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Paladugu P, Ong J, Kumar R, Waisberg E, Zaman N, Kamran SA, Tavakkoli A, Rivolta MC, Nelson N, Yoo T, Douglas VP, Douglas K, Song A, Tso H, Lee AG. Lower body negative pressure as a research tool and countermeasure for the physiological effects of spaceflight: A comprehensive review. LIFE SCIENCES IN SPACE RESEARCH 2024; 42:8-16. [PMID: 39067995 DOI: 10.1016/j.lssr.2024.03.007] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/23/2023] [Revised: 03/07/2024] [Accepted: 03/31/2024] [Indexed: 07/30/2024]
Abstract
Lower Body Negative Pressure (LBNP) redistributes blood from the upper body to the lower body. LBNP may prove to be a countermeasure for the multifaceted physiological changes endured by astronauts during spaceflight related to cephalad fluid shift. Over more than five decades, beginning with the era of Skylab, advancements in LBNP technology have expanded our understanding of neurological, ophthalmological, cardiovascular, and musculoskeletal adaptations in space, with particular emphasis on mitigating issues such as bone loss. To date however, no comprehensive review has been conducted that chronicles the evolution of this technology or elucidates the broad-spectrum potential of LBNP in managing the diverse physiological challenges encountered in the microgravity environment. Our study takes a chronological perspective, systematically reviewing the historical development and application of LBNP technology in relation to the various pathophysiological impacts of spaceflight. The primary objective is to illustrate how this technology, as it has evolved, offers an increasingly sophisticated lens through which to interpret the systemic effects of space travel on human physiology. We contend that the insights gained from LBNP studies can significantly aid in formulating targeted and effective countermeasures to ensure the health and safety of astronauts. Ultimately, this paper aspires to promote a more cohesive understanding of the broad applicability of LBNP as a countermeasure against multiple bodily effects of space travel, thereby contributing to a safer and more scientifically informed approach to human space exploration.
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Affiliation(s)
- Phani Paladugu
- Brigham and Women's Hospital, Harvard Medical School, Boston, MA, United States; Sidney Kimmel Medical College, Philadelphia, PA, United States
| | - Joshua Ong
- Michigan Medicine, University of Michigan, Ann Arbor, MI, United States
| | - Rahul Kumar
- University of Miami, Coral Gables, FL, United States
| | - Ethan Waisberg
- University College Dublin School of Medicine, Belfield, Dublin, Ireland
| | - Nasif Zaman
- Human-Machine Perception Laboratory, Department of Computer Science and Engineering, University of Nevada, Reno, Reno, NV, United States
| | - Sharif Amit Kamran
- Human-Machine Perception Laboratory, Department of Computer Science and Engineering, University of Nevada, Reno, Reno, NV, United States
| | - Alireza Tavakkoli
- Human-Machine Perception Laboratory, Department of Computer Science and Engineering, University of Nevada, Reno, Reno, NV, United States
| | | | - Nicolas Nelson
- Sidney Kimmel Medical College, Philadelphia, PA, United States
| | - Taehwan Yoo
- Sidney Kimmel Medical College, Philadelphia, PA, United States
| | | | - Konstantinos Douglas
- First Department of Ophthalmology, Gennimatas General Hospital, National and Kapodistrian University of Athens, School of Medicine, Athens, Greece
| | - Amy Song
- University of Illinois College of Medicine, Chicago, IL, United States
| | - Hanna Tso
- Department of Ophthalmology, Baylor College of Medicine, Houston, TX, United States
| | - Andrew G Lee
- Center for Space Medicine, Baylor College of Medicine, Houston, TX, United States; Department of Ophthalmology, Blanton Eye Institute, Houston Methodist Hospital, Houston, TX, United States; The Houston Methodist Research Institute, Houston Methodist Hospital, Houston, TX, United States; Departments of Ophthalmology, Neurology, and Neurosurgery, Weill Cornell Medicine, New York, NY, United States; Department of Ophthalmology, University of Texas Medical Branch, Galveston, TX, United States; University of Texas MD Anderson Cancer Center, Houston, TX, United States; Texas A&M College of Medicine, TX, United States; Department of Ophthalmology, The University of Iowa Hospitals and Clinics, Iowa City, IA, United States.
