre for Human and Applied Physiological Sciences, Faculty of Life Sciences and Medicine, Kings College London, London, UNITED KINGDOM
| | - Mu Huang
- Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas, Dallas, TX
- Office of Science, Medicine, and Health, American Heart Association, Dallas, TX
| | - Luke N. Belval
- Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas, Dallas, TX
| | - Craig G. Crandall
- Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas, Dallas, TX
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, TX
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Speroni G, Antedoro P, Marturet S, Martino G, Chavez C, Hidalgo C, Villacorta MV, Ahrtz I, Casadei M, Fuentes N, Kremeier P, Böhm SH, Tusman G. Finger photopletysmography detects early acute blood loss in compensated blood donors: a pilot study. Physiol Meas 2024; 45:055018. [PMID: 38749458 DOI: 10.1088/1361-6579/ad4c54] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2024] [Accepted: 05/15/2024] [Indexed: 05/29/2024]
Abstract
Objective.Diagnosis of incipient acute hypovolemia is challenging as vital signs are typically normal and patients remain asymptomatic at early stages. The early identification of this entity would affect patients' outcome if physicians were able to treat it precociously. Thus, the development of a noninvasive, continuous bedside monitoring tool to detect occult hypovolemia before patients become hemodynamically unstable is clinically relevant. We hypothesize that pulse oximeter's alternant (AC) and continuous (DC) components of the infrared light are sensitive to acute and small changes in patient's volemia. We aimed to test this hypothesis in a cohort of healthy blood donors as a model of slight hypovolemia.Approach.We planned to prospectively study blood donor volunteers removing 450 ml of blood in supine position. Noninvasive arterial blood pressure, heart rate, and finger pulse oximetry were recorded. Data was analyzed before donation, after donation and during blood auto-transfusion generated by the passive leg-rising (PLR) maneuver.Main results.Sixty-six volunteers (44% women) accomplished the protocol successfully. No clinical symptoms of hypovolemia, arterial hypotension (systolic pressure < 90 mmHg), brady-tachycardia (heart rate <60 and >100 beats-per-minute) or hypoxemia (SpO2< 90%) were observed during donation. The AC signal before donation (median 0.21 and interquartile range 0.17 a.u.) increased after donation [0.26(0.19) a.u;p< 0.001]. The DC signal before donation [94.05(3.63) a.u] increased after blood extraction [94.65(3.49) a.u;p< 0.001]. When the legs' blood was auto-transfused during the PLR, the AC [0.21(0.13) a.u.;p= 0.54] and the DC [94.25(3.94) a.u.;p= 0.19] returned to pre-donation levels.Significance.The AC and DC components of finger pulse oximetry changed during blood donation in asymptomatic volunteers. The continuous monitoring of these signals could be helpful in detecting occult acute hypovolemia. New pulse oximeters should be developed combining the AC/DC signals with a functional hemodynamic monitoring of fluid responsiveness to define which patient needs fluid administration.
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Affiliation(s)
- Gerardo Speroni
- Department of Hemotherapy, Hospital Privado de Comunidad, Mar del Plata, Buenos Aires, Argentina
| | - Patricia Antedoro
- Department of Hemotherapy, Hospital Privado de Comunidad, Mar del Plata, Buenos Aires, Argentina
| | - Silvia Marturet
- Department of Hemotherapy, Hospital Privado de Comunidad, Mar del Plata, Buenos Aires, Argentina
| | - Gabriela Martino
- Department of Hemotherapy, Hospital Privado de Comunidad, Mar del Plata, Buenos Aires, Argentina
| | - Celia Chavez
- Department of Hemotherapy, Hospital Privado de Comunidad, Mar del Plata, Buenos Aires, Argentina
| | - Cristian Hidalgo
- Department of Hemotherapy, Hospital Privado de Comunidad, Mar del Plata, Buenos Aires, Argentina
| | - María V Villacorta
- Department of Hemotherapy, Hospital Privado de Comunidad, Mar del Plata, Buenos Aires, Argentina
| | - Ivo Ahrtz
- Department of Hemotherapy, Hospital Privado de Comunidad, Mar del Plata, Buenos Aires, Argentina
| | - Manuel Casadei
- School of Engineering, Universidad Nacional de Mar del Plata, Mar del Plata, Buenos Aires, Argentina
| | - Nora Fuentes
- Department of Intensive Care Medicine, Hospital Privadode Comunidad, Mar del Plata, Buenos Aires, Argentina
| | - Peter Kremeier
- Simulation Center for Mechanical Ventilation, Karlsruhe, Germany
| | - Stephan H Böhm
- Clinic of Anesthesiology, Intensive Care Medicine and Pain Therapy, Rostock University Medical Center, Rostock, Germany
| | - Gerardo Tusman
- Department of Anesthesiology, Hospital Privado de Comunidad, Mar del Plata, Buenos Aires, Argentina
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Whiteside LA, Roy ME. Use of an Artificial Intelligence Device for Evaluating Blood Loss in Complex Major Orthopaedic Surgery Procedures. J Arthroplasty 2024:S0883-5403(24)00421-2. [PMID: 38705220 DOI: 10.1016/j.arth.2024.04.073] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/18/2023] [Revised: 04/25/2024] [Accepted: 04/25/2024] [Indexed: 05/07/2024] Open
Abstract
BACKGROUND An artificial intelligence algorithm that analyzes the pulse oximeter waveform in the fingertip can be used to determine the compensatory reserve index (CRI) in trauma patients. This measurement shows the remaining cardiovascular capacity and is known to be more specific and sensitive in detecting blood loss than are routine vital signs. We hypothesized that the CRI measurement could predict loss of reserve cardiovascular capacity in patients undergoing major orthopaedic surgery, and therefore could help in their management. METHODS A total of 304 patients undergoing lower extremity arthroplasty consented to participate in waveform monitoring. Pulse oximeter waveforms were sensed with a fingertip probe and processed with a tablet computer that remained with the patient during surgery and recovery in the hospital. The CRI, systolic blood pressure, and heart rate were evaluated throughout the postoperative period. RESULTS The CRI measurement identified a group of patients who were significantly more likely to require transfusions and emergency medical care (P = .000021). Patients who had morbid obesity were especially likely to have low CRI results and a high percentage of clinical events. A CRI of 0.40 or more was evaluated retrospectively as the criterion for withholding transfusion in 54 patients, but that group had a significantly higher incidence of transfusion later in treatment than did the cohort as a whole. The systolic blood pressure and heart rate were not useful in predicting the need for transfusion until late in treatment. CONCLUSIONS This study suggests that the CRI measurement can identify patients at risk for transfusion and the need for urgent medical care and may aid in the management of blood loss and transfusion in major orthopedic surgery.
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Affiliation(s)
- Leo A Whiteside
- Missouri Bone and Joint Center, Missouri Bone and Joint Research Foundation, St. Louis, Missouri
| | - Marie E Roy
- Missouri Bone and Joint Center, Missouri Bone and Joint Research Foundation, St. Louis, Missouri
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Anakmeteeprugsa S, Gonzalez-Fiol A, Vychodil R, Shelley K, Alian A. Assessment of changes in blood volume during lower body negative pressure-induced hypovolemia using bioelectrical impedance analysis. J Clin Monit Comput 2024; 38:293-299. [PMID: 37966562 DOI: 10.1007/s10877-023-01098-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2023] [Accepted: 10/21/2023] [Indexed: 11/16/2023]
Abstract
BACKGROUND Lower body negative Pressure (LBNP)-induced hypovolemia is simulating acute hemorrhage by sequestrating blood into lower extremities. Bioelectrical Impedance Analysis (BIA) is based on the electrical properties of biological tissues, as electrical current flows along highly conductive body tissues (such as blood). Changes in blood volume will lead to changes in bioimpedance. This study aims to study changes in upper (UL) and lower (LL) extremities bioimpedance during LBNP-induced hypovolemia. METHODS This was a prospective observational study of healthy volunteers who underwent gradual LBNP protocol which consisted of 3-minute intervals: at baseline, -15, -30, -45, -60 mmHg, then recovery phases at -30 mmHg and baseline. The UL&LL extremities bioimpedance were measured and recorded at each phase of LBNP and the percentage changes of bioimpedance from baseline were calculated and compared using student's t-test. A P-value of < 0.05 was considered significant. Correlation between relative changes in UL&LL bioimpedance and estimated blood loss (EBL) from LBNP was calculated using Pearson correlation. RESULTS 26 healthy volunteers were enrolled. As LBNP-induced hypovolemia progressed, there were a significant increase in UL bioimpedance and a significant decrease in LL bioimpedance. During recovery phases (where blood was shifted from the legs to the body), there were a significant increase in LL bioimpedance and a reduction in UL bioimpedance. There were significant correlations between estimated blood loss from LBNP model with UL (R = 0.97) and LL bioimpedance (R = - 0.97). CONCLUSION During LBNP-induced hypovolemia, there were reciprocal changes in UL&LL bioimpedance. These changes reflected hemodynamic compensatory mechanisms to hypovolemia.
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Affiliation(s)
- Suthawan Anakmeteeprugsa
- Department of Anesthesiology, Yale University School of Medicine, New Haven, CT, USA
- Department of Anesthesiology, Golden Jubilee Medical Center, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand
| | - Antonio Gonzalez-Fiol
- Department of Anesthesiology, Yale University School of Medicine, New Haven, CT, USA
| | | | - Kirk Shelley
- Department of Anesthesiology, Yale University School of Medicine, New Haven, CT, USA
| | - Aymen Alian
- Department of Anesthesiology, Yale University School of Medicine, New Haven, CT, USA.
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Tourula E, Lenzini M, Rhodes A, Hetz SE, Pearson J. Facial fanning reduces heart rate but not tolerance to a simulated hemorrhagic challenge following exercise heat stress in young healthy humans. Am J Physiol Regul Integr Comp Physiol 2024; 326:R210-R219. [PMID: 38105763 DOI: 10.1152/ajpregu.00180.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2023] [Revised: 11/02/2023] [Accepted: 12/12/2023] [Indexed: 12/19/2023]
Abstract
We investigated whether reducing face skin temperature alters arterial blood pressure control and lower body negative pressure (LBNP) tolerance after exercise heat stress. Eight subjects (1 female; age, 27 ± 9 yr) exercised at ∼63% V̇o2max until core temperature had increased ∼1.5°C before undergoing LBNP to presyncope either with fanning to return face skin temperature to baseline (Δ-5°C, Fan trial) or without (No Fan trial). LBNP tolerance was quantified as cumulative stress index (CSI; mmHg·min). Before LBNP, whole body and face skin temperatures were elevated from baseline in both trials (38.0 ± 0.5°C and 36.3 ± 0.5°C, respectively, both P < 0.001). During LBNP, face skin temperature decreased in the Fan trial (30.9 ± 1.0°C) but was unchanged in the No Fan trial (36.1 ± 0.6°C, between trials P < 0.001). Mean arterial pressure was not different between trials (P = 0.237) and was similarly reduced at presyncope in both trials (from 82 ± 7 to 67 ± 8 mmHg, P < 0.001). During LBNP, heart rate was attenuated in the Fan trial at Mid LBNP (146 ± 16 vs. 158 ± 12 beats/min, P = 0.036) and at peak heart rate (158 ± 15 vs. 170 ± 15 beats/min; P < 0.001). LBNP tolerance was not different between trials (321 ± 248 vs. 328 ± 115 mmHg·min, P = 0.851). In exercise heat-stressed individuals, lowering face skin temperature to normothermic values suppressed heart rate thereby altering cardiovascular control during a simulated hemorrhagic challenge without reducing tolerance.
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Affiliation(s)
- Erica Tourula
- William J. Hybl Sports Medicine and Performance Center, Department of Human Physiology and Nutrition, University of Colorado Colorado Springs, Colorado, United States
- Department of Kinesiology, H. H. Morris Human Performance Laboratories, School of Public Health, Indiana University, Bloomington, Indiana, United States
| | - Miramani Lenzini
- William J. Hybl Sports Medicine and Performance Center, Department of Human Physiology and Nutrition, University of Colorado Colorado Springs, Colorado, United States
| | - Addison Rhodes
- William J. Hybl Sports Medicine and Performance Center, Department of Human Physiology and Nutrition, University of Colorado Colorado Springs, Colorado, United States
| | - Sarah E Hetz
- William J. Hybl Sports Medicine and Performance Center, Department of Human Physiology and Nutrition, University of Colorado Colorado Springs, Colorado, United States
| | - James Pearson
- William J. Hybl Sports Medicine and Performance Center, Department of Human Physiology and Nutrition, University of Colorado Colorado Springs, Colorado, United States
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Gonzalez JE, Cooke WH. Acute fasting reduces tolerance to progressive central hypovolemia in humans. J Appl Physiol (1985) 2024; 136:362-371. [PMID: 38126086 PMCID: PMC11219002 DOI: 10.1152/japplphysiol.00622.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2023] [Revised: 12/14/2023] [Accepted: 12/18/2023] [Indexed: 12/23/2023] Open
Abstract
Potential health benefits of an acute fast include reductions in blood pressure and increases in vagal cardiac control. These purported health benefits could put fasted humans at risk for cardiovascular collapse when exposed to central hypovolemia. The purpose of this study was to test the hypothesis that an acute 24-h fast (vs. 3-h postprandial) would reduce tolerance to central hypovolemia induced via lower body negative pressure (LBNP). We measured blood ketones (β-OHB) to confirm a successful fast (n = 18). We recorded the electrocardiogram (ECG), beat-to-beat arterial pressure, muscle sympathetic nerve activity (MSNA; n = 7), middle cerebral artery blood velocity (MCAv), and forearm blood flow. Following a 5-min baseline, LBNP was increased by 15 mmHg until -60 mmHg and then increased by 10 mmHg in a stepwise manner until onset of presyncope. Each LBNP stage lasted 5-min. Data are expressed as means ± SE β-OHB increased (β-OHB; 0.12 ± 0.04 fed vs. 0.47 ± 0.11, P < 0.01 mmol/L fast). Tolerance to central hypovolemia was decreased by ∼10% in the fasted condition measured via total duration of negative pressure (1,370 [Formula: see text] 89 fed vs. 1,229 ± 94 s fast, P = 0.04), and was negatively associated with fasting blood ketones (R = -0.542, P = 0.02). During LBNP, heart rate and MSNA increased similarly, but in the fasted condition forearm vascular resistance was significantly reduced. Our results suggest that acute fasting reduces tolerance to central hypovolemia by blunting increases in peripheral resistance, indicating that prolonged fasting may hinder an individual's ability to compensate to a loss of blood volume.NEW & NOTEWORTHY An acute 24 h fasting reduces tolerance to central hypovolemia, and tolerance is negatively associated with blood ketone levels. Compared with a fed condition (3-h postprandial), fasted participants exhibited blunted peripheral vasoconstriction and greater reductions in stroke volume during stepwise lower body negative pressure. These findings suggest that a prolonged fast may lead to quicker decompensation during central hypovolemia.
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Affiliation(s)
- Joshua E Gonzalez
- Oregon Institute of Occupational Health Sciences, Oregon Health & Science University, Portland, Oregon, United States
- Department of Kinesiology & Integrative Physiology, Michigan Technological University, Houghton, Michigan, United States
| | - William H Cooke
- Department of Kinesiology & Integrative Physiology, Michigan Technological University, Houghton, Michigan, United States
- Health Research Institute, Michigan Technological University, Houghton, Michigan, United States
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Mastrandrea CJ, Greaves DK, Shoemaker JK, Blaber AP, Arbeille P, Hughson RL. Lower body negative pressure identifies altered central vein characteristics without accompanying changes to baroreflexes in astronauts within hours of landing. Sci Rep 2024; 14:1215. [PMID: 38216637 PMCID: PMC10786840 DOI: 10.1038/s41598-024-51643-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2023] [Accepted: 01/08/2024] [Indexed: 01/14/2024] Open
Abstract
Cardiovascular deconditioning and altered baroreflexes predispose returning astronauts to Orthostatic Intolerance. We assessed 7 astronauts (1 female) before and following long-duration spaceflight (146 ± 43 days) with minimal upright posture prior to testing. We applied lower body negative pressure (LBNP) of up to - 30 mmHg to supine astronauts instrumented for continual synchronous measurements of cardiovascular variables, and intermittent imaging the Portal Vein (PV) and Inferior Vena Cava (IVC). During supine rest without LBNP, postflight elevations to total peripheral resistance (TPR; 15.8 ± 4.6 vs. 20.8 ± 7.1 mmHg min/l, p < 0.05) and reductions in stroke volume (SV; 104.4 ± 16.7 vs. 87.4 ± 11.5 ml, p < 0.05) were unaccompanied by changes to heart rate (HR) or estimated central venous pressure (CVP). Small increases to systolic blood pressure (SBP) and diastolic blood pressure (DBP) were not statistically significant. Autoregressive moving average modelling (ARMA) during LBNP did not identify differences to either arterial (DBP → TPR and SBP → HR) or cardiopulmonary (CVP → TPR) baroreflexes consistent with intact cardiovascular control. On the other hand, IVC and PV diameter-CVP relationships during LBNP revealed smaller diameter for a given CVP postflight consistent with altered postflight venous wall dynamics.
