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Wirkus JM, Goss F, David M, Hartmann EK, Fukui K, Schmidtmann I, Wittenmeier E, Pestel GJ, Griemert EV. Changes of pulse wave transit time after haemodynamic manoeuvres in healthy adults: a prospective randomised observational trial (PWTT volunteer study). BJA OPEN 2024; 11:100291. [PMID: 39027721 PMCID: PMC11255098 DOI: 10.1016/j.bjao.2024.100291] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/24/2023] [Accepted: 05/19/2024] [Indexed: 07/20/2024]
Abstract
Background Pulse wave transit time (PWTT) shows promise for monitoring intravascular fluid status intraoperatively. Presently, it is unknown how PWTT mirrors haemodynamic variables representing preload, inotropy, or afterload. Methods PWTT was measured continuously in 24 adult volunteers. Stroke volume was assessed by transthoracic echocardiography. Volunteers underwent four randomly assigned manoeuvres: 'Stand-up' (decrease in preload), passive leg raise (increase in preload), a 'step-test' (adrenergic stimulation), and a 'Valsalva manoeuvre' (increase in intrathoracic pressure). Haemodynamic measurements were performed before and 1 and 5 min after completion of each manoeuvre. Correlations between PWTT and stroke volume were analysed using the Pearson correlation coefficient. Results 'Stand-up' caused an immediate increase in PWTT (mean change +55.9 ms, P-value <0.0001, 95% confidence interval 46.0-65.7) along with an increase in mean arterial pressure and heart rate and a drop in stroke volume (P-values <0.0001). Passive leg raise caused an immediate drop in PWTT (mean change -15.4 ms, P-value=0.0024, 95% confidence interval -25.2 to -5.5) along with a decrease in mean arterial pressure (P-value=0.0052) and an increase in stroke volume (P-value=0.001). After 1 min, a 'step-test' caused no significant change in PWTT measurements (P-value=0.5716) but an increase in mean arterial pressure and heart rate (P-values <0.0001), without changes in stroke volume (P-value=0.1770). After 5 min, however, PWTT had increased significantly (P-value <0.0001). Measurements after the Valsalva manoeuvre caused heterogeneous results. Conclusion Noninvasive assessment of PWTT shows promise to register immediate preload changes in healthy adults. The clinical usefulness of PWTT may be hampered by late changes because of reasons different from fluid shifts. Clinical trial registration German clinical trial register (DRKS, ID: DRKS00031978, https://www.drks.de/DRKS00031978).
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Affiliation(s)
- Johannes M. Wirkus
- Department of Anaesthesiology, University Medical Center of the Johannes Gutenberg-University, Mainz, Germany
| | - Fabienne Goss
- Department of Anaesthesiology, University Medical Center of the Johannes Gutenberg-University, Mainz, Germany
| | - Matthias David
- Department of Anaesthesiology, Marienhaus Hospital, Mainz, Germany
| | - Erik K. Hartmann
- Department of Anaesthesiology, University Medical Center of the Johannes Gutenberg-University, Mainz, Germany
| | - Kimiko Fukui
- Department of Anaesthesiology, University Medical Center of the Johannes Gutenberg-University, Mainz, Germany
| | - Irene Schmidtmann
- Institute of Medical Biostatistics, Epidemiology and Informatics (IMBEI), University Medical Center of the Johannes Gutenberg-University, Mainz, Germany
| | - Eva Wittenmeier
- Department of Anaesthesiology, University Medical Center of the Johannes Gutenberg-University, Mainz, Germany
| | - Gunther J. Pestel
- Department of Anaesthesiology, University Medical Center of the Johannes Gutenberg-University, Mainz, Germany
| | - Eva-Verena Griemert
- Department of Anaesthesiology, University Medical Center of the Johannes Gutenberg-University, Mainz, Germany