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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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Shankhwar V, Urvec J, Steuber B, Schmid Zalaudek K, Bergauer A, Alsuwaidi H, Du Plessis S, Alsheikh-Ali A, Kellett C, Bayoumi R, Blaber AP, Goswami N. Association of gender with cardiovascular and autonomic responses to central hypovolemia. Front Cardiovasc Med 2023; 10:1211774. [PMID: 37719984 PMCID: PMC10501725 DOI: 10.3389/fcvm.2023.1211774] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2023] [Accepted: 08/14/2023] [Indexed: 09/19/2023] Open
Abstract
Introduction Lower body negative pressure (LBNP) eliminates the impact of weight-bearing muscles on venous return, as well as the vestibular component of cardiovascular and autonomic responses. We evaluated the hemodynamic and autonomic responses to central hypovolemia, induced by LBNP in both males and females. Methodology A total of 44 participants recruited in the study. However, 9 participants did not complete the study protocol. Data from the remaining 35 participants were analysed, 18 males (25.28 ± 3.61 years, 181.50 ± 7.43 cm height, 74.22 ± 9.16 kg weight) and 17 females (22.41 ± 2.73 years, 167.41 ± 6.29 cm height, 59.06 ± 6.91 kg weight). During the experimental protocol, participants underwent three phases, which included 30 min of supine rest, four 4 min intervals of stepwise increases in LBNP from -10 mmHg to -40 mmHg, and 5 min of supine recovery. Throughout the protocol, hemodynamic variables such as blood pressure, heart rate, stroke index, cardiac index, and total peripheral resistance index were continuously monitored. Autonomic variables were calculated from heart rate variability measures, using low and high-frequency spectra, as indicators of sympathetic and parasympathetic activity, respectively. Results At rest, males exhibited higher systolic (118.56 ± 9.59 mmHg and 110.03 ± 10.88 mmHg, p < 0.05) and mean arterial (89.70 ± 6.86 and 82.65 ± 9.78, p < 0.05) blood pressure as compared to females. Different levels of LBNP altered hemodynamic variables in both males and females: heart rate [F(1,16) = 677.46, p < 0.001], [F(1,16) = 550.87, p < 0.001]; systolic blood pressures [F(1,14) = 3,186.77, p < 0.001], [F(1,17) = 1,345.61, p < 0.001]; diastolic blood pressure [F(1,16) = 1,669.458, p < 0.001], [F(1,16) = 1,127.656, p < 0.001]; mean arterial pressures [F(1,16) = 2,330.44, p < 0.001], [F(1,16) = 1,815.68, p < 0.001], respectively. The increment in heart rates during LBNP was significantly different between both males and females (p = 0.025). The low and high-frequency powers were significantly different for males and females (p = 0.002 and p = 0.001, respectively), with the females having a higher increase in low-frequency spectral power. Conclusions and future directions Cardiovascular activity and autonomic function at rest are influenced by gender. During LBNP application, hemodynamic and autonomic responses differed between genders. These gender-based differences in responses during central hypovolemia could potentially be attributed to the lower sympathetic activity in females. With an increasing number of female crew members in space missions, it is important to understand the role sex-steroid hormones play in the regulation of cardiovascular and autonomic activity, at rest and during LBNP.
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Affiliation(s)
- Vishwajeet Shankhwar
- College of Medicine, Mohammed Bin Rashid University of Medicine and Health Sciences, Dubai, United Arab Emirates
| | - Janez Urvec
- Faculty of Mechanical Engineering, University of Ljubljana, Ljubljana, Slovenia
| | - Bianca Steuber
- Division of Physiology, Otto Löwi Research Center of Vascular Biology, Immunity and Inflammation, Medical University of Graz, Graz, Austria
| | - Karin Schmid Zalaudek
- Division of Physiology, Otto Löwi Research Center of Vascular Biology, Immunity and Inflammation, Medical University of Graz, Graz, Austria
| | - Andrej Bergauer
- Faculty of Mechanical Engineering, University of Ljubljana, Ljubljana, Slovenia