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Affiliation(s)
- C J Mastrandrea
- Schlegel-UW Research Institute for Aging, Waterloo, ON, Canada.
- University of Waterloo, Waterloo, ON, Canada.
| | - D K Greaves
- Schlegel-UW Research Institute for Aging, Waterloo, ON, Canada
| | - J K Shoemaker
- School of Kinesiology and Department of Physiology and Pharmacology, University of Western Ontario, London, ON, Canada
| | - A P Blaber
- Department of Biomedical Physiology and Kinesiology, Simon Fraser University, Burnaby, BC, Canada
| | - P Arbeille
- Unite Médecine Physiologie Spatiale, CERCOM, Faculté de Médecine-Université de Tours, Tours, France
| | - R L Hughson
- Schlegel-UW Research Institute for Aging, Waterloo, ON, Canada
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Iwakuma Y, Clonch DA, Liu J, Lam CM, Holwerda S. Cardiopulmonary baroreceptors modify pain intensity in patients with chronic back pain. RESEARCH SQUARE 2023:rs.3.rs-3154622. [PMID: 37502833 PMCID: PMC10371169 DOI: 10.21203/rs.3.rs-3154622/v1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/29/2023]
Abstract
Objective Baroreceptors play a significant role in nociceptive pain. However, the extent to which baroreceptors modulate nociception in patients with chronic pain is unclear. We tested the hypothesis that cardiopulmonary baroreceptor unloading via LBNP would significantly increase pressure pain threshold and habituation to heat pain among patients with chronic back pain. Methods Mechanical pressure pain threshold at the upper trapezius (hand-held algometer) and habituation to heat pain at the forearm were performed during sitting and supine position, and during baroreceptor unloading via lower body negative pressure (LBNP) of -10 mmHg in 12 patients with chronic back pain (54 ± 11 years of age). To determine whether pain reduction is normal during LBNP, studies were repeated in 7 young, healthy participants (23 ± 7). Results Mechanical pressure pain threshold (P < 0.01) and habituation to heat pain (P = 0.04) were significantly reduced during supine compared with sitting. Conversely, baroreceptor unloading via LBNP significantly increased pressure pain threshold (P = 0.03) and heat pain habituation (P < 0.01) compared with supine. In young healthy controls, pressure pain threshold was similarly affected when comparing sitting and supine (P = 0.01) and during LBNP (P < 0.01), whereas habituation to heat pain was unaltered when comparing sitting and supine (P = 0.93) and during LBNP (P = 0.90). Total peripheral resistance was increased during LBNP (P = 0.01) but not among young, healthy controls (P = 0.71). Conclusions The findings demonstrate cardiopulmonary baroreceptor modulation of nociceptive pain in patients with chronic pain. Interestingly, habituation to heat pain appears more readily modified by cardiopulmonary baroreceptors in patients with chronic back pain compared with young, healthy individuals.
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Jain M, Chitturi V, Chandran DS, Jaryal AK, Deepak KK. Vasoconstriction during non-hypotensive hypovolemia is not associated with activation of baroreflex: A causality-based approach. Pflugers Arch 2023; 475:747-755. [PMID: 37076560 DOI: 10.1007/s00424-023-02811-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2022] [Revised: 02/23/2023] [Accepted: 04/02/2023] [Indexed: 04/21/2023]
Abstract
Non-hypotensive hypovolemia simulated with oscillatory lower body negative pressure in the range of -10 to -20 mmHg is associated with vasoconstriction {increase in total peripheral vascular resistance (TPVR)}. Due to the mechanical stiffening of vessels, there is a disjuncture of mechano-neural coupling at the level of arterial baroreceptors which has not been investigated. The study was designed to quantify both the cardiac and vascular arms of the baroreflex using an approach based on Wiener-Granger causality (WGC) - partial directed coherence (PDC). Thirty-three healthy human volunteers were recruited and continuous heart rate and blood pressure {systolic (SBP), diastolic (DBP), and mean (MBP)} were recorded. The measurements were taken in resting state, at -10 mmHg (level 1) and -15 mmHg (level 2). Spectral causality - PDC was estimated from the MVAR model in the low-frequency band using the GMAC MatLab toolbox. PDC from SBP and MBP to RR interval and TPVR was calculated. The PDC from MBP to RR interval showed no significant change at -10 mmHg and -15 mmHg. No significant change in PDC from MBP to TPVR at -10 mmHg and -15 mmHg was observed. Similar results were obtained for PDC estimation using SBP as input. However, a significant increase in TPVR from baseline at both levels of oscillatory LBNP (p-value <0.001). No statistically significant change in PDC from blood pressure to RR interval and blood pressure to TPVR implies that vasoconstriction is not associated with activation of the arterial baroreflex in ≤-15 mmHg LBNP. Thereby, indicating the role of cardiopulmonary reflexes during the low level of LBNP simulated non-hypotensive hypovolemia.
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Affiliation(s)
- Mansi Jain
- Department of Physiology, All India Institute of Medical Sciences, New Delhi, 110029, India
| | - Vinay Chitturi
- Department of Physiology, All India Institute of Medical Sciences, Rajkot, India
| | - Dinu S Chandran
- Department of Physiology, All India Institute of Medical Sciences, New Delhi, 110029, India
| | - Ashok Kumar Jaryal
- Department of Physiology, All India Institute of Medical Sciences, New Delhi, 110029, India
| | - K K Deepak
- Department of Physiology, All India Institute of Medical Sciences, New Delhi, 110029, India.
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12
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Cerebral blood flow response to cardiorespiratory oscillations in healthy humans. Auton Neurosci 2023; 245:103069. [PMID: 36584666 DOI: 10.1016/j.autneu.2022.103069] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2021] [Revised: 12/12/2022] [Accepted: 12/19/2022] [Indexed: 12/24/2022]
Abstract
Dynamic cerebral autoregulation (CA) characterizes the cerebral blood flow (CBF) response to abrupt changes in arterial blood pressure (ABP). CA operates at frequencies below 0.15 Hz. ABP regulation and probably CA are modified by autonomic nervous activity. We investigated the CBF response and CA dynamics to mild increase in sympathetic activity. Twelve healthy volunteers underwent oscillatory lower body negative pressure (oLBNP), which induced respiratory-related ABP oscillations at an average of 0.22 Hz. We recorded blood velocity in the internal carotid artery (ICA) by Doppler ultrasound and ABP. We quantified variability and peak wavelet power of ABP and ICA blood velocity by wavelet analysis at low frequency (LF, 0.05-0.15 Hz) and Mayer waves (0.08-0.12 Hz), respectively. CA was quantified by calculation of the wavelet synchronization gamma index for the pair ABP-ICA blood velocity in the LF and Mayer wave band. oLBNP increased ABP peak wavelet power at the Mayer wave frequency. At the Mayer wave, ABP peak wavelet power increased by >70 % from rest to oLBNP (p < 0.05), while ICA blood flow velocity peak wavelet power was unchanged, and gamma index increased (from 0.49 to 0.69, p < 0.05). At LF, variability in both ABP and ICA blood velocity and gamma index were unchanged from rest to oLBNP. Despite an increased gamma index at Mayer wave, ICA blood flow variability was unchanged during increased ABP variability. The increased synchronization during oLBNP did not cause less stable CBF or less active CA. Sympathetic activation seems to improve the mechanisms of CA.
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Watso JC, Huang M, Hendrix JM, Belval LN, Moralez G, Cramer MN, Foster J, Hinojosa-Laborde C, Crandall CG. Comparing the Effects of Low-Dose Ketamine, Fentanyl, and Morphine on Hemorrhagic Tolerance and Analgesia in Humans. PREHOSP EMERG CARE 2023; 27:600-612. [PMID: 36689353 PMCID: PMC10329983 DOI: 10.1080/10903127.2023.2172493] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2022] [Revised: 01/09/2023] [Accepted: 01/19/2023] [Indexed: 01/24/2023]
Abstract
Hemorrhage is a leading cause of preventable battlefield and civilian trauma deaths. Ketamine, fentanyl, and morphine are recommended analgesics for use in the prehospital (i.e., field) setting to reduce pain. However, it is unknown whether any of these analgesics reduce hemorrhagic tolerance in humans. We tested the hypothesis that fentanyl (75 µg) and morphine (5 mg), but not ketamine (20 mg), would reduce tolerance to simulated hemorrhage in conscious humans. Each of the three analgesics was evaluated independently among different cohorts of healthy adults in a randomized, crossover (within drug/placebo comparison), placebo-controlled fashion using doses derived from the Tactical Combat Casualty Care Guidelines for Medical Personnel. One minute after an intravenous infusion of the analgesic or placebo (saline), we employed a pre-syncopal limited progressive lower-body negative pressure (LBNP) protocol to determine hemorrhagic tolerance. Hemorrhagic tolerance was quantified as a cumulative stress index (CSI), which is the sum of products of the LBNP and the duration (e.g., [40 mmHg x 3 min] + [50 mmHg x 3 min] …). Compared with ketamine (p = 0.002 post hoc result) and fentanyl (p = 0.02 post hoc result), morphine reduced the CSI (ketamine (n = 30): 99 [73-139], fentanyl (n = 28): 95 [68-130], morphine (n = 30): 62 [35-85]; values expressed as a % of the respective placebo trial's CSI; median [IQR]; Kruskal-Wallis test p = 0.002). Morphine-induced reductions in tolerance to central hypovolemia were not well explained by a prediction model including biological sex, body mass, and age (R2=0.05, p = 0.74). These experimental data demonstrate that morphine reduces tolerance to simulated hemorrhage while fentanyl and ketamine do not affect tolerance. Thus, these laboratory-based data, captured via simulated hemorrhage, suggest that morphine should not be used for a hemorrhaging individual in the prehospital setting.
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Affiliation(s)
- Joseph Charles Watso
- Department of Nutrition & Integrative Physiology, Florida State University, Tallahassee, Florida, USA
- Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas, Dallas, Texas, USA
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas, USA
- Department of Applied Clinical Research, University of Texas Southwestern Medical Center, Dallas, Texas, USA
| | - Mu Huang
- Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas, Dallas, Texas, USA
- Department of Applied Clinical Research, University of Texas Southwestern Medical Center, Dallas, Texas, USA
- Office of Science, Medicine, and Health, American Heart Association, Dallas, Texas, USA
| | - Joseph Maxwell Hendrix
- Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas, Dallas, Texas, USA
- Department of Anesthesiology, University of Texas Southwestern Medical Center, Dallas, Texas, USA
| | - Luke Norman Belval
- Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas, Dallas, Texas, USA
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas, USA
| | - Gilbert Moralez
- Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas, Dallas, Texas, USA
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas, USA
- Department of Applied Clinical Research, University of Texas Southwestern Medical Center, Dallas, Texas, USA
| | - Matthew Nathaniel Cramer
- Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas, Dallas, Texas, USA
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas, USA
| | - Josh Foster
- Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas, Dallas, Texas, USA
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas, USA
| | | | - Craig Gerald Crandall
- Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas, Dallas, Texas, USA
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas, USA
- Department of Applied Clinical Research, University of Texas Southwestern Medical Center, Dallas, Texas, USA
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14
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Alian A, Shelley K, Wu HT. Amplitude and phase measurements from harmonic analysis may lead to new physiologic insights: lower body negative pressure photoplethysmographic waveforms as an example. J Clin Monit Comput 2023; 37:127-137. [PMID: 35896756 DOI: 10.1007/s10877-022-00866-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2022] [Accepted: 04/13/2022] [Indexed: 01/24/2023]
Abstract
The photoplethysmographic (PPG) waveform contains hemodynamic information in its oscillations. We provide a new method for quantitative study of the waveform morphology and its relationship to the hemodynamics. A data adaptive modeling of the waveform shape is used to describe the PPG waveforms recorded from ear and finger. Several indices, based on the phase and amplitude information of different harmonics, are proposed to describe the PPG morphology. The proposed approach is illustrated by analyzing PPG waveforms recorded during a lower body negative pressure (LBNP) experiment. Different phase and amplitude dynamics are observed during the LBNP experiment. Specifically, we observe that the phase difference between the high order harmonics and fundamental components change more significantly when the PPG signal is recorded from the ear than the finger at the beginning of the study. In contrast, the finger PPG amplitude changes more when compared to the ear PPG during the recovery period. A more complete harmonic analysis of the PPG appears to provide new hemodynamic information when used during a LBNP experiment. We encourage other investigators who possess modulated clinical waveform data (e.g. PPG, arterial pressure, respiratory, and autonomic) to re-examine their data, using phase information and higher harmonics as a potential source of new insights into underlying physiologic mechanisms.
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Affiliation(s)
- Aymen Alian
- Department of Anesthesiology, Yale University, New Haven, CT, 06510, USA
| | - Kirk Shelley
- Department of Anesthesiology, Yale University, New Haven, CT, 06510, USA
| | - Hau-Tieng Wu
- Department of Mathematics and Department of Statistical Science, Duke University, 140 Science Drive, Durham, NC, 27705, USA.
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15
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Rosenberg AJ, Kay VL, Anderson GK, Luu ML, Barnes HJ, Sprick JD, Alvarado HB, Rickards CA. The reciprocal relationship between cardiac baroreceptor sensitivity and cerebral autoregulation during simulated hemorrhage in humans. Auton Neurosci 2022; 241:103007. [PMID: 35716525 PMCID: PMC10424721 DOI: 10.1016/j.autneu.2022.103007] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2021] [Revised: 04/07/2022] [Accepted: 06/09/2022] [Indexed: 11/16/2022]
Abstract
A reciprocal relationship between the baroreflex and cerebral autoregulation (CA) has been demonstrated at rest and in response to acute hypotension. We hypothesized that the reciprocal relationship between cardiac baroreflex sensitivity (BRS) and CA would be maintained during sustained central hypovolemia induced by lower body negative pressure (LBNP), and that the strength of this relationship would be greater in subjects with higher tolerance to this stress. Healthy young adults (n = 51; 23F/28M) completed a LBNP protocol to presyncope. Subjects were classified as high tolerant (HT; completion of -60 mmHg LBNP stage, ≥20-min) or low tolerant (LT; did not complete -60 mmHg LBNP stage, <20-min). R-R intervals (RRI), systolic arterial pressure (SAP), mean arterial pressure (MAP), and middle cerebral artery velocity (MCAv) were measured continuously. Cardiac BRS was calculated in the time domain (ΔHR/ΔSAP) and frequency domain (RRI-SAP low frequency (LF) transfer function gain), and CA was calculated in the time domain (ΔMCAv/ΔMAP) and frequency domain (MAP-mean MCAv LF transfer function gain). There was a moderate relationship between cardiac BRS and CA for the group of 51 subjects in both the time (R = -0.54, P < 0.0001) and frequency (R = 0.61, P < 0.001) domains; there was a stronger relationship in the HT group (R = 0.73) compared to the LT group (R = 0.31) in the frequency domain (P = 0.08), but no difference between groups in the time domain (HT: R = -0.73 vs. LT: R = -0.63; P = 0.27). These findings suggest that an interaction between BRS and CA may be an important compensatory mechanism that contributes to tolerance to simulated hemorrhage in young healthy adults.