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Nordine M, Pille M, Kraemer J, Berger C, Brandhorst P, Kaeferstein P, Kopetsch R, Wessel N, Trauzeddel RF, Treskatsch S. Intraoperative Beat-to-Beat Pulse Transit Time (PTT) Monitoring via Non-Invasive Piezoelectric/Piezocapacitive Peripheral Sensors Can Predict Changes in Invasively Acquired Blood Pressure in High-Risk Surgical Patients. SENSORS (BASEL, SWITZERLAND) 2023; 23:3304. [PMID: 36992016 PMCID: PMC10059272 DOI: 10.3390/s23063304] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/16/2023] [Revised: 03/14/2023] [Accepted: 03/17/2023] [Indexed: 06/19/2023]
Abstract
BACKGROUND Non-invasive tracking of beat-to-beat pulse transit time (PTT) via piezoelectric/piezocapacitive sensors (PES/PCS) may expand perioperative hemodynamic monitoring. This study evaluated the ability for PTT via PES/PCS to correlate with systolic, diastolic, and mean invasive blood pressure (SBPIBP, DBPIBP, and MAPIBP, respectively) and to detect SBPIBP fluctuations. METHODS PES/PCS and IBP measurements were performed in 20 patients undergoing abdominal, urological, and cardiac surgery. A Pearson's correlation analysis (r) between 1/PTT and IBP was performed. The predictive ability of 1/PTT with changes in SBPIBP was determined by area under the curve (reported as AUC, sensitivity, specificity). RESULTS Significant correlations between 1/PTT and SBPIBP were found for PES (r = 0.64) and PCS (r = 0.55) (p < 0.01), as well as MAPIBP/DBPIBP for PES (r = 0.6/0.55) and PCS (r = 0.5/0.45) (p < 0.05). A 7% decrease in 1/PTTPES predicted a 30% SBPIBP decrease (0.82, 0.76, 0.76), while a 5.6% increase predicted a 30% SBPIBP increase (0.75, 0.7, 0.68). A 6.6% decrease in 1/PTTPCS detected a 30% SBPIBP decrease (0.81, 0.72, 0.8), while a 4.8% 1/PTTPCS increase detected a 30% SBPIBP increase (0.73, 0.64, 0.68). CONCLUSIONS Non-invasive beat-to-beat PTT via PES/PCS demonstrated significant correlations with IBP and detected significant changes in SBPIBP. Thus, PES/PCS as a novel sensor technology may augment intraoperative hemodynamic monitoring during major surgery.
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Affiliation(s)
- Michael Nordine
- Department of Anesthesiology and Intensive Care Medicine, Hindenburgdamm 30, Charité–Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin and Humboldt Universität zu Berlin, 12203 Berlin, Germany; (M.N.)
| | - Marius Pille
- Berlin Institute of Health at Charité, Universitätsmedizin Berlin, Charitéplatz 1, 10117 Berlin, Germany
- Department of Physics, Humboldt University zu Berlin, 10115 Berlin, Germany
| | - Jan Kraemer
- Department of Physics, Humboldt University zu Berlin, 10115 Berlin, Germany
| | - Christian Berger
- Department of Anesthesiology and Intensive Care Medicine, Hindenburgdamm 30, Charité–Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin and Humboldt Universität zu Berlin, 12203 Berlin, Germany; (M.N.)
| | - Philipp Brandhorst
- Department of Anesthesiology and Intensive Care Medicine, Hindenburgdamm 30, Charité–Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin and Humboldt Universität zu Berlin, 12203 Berlin, Germany; (M.N.)
| | | | | | - Niels Wessel
- Department of Physics, Humboldt University zu Berlin, 10115 Berlin, Germany
- Department of Human Medicine, MSB Medical School Berlin GmbH, 14197 Berlin, Germany
| | - Ralf Felix Trauzeddel
- Department of Anesthesiology and Intensive Care Medicine, Hindenburgdamm 30, Charité–Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin and Humboldt Universität zu Berlin, 12203 Berlin, Germany; (M.N.)
| | - Sascha Treskatsch
- Department of Anesthesiology and Intensive Care Medicine, Hindenburgdamm 30, Charité–Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin and Humboldt Universität zu Berlin, 12203 Berlin, Germany; (M.N.)