- Department of Surgery, General Hospital (LKH Südsteiermark), Wagna, Austria
| | - Hanan Alsuwaidi
- College of Medicine, Mohammed Bin Rashid University of Medicine and Health Sciences, Dubai, United Arab Emirates
| | - Stefan Du Plessis
- College of Medicine, Mohammed Bin Rashid University of Medicine and Health Sciences, Dubai, United Arab Emirates
| | - Alawi Alsheikh-Ali
- College of Medicine, Mohammed Bin Rashid University of Medicine and Health Sciences, Dubai, United Arab Emirates
| | - Catherine Kellett
- College of Medicine, Mohammed Bin Rashid University of Medicine and Health Sciences, Dubai, United Arab Emirates
| | - Riad Bayoumi
- College of Medicine, Mohammed Bin Rashid University of Medicine and Health Sciences, Dubai, United Arab Emirates
| | - Andrew Phillip Blaber
- Department of Biomedical Physiology and Kinesiology, Simon Fraser University, Burnaby, BC, Canada
| | - Nandu Goswami
- College of Medicine, Mohammed Bin Rashid University of Medicine and Health Sciences, Dubai, United Arab Emirates
- Division of Physiology, Otto Löwi Research Center of Vascular Biology, Immunity and Inflammation, Medical University of Graz, Graz, Austria
- Department of Integrative Medicine, Alma Mater Europea, Maribor, Slovenia
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Miutz LN, Burma JS, Van Roessel RK, Johnson NE, Phillips AA, Emery CA, Brassard P, Smirl JD. The effect of supine cycling and progressive lower body negative pressure on cerebral blood velocity responses. J Appl Physiol (1985) 2023; 135:316-325. [PMID: 37348016 DOI: 10.1152/japplphysiol.00758.2022] [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: 12/15/2022] [Revised: 06/08/2023] [Accepted: 06/08/2023] [Indexed: 06/24/2023] Open
Abstract
Moderate-intensity aerobic exercise increases cerebral blood velocity (CBv) primarily due to hyperpnea-induced vasodilation; however, the integrative control of cerebral blood flow (CBF) allows other factors to contribute to the vasodilation. Although lower body negative pressure (LBNP) can reduce CBv, the exact LBNP intensity required to blunt the aforementioned exercise-induced CBv response is unknown. This could hold utility for concussion recovery, allowing individuals to exercise at higher intensities without symptom exacerbation. Thirty-two healthy adults (age: 20-33 yr; 19 females/13 males) completed a stepwise maximal exercise test during a first visit to determine each participant's wattage associated with their exercise-induced maximal CBv increase. During the second visit, following supine rest, participants completed moderate-intensity exercise at their determined threshold, while progressive LBNP was applied at 0, -20, -40, -60, -70, -80, and ∼88 Torr. Bilateral middle cerebral artery blood velocities (MCAvs), mean arterial pressure (MAP), heart rate, respiratory rate, and end-tidal carbon dioxide levels were measured continuously. Two-way analysis of variance with effect sizes compared between sexes and stages. Compared with resting supine baseline, averaged MCAv was elevated during 0 and -20 Torr LBNP (q value > 7.73; P < 0.001); however, no differences were noted between baseline and -40 to -70 Torr (q value < |4.24|; P > 0.262). Differences were present between females and males for absolute MCAv measures (q value > 11.2; P < 0.001), but not when normalized to baseline (q value < 0.03; P > 0.951). Supine cycling-elicited increases in MCAv are able to be blunted during the application of LBNP ranging from -40 to -70 Torr. The blunted CBv response demonstrates the potential benefit of allowing individuals to aerobically train (moderate-intensity supine cycling with LBNP) without exacerbating symptoms during the concussion recovery phase.NEW & NOTEWORTHY The current investigation demonstrated that moderate-intensity supine cycling-induced increases in cerebral blood velocities were balanced by the lower body negative pressure-induced decreases in cerebral blood velocity. Although performed in a healthy population, the results may lend themselves to a potential treatment option for individuals recovering from concussion or experience persistent concussion symptoms.