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Affiliation(s)
- Alexander J Rosenberg
- Cerebral and Cardiovascular Physiology Laboratory, Department of Physiology and Anatomy, University of North Texas Health Science Center, Fort Worth, TX, USA; Integrative Physiology Laboratory, Department of Kinesiology and Nutrition, University of Illinois at Chicago, IL, USA; Physiology Department, Midwestern University, IL, USA
| | - Victoria L Kay
- Cerebral and Cardiovascular Physiology Laboratory, Department of Physiology and Anatomy, University of North Texas Health Science Center, Fort Worth, TX, USA
| | - Garen K Anderson
- Cerebral and Cardiovascular Physiology Laboratory, Department of Physiology and Anatomy, University of North Texas Health Science Center, Fort Worth, TX, USA
| | - My-Loan Luu
- Cerebral and Cardiovascular Physiology Laboratory, Department of Physiology and Anatomy, University of North Texas Health Science Center, Fort Worth, TX, USA
| | - Haley J Barnes
- Cerebral and Cardiovascular Physiology Laboratory, Department of Physiology and Anatomy, University of North Texas Health Science Center, Fort Worth, TX, USA
| | - Justin D Sprick
- Cerebral and Cardiovascular Physiology Laboratory, Department of Physiology and Anatomy, University of North Texas Health Science Center, Fort Worth, TX, USA; Division of Renal Medicine, Department of Medicine, Emory University School of Medicine, Atlanta, GA, USA
| | - Hannah B Alvarado
- Cerebral and Cardiovascular Physiology Laboratory, Department of Physiology and Anatomy, University of North Texas Health Science Center, Fort Worth, TX, USA; Department of Family Medicine, Mayo Clinic, Jacksonville, FL, USA
| | - Caroline A Rickards
- Cerebral and Cardiovascular Physiology Laboratory, Department of Physiology and Anatomy, University of North Texas Health Science Center, Fort Worth, TX, USA.
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16
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Detection of a Stroke Volume Decrease by Machine-Learning Algorithms Based on Thoracic Bioimpedance in Experimental Hypovolaemia. SENSORS 2022; 22:s22145066. [PMID: 35890746 PMCID: PMC9316072 DOI: 10.3390/s22145066] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/17/2022] [Revised: 06/23/2022] [Accepted: 07/01/2022] [Indexed: 02/04/2023]
Abstract
Compensated shock and hypovolaemia are frequent conditions that remain clinically undetected and can quickly cause deterioration of perioperative and critically ill patients. Automated, accurate and non-invasive detection methods are needed to avoid such critical situations. In this experimental study, we aimed to create a prediction model for stroke volume index (SVI) decrease based on electrical cardiometry (EC) measurements. Transthoracic echo served as reference for SVI assessment (SVI-TTE). In 30 healthy male volunteers, central hypovolaemia was simulated using a lower body negative pressure (LBNP) chamber. A machine-learning algorithm based on variables of EC was designed. During LBNP, SVI-TTE declined consecutively, whereas the vital signs (arterial pressures and heart rate) remained within normal ranges. Compared to heart rate (AUC: 0.83 (95% CI: 0.73–0.87)) and systolic arterial pressure (AUC: 0.82 (95% CI: 0.74–0.85)), a model integrating EC variables (AUC: 0.91 (0.83–0.94)) showed a superior ability to predict a decrease in SVI-TTE ≥ 20% (p = 0.013 compared to heart rate, and p = 0.002 compared to systolic blood pressure). Simulated central hypovolaemia was related to a substantial decline in SVI-TTE but only minor changes in vital signs. A model of EC variables based on machine-learning algorithms showed high predictive power to detect a relevant decrease in SVI and may provide an automated, non-invasive method to indicate hypovolaemia and compensated shock.
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17
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Sejersen C, Christiansen T, Secher NH. To identify normovolemia in humans: The stroke volume response to passive leg raising vs. head-down tilt. Physiol Rep 2022; 10:e15216. [PMID: 35854636 PMCID: PMC9296869 DOI: 10.14814/phy2.15216] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2022] [Revised: 02/10/2022] [Accepted: 02/14/2022] [Indexed: 06/15/2023] Open
Abstract
Volume responsiveness can be evaluated by tilting maneuvers such as head-down tilt (HDT) and passive leg raising (PLR), but the two procedures use different references (HDT the supine position; PLR the semi-recumbent position). We tested whether the two procedures identify "normovolemia" by evaluating the stroke volume (SV) and cardiac output (CO) responses and whether the peripheral perfusion index (PPI) derived from pulse oximetry provides similar information. In randomized order, 10 healthy men were exposed to both HDT and PLR, and evaluations were made also when the subjects fasted. Central cardiovascular variables were derived by pulse contour analysis and changes in central blood volume assessed by thoracic electrical admittance (TEA). During HDT, SV remained stable (fasted 110 ± 16 vs. 109 ± 16 ml; control 113 ± 16 vs. 111 ± 16 ml, p > 0.05) with no change in CO, TEA, PPI, or SV variation (SVV). In contrast during PLR, SV increased (fasted 108 ± 17 vs. 117 ± 17 ml; control 108 ± 18 vs. 117 ± 18 ml, p < 0.05) followed by an increase in TEA (p < 0.05) and CO increased when subjects fasted (6.7 ± 1.5 vs. 7.1 ± 1.5, p = 0.007) with no change in PPI or SVV. In conclusion, SV has a maximal value for rest in supine men, while PLR restores SV as CBV is reduced in a semi-recumbent position and the procedure thereby makes healthy volunteers seem fluid responsive.
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Affiliation(s)
- Casper Sejersen
- Department of AnaesthesiaInstitute for Clinical MedicineUniversity of CopenhagenCopenhagenDenmark
| | - Till Christiansen
- Department of AnaesthesiaInstitute for Clinical MedicineUniversity of CopenhagenCopenhagenDenmark
| | - Niels H. Secher
- Department of AnaesthesiaInstitute for Clinical MedicineUniversity of CopenhagenCopenhagenDenmark
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18
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Watso JC, Belval LN, Cimino FA, Orth BD, Hendrix JM, Huang M, Johnson E, Foster J, Hinojosa-Laborde C, Crandall CG. Low-dose morphine reduces tolerance to central hypovolemia in healthy adults without affecting muscle sympathetic outflow. Am J Physiol Heart Circ Physiol 2022; 323:H89-H99. [PMID: 35452317 PMCID: PMC9190738 DOI: 10.1152/ajpheart.00091.2022] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/22/2022] [Revised: 04/19/2022] [Accepted: 04/20/2022] [Indexed: 11/22/2022]
Abstract
Hemorrhage is a leading cause of preventable battlefield and civilian trauma deaths. Low-dose (i.e., an analgesic dose) morphine is recommended for use in the prehospital (i.e., field) setting. Morphine administration reduces hemorrhagic tolerance in rodents. However, it is unknown whether morphine impairs autonomic cardiovascular regulation and consequently reduces hemorrhagic tolerance in humans. Thus, the purpose of this study was to test the hypothesis that low-dose morphine reduces hemorrhagic tolerance in conscious humans. Thirty adults (15 women/15 men; 29 ± 6 yr; 26 ± 4 kg·m-2, means ± SD) completed this randomized, crossover, double-blinded, placebo-controlled trial. One minute after intravenous administration of morphine (5 mg) or placebo (saline), we used a presyncopal limited progressive lower-body negative pressure (LBNP) protocol to determine hemorrhagic tolerance. Hemorrhagic tolerance was quantified as a cumulative stress index (mmHg·min), which was compared between trials using a Wilcoxon matched-pairs signed-rank test. We also compared muscle sympathetic nerve activity (MSNA; microneurography) and beat-to-beat blood pressure (photoplethysmography) during the LBNP test using mixed-effects analyses [time (LBNP stage) × trial]. Median LBNP tolerance was lower during morphine trials (placebo: 692 [473-997] vs. morphine: 385 [251-728] mmHg·min, P < 0.001, CI: -394 to -128). Systolic blood pressure was 8 mmHg lower during moderate central hypovolemia during morphine trials (post hoc P = 0.02; time: P < 0.001, trial: P = 0.13, interaction: P = 0.006). MSNA burst frequency responses were not different between trials (time: P < 0.001, trial: P = 0.80, interaction: P = 0.51). These data demonstrate that low-dose morphine reduces hemorrhagic tolerance in conscious humans. Thus, morphine is not an ideal analgesic for a hemorrhaging individual in the prehospital setting.NEW & NOTEWORTHY In this randomized, crossover, placebo-controlled trial, we found that tolerance to simulated hemorrhage was lower after low-dose morphine administration. Such reductions in hemorrhagic tolerance were observed without differences in MSNA burst frequency responses between morphine and placebo trials. These data, the first to be obtained in conscious humans, demonstrate that low-dose morphine reduces hemorrhagic tolerance. Thus, morphine is not an ideal analgesic for a hemorrhaging individual in the prehospital setting.
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Affiliation(s)
- Joseph C Watso
- Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas, Dallas, Texas
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas
- Department of Applied Clinical Research, University of Texas Southwestern Medical Center, Dallas, Texas
| | - Luke N Belval
- Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas, Dallas, Texas
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas
| | - Frank A Cimino
- Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas, Dallas, Texas
| | - Bonnie D Orth
- Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas, Dallas, Texas
| | - Joseph M Hendrix
- Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas, Dallas, Texas
- Department of Anesthesiology, University of Texas Southwestern Medical Center, Dallas, Texas
| | - Mu Huang
- Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas, Dallas, Texas
- Department of Applied Clinical Research, University of Texas Southwestern Medical Center, Dallas, Texas
| | - Elias Johnson
- Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas, Dallas, Texas
| | - Josh Foster
- Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas, Dallas, Texas
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas
| | - Carmen Hinojosa-Laborde
- United States Army Institute of Surgical Research, Joint Base San Antonio Fort Sam Houston, Houston, Texas
| | - Craig G Crandall
- Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas, Dallas, Texas
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas
- Department of Applied Clinical Research, University of Texas Southwestern Medical Center, Dallas, Texas
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19
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Yadav K, Singh A, Jaryal AK, Coshic P, Deepak KK. Temporal Analysis of Sequential Changes in Heart Rate Variability During Non-hypotensive Hypovolemia. High Blood Press Cardiovasc Prev 2022; 29:385-391. [PMID: 35670948 DOI: 10.1007/s40292-022-00525-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2022] [Accepted: 05/10/2022] [Indexed: 11/25/2022] Open
Abstract
INTRODUCTION Haemorrhage is associated with changes in the cardiac autonomic drive which begins during early stages of mild haemorrhage. The knowledge of chronology of the autonomic changes at smaller timescale during the period of haemorrhage can help identify the primary autonomic parameter which signals the institution of cardiovascular reflex mechanisms. AIM To evaluate the heart rate variability in 2-min sequential segments with one minute overlap during and after the period of mild haemorrhage (450 ml) using blood donation as a model of acute blood loss. METHODS 47 male blood donors who had volunteered for blood donation were recruited for the study. Continuous lead II ECG was recorded before the start of the blood donation (5 min), during the period of the blood donation (~ 5-7 min) and after blood donation (5 min). The parasympathetic and sympathetic drive to heart was estimated by measures of heart rate variability in time and frequency domain. RESULTS A significant decrease in the parameters assessing parasympathetic drive i.e., normalised High frequency (HFn) and NN50 (Number of pairs of adjacent NN intervals differing by more than 50 ms) and pNN50 (NN50 divided by the total number of all NN Intervals) was observed during blood donation at 3-5 min, as compared to baseline. An increase in parameters associated with sympathetic drive i.e., normalised low frequency (LFn) was observed only in the post donation period at 2-3 min. A significant rise in LF/HF ratio which is a marker of sympatho vagal balance was observed at 4-5 min during blood donation when compared to baseline. CONCLUSION The initial cardiac autonomic change during mild haemorrhage is withdrawal of parasympathetic drive, followed by an increase in sympathetic tone which occurs much later.
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Affiliation(s)
- Kavita Yadav
- Department of Physiology, Pt. BD Sharma Post graduate Institute of Medical Sciences, 1st Floor, Rohtak, India
| | - Akanksha Singh
- Department of Physiology, All India Institute of Medical Sciences, Room no. 2017, Teaching Block, Second Floor, Ansari Nagar, New Delhi, India
| | - Ashok Kumar Jaryal
- Department of Physiology, All India Institute of Medical Sciences, Room no. 2009, Teaching Block, Second Floor, Ansari Nagar, New Delhi, India.
| | - Poonam Coshic
- Department of Transfusion Medicine (Blood Bank), All India Institute of Medical Sciences, Ground Floor, Main Blood Bank Unit 1, Ansari Nagar, New Delhi, India
| | - K K Deepak
- Department of Physiology, All India Institute of Medical Sciences, Room no. 2009, Teaching Block, Second Floor, Ansari Nagar, New Delhi, India
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20
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Djupedal H, Nøstdahl T, Hisdal J, Landsverk SA, Høiseth LØ. Effects of experimental hypovolemia and pain on pre-ejection period and pulse transit time in healthy volunteers. Physiol Rep 2022; 10:e15355. [PMID: 35748055 PMCID: PMC9226798 DOI: 10.14814/phy2.15355] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2022] [Revised: 05/20/2022] [Accepted: 05/20/2022] [Indexed: 11/25/2022] Open
Abstract
Trauma patients may suffer significant blood loss, and noninvasive methods to diagnose hypovolemia in these patients are needed. Physiologic effects of hypovolemia, aiming to maintain blood pressure, are largely mediated by increased sympathetic nervous activity. Trauma patients may however experience pain, which also increases sympathetic nervous activity, potentially confounding measures of hypovolemia. Elucidating the common and separate effects of the two stimuli on diagnostic methods is therefore important. Lower body negative pressure (LBNP) and cold pressor test (CPT) are experimental models of central hypovolemia and pain, respectively. In the present analysis, we explored the effects of LBNP and CPT on pre‐ejection period and pulse transit time, aiming to further elucidate the potential use of these variables in diagnosing hypovolemia in trauma patients. We exposed healthy volunteers to four experimental sequences with hypovolemia (LBNP 60 mmHg) or normovolemia (LBNP 0 mmHg) and pain (CPT) or no pain (sham) in a 2 × 2 fashion. We calculated pre‐ejection period and pulse transit time from ECG and ascending aortic blood velocity (suprasternal Doppler) and continuous noninvasive arterial pressure waveform (volume‐clamp method). Fourteen subjects were available for the current analyses. This experimental study found that pre‐ejection period increased with hypovolemia and remained unaltered with pain. Pulse transit time was reduced by pain and increased with hypovolemia. Thus, the direction of change in pulse transit time has the potential to distinguish hypovolemia and pain.
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Affiliation(s)
- Håvard Djupedal
- Department of Anesthesiology, Telemark Hospital, Skien, Norway
| | | | - Jonny Hisdal
- University of Oslo, Oslo, Norway.,Department of Vascular Surgery, Division of Cardiovascular and Pulmonary Diseases, Oslo University Hospital, Oslo, Norway
| | - Svein Aslak Landsverk
- Department of Anesthesiology and Intensive Care, Oslo University Hospital, Oslo, Norway
| | - Lars Øivind Høiseth
- Department of Anesthesiology and Intensive Care, Oslo University Hospital, Oslo, Norway.,Norwegian Air Ambulance Foundation, Oslo, Norway
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21
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A Wireless Ultrasound Patch Detects Mild-to-Moderate Central Hypovolemia during Lower Body Negative Pressure. J Trauma Acute Care Surg 2022; 93:S35-S40. [PMID: 35594422 PMCID: PMC9323554 DOI: 10.1097/ta.0000000000003698] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Can a wireless, wearable Doppler ultrasound detect simulated mild hemorrhage during lower body negative pressure? What is the Doppler Shock Index? Read the recent study performed by Kenny et al. @MayoClinic published in @JTraumAcuteSurg #FOAMed We have developed a wireless, wearable Doppler ultrasound system that continuously measures the common carotid artery Doppler pulse. A novel measure from this device, the Doppler shock index, accurately detected moderate-to-severe central blood volume loss in a human hemorrhage model generated by lower body negative pressure. In this analysis, we tested whether the wearable Doppler could identify only mild-to-moderate central blood volume loss.