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Villegas-Martinez M, Odland HH, Hammersbøen LE, Sletten OJ, Stugaard M, Witsø M, Khan F, Wajdan A, Elle OJ, Remme EW. Pulse arrival time variation as a non-invasive marker of acute response to cardiac resynchronization therapy. Europace 2023; 25:1183-1192. [PMID: 36734281 PMCID: PMC10062362 DOI: 10.1093/europace/euad013] [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: 09/16/2022] [Accepted: 12/29/2022] [Indexed: 02/04/2023] Open
Abstract
AIMS Successful cardiac resynchronization therapy (CRT) shortens the pre-ejection period (PEP) which is prolonged in the left bundle branch block (LBBB). In a combined animal and patient study, we investigated if changes in the pulse arrival time (PAT) could be used to measure acute changes in PEP during CRT implantation and hence be used to evaluate acute CRT response non-invasively and in real time. METHODS AND RESULTS In six canines, a pulse transducer was attached to a lower limb and PAT was measured together with left ventricular (LV) pressure by micromanometer at baseline, after induction of LBBB and during biventricular pacing. Time-to-peak LV dP/dt (Td) was used as a surrogate for PEP. In twelve LBBB patients during implantation of CRT, LV and femoral pressures were measured at baseline and during five different pacing configurations. PAT increased from baseline (277 ± 9 ms) to LBBB (313 ± 16 ms, P < 0.05) and shortened with biventricular pacing (290 ± 16 ms, P < 0.05) in animals. There was a strong relationship between changes in PAT and Td in patients (r2 = 0.91). Two patients were classified as non-responders at 6 months follow-up. CRT decreased PAT from 320 ± 41 to 298 ± 39 ms (P < 0.05) in the responders, while PAT increased by 5 and 8 ms in the two non-responders. CONCLUSION This proof-of-concept study indicates that PAT can be used as a simple, non-invasive method to assess the acute effects of CRT in real time with the potential to identify long-term response in patients.
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Affiliation(s)
- Manuel Villegas-Martinez
- The Intervention Centre, Oslo University Hospital, Rikshospitalet, Postboks 4950 Nydalen, 0424 Oslo, Norway.,Institute of Clinical Medicine, University of Oslo, Oslo, Norway
| | - Hans Henrik Odland
- Department of Cardiology and Pediatric Cardiology, Oslo University Hospital, Rikshospitalet, Oslo, Norway.,Pacertool AS, Oslo, Norway
| | - Lars-Egil Hammersbøen
- Institute of Clinical Medicine, University of Oslo, Oslo, Norway.,Department of Cardiology and Pediatric Cardiology, Oslo University Hospital, Rikshospitalet, Oslo, Norway.,Institute for Surgical Research, Oslo University Hospital, Rikshospitalet, Oslo, Norway
| | - Ole Jakob Sletten
- Institute of Clinical Medicine, University of Oslo, Oslo, Norway.,Department of Cardiology and Pediatric Cardiology, Oslo University Hospital, Rikshospitalet, Oslo, Norway.,Institute for Surgical Research, Oslo University Hospital, Rikshospitalet, Oslo, Norway
| | - Marie Stugaard
- Institute for Surgical Research, Oslo University Hospital, Rikshospitalet, Oslo, Norway
| | - Marit Witsø
- Institute of Clinical Medicine, University of Oslo, Oslo, Norway.,Department of Cardiology and Pediatric Cardiology, Oslo University Hospital, Rikshospitalet, Oslo, Norway.,Institute for Surgical Research, Oslo University Hospital, Rikshospitalet, Oslo, Norway
| | - Faraz Khan
- Institute of Clinical Medicine, University of Oslo, Oslo, Norway.,Department of Cardiology and Pediatric Cardiology, Oslo University Hospital, Rikshospitalet, Oslo, Norway.,Institute for Surgical Research, Oslo University Hospital, Rikshospitalet, Oslo, Norway
| | - Ali Wajdan
- The Intervention Centre, Oslo University Hospital, Rikshospitalet, Postboks 4950 Nydalen, 0424 Oslo, Norway.,Department of Informatics, University of Oslo, Oslo, Norway
| | - Ole Jakob Elle
- The Intervention Centre, Oslo University Hospital, Rikshospitalet, Postboks 4950 Nydalen, 0424 Oslo, Norway.,Department of Informatics, University of Oslo, Oslo, Norway
| | - Espen W Remme
- The Intervention Centre, Oslo University Hospital, Rikshospitalet, Postboks 4950 Nydalen, 0424 Oslo, Norway.,Pacertool AS, Oslo, Norway
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Koppula A, Asif AR, Barra RR, Sridharan KS. Feasibility of home-based tracking of insulin resistance from vascular stiffness estimated from the photoplethysmographic finger pulse waveform. Physiol Meas 2022; 43. [PMID: 35512706 DOI: 10.1088/1361-6579/ac6d3f] [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: 01/17/2022] [Accepted: 05/05/2022] [Indexed: 11/12/2022]
Abstract
In this study, we explored the utility of post-prandial vascular stiffness as a surrogate measure for the estimation of insulin resistance (IR), which is a pre-diabetic condition. A cohort of 51 healthy young adults of varying Body mass index values (BMI) were studied by fasting plasma values of insulin and glucose; fasting and post-meal finger photoplethysmography (PPG), and electrocardiogram (ECG). Insulin resistance was estimated by Homeostatic model assessment-Insulin resistance 2 (HOMA-IR2) using fasting plasma insulin and glucose. Vascular stiffness was estimated by reciprocal of pulse arrival time (rPAT) from ECG and finger PPG at five time points from fasting to 2-hours post oral glucose ingestion. We examined if insulin resistance is correlated with meal induced vascular stiffness changes supporting the feasibility of using finger PPG for the estimation of insulin resistance. HOMA-IR2 was found to be positively correlated with early rise (0- to 30- minutes post meal) and delayed fall (30- to 120-minutes) of rPAT. Correlation persisted even after the effect of BMI has been partialled out in sub-group analysis. We conclude that finger PPG based pulse waveform and single lead ECG has the potential to be used as a non-invasive method for the assessment of insulin resistance. As both signals viz., ECG and PPG can be easily acquired using wearable and other low-cost sensing systems, the present study can serve as a pointer for the development of accessible methods of monitoring and longitudinal tracking of insulin resistance in health and pathophysiological states.