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Affiliation(s)
- Lauren N Miutz
- Cerebrovascular Concussion Laboratory, Faculty of Kinesiology, University of Calgary, Calgary, Alberta, Canada
- Sport Injury Prevention Research Centre, Faculty of Kinesiology, University of Calgary, Calgary, Alberta, Canada
- Integrated Concussion Research Program, University of Calgary, Calgary, Alberta, Canada
- Alberta Children's Hospital Research Institute, University of Calgary, Calgary, Alberta, Canada
- Libin Cardiovascular Institute of Alberta, University of Calgary, Calgary, Alberta, Canada
- Department of Health and Sport Science, University of Dayton, Dayton, Ohio, United States
| | - Joel S Burma
- Cerebrovascular Concussion Laboratory, Faculty of Kinesiology, University of Calgary, Calgary, Alberta, Canada
- Sport Injury Prevention Research Centre, Faculty of Kinesiology, University of Calgary, Calgary, Alberta, Canada
- Integrated Concussion Research Program, University of Calgary, Calgary, Alberta, Canada
- Alberta Children's Hospital Research Institute, University of Calgary, Calgary, Alberta, Canada
- Libin Cardiovascular Institute of Alberta, University of Calgary, Calgary, Alberta, Canada
- Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta, Canada
- Human Performance Laboratory, Faculty of Kinesiology, University of Calgary, Calgary, Alberta, Canada
| | - Rowan K Van Roessel
- Cerebrovascular Concussion Laboratory, Faculty of Kinesiology, University of Calgary, Calgary, Alberta, Canada
| | - Nathan E Johnson
- Cerebrovascular Concussion Laboratory, Faculty of Kinesiology, University of Calgary, Calgary, Alberta, Canada
| | - Aaron A Phillips
- Libin Cardiovascular Institute of Alberta, University of Calgary, Calgary, Alberta, Canada
- Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta, Canada
- Departments of Physiology and Pharmacology, Clinical Neurosciences, Cardiac Sciences, University of Calgary, Calgary, Alberta, Canada
- Biomedical Engineering, and Kinesiology, University of Calgary, Calgary, Alberta, Canada
- Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada
| | - Carolyn A Emery
- Sport Injury Prevention Research Centre, Faculty of Kinesiology, University of Calgary, Calgary, Alberta, Canada
- Integrated Concussion Research Program, University of Calgary, Calgary, Alberta, Canada
- Alberta Children's Hospital Research Institute, University of Calgary, Calgary, Alberta, Canada
- Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta, Canada
- Human Performance Laboratory, Faculty of Kinesiology, University of Calgary, Calgary, Alberta, Canada
| | - Patrice Brassard
- Department of Kinesiology, Faculty of Medicine, University Laval, Quebec City, Québec, Canada
- Research center of the Institut universitaire de cardiologie et de pneumologie de Québec, Quebec City, Québec, Canada
| | - Jonathan D Smirl
- Cerebrovascular Concussion Laboratory, Faculty of Kinesiology, University of Calgary, Calgary, Alberta, Canada
- Sport Injury Prevention Research Centre, Faculty of Kinesiology, University of Calgary, Calgary, Alberta, Canada
- Integrated Concussion Research Program, University of Calgary, Calgary, Alberta, Canada
- Alberta Children's Hospital Research Institute, University of Calgary, Calgary, Alberta, Canada
- Libin Cardiovascular Institute of Alberta, University of Calgary, Calgary, Alberta, Canada
- Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta, Canada
- Human Performance Laboratory, Faculty of Kinesiology, University of Calgary, Calgary, Alberta, Canada
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Worley ML, Reed EL, Chapman CL, Kueck P, Seymour L, Fitts T, Zazulak H, Schlader ZJ, Johnson BD. Acute beetroot juice consumption does not alter cerebral autoregulation or cardiovagal baroreflex sensitivity during lower-body negative pressure in healthy adults. Front Hum Neurosci 2023; 17:1115355. [PMID: 36742355 PMCID: PMC9892911 DOI: 10.3389/fnhum.2023.1115355] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2022] [Accepted: 01/06/2023] [Indexed: 01/20/2023] Open
Abstract
Introduction Beetroot juice (BRJ) improves peripheral endothelial function and vascular compliance, likely due to increased nitric oxide bioavailability. It is unknown if BRJ alters cerebrovascular function and cardiovagal baroreflex control in healthy individuals. Purpose We tested the hypotheses that BRJ consumption improves cerebral autoregulation (CA) and cardiovagal baroreflex sensitivity (cBRS) during lower-body negative pressure (LBNP). Methods Thirteen healthy adults (age: 26 ± 4 years; 5 women) performed oscillatory (O-LBNP) and static LBNP (S-LBNP) before (PRE) and 3 h after consuming 500 mL of BRJ (POST). Participants inhaled 3% CO2 (21% O2, 76% N2) during a 5 min baseline and throughout LBNP to attenuate reductions in end-tidal CO2 tension (PETCO2). O-LBNP was conducted at ∼0.02 Hz for six cycles (-70 mmHg), followed by a 3-min recovery before S-LBNP (-40 mmHg) for 7 min. Beat-to-beat middle cerebral artery blood velocity (MCAv) (transcranial Doppler) and blood pressure were continuously recorded. CA was assessed using transfer function analysis to calculate coherence, gain, and phase in the very-low-frequency (VLF; 0.020-0.070 Hz) and low-frequency bands (LF; 0.07-0.20 Hz). cBRS was calculated using the sequence method. Comparisons between POST vs. PRE are reported as mean ± SD. Results During O-LBNP, coherence VLF was greater at POST (0.55 ± 0.06 vs. 0.46 ± 0.08; P < 0.01), but phase VLF (P = 0.17) and gain VLF (P = 0.69) were not different. Coherence LF and phase LF were not different, but gain LF was lower at POST (1.03 ± 0.20 vs. 1.12 ± 0.30 cm/s/mmHg; P = 0.05). During S-LBNP, CA was not different in the VLF or LF bands (all P > 0.10). Up-cBRS and Down-cBRS were not different during both LBNP protocols. Conclusion These preliminary data indicate that CA and cBRS during LBNP in healthy, young adults is largely unaffected by an acute bolus of BRJ.