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22
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Berboth L, Zirngast B, Manninger M, Steendijk P, Tschöpe C, Scherr D, Hinghofer-Szalkay HG, Goswami N, Petersen LG, Mächler H, Alogna A. Graded lower body negative pressure induces intraventricular negative pressures and incremental diastolic suction: a pressure volume study in a porcine model. J Appl Physiol (1985) 2022; 133:20-26. [PMID: 35546125 DOI: 10.1152/japplphysiol.00110.2022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Lower body negative pressure (LBNP) has been a tool to study compensatory mechanisms to central hypovolemia for decades. However, underlying hemodynamic mechanisms were mostly assessed non-invasively and remain unclear. We hypothesized that incremental LBNP reduces diastolic filling and thereby affects left ventricular (LV) diastolic suction (DS). Here, we investigated the impact of graded LBNP at 3 different levels of seal as well as during beta-adrenergic stimulation by invasive pressure-volume (PV) analysis. Eight Landrace pigs were instrumented closed-chest for PV assessment. LBNP was applied at three consecutive locations: I) cranial, 10cm below xiphoid process; II) medial, half-way between cranial and caudal; III) caudal, at the iliac spine. Level III) was repeated under dobutamine infusion. At each level, baseline measurements were followed by application of incremental LBNP of -15, -30 and -45 mmHg. LBNP induced varying degrees of preload-dependent hemodynamic changes, with cranial LBNP inducing more pronounced effects than caudal. According to the Frank-Starling mechanism, graded LBNP progressively reduced LV stroke volume (LV SV) following a decrease in LV end-diastolic volume. Negative intraventricular minimal pressures were observed during dobutamine-infusion as well as higher levels of LBNP. Of note, incremental LV negative pressures were accompanied by increasing DS volumes, derived by extrapolating the volume at zero transmural pressure, the so-called equilibrium volume (V0), related to LV SV. In conclusion, graded preload reduction shifts the PV loop to smaller volumes and end-systolic volume below V0, which induces negative LV pressures and increases LV suction. Accordingly, LBNP induced central hypovolemia is associated with increased DS.
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Affiliation(s)
- Leonhard Berboth
- Department of Internal Medicine and Cardiology, Charité, Universitätsmedizin Berlin, Berlin, Germany
| | - Birgit Zirngast
- Department of Cardiac Surgery, Medical University of Graz, Graz, Austria
| | - Martin Manninger
- Department of Cardiology, Medical University of Graz, Graz, Austria
| | - Paul Steendijk
- Department of Cardiology, Leiden University Medical Center, Leiden, Netherlands
| | - Carsten Tschöpe
- Department of Internal Medicine and Cardiology, Charité, Universitätsmedizin Berlin, Berlin, Germany
| | - Daniel Scherr
- Department of Cardiology, Medical University of Graz, Graz, Austria
| | | | - Nandu Goswami
- Institute of Physiology, Medical University of Graz, Graz, Austria, Austria
| | - Lonnie G Petersen
- Department of Radiology, University of California, San Diego, La Jolla, CA, United States.,Mechanical and Aerospace Engineering, University of California, San Diego, La Jolla, CA, United States
| | - Heinrich Mächler
- Department of Cardiac Surgery, Medical University of Graz, Graz, Austria
| | - Alessio Alogna
- Department of Internal Medicine and Cardiology, Charité, Universitätsmedizin Berlin, Berlin, Germany.,Berlin Institute of Health, Charité, Universitätsmedizin Berlin, Berlin, Germany.,DZHK (German Centre for Cardiovascular Research), partner site Berlin, Germany
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23
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Patterson CA, Amelard R, Saarikoski E, Heigold H, Hughson RL, Robertson AD. Sex-dependent jugular vein optical attenuation and distension during head-down tilt and lower body negative pressure. Physiol Rep 2022; 10:e15179. [PMID: 35150210 PMCID: PMC8838633 DOI: 10.14814/phy2.15179] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2022] [Accepted: 01/20/2022] [Indexed: 11/24/2022] Open
Abstract
Non‐contact coded hemodynamic imaging (CHI) is a novel wide‐field near‐infrared spectroscopy system which monitors blood volume by quantifying attenuation of light passing through the underlying vessels. This study tested the hypothesis that CHI‐based jugular venous attenuation (JVA) would be larger in men, and change in JVA would be greater in men compared to women during two fluid shift challenges. The association of JVA with ultrasound‐based cross‐sectional area (CSA) was also tested. Ten men and 10 women completed three levels of head‐down tilt (HDT) and four levels of lower body negative pressure (LBNP). Both JVA and CSA were increased by HDT and reduced by LBNP (all p < 0.001). Main effects of sex indicated that JVA was higher in men than women during both HDT (p = 0.003) and LBNP (p = 0.011). Interaction effects of sex and condition were observed for JVA during HDT (p = 0.005) and LBNP (p < 0.001). We observed moderate repeated‐measures correlations (rrm) between JVA and CSA in women during HDT (rrm = 0.57, p = 0.011) and in both men (rrm = 0.74, p < 0.001) and women (rrm = 0.66, p < 0.001) during LBNP. While median within‐person correlation coefficients indicated an even stronger association between JVA and CSA, this association became unreliable for small changes in CSA. As hypothesized, JVA was greater and changed more in men compared to women during both HDT and LBNP. CHI provides a non‐contact method of tracking large changes in internal jugular vein blood volume that occur with acute fluid shifts, but data should be interpreted in a sex‐dependent manner.
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Affiliation(s)
- Courtney A Patterson
- Schlegel-University of Waterloo Research Institute for Aging, Waterloo, Ontario, Canada.,Department of Kinesiology, University of Waterloo, Waterloo, Ontario, Canada
| | - Robert Amelard
- Schlegel-University of Waterloo Research Institute for Aging, Waterloo, Ontario, Canada.,KITE-Toronto Rehabilitation Institute, University Health Network, Toronto, Ontario, Canada
| | - Essi Saarikoski
- Schlegel-University of Waterloo Research Institute for Aging, Waterloo, Ontario, Canada
| | - Hannah Heigold
- Department of Systems Design Engineering, University of Waterloo, Waterloo, Ontario, Canada
| | - Richard L Hughson
- Schlegel-University of Waterloo Research Institute for Aging, Waterloo, Ontario, Canada
| | - Andrew D Robertson
- Schlegel-University of Waterloo Research Institute for Aging, Waterloo, Ontario, Canada.,Department of Kinesiology, University of Waterloo, Waterloo, Ontario, Canada
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24
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Malik V, Elliott AD, Thomas G, Mishima RS, Pitman B, Middeldorp ME, Fitzgerald JL, Young GD, Roberts-Thomson KC, Arnolda LF, Lau DH, Sanders P. Autonomic Afferent Dysregulation in Atrial Fibrillation. JACC Clin Electrophysiol 2022; 8:152-164. [PMID: 35210071 DOI: 10.1016/j.jacep.2021.10.010] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2021] [Revised: 10/21/2021] [Accepted: 10/24/2021] [Indexed: 12/22/2022]
Abstract
OBJECTIVES This study sought to evaluate the role of cardiac afferent reflexes in atrial fibrillation (AF). BACKGROUND Efferent autonomic tone is not associated with atrial remodeling and AF persistence. However, the role of cardiac afferents is unknown. METHODS Individuals with nonpermanent AF (n = 48) were prospectively studied (23 in the in-AF group and 25 in sinus rhythm [SR]) with 12 matched control subjects. We performed: 1) low-level lower body negative pressure (LBNP), which decreases cardiac volume, offloading predominantly cardiac afferent (volume-sensitive) low-pressure baroreceptors; 2) Valsalva reflex (predominantly arterial high-pressure baroreceptors); and 3) isometric handgrip reflex (both baroreceptors). We measured beat-to-beat mean arterial pressure (MAP) and heart rate (HR). LBNP elicits reflex vasoconstriction, estimated using venous occlusion plethysmography-derived forearm blood flow (∝1/vascular resistance), maintaining MAP. To assess reversibility, we repeated LBNP (same day) after 1-hour low-level tragus stimulation (in n = 5 in the in-AF group and n = 10 in the in-SR group) and >6 weeks post-cardioversion (n = 7). RESULTS The 3 groups were well matched for age (59 ± 12 years, 83% male), body mass index, and risk factors (P = NS). The in-AF group had higher left atrial volume (P < 0.001) and resting HR (P = 0.01) but similar MAP (P = 0.7). The normal LBNP vasoconstriction (-49 ± 5%) maintaining MAP (control subjects) was attenuated in the in-SR group (-12 ± 9%; P = 0.005) and dysfunctional in the in-AF group (+11 ± 6%; P < 0.001), in which MAP decreased and HR was unchanged. Valsalva was normal throughout. Handgrip MAP response was lowest in the in-AF group (P = 0.01). Interestingly, low-level tragus stimulation and cardioversion improved LBNP vasoconstriction (-48 ± 15%; P = 0.04; and -32 ± 9%; P = 0.02, respectively). CONCLUSIONS Cardiac afferent (volume-sensitive) reflexes are abnormal in AF patients during SR and dysfunctional during AF. This could contribute to AF progression, thus explaining "AF begets AF." (Characterisation of Autonomic function in Atrial Fibrillation [AF-AF Study]; ACTRN12619000186156).
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Affiliation(s)
- Varun Malik
- Centre for Heart Rhythm Disorders, University of Adelaide and Royal Adelaide Hospital, Adelaide, Australia
| | - Adrian D Elliott
- Centre for Heart Rhythm Disorders, University of Adelaide and Royal Adelaide Hospital, Adelaide, Australia
| | - Gijo Thomas
- Centre for Heart Rhythm Disorders, University of Adelaide and Royal Adelaide Hospital, Adelaide, Australia
| | - Ricardo S Mishima
- Centre for Heart Rhythm Disorders, University of Adelaide and Royal Adelaide Hospital, Adelaide, Australia
| | - Bradley Pitman
- Centre for Heart Rhythm Disorders, University of Adelaide and Royal Adelaide Hospital, Adelaide, Australia
| | - Melissa E Middeldorp
- Centre for Heart Rhythm Disorders, University of Adelaide and Royal Adelaide Hospital, Adelaide, Australia
| | - John L Fitzgerald
- Centre for Heart Rhythm Disorders, University of Adelaide and Royal Adelaide Hospital, Adelaide, Australia
| | - Glenn D Young
- Centre for Heart Rhythm Disorders, University of Adelaide and Royal Adelaide Hospital, Adelaide, Australia
| | - Kurt C Roberts-Thomson
- Centre for Heart Rhythm Disorders, University of Adelaide and Royal Adelaide Hospital, Adelaide, Australia
| | - Leonard F Arnolda
- Centre for Heart Rhythm Disorders, University of Adelaide and Royal Adelaide Hospital, Adelaide, Australia
| | - Dennis H Lau
- Centre for Heart Rhythm Disorders, University of Adelaide and Royal Adelaide Hospital, Adelaide, Australia
| | - Prashanthan Sanders
- Centre for Heart Rhythm Disorders, University of Adelaide and Royal Adelaide Hospital, Adelaide, Australia.
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Hinojosa-Laborde C, Hudson IL, Ross E, Xiang L, Ryan KL. Pathophysiology of Hemorrhage as It Relates to the Warfighter. Physiology (Bethesda) 2022; 37:141-153. [PMID: 35001653 PMCID: PMC8977138 DOI: 10.1152/physiol.00028.2021] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
Saving lives of wounded military Warfighters often depends on the ability to resolve or mitigate the pathophysiology of hemorrhage, specifically diminished oxygen delivery to vital organs that leads to multi-organ failure and death. However, caring for hemorrhaging patients on the battlefield presents unique challenges that extend beyond applying a tourniquet and giving a blood transfusion, especially when battlefield care must be provided for a prolonged period. This review will describe these challenges and potential strategies for treating hemorrhage on the battlefield in a prolonged casualty care situation.
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Affiliation(s)
| | - Ian L Hudson
- U.S. Army Institute of Surgical Research, JBSA Fort Sam Houston, TX, United States
| | - Evan Ross
- U.S. Army Institute of Surgical Research, JBSA Fort Sam Houston, TX, United States
| | - Lusha Xiang
- U.S. Army Institute of Surgical Research, JBSA Fort Sam Houston, TX, United States
| | - Kathy L Ryan
- U.S. Army Institute of Surgical Research, JBSA Fort Sam Houston, TX, United States
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26
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Huang M, Watso JC, Belval LN, Cimino FA, Fischer M, Jarrard CP, Hendrix JM, Laborde CH, Crandall CG. Low-dose fentanyl does not alter muscle sympathetic nerve activity, blood pressure, or tolerance during progressive central hypovolemia. Am J Physiol Regul Integr Comp Physiol 2022; 322:R55-R63. [PMID: 34851734 PMCID: PMC8742719 DOI: 10.1152/ajpregu.00217.2021] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Hemorrhage is a leading cause of battlefield and civilian trauma deaths. Several pain medications, including fentanyl, are recommended for use in the prehospital (i.e., field setting) for a hemorrhaging solider. However, it is unknown whether fentanyl impairs arterial blood pressure (BP) regulation, which would compromise hemorrhagic tolerance. Thus, the purpose of this study was to test the hypothesis that an analgesic dose of fentanyl impairs hemorrhagic tolerance in conscious humans. Twenty-eight volunteers (13 females) participated in this double-blinded, randomized, placebo-controlled trial. We conducted a presyncopal limited progressive lower body negative pressure test (LBNP; a validated model to simulate hemorrhage) following intravenous administration of fentanyl (75 µg) or placebo (saline). We quantified tolerance as a cumulative stress index (mmHg·min), which was compared between trials using a paired, two-tailed t test. We also compared muscle sympathetic nerve activity (MSNA; microneurography) and beat-to-beat BP (photoplethysmography) during the LBNP test using a mixed effects model [time (LBNP stage) × trial]. LBNP tolerance was not different between trials (fentanyl: 647 ± 386 vs. placebo: 676 ± 295 mmHg·min, P = 0.61, Cohen's d = 0.08). Increases in MSNA burst frequency (time: P < 0.01, trial: P = 0.29, interaction: P = 0.94) and reductions in mean BP (time: P < 0.01, trial: P = 0.50, interaction: P = 0.16) during LBNP were not different between trials. These data, the first to be obtained in conscious humans, demonstrate that administration of an analgesic dose of fentanyl does not alter MSNA or BP during profound central hypovolemia, nor does it impair tolerance to this simulated hemorrhagic insult.
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Affiliation(s)
- Mu Huang
- 1Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas, Dallas, Texas,2Department of Applied Clinical Research, University of Texas Southwestern Medical Center, Dallas, Texas
| | - Joseph C. Watso
- 1Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas, Dallas, Texas,3Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas
| | - Luke N. Belval
- 1Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas, Dallas, Texas,3Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas
| | - Frank A. Cimino
- 1Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas, Dallas, Texas
| | - Mads Fischer
- 2Department of Applied Clinical Research, University of Texas Southwestern Medical Center, Dallas, Texas,4Department of Nutrition, Exercise and Sports, University of Copenhagen, Copenhagen, Denmark
| | - Caitlin P. Jarrard
- 2Department of Applied Clinical Research, University of Texas Southwestern Medical Center, Dallas, Texas
| | - Joseph M. Hendrix
- 1Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas, Dallas, Texas,5Department of Anesthesiology and Pain Management, University of Texas Southwestern Medical Center, Dallas, Texas
| | - Carmen Hinojosa Laborde
- 6United States Army Institute of Surgical Research, JBSA Fort Sam Houston, San Antonio, Texas
| | - Craig G. Crandall
- 1Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas, Dallas, Texas,3Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas
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27
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Hutchings SD, Watchorn J, McDonald R, Jeffreys S, Bates M, Watts S, Kirkman E. Quantification of stroke volume in a simulated healthy volunteer model of traumatic haemorrhage; a comparison of two non-invasive monitoring devices using error grid analysis alongside traditional measures of agreement. PLoS One 2021; 16:e0261546. [PMID: 34941918 PMCID: PMC8699736 DOI: 10.1371/journal.pone.0261546] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2021] [Accepted: 12/03/2021] [Indexed: 11/19/2022] Open
Abstract
Introduction Haemorrhage is a leading cause of death following traumatic injury and the early detection of hypovolaemia is critical to effective management. However, accurate assessment of circulating blood volume is challenging when using traditional vital signs such as blood pressure. We conducted a study to compare the stroke volume (SV) recorded using two devices, trans-thoracic electrical bioimpedance (TEB) and supra-sternal Doppler (SSD), against a reference standard using trans- thoracic echocardiography (TTE). Methods A lower body negative pressure (LBNP) model was used to simulate hypovolaemia and in half of the study sessions lower limb tourniquets were applied as these are common in military practice and can potentially affect some haemodynamic monitoring systems. In order to provide a clinically relevant comparison we constructed an error grid alongside more traditional measures of agreement. Results 21 healthy volunteers aged 18–40 were enrolled and underwent 2 sessions of LBNP, with and without lower limb tourniquets. With respect to absolute SV values Bland Altman analysis showed significant bias in both non-tourniquet and tourniquet strands for TEB (-42.5 / -49.6 ml), rendering further analysis impossible. For SSD bias was minimal but percentage error was unacceptably high (35% / 48%). Degree of agreement for dynamic change in SV, assessed using 4 quadrant plots showed a seemingly acceptable concordance rate for both TEB (86% / 93%) and SSD (90% / 91%). However, when results were plotted on an error grid, constructed based on expert clinical opinion, a significant minority of measurement errors were identified that had potential to lead to moderate or severe patient harm. Conclusion Thoracic bioimpedance and suprasternal Doppler both demonstrated measurement errors that had the potential to lead to clinical harm and caution should be applied in interpreting the results in the detection of early hypovolaemia following traumatic injury.
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Affiliation(s)
- Sam D. Hutchings
- Department of Inflammation Biology, School of Immunology and Microbial Sciences, King’s College London, London, United Kingdom
- Academic Department of Military Anaesthesia and Critical Care, Royal Centre for Defence Medicine, Birmingham, United Kingdom
- * E-mail:
| | - Jim Watchorn
- Department of Inflammation Biology, School of Immunology and Microbial Sciences, King’s College London, London, United Kingdom
| | - Rory McDonald
- Academic Department of Military Anaesthesia and Critical Care, Royal Centre for Defence Medicine, Birmingham, United Kingdom
| | - Su Jeffreys
- Academic Department of Military Anaesthesia and Critical Care, Royal Centre for Defence Medicine, Birmingham, United Kingdom
| | - Mark Bates
- Defence Science and Technology Laboratory, Porton Down, Wiltshire, United Kingdom
| | - Sarah Watts
- Defence Science and Technology Laboratory, Porton Down, Wiltshire, United Kingdom
| | - Emrys Kirkman
- Defence Science and Technology Laboratory, Porton Down, Wiltshire, United Kingdom
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28
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MacNamara JP, Koshti V, Dias KA, Howden E, Hearon CM, Cheng I, Hynan LS, Levine BD, Sarma S. The impact of cardiac loading on a novel metric of left ventricular diastolic function in healthy middle-aged adults: Systolic-diastolic coupling. Physiol Rep 2021; 9:e15129. [PMID: 34873864 PMCID: PMC8649710 DOI: 10.14814/phy2.15129] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2021] [Revised: 11/24/2021] [Accepted: 11/14/2021] [Indexed: 11/24/2022] Open
Abstract
AIMS Left ventricular (LV) restoring forces are primed by ventricular deformation during systole and contribute to cardiac relaxation and early diastolic suction. Systolic-diastolic coupling, the relationship between systolic contraction and diastolic recoil, is a novel marker of restoring forces, but the effect of left atrial pressure (LAP) is unknown. We tested preliminary methods of systolic-diastolic coupling comparing mitral annular velocities versus excursion distances and hypothesized a recoil/contraction distance ratio would remain unaffected across varying LAP, providing a surrogate for quantifying LV restoring forces. METHODS AND RESULTS Healthy subjects (n = 61, age 52 ± 5 years) underwent manipulation of LAP with lower body negative pressure (LBNP) and rapid normal saline (NS) infusion. Pulmonary capillary wedge pressure (PCWP; pulmonary artery catheter) and tissue Doppler imaging of the mitral annulus were measured. Two models of systolic-diastolic coupling--early diastolic excursion (EDexc )/systolic contraction (Sexc ) distances and e'/systolic (s') velocities were compared. Velocity (e'/s') coupling ratios varied significantly (mean e'/s', slope = 0.022, p < 0.001) in relationship with PCWP (5-20 mmHg). Excursion (EDexc /Sexc ) coupling ratio did not vary in relationship with PCWP (EDexc /Sexc : slope = -0.001, p = 0.19). CONCLUSIONS Systolic-diastolic coupling using mitral annular distance ratios to standardize early diastolic recoil to systolic contraction was not significantly impacted by LAP, in contrast to coupling ratios using velocities. The pressure invariance of annular distance coupling ratios suggests this metric quantifies the efficiency of LV restoring forces by isolating systolic contributions to early diastolic restoring forces independent from changes in LAP.
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Affiliation(s)
- James P. MacNamara
- Institute for Exercise and Environmental MedicineTexas Health Presbyterian HospitalDallasTexasUSA
- University of Texas Southwestern Medical CenterDallasTexasUSA
| | - Vivek Koshti
- University of Texas Southwestern Medical CenterDallasTexasUSA
| | - Katrin A. Dias
- Institute for Exercise and Environmental MedicineTexas Health Presbyterian HospitalDallasTexasUSA
- University of Texas Southwestern Medical CenterDallasTexasUSA
| | - Erin Howden
- Baker Heart and Diabetes InstituteMelbourneVictoriaAustralia
| | - Christopher M. Hearon
- Institute for Exercise and Environmental MedicineTexas Health Presbyterian HospitalDallasTexasUSA
- University of Texas Southwestern Medical CenterDallasTexasUSA
| | - I‐Jou Cheng
- Institute for Exercise and Environmental MedicineTexas Health Presbyterian HospitalDallasTexasUSA
- Tri‐Service General HospitalNational Defense Medical CenterTaipei CityTaiwan
| | - Linda S. Hynan
- Departments of Population & Data Sciences and PsychiatryUniversity of Texas Southwestern Medical CenterDallasTexasUSA
| | - Benjamin D. Levine
- Institute for Exercise and Environmental MedicineTexas Health Presbyterian HospitalDallasTexasUSA
- University of Texas Southwestern Medical CenterDallasTexasUSA
| | - Satyam Sarma
- Institute for Exercise and Environmental MedicineTexas Health Presbyterian HospitalDallasTexasUSA
- University of Texas Southwestern Medical CenterDallasTexasUSA
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29
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Clemency BM, Bola A, Schlader ZJ, Hostler D, Lin H, St James E, Lema PC, Johnson BD. Ultrasonographic Inferior Vena Cava Measurement is More Sensitive Than Vital Sign Abnormalities for Identifying Moderate and Severe Hemorrhage. J Emerg Med 2021; 62:64-71. [PMID: 34544622 DOI: 10.1016/j.jemermed.2021.07.049] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2021] [Revised: 06/02/2021] [Accepted: 07/25/2021] [Indexed: 11/19/2022]
Abstract
BACKGROUND Ultrasound inferior vena cava (IVC) diameter has been shown to decrease in response to hemorrhage. IVC diameter cut points to identify moderate and severe blood loss have not been established. OBJECTIVES This study sought to find ultrasound IVC diameter cut points to identify moderate and severe hemorrhage and assess the performance of these cut points vs. vital sign abnormalities. METHODS This is a secondary analysis of data from a study that described changes in vital signs and sonographic measurements of the IVC during a lower body negative pressure model of hemorrhage. Using receiver operator curve analyses, optimal cut points for identifying moderate and severe hemorrhage were identified. The ability of these cut points to identify hemorrhage in patients with no vital sign abnormalities was then assessed. RESULTS In both long- and short-axis views, maximum and minimum IVC diameters (IVCmax and IVCmin) were significantly lower than baseline in severe blood loss. The optimal cut point for IVCmax in both axes was found to be ≤ 0.8 cm. This cut point is able to distinguish between no blood loss vs. moderate blood loss, and no blood loss vs. severe blood loss. The optimal cut point for IVCmin was variable between axes and blood loss severity. IVC diameter cut points obtained were able to identify hemorrhage in patients with no vital sign abnormalities. CONCLUSION An ultrasound IVCmax of ≤ 0.8 cm may be useful in identifying moderate and severe hemorrhage before vital sign abnormalities are evident.
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Affiliation(s)
- Brian M Clemency
- Department of Emergency Medicine, University at Buffalo Jacobs School of Medicine and Biomedical Sciences, Buffalo, New York; Center for Research and Education in Special Environments, Department of Exercise and Nutrition Sciences, University at Buffalo, Buffalo, New York
| | - Aaron Bola
- Department of Emergency Medicine, University at Buffalo Jacobs School of Medicine and Biomedical Sciences, Buffalo, New York
| | - Zachary J Schlader
- Department of Kinesiology, School of Public Health - Bloomington, Indiana University, Bloomington, Indiana
| | - David Hostler
- Department of Emergency Medicine, University at Buffalo Jacobs School of Medicine and Biomedical Sciences, Buffalo, New York; Center for Research and Education in Special Environments, Department of Exercise and Nutrition Sciences, University at Buffalo, Buffalo, New York
| | - Howard Lin
- Department of Emergency Medicine, University at Buffalo Jacobs School of Medicine and Biomedical Sciences, Buffalo, New York
| | - Erika St James
- Department of Emergency Medicine, University at Buffalo Jacobs School of Medicine and Biomedical Sciences, Buffalo, New York; Center for Research and Education in Special Environments, Department of Exercise and Nutrition Sciences, University at Buffalo, Buffalo, New York
| | - Penelope C Lema
- Department of Emergency Medicine, Columbia University Vagelos College of Physicians and Surgeons, New York, New York
| | - Blair D Johnson
- Department of Kinesiology, School of Public Health - Bloomington, Indiana University, Bloomington, Indiana
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30
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D'Orsi L, Curcio L, Cibella F, Borri A, Gavish L, Eisenkraft A, De Gaetano A. A mathematical model of cardiovascular dynamics for the diagnosis and prognosis of hemorrhagic shock. MATHEMATICAL MEDICINE AND BIOLOGY-A JOURNAL OF THE IMA 2021; 38:417-441. [PMID: 34499176 DOI: 10.1093/imammb/dqab011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/03/2020] [Revised: 08/16/2021] [Accepted: 08/16/2021] [Indexed: 11/13/2022]
Abstract
A variety of mathematical models of the cardiovascular system have been suggested over several years in order to describe the time-course of a series of physiological variables (i.e. heart rate, cardiac output, arterial pressure) relevant for the compensation mechanisms to perturbations, such as severe haemorrhage. The current study provides a simple but realistic mathematical description of cardiovascular dynamics that may be useful in the assessment and prognosis of hemorrhagic shock. The present work proposes a first version of a differential-algebraic equations model, the model dynamical ODE model for haemorrhage (dODEg). The model consists of 10 differential and 14 algebraic equations, incorporating 61 model parameters. This model is capable of replicating the changes in heart rate, mean arterial pressure and cardiac output after the onset of bleeding observed in four experimental animal preparations and fits well to the experimental data. By predicting the time-course of the physiological response after haemorrhage, the dODEg model presented here may be of significant value for the quantitative assessment of conventional or novel therapeutic regimens. The model may be applied to the prediction of survivability and to the determination of the urgency of evacuation towards definitive surgical treatment in the operational setting.
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Affiliation(s)
- Laura D'Orsi
- National Research Council of Italy, Institute for Systems Analysis and Computer Science 'A. Ruberti', Biomathematics Laboratory, UCSC Largo A. Gemelli 8, 00168 Rome, Italy
| | - Luciano Curcio
- National Research Council of Italy, Institute for Biomedical Research and Innovation, Biomathematics Laboratory, Via Ugo La Malfa, 153, 90146 Palermo, Italy
| | - Fabio Cibella
- National Research Council of Italy, Institute for Biomedical Research and Innovation, Biomathematics Laboratory, Via Ugo La Malfa, 153, 90146 Palermo, Italy
| | - Alessandro Borri
- National Research Council of Italy, Institute for Systems Analysis and Computer Science 'A. Ruberti', Biomathematics Laboratory, UCSC Largo A. Gemelli 8, 00168 Rome, Italy
| | - Lilach Gavish
- Institute for Research in Military Medicine (IRMM), Faculty of Medicine, The Hebrew University of Jerusalem, 9112001, Israel, Institute for Medical Research (IMRIC), Faculty of Medicine, The Hebrew University of Jerusalem, 9112001, Israel
| | - Arik Eisenkraft
- Institute for Research in Military Medicine (IRMM), Faculty of Medicine, The Hebrew University of Jerusalem, 9112001, Israel
| | - Andrea De Gaetano
- National Research Council of Italy, Institute for Systems Analysis and Computer Science 'A. Ruberti', Biomathematics Laboratory, UCSC Largo A. Gemelli 8, 00168 Rome, Italy
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Kenny JS, Elfarnawany M, Yang Z, Myers M, Eibl AM, Eibl JK, Taylor JL, Kim CH, Johnson BD. The Doppler shock index measured by a wearable ultrasound patch accurately detects moderate-to-severe central hypovolemia during lower body negative pressure. J Am Coll Emerg Physicians Open 2021; 2:e12533. [PMID: 34401869 PMCID: PMC8349221 DOI: 10.1002/emp2.12533] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2021] [Revised: 06/22/2021] [Accepted: 07/20/2021] [Indexed: 12/05/2022] Open
Abstract
OBJECTIVE Moderate-to-severe hemorrhage is a life-threatening condition, which is challenging to detect in a timely fashion using traditional vital signs because of the human body's robust physiologic compensatory mechanisms. Measuring and trending blood flow could improve diagnosis of clinically significant exsanguination. A lightweight, wireless, wearable Doppler ultrasound patch that captures and trends blood flow velocity could enhance hemorrhage detection. METHODS In 11 healthy volunteers undergoing simulated hemorrhage and resuscitation during graded lower body negative pressure (LBNP) and release, we studied the relationship between stroke volume (SV) and common carotid artery velocity time integral (VTI) and corrected flow time (FTc). We assessed the diagnostic accuracy of 2 variations of a novel metric, the Doppler shock index (ie, the DSIVTI and DSIFTc), at capturing moderate-to-severe central hypovolemia defined as a 30% reduction in SV. The DSIVTI and DSIFTc are calculated as the heart rate divided by either the VTI or FTc, respectively. RESULTS A total of 17,822 cardiac cycles were analyzed across 22 LBNP protocols. The average SV reduction to the lowest tolerated LBNP stage was 40%; there was no clinically significant fall in the mean arterial pressure. Correlations between changing SV and the common carotid artery VTI and FTc were strong (R 2 of 0.87, respectively) and concordant. The DSIVTI and DSIFTc accurately detected moderate-to-severe central hypovolemia with values for the area under the receiver operator curves of 0.96 and 0.97, respectively. CONCLUSION In a human model of hemorrhage and resuscitation, measures from a wearable Doppler ultrasound patch correlated strongly with SV and identified moderate-to-severe central hypovolemia with excellent diagnostic accuracy.
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Affiliation(s)
| | - Mai Elfarnawany
- Health Sciences North Research InstituteSudburyOntarioCanada
- Flosonics MedicalSudburyOntarioCanada
| | - Zhen Yang
- Health Sciences North Research InstituteSudburyOntarioCanada
- Flosonics MedicalSudburyOntarioCanada
| | - Matt Myers
- Health Sciences North Research InstituteSudburyOntarioCanada
- Flosonics MedicalSudburyOntarioCanada
| | - Andrew M. Eibl
- Health Sciences North Research InstituteSudburyOntarioCanada
| | - Joseph K. Eibl
- Health Sciences North Research InstituteSudburyOntarioCanada
- Northern Ontario School of MedicineSudburyOntarioCanada
| | - Jenna L. Taylor
- Human Integrative and Environmental Physiology LaboratoryDepartment of Cardiovascular DiseasesMayo ClinicRochesterMinnesotaUSA
| | - Chul Ho Kim
- Human Integrative and Environmental Physiology LaboratoryDepartment of Cardiovascular DiseasesMayo ClinicRochesterMinnesotaUSA
| | - Bruce D. Johnson
- Human Integrative and Environmental Physiology LaboratoryDepartment of Cardiovascular DiseasesMayo ClinicRochesterMinnesotaUSA
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Seven Mathematical Models of Hemorrhagic Shock. COMPUTATIONAL AND MATHEMATICAL METHODS IN MEDICINE 2021; 2021:6640638. [PMID: 34188690 PMCID: PMC8195646 DOI: 10.1155/2021/6640638] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/29/2020] [Accepted: 04/02/2021] [Indexed: 11/17/2022]
Abstract
Although mathematical modelling of pressure-flow dynamics in the cardiocirculatory system has a lengthy history, readily finding the appropriate model for the experimental situation at hand is often a challenge in and of itself. An ideal model would be relatively easy to use and reliable, besides being ethically acceptable. Furthermore, it would address the pathogenic features of the cardiovascular disease that one seeks to investigate. No universally valid model has been identified, even though a host of models have been developed. The object of this review is to describe several of the most relevant mathematical models of the cardiovascular system: the physiological features of circulatory dynamics are explained, and their mathematical formulations are compared. The focus is on the whole-body scale mathematical models that portray the subject's responses to hypovolemic shock. The models contained in this review differ from one another, both in the mathematical methodology adopted and in the physiological or pathological aspects described. Each model, in fact, mimics different aspects of cardiocirculatory physiology and pathophysiology to varying degrees: some of these models are geared to better understand the mechanisms of vascular hemodynamics, whereas others focus more on disease states so as to develop therapeutic standards of care or to test novel approaches. We will elucidate key issues involved in the modeling of cardiovascular system and its control by reviewing seven of these models developed to address these specific purposes.