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Affiliation(s)
- Morgan L. Worley
- Department of Exercise and Nutrition Sciences, School of Public Health and Health Professions, University at Buffalo, Buffalo, NY, United States
| | - Emma L. Reed
- Department of Exercise and Nutrition Sciences, School of Public Health and Health Professions, University at Buffalo, Buffalo, NY, United States
- Department of Human Physiology, Bowerman Sports Science Center, University of Oregon, Eugene, OR, United States
| | - Christopher L. Chapman
- Department of Exercise and Nutrition Sciences, School of Public Health and Health Professions, University at Buffalo, Buffalo, NY, United States
- Department of Human Physiology, Bowerman Sports Science Center, University of Oregon, Eugene, OR, United States
| | - Paul Kueck
- Department of Exercise and Nutrition Sciences, School of Public Health and Health Professions, University at Buffalo, Buffalo, NY, United States
| | - Lauren Seymour
- Department of Exercise and Nutrition Sciences, School of Public Health and Health Professions, University at Buffalo, Buffalo, NY, United States
| | - Triniti Fitts
- Department of Exercise and Nutrition Sciences, School of Public Health and Health Professions, University at Buffalo, Buffalo, NY, United States
| | - Hannah Zazulak
- Department of Exercise and Nutrition Sciences, School of Public Health and Health Professions, University at Buffalo, Buffalo, NY, United States
| | - Zachary J. Schlader
- Department of Exercise and Nutrition Sciences, School of Public Health and Health Professions, University at Buffalo, Buffalo, NY, United States
- Department of Kinesiology, School of Public Health, Indiana University Bloomington, Bloomington, IN, United States
| | - Blair D. Johnson
- Department of Exercise and Nutrition Sciences, School of Public Health and Health Professions, University at Buffalo, Buffalo, NY, United States
- Department of Kinesiology, School of Public Health, Indiana University Bloomington, Bloomington, IN, United States
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Gupta JF, Arshad SH, Telfer BA, Snider EJ, Convertino VA. Noninvasive Monitoring of Simulated Hemorrhage and Whole Blood Resuscitation. BIOSENSORS 2022; 12:bios12121168. [PMID: 36551134 PMCID: PMC9775873 DOI: 10.3390/bios12121168] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/19/2022] [Revised: 12/03/2022] [Accepted: 12/08/2022] [Indexed: 06/01/2023]
Abstract
Hemorrhage is the leading cause of preventable death from trauma. Accurate monitoring of hemorrhage and resuscitation can significantly reduce mortality and morbidity but remains a challenge due to the low sensitivity of traditional vital signs in detecting blood loss and possible hemorrhagic shock. Vital signs are not reliable early indicators because of physiological mechanisms that compensate for blood loss and thus do not provide an accurate assessment of volume status. As an alternative, machine learning (ML) algorithms that operate on an arterial blood pressure (ABP) waveform have been shown to provide an effective early indicator. However, these ML approaches lack physiological interpretability. In this paper, we evaluate and compare the performance of ML models trained on nine ABP-derived features that provide physiological insight, using a database of 13 human subjects from a lower-body negative pressure (LBNP) model of progressive central hypovolemia and subsequent progressive restoration to normovolemia (i.e., simulated hemorrhage and whole blood resuscitation). Data were acquired at multiple repressurization rates for each subject to simulate varying resuscitation rates, resulting in 52 total LBNP collections. This work is the first to use a single ABP-based algorithm to monitor both simulated hemorrhage and resuscitation. A gradient-boosted regression tree model trained on only the half-rise to dicrotic notch (HRDN) feature achieved a root-mean-square error (RMSE) of 13%, an R2 of 0.82, and area under the receiver operating characteristic curve of 0.97 for detecting decompensation. This single-feature model's performance compares favorably to previously reported results from more-complex black box machine learning models. This model further provides physiological insight because HRDN represents an approximate measure of the delay between the ABP ejected and reflected wave and therefore is an indication of cardiac and peripheral vascular mechanisms that contribute to the compensatory response to blood loss and replacement.