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Rashedi N, Sun Y, Vaze V, Shah P, Halter R, Elliott JT, Paradis NA. Early Detection of Hypotension Using a Multivariate Machine Learning Approach. Mil Med 2021; 186:440-444. [PMID: 33499451 DOI: 10.1093/milmed/usaa323] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2020] [Revised: 07/28/2020] [Accepted: 09/04/2020] [Indexed: 11/14/2022] Open
Abstract
INTRODUCTION The ability to accurately detect hypotension in trauma patients at the earliest possible time is important in improving trauma outcomes. The earlier an accurate detection can be made, the more time is available to take corrective action. Currently, there is limited research on combining multiple physiological signals for an early detection of hemorrhagic shock. We studied the viability of early detection of hypotension based on multiple physiologic signals and machine learning methods. We explored proof of concept with a small (5 minutes) prediction window for application of machine learning tools and multiple physiologic signals to detecting hypotension. MATERIALS AND METHODS Multivariate physiological signals from a preexisting dataset generated by an experimental hemorrhage model were employed. These experiments were conducted previously by another research group and the data made available publicly through a web portal. This dataset is among the few publicly available which incorporate measurement of multiple physiological signals from large animals during experimental hemorrhage. The data included two hemorrhage studies involving eight sheep. Supervised machine learning experiments were conducted in order to develop deep learning (viz., long short-term memory or LSTM), ensemble learning (viz., random forest), and classical learning (viz., support vector machine or SVM) models for the identification of physiological signals that can detect whether or not overall blood loss exceeds a predefined threshold 5 minutes ahead of time. To evaluate the performance of the machine learning technologies, 3-fold cross-validation was conducted and precision (also called positive predictive value) and recall (also called sensitivity) values were compared. As a first step in this development process, 5 minutes prediction windows were utilized. RESULTS The results showed that SVM and random forest outperform LSTM neural networks, likely because LSTM tends to overfit the data on small sized datasets. Random forest has the highest recall (84%) with 56% precision while SVM has 62% recall with 82% precision. Upon analyzing the feature importance, it was observed that electrocardiogram has the highest significance while arterial blood pressure has the least importance among all other signals. CONCLUSION In this research, we explored the viability of early detection of hypotension based on multiple signals in a preexisting animal hemorrhage dataset. The results show that a multivariate approach might be more effective than univariate approaches for this detection task.
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Affiliation(s)
- Navid Rashedi
- Thayer School of Engineering, Dartmouth College, Hanover, NH 03755, USA
| | - Yifei Sun
- Thayer School of Engineering, Dartmouth College, Hanover, NH 03755, USA
| | - Vikrant Vaze
- Thayer School of Engineering, Dartmouth College, Hanover, NH 03755, USA
| | - Parikshit Shah
- Insight Research, Research and development, Emerald Hills, CA 94065, USA
| | - Ryan Halter
- Thayer School of Engineering, Dartmouth College, Hanover, NH 03755, USA
| | - Jonathan T Elliott
- Geisel School of Medicine, Emergency Medicine, Dartmouth College, Hanover, NH 037, USA
| | - Norman A Paradis
- Geisel School of Medicine, Emergency Medicine, Dartmouth College, Hanover, NH 037, USA
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Amelard R, Robertson AD, Patterson CA, Heigold H, Saarikoski E, Hughson RL. Optical Hemodynamic Imaging of Jugular Venous Dynamics During Altered Central Venous Pressure. IEEE Trans Biomed Eng 2021; 68:2582-2591. [PMID: 33769929 DOI: 10.1109/tbme.2021.3069133] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
OBJECTIVE An optical imaging system is proposed for quantitatively assessing jugular venous response to altered central venous pressure. METHODS The proposed system assesses sub-surface optical absorption changes from jugular venous waveforms with a spatial calibration procedure to normalize incident tissue illumination. Widefield frames of the right lateral neck were captured and calibrated using a novel flexible surface calibration method. A hemodynamic optical model was derived to quantify jugular venous optical attenuation (JVA) signals, and generate a spatial jugular venous pulsatility map. JVA was assessed in three cardiovascular protocols that altered central venous pressure: acute central hypovolemia (lower body negative pressure), venous congestion (head-down tilt), and impaired cardiac filling (Valsalva maneuver). RESULTS JVA waveforms exhibited biphasic wave properties consistent with jugular venous pulse dynamics when time-aligned with an electrocardiogram. JVA correlated strongly (median, interquartile range) with invasive central venous pressure during graded central hypovolemia (r = 0.85, [0.72, 0.95]), graded venous congestion (r = 0.94, [0.84, 0.99]), and impaired cardiac filling (r = 0.94, [0.85, 0.99]). Reduced JVA during graded acute hypovolemia was strongly correlated with reductions in stroke volume (SV) (r = 0.85, [0.76, 0.92]) from baseline (SV: 79 ± 15 mL, JVA: 0.56 ± 0.10 a.u.) to -40 mmHg suction (SV: 59 ± 18 mL, JVA: 0.47 ± 0.05 a.u.; p 0.01). CONCLUSION The proposed non-contact optical imaging system demonstrated jugular venous dynamics consistent with invasive central venous monitoring during three protocols that altered central venous pressure. SIGNIFICANCE This system provides non-invasive monitoring of pressure-induced jugular venous dynamics in clinically relevant conditions where catheterization is traditionally required, enabling monitoring in non-surgical environments.
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Hamilton MCK, Neumann S, Szantho G, Rydon L, Lawton CB, Hart E, Manghat NE, Turner MS. The design and use of a simple device for the MRI assessment of changes in cardiovascular function by lower-body negative-pressure-simulated reduction of central blood volume. Clin Radiol 2021; 76:471.e9-471.e16. [PMID: 33637308 DOI: 10.1016/j.crad.2021.01.016] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2020] [Accepted: 01/18/2021] [Indexed: 11/19/2022]
Abstract
AIM To use a locally designed and simple lower-body negative-pressure (LBNP) device and 1.5 T magnetic resonance imaging (MRI) to demonstrate the ability to assess changes in cardiovascular function during preload reduction. These effects were evaluated on ventricular volumes and great vessel flow in healthy volunteers, for which there are limited published data. MATERIAL AND METHODS After ethical review, 14 volunteers (mean age 33.9 ± 7 years, mean body mass index [BMI] 23.1 ± 2.5) underwent LBNP prospectively at 0, -5, -10, and -20 mmHg pressure, using a locally designed LBNP box. Expiratory breath-hold biventricular volumes, and free-breathing flow imaging of the ascending aorta and main pulmonary artery were acquired at each level of LBNP. RESULTS At -5 mmHg, there was no change in aortic flow or left ventricular volumes versus baseline. Right ventricular output (p=0.013) and pulmonary net flow (p=0.026) decreased. At -20 mmHg, aortic and pulmonary net flow (p<0.001) decreased, as were left and right ventricular end diastolic volume (p<0.001) and left and right end systolic volumes (p=0.038 and p=0.003 respectively). CONCLUSIONS Use of a MRI-compatible LBNP device is feasible to measure changes in ventricular volume and great arterial flow in the same experiment. This may enhance further research into the effects of preload reduction by MRI in a wide range of important cardiovascular pathologies.
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Affiliation(s)
- M C K Hamilton
- Department of Clinical Radiology, Bristol Royal Infirmary, Bristol BS28HW, UK.
| | - S Neumann
- School of Physiology, Pharmacology and Neurosciences, University of Bristol, Bristol BS8 1TD, UK
| | - G Szantho
- Department of Cardiology, Bristol Heart Institute, Bristol BS28HW, UK
| | - L Rydon
- MEMO Clinical Engineering, Bristol Royal Infirmary, Bristol BS28HW, UK
| | - C B Lawton
- Department of Clinical Radiology, Bristol Royal Infirmary, Bristol BS28HW, UK
| | - E Hart
- School of Physiology, Pharmacology and Neurosciences, University of Bristol, Bristol BS8 1TD, UK
| | - N E Manghat
- Department of Clinical Radiology, Bristol Royal Infirmary, Bristol BS28HW, UK
| | - M S Turner
- Department of Cardiology, Bristol Heart Institute, Bristol BS28HW, UK
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Convertino VA, Koons NJ, Suresh MR. Physiology of Human Hemorrhage and Compensation. Compr Physiol 2021; 11:1531-1574. [PMID: 33577122 DOI: 10.1002/cphy.c200016] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Hemorrhage is a leading cause of death following traumatic injuries in the United States. Much of the previous work in assessing the physiology and pathophysiology underlying blood loss has focused on descriptive measures of hemodynamic responses such as blood pressure, cardiac output, stroke volume, heart rate, and vascular resistance as indicators of changes in organ perfusion. More recent work has shifted the focus toward understanding mechanisms of compensation for reduced systemic delivery and cellular utilization of oxygen as a more comprehensive approach to understanding the complex physiologic changes that occur following and during blood loss. In this article, we begin with applying dimensional analysis for comparison of animal models, and progress to descriptions of various physiological consequences of hemorrhage. We then introduce the complementary side of compensation by detailing the complexity and integration of various compensatory mechanisms that are activated from the initiation of hemorrhage and serve to maintain adequate vital organ perfusion and hemodynamic stability in the scenario of reduced systemic delivery of oxygen until the onset of hemodynamic decompensation. New data are introduced that challenge legacy concepts related to mechanisms that underlie baroreflex functions and provide novel insights into the measurement of the integrated response of compensation to central hypovolemia known as the compensatory reserve. The impact of demographic and environmental factors on tolerance to hemorrhage is also reviewed. Finally, we describe how understanding the physiology of compensation can be translated to applications for early assessment of the clinical status and accurate triage of hypovolemic and hypotensive patients. © 2021 American Physiological Society. Compr Physiol 11:1531-1574, 2021.
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Affiliation(s)
- Victor A Convertino
- Battlefield Healthy & Trauma Center for Human Integrative Physiology, United States Army Institute of Surgical Research, JBSA San Antonio, Texas, USA
| | - Natalie J Koons
- Battlefield Healthy & Trauma Center for Human Integrative Physiology, United States Army Institute of Surgical Research, JBSA San Antonio, Texas, USA
| | - Mithun R Suresh
- Battlefield Healthy & Trauma Center for Human Integrative Physiology, United States Army Institute of Surgical Research, JBSA San Antonio, Texas, USA
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Rosenberg AJ, Kay VL, Anderson GK, Sprick JD, Rickards CA. A comparison of protocols for simulating hemorrhage in humans: step versus ramp lower body negative pressure. J Appl Physiol (1985) 2021; 130:380-389. [PMID: 33211600 DOI: 10.1152/japplphysiol.00230.2020] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Lower body negative pressure (LBNP) elicits central hypovolemia, and it has been used to simulate the cardiovascular and cerebrovascular responses to hemorrhage in humans. LBNP protocols commonly use progressive stepwise reductions in chamber pressure for specific time periods. However, continuous ramp LBNP protocols have also been utilized to simulate the continuous nature of most bleeding injuries. The aim of this study was to compare tolerance and hemodynamic responses between these two LBNP profiles. Healthy human subjects (N = 19; age, 27 ± 4 y; 7 female/12 male) completed a 1) step LBNP protocol (5-min steps) and 2) continuous ramp LBNP protocol (3 mmHg/min), both to presyncope. Heart rate (HR), mean arterial pressure (MAP), stroke volume (SV), middle and posterior cerebral artery velocity (MCAv and PCAv), cerebral oxygen saturation (ScO2), and end-tidal CO2 (etCO2) were measured. LBNP tolerance, via the cumulative stress index (CSI, summation of chamber pressure × time at each pressure), and hemodynamic responses were compared between the two protocols. The CSI (step: 911 ± 97 mmHg/min vs. ramp: 823 ± 83 mmHg/min; P = 0.12) and the magnitude of central hypovolemia (%Δ SV, step: -54.6% ± 2.6% vs. ramp: -52.1% ± 2.8%; P = 0.32) were similar between protocols. Although there were no differences between protocols for the maximal %Δ HR (P = 0.88), the %Δ MAP during the step protocol was attenuated (P = 0.05), and the reductions in MCAv, PCAv, ScO2, and etCO2 were greater (P ≤ 0.08) when compared with the ramp protocol at presyncope. These results indicate that when comparing cardiovascular responses to LBNP across different laboratories, the specific pressure profile must be considered as a potential confounding factor.NEW & NOTEWORTHY Ramp lower body negative pressure (LBNP) protocols have been utilized to simulate the continuous nature of bleeding injuries. However, it unknown if tolerance or the physiological responses to ramp LBNP are similar to the more common stepwise LBNP protocol. We report similar tolerance between the two protocols, but the step protocol elicited a greater increase in cerebral oxygen extraction in the presence of reduced blood flow, presumably facilitating the matching of metabolic supply and demand.
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Affiliation(s)
- Alexander J Rosenberg
- Cerebral and Cardiovascular Physiology Laboratory, Department of Physiology and Anatomy, University of North Texas Health Science Center, Fort Worth, Texas
| | - Victoria L Kay
- Cerebral and Cardiovascular Physiology Laboratory, Department of Physiology and Anatomy, University of North Texas Health Science Center, Fort Worth, Texas
| | - Garen K Anderson
- Cerebral and Cardiovascular Physiology Laboratory, Department of Physiology and Anatomy, University of North Texas Health Science Center, Fort Worth, Texas
| | - Justin D Sprick
- Cerebral and Cardiovascular Physiology Laboratory, Department of Physiology and Anatomy, University of North Texas Health Science Center, Fort Worth, Texas.,Division of Renal Medicine, Department of Medicine, Emory University School of Medicine, Atlanta, Georgia
| | - Caroline A Rickards
- Cerebral and Cardiovascular Physiology Laboratory, Department of Physiology and Anatomy, University of North Texas Health Science Center, Fort Worth, Texas
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Huang M, Watso JC, Moralez G, Cramer MN, Hendrix JM, Yoo JK, Badrov MB, Fu Q, Hinojosa-Laborde C, Crandall CG. Low-dose ketamine affects blood pressure, but not muscle sympathetic nerve activity, during progressive central hypovolemia without altering tolerance. J Physiol 2020; 598:5661-5672. [PMID: 33084081 DOI: 10.1113/jp280491] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2020] [Accepted: 09/02/2020] [Indexed: 11/08/2022] Open
Abstract
KEY POINTS Haemorrhage is the leading cause of battlefield and civilian trauma deaths. Given that a haemorrhagic injury on the battlefield is almost always associated with pain, it is paramount that the administered pain medication does not disrupt the physiological mechanisms that are beneficial in defending against the haemorrhagic insult. Current guidelines from the US Army's Committee on Tactical Combat Casualty Care (CoTCCC) for the selection of pain medications administered to a haemorrhaging soldier are based upon limited scientific evidence, with the clear majority of supporting studies being conducted on anaesthetized animals. Specifically, the influence of low-dose ketamine, one of three analgesics employed in the pre-hospital setting by the US Army, on haemorrhagic tolerance in humans is unknown. For the first time in conscious males and females, the findings of the present study demonstrate that the administration of an analgesic dose of ketamine does not compromise tolerance to a simulated haemorrhagic insult. Increases in muscle sympathetic nerve activity during progressive lower-body negative pressure were not different between trials. Despite the lack of differences for muscle sympathetic nerve activity responses, mean blood pressure and heart rate were higher during moderate hypovolemia after ketamine vs. placebo administration. ABSTRACT Haemorrhage is the leading cause of battlefield and civilian trauma deaths. For a haemorrhaging soldier, there are several pain medications (e.g. ketamine) recommended for use in the prehospital, field setting. However, the data to support these recommendations are primarily limited to studies in animals. Therefore, it is unknown whether ketamine adversely affects physiological mechanisms responsible for maintenance of arterial blood pressure (BP) during haemorrhage in humans. In humans, ketamine has been demonstrated to raise resting BP, although it has not been studied with the concomitant central hypovolemia that occurs during haemorrhage. Thus, the present study aimed to test the hypothesis that ketamine does not impair haemorrhagic tolerance in humans. Thirty volunteers (15 females) participated in this double-blinded, randomized, placebo-controlled trial. A pre-syncopal limited progressive lower-body negative pressure (LBNP; a validated model for simulating haemorrhage) test was conducted following the administration of ketamine (20 mg) or placebo (saline). Tolerance was quantified as a cumulative stress index and compared between trials using a paired, two-tailed t test. We compared muscle sympathetic nerve activity (MSNA; microneurography), beat-to-beat BP (photoplethysmography) and heart rate (electrocardiogram) responses during the LBNP test using a mixed effects model (time [LBNP stage] × drug). Tolerance to the LBNP test was not different between trials (Ketamine: 635 ± 391 vs. Placebo: 652 ± 360 mmHg‧min, p = 0.77). Increases in MSNA burst frequency (time: P < 0.01, trial: p = 0.27, interaction: p = 0.39) during LBNP stages were no different between trials. Despite the lack of differences for MSNA responses, mean BP (time: P < 0.01, trial: P < 0.01, interaction: p = 0.01) and heart rate (time: P < 0.01, trial: P < 0.01, interaction: P < 0.01) were higher during moderate hypovolemia after ketamine vs. placebo administration (P < 0.05 for all, post hoc), but not at the end of LBNP. These data, which are the first to be obtained in conscious humans, demonstrate that the administration of low-dose ketamine does not impair tolerance to simulated haemorrhage or mechanisms responsible for maintenance of BP.
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Affiliation(s)
- Mu Huang
- Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas, Dallas, TX, USA.,Department of Applied Clinical Research, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Joseph C Watso
- Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas, Dallas, TX, USA.,Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Gilbert Moralez
- Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas, Dallas, TX, USA.,Department of Applied Clinical Research, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Matthew N Cramer
- Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas, Dallas, TX, USA.,Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, TX, USA.,Present address: Defense Research and Development Canada-Toronto Research Centre, Toronto, ON, Canada
| | - Joseph M Hendrix
- Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas, Dallas, TX, USA.,Department of Anesthesiology and Pain Management, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Jeung-Ki Yoo
- Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas, Dallas, TX, USA.,Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Mark B Badrov
- Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas, Dallas, TX, USA.,Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, TX, USA.,Present address: University Health Network and Sinai Health System Division of Cardiology, Department of Medicine, University of Toronto, Toronto, ON, Canada
| | - Qi Fu
- Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas, Dallas, TX, USA.,Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | | | - Craig G Crandall
- Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas, Dallas, TX, USA.,Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, TX, USA
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Aarotale PN, Blaber AP, Tavakolian K. Effect of Blood Volume Shift Simulated via Head-up Tilt on Photoplethysmography Morphology. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2020; 2020:2695-269. [PMID: 33018562 DOI: 10.1109/embc44109.2020.9176555] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
PPG can provide information on cardiovascular responses to fluid shifts from upper to lower part of body under the condition of orthostatic stress. The current study investigated ability of PPG derived LVET and other PPG derived features to identify progressive central hypovolemia induced by head up tilt (HUT) and evaluated potential use of LVET as early noninvasive indicator of blood loss. Continuous finger PPG, blood pressure, and electrocardiography were recorded simultaneously during 5-minutes of baseline and HUT of 20°, 40°, and 60° from 15 participants (age: 26.5 ± 3 years; height: 177 ± 8 cm; weight: 72 ± 10 kg, mean ± SD). Beat-by-beat pulse rate (PR), systolic amplitude (SA), systolic time (ST), diastolic time (DT), and PP Interval (PPI) and Ratio of pulse rate over systolic amplitude (PR/SA) were derived for each stage. LVET was derived from each stage. Friedman test followed by post-hoc analysis using Tukey-HSD was conducted to highlight the significance of changes induced by HUT. Application of 60° HUT (i.e. moderate category simulated hypovolemia) resulted in a significant change in PR (80±3 bpm vs 68±3 bpm, p=0.0008), DT (264±7 ms vs 303±4 ms, p=0.0008), ST (110±6 ms vs 117±7 ms, p=0.02), PP interval (764±39 ms vs 869±25 ms, p=0.0045), PR/SA (112±16 vs 82±21, p=0.012) , SA (0.875± 0.2 vs 1.69±0.6, p=0.012) and LVET(292 vs 351ms,p=0.0008) compared to baseline. LVET has a strong association with the change in central blood volume and may be used as a sensitive early marker of progressive hypovolemia. The findings of the study support the hypothesis of differentiating simulated hypovolemia based on PPG alone. Keywords: Hypovolemia, HUT, LVET.
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Assessment of Upper Extremity Venous Compliance in Patients With Abdominal Aortic Aneurysms. Eur J Vasc Endovasc Surg 2020; 60:739-746. [PMID: 32778487 DOI: 10.1016/j.ejvs.2020.07.009] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2019] [Revised: 06/28/2020] [Accepted: 07/03/2020] [Indexed: 11/21/2022]
Abstract
OBJECTIVE Abdominal aortic aneurysm (AAA) is associated with morphological and functional changes in both aneurysmal and non-aneurysmal arteries. However, it remains uncertain whether similar changes also exist in the venous vasculature. The aim of this study was to evaluate global venous function in patients with AAA and controls. METHODS This experimental study comprised 31 men with AAA (mean ± standard deviation age 70.0 ± 2.8 years) and 29 male controls (aged 70.6 ± 3.4 years). Venous occlusion plethysmography (VOP) was used to evaluate arm venous compliance at venous pressures between 10 and 60 mmHg in steps of 5 mmHg. Compensatory mobilisation of venous capacitance blood (capacitance response) was measured with a volumetric technique during experimental hypovolaemia induced by lower body negative pressure (LBNP). RESULTS The VOP induced pressure-volume curve was significantly less steep in patients with AAA (interaction, p < .001), indicating lower venous compliance. Accordingly, the corresponding pressure-compliance curves displayed reduced venous compliance at lower venous pressures in patients with AAA vs. controls (interaction, p < .001; AAA vs. control, p = .018). After adjusting for arterial hypertension, diabetes mellitus, hyperlipidaemia, chronic obstructive pulmonary disease, and smoking, VOP detected differences in venous compliance remained significant at low venous pressures, that is, at 10 mmHg (p = .008), 15 mmHg (p = .013), and 20 mmHg (p = .026). Mean venous compliance was negatively correlated with aortic diameter (r = -.332, p = .010). Mobilisation of venous capacitance response during LBNP was reduced by approximately 25% in patients with AAA (p = .030), and the redistribution of venous blood during LBNP was negatively correlated with aortic diameter (r = -.417, p = .007). CONCLUSION Men with AAA demonstrated reduced venous compliance and, as a result, a lesser capacity to mobilise peripheral venous blood to the central circulation during hypovolaemic stress. These findings imply that the AAA disease may be accompanied by functional changes in the venous vascular wall.
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Wojcik P, Batliwala S, Rowsey T, Galdamez LA, Lee AG. Spaceflight-Associated Neuro-ocular Syndrome (SANS): a review of proposed mechanisms and analogs. EXPERT REVIEW OF OPHTHALMOLOGY 2020. [DOI: 10.1080/17469899.2020.1787155] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Affiliation(s)
- Peter Wojcik
- Department of Ophthalmology, Blanton Eye Institute, Houston Methodist Hospital, Houston, TX, USA
| | - Shehzad Batliwala
- Department of Ophthalmology, Dean McGee Eye Institute, University of Oklahoma Health Science Center, Oklahoma City, OK, USA
| | - Tyler Rowsey
- College of Medicine, University of Oklahoma Health Science Center, Oklahoma City, OK, USA
| | - Laura A. Galdamez
- Department of Emergency Medicine, Memorial Hermann The Woodlands, Shenandoah, TX, USA
| | - Andrew G. Lee
- Department of Ophthalmology, Blanton Eye Institute, Houston Methodist Hospital, Houston, TX, USA
- Departments of Ophthalmology, Neurology, and Neurosurgery, Weill Cornell Medicine, New York, NY, USA
- Department of Ophthalmology, University of Texas Medical Branch, Galveston, TX, USA
- Department of Ophthalmology, University of Texas MD Anderson Cancer Center, Houston, TX, USA
- Texas A and M College of Medicine, Bryan, TX, USA
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Johnson BD, Schlader ZJ, Schaake MW, O'Leary MC, Hostler D, Lin H, St James E, Lema PC, Bola A, Clemency BM. Inferior Vena Cava Diameter is an Early Marker of Central Hypovolemia during Simulated Blood Loss. PREHOSP EMERG CARE 2020; 25:341-346. [PMID: 32628063 DOI: 10.1080/10903127.2020.1778823] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
INTRODUCTION Inferior vena cava (IVC) diameter decreases under conditions of hypovolemia. Point-of-care ultrasound (POCUS) may be useful to emergently assess IVC diameter. This study tested the hypothesis that ultrasound measurements of IVC diameter decreases during severe simulated blood loss. METHODS Blood loss was simulated in 14 healthy men (22 ± 2 years) using lower body negative pressure (LBNP). Pressure within the LBNP chamber was reduced 10 mmHg of LBNP every four minutes until participants experienced pre-syncopal symptoms or until 80 mmHg of LBNP was completed. IVC diameter was imaged with POCUS using B-mode in the long and short axis views between minutes two and four of each stage. RESULTS Maximum IVC diameter in the long axis view was lower than baseline (1.5 ± 0.4 cm) starting at -20 mmHg of LBNP (1.0 ± 0.3 cm; p < 0.01) and throughout LBNP (p < 0.01). The minimum IVC diameter in the long axis view was lower than baseline (0.9 ± 0.3 cm) at -20 mmHg of LBNP (0.5 ± 0.3 cm; p < 0.01) and throughout LBNP (p < 0.01). Maximum IVC diameter in the short axis view was lower than baseline (0.9 ± 0.2 cm) at 40 mmHg of LBNP (0.6 ± 0.2; p = 0.01) and the final LBNP stage (0.6 ± 0.2 cm; p < 0.01). IVC minimum diameter in the short axis view was lower than baseline (0.5 ± 0.2 cm) at the final LBNP stage (0.3 ± 0.2 cm; p = 0.01). CONCLUSION These data demonstrate that IVC diameter decreases prior to changes in traditional vital signs during simulated blood loss. Further study is needed to determine the view and diameter threshold that most accurate for identifying hemorrhage requiring emergent intervention.
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Zaar M, Herzig MC, Fedyk CG, Montgomery RK, Prat N, Parida BK, Hinojosa-Laborde C, Muniz GW, Shade RE, Bauer C, Delacruz W, Bynum JA, Convertino VA, Cap AP, Pidcoke HF. Similar hemostatic responses to hypovolemia induced by hemorrhage and lower body negative pressure reveal a hyperfibrinolytic subset of non-human primates. PLoS One 2020; 15:e0234844. [PMID: 32579572 PMCID: PMC7314422 DOI: 10.1371/journal.pone.0234844] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2019] [Accepted: 05/18/2020] [Indexed: 02/07/2023] Open
Abstract
BACKGROUND To study central hypovolemia in humans, lower body negative pressure (LBNP) is a recognized alternative to blood removal (HEM). While LBNP mimics the cardiovascular responses of HEM in baboons, similarities in hemostatic responses to LBNP and HEM remain unknown in this species. METHODS Thirteen anesthetized baboons were exposed to progressive hypovolemia by HEM and, four weeks later, by LBNP. Hemostatic activity was evaluated by plasma markers, thromboelastography (TEG), flow cytometry, and platelet aggregometry at baseline (BL), during and after hypovolemia. RESULTS BL values were indistinguishable for most parameters although platelet count, maximal clot strength (MA), protein C, thrombin anti-thrombin complex (TAT), thrombin activatable fibrinolysis inhibitor (TAFI) activity significantly differed between HEM and LBNP. Central hypovolemia induced by either method activated coagulation; TEG R-time decreased and MA increased during and after hypovolemia compared to BL. Platelets displayed activation by flow cytometry; platelet count and functional aggregometry were unchanged. TAFI activity and protein, Factors V and VIII, vWF, Proteins C and S all demonstrated hemodilution during HEM and hemoconcentration during LBNP, whereas tissue plasminogen activator (tPA), plasmin/anti-plasmin complex, and plasminogen activator inhibitor-1 did not. Fibrinolysis (TEG LY30) was unchanged by either method; however, at BL, fibrinolysis varied greatly. Post-hoc analysis separated baboons into low-lysis (LY30 <2%) or high-lysis (LY30 >2%) whose fibrinolytic state matched at both HEM and LBNP BL. In high-lysis, BL tPA and LY30 correlated strongly (r = 0.95; P<0.001), but this was absent in low-lysis. In low-lysis, BL TAFI activity and tPA correlated (r = 0.88; P<0.050), but this was absent in high-lysis. CONCLUSIONS Central hypovolemia induced by either LBNP or HEM resulted in activation of coagulation; thus, LBNP is an adjunct to study hemorrhage-induced pro-coagulation in baboons. Furthermore, this study revealed a subset of baboons with baseline hyperfibrinolysis, which was strongly coupled to tPA and uncoupled from TAFI activity.
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Affiliation(s)
- Morten Zaar
- Center for Human Integrative Physiology, United States Army Institute of Surgical Research, Fort Sam Houston, Texas, United States of America
| | - Maryanne C. Herzig
- Coagulation and Blood Research, United States Army Institute of Surgical Research, Fort Sam Houston, Texas, United States of America
- * E-mail:
| | - Chriselda G. Fedyk
- Coagulation and Blood Research, United States Army Institute of Surgical Research, Fort Sam Houston, Texas, United States of America
| | - Robbie K. Montgomery
- Coagulation and Blood Research, United States Army Institute of Surgical Research, Fort Sam Houston, Texas, United States of America
| | - Nicolas Prat
- Coagulation and Blood Research, United States Army Institute of Surgical Research, Fort Sam Houston, Texas, United States of America
- French Armed Forces Biomedical Research Institute (IRBA), Brétigny-sur-Orge, France
| | - Bijaya K. Parida
- Coagulation and Blood Research, United States Army Institute of Surgical Research, Fort Sam Houston, Texas, United States of America
| | - Carmen Hinojosa-Laborde
- Center for Human Integrative Physiology, United States Army Institute of Surgical Research, Fort Sam Houston, Texas, United States of America
| | - Gary W. Muniz
- Center for Human Integrative Physiology, United States Army Institute of Surgical Research, Fort Sam Houston, Texas, United States of America
| | - Robert E. Shade
- Southwest National Primate Research Center, Texas Biomedical Research Institute, San Antonio, Texas, United States of America
| | - Cassondra Bauer
- Southwest National Primate Research Center, Texas Biomedical Research Institute, San Antonio, Texas, United States of America
| | - Wilfred Delacruz
- Center for Human Integrative Physiology, United States Army Institute of Surgical Research, Fort Sam Houston, Texas, United States of America
| | - James A. Bynum
- Coagulation and Blood Research, United States Army Institute of Surgical Research, Fort Sam Houston, Texas, United States of America
| | - Victor A. Convertino
- Center for Human Integrative Physiology, United States Army Institute of Surgical Research, Fort Sam Houston, Texas, United States of America
| | - Andrew P. Cap
- Coagulation and Blood Research, United States Army Institute of Surgical Research, Fort Sam Houston, Texas, United States of America
| | - Heather F. Pidcoke
- Coagulation and Blood Research, United States Army Institute of Surgical Research, Fort Sam Houston, Texas, United States of America
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Colombo R, Wu MA, Perotti A, Saia L, Fossali T, Ottolina D, Borghi B, Castelli A, Rech R, Cogliati C, Catena E. Tethering role of the autonomic nervous system on cardioventilatory coupling. Respir Physiol Neurobiol 2020; 279:103466. [PMID: 32454241 DOI: 10.1016/j.resp.2020.103466] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2019] [Revised: 04/10/2020] [Accepted: 05/10/2020] [Indexed: 11/28/2022]
Abstract
Hypovolemia and intermittent positive pressure ventilation are conditions that frequently characterize the state of critical illness, but their interaction and resulting cardioventilatory coupling is poorly understood even in healthy humans. We explored heart rate variability, baroreflex activity, and their interaction in an experimental protocol involving twelve mildly hypovolemic healthy subjects during spontaneous breathing and noninvasive positive-pressure ventilation. In seven subjects, an echocardiographic assessment was also performed. Correction of hypovolemia, raising cardiac preload, produced an increase in high-frequency spectral power density of heart rate, left low-frequency spectral power density unchanged but enhanced baroreflex sensitivity. Cardioventilatory coupling was affected by both central blood volume and ventilatory mode and was mainly entrained by the respiratory oscillation. In conclusion, the autonomic nervous system and baroreflex have a significant role in compensating the hemodynamic perturbation due to changes of volemia and ventilatory-induced fluctuations of venous return. They exert an integrative function on the adaptive pattern of cardioventilatory coupling.