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Affiliation(s)
- Jay F. Gupta
- Lincoln Laboratory, Massachusetts Institute of Technology, Lexington, MA 02421, USA
| | - Saaid H. Arshad
- Lincoln Laboratory, Massachusetts Institute of Technology, Lexington, MA 02421, USA
| | - Brian A. Telfer
- Lincoln Laboratory, Massachusetts Institute of Technology, Lexington, MA 02421, USA
| | - Eric J. Snider
- U.S. Army Institute of Surgical Research, San Antonio, TX 78234, USA
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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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9
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van der Ster BJP, Kim YS, Westerhof BE, van Lieshout JJ. Central Hypovolemia Detection During Environmental Stress-A Role for Artificial Intelligence? Front Physiol 2021; 12:784413. [PMID: 34975538 PMCID: PMC8715014 DOI: 10.3389/fphys.2021.784413] [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: 09/27/2021] [Accepted: 11/18/2021] [Indexed: 11/19/2022] Open
Abstract
The first step to exercise is preceded by the required assumption of the upright body position, which itself involves physical activity. The gravitational displacement of blood from the chest to the lower parts of the body elicits a fall in central blood volume (CBV), which corresponds to the fraction of thoracic blood volume directly available to the left ventricle. The reduction in CBV and stroke volume (SV) in response to postural stress, post-exercise, or to blood loss results in reduced left ventricular filling, which may manifest as orthostatic intolerance. When termination of exercise removes the leg muscle pump function, CBV is no longer maintained. The resulting imbalance between a reduced cardiac output (CO) and a still enhanced peripheral vascular conductance may provoke post-exercise hypotension (PEH). Instruments that quantify CBV are not readily available and to express which magnitude of the CBV in a healthy subject should remains difficult. In the physiological laboratory, the CBV can be modified by making use of postural stressors, such as lower body "negative" or sub-atmospheric pressure (LBNP) or passive head-up tilt (HUT), while quantifying relevant biomedical parameters of blood flow and oxygenation. Several approaches, such as wearable sensors and advanced machine-learning techniques, have been followed in an attempt to improve methodologies for better prediction of outcomes and to guide treatment in civil patients and on the battlefield. In the recent decade, efforts have been made to develop algorithms and apply artificial intelligence (AI) in the field of hemodynamic monitoring. Advances in quantifying and monitoring CBV during environmental stress from exercise to hemorrhage and understanding the analogy between postural stress and central hypovolemia during anesthesia offer great relevance for healthy subjects and clinical populations.
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Affiliation(s)
- Björn J. P. van der Ster
- Department of Internal Medicine, Amsterdam University Medical Center, University of Amsterdam, Amsterdam, Netherlands
- Department of Anesthesiology, Amsterdam University Medical Center, University of Amsterdam, Amsterdam, Netherlands
- Laboratory for Clinical Cardiovascular Physiology, Amsterdam University Medical Center, University of Amsterdam, Amsterdam, Netherlands
| | - Yu-Sok Kim
- Laboratory for Clinical Cardiovascular Physiology, Amsterdam University Medical Center, University of Amsterdam, Amsterdam, Netherlands
- Department of Internal Medicine, Medisch Centrum Leeuwarden, Leeuwarden, Netherlands
| | - Berend E. Westerhof
- Laboratory for Clinical Cardiovascular Physiology, Amsterdam University Medical Center, University of Amsterdam, Amsterdam, Netherlands
- Department of Pulmonary Medicine, Amsterdam University Medical Center, Vrije Universiteit Amsterdam, Amsterdam Cardiovascular Sciences, Amsterdam, Netherlands
| | - Johannes J. van Lieshout
- Department of Internal Medicine, Amsterdam University Medical Center, University of Amsterdam, Amsterdam, Netherlands
- Laboratory for Clinical Cardiovascular Physiology, Amsterdam University Medical Center, University of Amsterdam, Amsterdam, Netherlands
- Medical Research Council Versus Arthritis Centre for Musculoskeletal Ageing Research, Division of Physiology, Pharmacology and Neuroscience, School of Life Sciences, The Medical School, University of Nottingham Medical School, Queen's Medical Centre, Nottingham, United Kingdom
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