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Affiliation(s)
- Riccardo Colombo
- Department of Anesthesiology and Intensive Care, ASST Fatebenefratelli Sacco, Luigi Sacco Hospital - Polo Universitario, University of Milan, Milan, Italy.
| | - Maddalena Alessandra Wu
- Department of Internal Medicine, ASST Fatebenefratelli Sacco, "Luigi Sacco" Hospital - Polo Universitario - University of Milan, Via G.B. Grassi 74, 20157 Milan, Italy
| | - Andrea Perotti
- Department of Anesthesiology and Intensive Care, ASST Fatebenefratelli Sacco, Luigi Sacco Hospital - Polo Universitario, University of Milan, Milan, Italy
| | - Laura Saia
- School of Anesthesia and Intensive Care, University of Milan, Milan, Italy
| | - Tommaso Fossali
- Department of Anesthesiology and Intensive Care, ASST Fatebenefratelli Sacco, Luigi Sacco Hospital - Polo Universitario, University of Milan, Milan, Italy
| | - Davide Ottolina
- Department of Anesthesiology and Intensive Care, ASST Fatebenefratelli Sacco, Luigi Sacco Hospital - Polo Universitario, University of Milan, Milan, Italy
| | - Beatrice Borghi
- Department of Anesthesiology and Intensive Care, ASST Fatebenefratelli Sacco, Luigi Sacco Hospital - Polo Universitario, University of Milan, Milan, Italy
| | - Antonio Castelli
- Department of Anesthesiology and Intensive Care, ASST Fatebenefratelli Sacco, Luigi Sacco Hospital - Polo Universitario, University of Milan, Milan, Italy
| | - Roberto Rech
- Department of Anesthesiology and Intensive Care, ASST Fatebenefratelli Sacco, Luigi Sacco Hospital - Polo Universitario, University of Milan, Milan, Italy
| | - Chiara Cogliati
- Department of Internal Medicine, ASST Fatebenefratelli Sacco, "Luigi Sacco" Hospital - Polo Universitario - University of Milan, Via G.B. Grassi 74, 20157 Milan, Italy
| | - Emanuele Catena
- Department of Anesthesiology and Intensive Care, ASST Fatebenefratelli Sacco, Luigi Sacco Hospital - Polo Universitario, University of Milan, Milan, Italy
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Trotter CE, Tourula E, Pizzey FK, Batterson PM, Jacobs RA, Pearson J. High‐intensity interval exercise reduces tolerance to a simulated haemorrhagic challenge in heat‐stressed individuals. Exp Physiol 2020; 106:212-221. [DOI: 10.1113/ep088377] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2019] [Accepted: 01/28/2020] [Indexed: 11/08/2022]
Affiliation(s)
- Claire E. Trotter
- Department of Human Physiology and Nutrition University of Colorado at Colorado Springs Colorado Springs CO USA
- Department of Applied Physiology and Wellness Southern Methodist University Dallas TX USA
| | - Erica Tourula
- Department of Human Physiology and Nutrition University of Colorado at Colorado Springs Colorado Springs CO USA
| | - Faith K. Pizzey
- Department of Human Physiology and Nutrition University of Colorado at Colorado Springs Colorado Springs CO USA
- School of Human Movement and Nutrition Sciences The University of Queensland Brisbane Australia
| | - Philip M. Batterson
- Department of Human Physiology and Nutrition University of Colorado at Colorado Springs Colorado Springs CO USA
- College of Biological and Population Health Sciences Oregon State University Corvallis OR USA
| | - Robert A. Jacobs
- Department of Human Physiology and Nutrition University of Colorado at Colorado Springs Colorado Springs CO USA
| | - James Pearson
- Department of Human Physiology and Nutrition University of Colorado at Colorado Springs Colorado Springs CO USA
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Gerega A, Wojtkiewicz S, Sawosz P, Kacprzak M, Toczylowska B, Bejm K, Skibniewski F, Sobotnicki A, Gacek A, Maniewski R, Liebert A. Assessment of the brain ischemia during orthostatic stress and lower body negative pressure in air force pilots by near-infrared spectroscopy. BIOMEDICAL OPTICS EXPRESS 2020; 11:1043-1060. [PMID: 32133236 PMCID: PMC7041453 DOI: 10.1364/boe.377779] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/23/2019] [Revised: 01/09/2020] [Accepted: 01/10/2020] [Indexed: 05/26/2023]
Abstract
A methodology for the assessment of the cerebral hemodynamic reaction to normotensive hypovolemia, reduction in cerebral perfusion and orthostatic stress leading to ischemic hypoxia and reduced muscular tension is presented. Most frequently, the pilots of highly maneuverable aircraft are exposed to these phenomena. Studies were carried out using the system consisting of a chamber that generates low pressure around the lower part of the body - LBNP (lower body negative pressure) placed on the tilt table. An in-house developed 6-channel NIRS system operating at 735 and 850 nm was used in order to assess the oxygenation of the cerebral cortex, based on measurements of diffusely reflected light in reflectance geometry. The measurements were carried out on a group of 12 active pilots and cadets of the Polish Air Force Academy and 12 healthy volunteers. The dynamics of changes in cerebral oxygenation was evaluated as a response to LBNP stimuli with a simultaneous rapid change of the tilt table angle. Parameters based on calculated changes of total hemoglobin concentration were proposed allowing to evaluate differences in reactions observed in control subjects and pilots/cadets. The results of orthogonal partial least squares-discriminant analysis based on these parameters show that the subjects can be classified into their groups with 100% accuracy.
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Affiliation(s)
- Anna Gerega
- Nalecz Institute of Biocybernetics and Biomedical Engineering, Polish Academy of Sciences, Warsaw, Poland
| | - Stanislaw Wojtkiewicz
- Nalecz Institute of Biocybernetics and Biomedical Engineering, Polish Academy of Sciences, Warsaw, Poland
| | - Piotr Sawosz
- Nalecz Institute of Biocybernetics and Biomedical Engineering, Polish Academy of Sciences, Warsaw, Poland
| | - Michal Kacprzak
- Nalecz Institute of Biocybernetics and Biomedical Engineering, Polish Academy of Sciences, Warsaw, Poland
| | - Beata Toczylowska
- Nalecz Institute of Biocybernetics and Biomedical Engineering, Polish Academy of Sciences, Warsaw, Poland
| | - Karolina Bejm
- Nalecz Institute of Biocybernetics and Biomedical Engineering, Polish Academy of Sciences, Warsaw, Poland
| | - Franciszek Skibniewski
- Technical Department of Aeromedical Research and Flight Simulators, Military Institute of Aviation Medicine, Warsaw, Poland
| | - Aleksander Sobotnicki
- Department of Research and Development, Institute of Medical Technology and Equipment, Zabrze, Poland
| | - Adam Gacek
- Department of Research and Development, Institute of Medical Technology and Equipment, Zabrze, Poland
| | - Roman Maniewski
- Nalecz Institute of Biocybernetics and Biomedical Engineering, Polish Academy of Sciences, Warsaw, Poland
| | - Adam Liebert
- Nalecz Institute of Biocybernetics and Biomedical Engineering, Polish Academy of Sciences, Warsaw, Poland
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Tigges T, Feldheiser A, Pielmus A, Klum M, Wiegank L, Orglmeister R. Evaluation of Pulse Arrival Times during Lower Body Negative Pressure Test for the Non-Invasive Detection of Hypovolemia. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2020; 2019:3770-3774. [PMID: 31946695 DOI: 10.1109/embc.2019.8856652] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
The early detection of occult bleeding is a difficult problem for clinicians because physiological variables such as heart rate and blood pressure that are measured with standard patient monitoring equipment are insensitive to blood loss. In this study, the pulse arrival time (PAT) was investigated as an easily recorded, non-invasive indicator of hypovolemia. A lower body negative pressure (LBNP) study with a stepwise increase of negative pressure was conducted to induce central hypovolemia in a study population of 30 subjects. PAT values were extracted from simultaneous recordings of the electrocardiogram (ECG) and photoplethysmographic (PPG) recordings both from the index finger and from within the outer ear canal. Stroke volume (SV) was recorded as a reference measure by transthoracic echocardiography. An inter- and intra-individual correlation analysis between changes in SV and the PAT measurements was performed. Furthermore, it was assessed if PAT measurements can indicate a diminished SV in this scenario. It could be demonstrated that the measured PAT values are significantly increased at the lowest LBNP pressure level. A very strong intra-individual correlation (ρ ≥ 0.8) and a moderate inter-individual correlation (ρ ≥ 0.5) between PAT and SV measurements were found. Thus, PAT measurements could be a viable tool to monitor patient specific volemic trends. Further research is needed to investigate if PAT information can be utilized for a more robust inter-subject quantification of the degree of hypovolemia.
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Schlotman TE, Lehnhardt KR, Abercromby AF, Easter BD, Downs ME, Akers LTCKS, Convertino VA. Bridging the gap between military prolonged field care monitoring and exploration spaceflight: the compensatory reserve. NPJ Microgravity 2019; 5:29. [PMID: 31815179 PMCID: PMC6893012 DOI: 10.1038/s41526-019-0089-9] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2019] [Accepted: 10/31/2019] [Indexed: 01/03/2023] Open
Abstract
The concept of prolonged field care (PFC), or medical care applied beyond doctrinal planning timelines, is the top priority capability gap across the US Army. PFC is the idea that combat medics must be prepared to provide medical care to serious casualties in the field without the support of robust medical infrastructure or resources in the event of delayed medical evacuation. With limited resources, significant distances to travel before definitive care, and an inability to evacuate in a timely fashion, medical care during exploration spaceflight constitutes the ultimate example PFC. One of the main capability gaps for PFC in both military and spaceflight settings is the need for technologies for individualized monitoring of a patient's physiological status. A monitoring capability known as the compensatory reserve measurement (CRM) meets such a requirement. CRM is a small, portable, wearable technology that uses a machine learning and feature extraction-based algorithm to assess real-time changes in hundreds of specific features of arterial waveforms. Future development and advancement of CRM still faces engineering challenges to develop ruggedized wearable sensors that can measure waveforms for determining CRM from multiple sites on the body and account for less than optimal conditions (sweat, water, dirt, blood, movement, etc.). We show here the utility of a military wearable technology, CRM, which can be translated to space exploration.
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Affiliation(s)
- Taylor E. Schlotman
- United States Army Institute of Surgical Research 3698 Chambers Pass, Bldg. 3611 JBSA Fort Sam, Houston, TX 78234 USA
| | | | | | | | - Meghan E. Downs
- NASA Johnson Space Center, 2101 E NASA Pkwy, Houston, TX 77058 USA
| | - L. T. C. Kevin S. Akers
- United States Army Institute of Surgical Research 3698 Chambers Pass, Bldg. 3611 JBSA Fort Sam, Houston, TX 78234 USA
| | - Victor A. Convertino
- United States Army Institute of Surgical Research 3698 Chambers Pass, Bldg. 3611 JBSA Fort Sam, Houston, TX 78234 USA
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Medow MS, Guber K, Chokshi S, Terilli C, Visintainer P, Stewart JM. The Benefits of Oral Rehydration on Orthostatic Intolerance in Children with Postural Tachycardia Syndrome. J Pediatr 2019; 214:96-102. [PMID: 31405524 PMCID: PMC6815702 DOI: 10.1016/j.jpeds.2019.07.041] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/09/2019] [Revised: 07/11/2019] [Accepted: 07/15/2019] [Indexed: 11/18/2022]
Abstract
OBJECTIVE To evaluate whether equal volumes of oral rehydration solution (ORS) or intravenous (IV) saline provide similar improvements in cardiovascular status during controlled orthostatic challenge when administered to subjects with postural tachycardia syndrome (POTS) with orthostatic intolerance. STUDY DESIGN We studied the neurovascular response to fluid loading during orthostatic stress using lower body negative pressure (LBNP) in 10 subjects with POTS with orthostatic intolerance and 15 controls, and on subsequent days before and 1 hour after IV saline infusion or ingestion of ORS. RESULTS Subjects with POTS exhibited reduced tolerance to LBNP (P < .0001) compared with controls (Orthostatic Index of 35 715 ± 3469 vs 93 980 ± 7977, respectively). In POTS, following ORS but not saline infusion, cerebral blood flow velocity (CBFv) was significantly higher than that with no treatment, at -45 mm Hg (P < .0005). Although fluid loading did not confer any advantage in controls, subjects with POTS experienced a significant improvement in orthostatic tolerance following both saline infusion (100 ± 9.7 vs 134.5 ± 17.4; P < .05) and ORS (100 ± 9.7 vs 155.6 ± 15.7; P < .001) when evaluated by normalized orthostatic index (P < .001, compared with untreated baseline). CONCLUSIONS Maintenance of CBFv may have resulted in the improved short-term orthostatic tolerance exhibited by the subjects with POTS following ORS administration. ORS is a convenient, safe, and effective therapy for short-term relief of orthostatic intolerance.
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Affiliation(s)
- Marvin S Medow
- Department of Pediatrics, New York Medical College, Valhalla, NY; Department of Physiology, New York Medical College, Valhalla, NY.
| | | | | | - Courtney Terilli
- Department of Pediatrics, New York Medical College, Valhalla, NY
| | - Paul Visintainer
- Department of Epidemiology and Biostatistics, Baystate Medical Center, University of Massachusetts School of Medicine, Worcester, MA
| | - Julian M Stewart
- Department of Pediatrics, New York Medical College, Valhalla, NY; Department of Physiology, New York Medical College, Valhalla, NY
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Hoff IE, Hisdal J, Landsverk SA, Røislien J, Kirkebøen KA, Høiseth LØ. Respiratory variations in pulse pressure and photoplethysmographic waveform amplitude during positive expiratory pressure and continuous positive airway pressure in a model of progressive hypovolemia. PLoS One 2019; 14:e0223071. [PMID: 31560715 PMCID: PMC6764667 DOI: 10.1371/journal.pone.0223071] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2019] [Accepted: 09/12/2019] [Indexed: 11/18/2022] Open
Abstract
PURPOSE Respiratory variations in pulse pressure (dPP) and photoplethysmographic waveform amplitude (dPOP) are used for evaluation of volume status in mechanically ventilated patients. Amplification of intrathoracic pressure changes may enable their use also during spontaneous breathing. We investigated the association between the degree of hypovolemia and dPP and dPOP at different levels of two commonly applied clinical interventions; positive expiratory pressure (PEP) and continuous positive airway pressure (CPAP). METHODS 20 healthy volunteers were exposed to progressive hypovolemia by lower body negative pressure (LBNP). PEP of 0 (baseline), 5 and 10 cmH2O was applied by an expiratory resistor and CPAP of 0 (baseline), 5 and 10 cmH2O by a facemask. dPP was obtained non-invasively with the volume clamp method and dPOP from a pulse oximeter. Central venous pressure was measured in 10 subjects. Associations between changes were examined using linear mixed-effects regression models. RESULTS dPP increased with progressive LBNP at all levels of PEP and CPAP. The LBNP-induced increase in dPP was amplified by PEP 10 cmH20. dPOP increased with progressive LBNP during PEP 5 and PEP 10, and during all levels of CPAP. There was no additional effect of the level of PEP or CPAP on dPOP. Progressive hypovolemia and increasing levels of PEP were reflected by increasing respiratory variations in CVP. CONCLUSION dPP and dPOP reflected progressive hypovolemia in spontaneously breathing healthy volunteers during PEP and CPAP. An increase in PEP from baseline to 10 cmH2O augmented the increase in dPP, but not in dPOP.
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Affiliation(s)
- Ingrid Elise Hoff
- Norwegian Air Ambulance Foundation, Sentrum, Oslo, Norway
- Department of Anesthesiology, Oslo University Hospital, Nydalen, Oslo, Norway
- * E-mail:
| | - Jonny Hisdal
- Section of Vascular Investigations, Department of Vascular Surgery, Oslo University Hospital, Nydalen, Oslo, Norway
- Faculty of Medicine, University of Oslo, Blindern, Oslo, Norway
| | | | - Jo Røislien
- Norwegian Air Ambulance Foundation, Sentrum, Oslo, Norway
| | | | - Lars Øivind Høiseth
- Department of Anesthesiology, Oslo University Hospital, Nydalen, Oslo, Norway
- Section of Vascular Investigations, Department of Vascular Surgery, Oslo University Hospital, Nydalen, Oslo, Norway
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