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Affiliation(s)
- Aditya Koppula
- Biomedical Engineering, Indian Institute of Technology Hyderabad, Indian Institute of Technology Hyderabad, Kandi, Sangareddy, Telangana state, India, Hyderabad, 502205, INDIA
| | - Abdur Rehman Asif
- Biochemistry, Apollo Institute of Medical Sciences and Research, Road.No.92, Film nagar, Apollo health city campus, Jubilee Hills, Hyderabad, Telangana, 500096, INDIA
| | - Ram Reddy Barra
- Physiology, Apollo Institute of Medical Sciences and Research, Apollo health city campus, Road.No.92, Jubilee hills, Hyderabad, India, Hyderabad, Telangana, 500090, INDIA
| | - Kousik Sarathy Sridharan
- Biomedical Engineering, Indian Institute of Technology Hyderabad, Indian Institute of Technology Hyderabad, Kandi, Sangareddy, Telangana state, India, Hyderabad, Telangana, 502285, INDIA
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Lim K, Jung S, Kim H. Integrative review of non-pharmacological intervention and multidimensional evaluation for intraoperative anxiety under spinal anaesthesia. J Clin Nurs 2022; 32:2114-2127. [PMID: 35352416 DOI: 10.1111/jocn.16309] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2021] [Revised: 11/22/2021] [Accepted: 03/07/2022] [Indexed: 11/28/2022]
Abstract
INTRODUCTION Patients under spinal anaesthesia experience high levels of anxiety during surgery. Clinical nurses tried to manage patient's anxiety under spinal anaesthesia using non-pharmacological interventions for its benefit. Thus, it is required to identify comprehensive evidences of various non-pharmacological interventions and of how to measure anxiety under spinal anaesthesia. AIMS This study aims to review current research on the non-pharmacological interventions to relieve intraoperative anxiety under spinal anaesthesia and to identify subjective and objective measures of intraoperative anxiety under spinal anaesthesia. METHODS Wittemore and Knafl's integrative review methodology was used. Researchers conducted five scientific rigor steps; problem identification, searching literature, evaluation of literature, analysis of literature and presentation of results. The PRISMA checklist was used. To evaluate the level of evidence, critical appraisal tools of Joanna Briggs Institute were used. RESULTS Eleven studies were included in this integrative review. Delivering music is the most frequently used as non-pharmacological intervention by researchers. They tried to manage intraoperative anxiety under spinal anaesthesia with using diverse genre and application of music. In addition, dry cupping method, progressive muscle relaxation (PMR) exercise and virtual reality (VR) goggles were used in included studies. Researchers measured intraoperative anxiety under spinal anaesthesia with objective or subjective way. The State-Trait Anxiety Inventory and visual analogue scale were used as subjective method to approach intraoperative anxiety. In contrary, researchers tried to obtain objective evidence of intraoperative anxiety with vital signs, cortisol, blood glucose, alpha-amylase and adrenocorticotropic hormone. CONCLUSION Various types of non-pharmacological interventions are effective to manage patient's intraoperative anxiety under spinal anaesthesia. It is recommended to measure intraoperative anxiety under spinal anaesthesia with using both objective and subjective methods. RELEVANCE TO CLINICAL PRACTICE Clinical nurses can use non-pharmacological interventions to manage intraoperative anxiety under spinal anaesthesia by comprehensive monitoring with diverse measures.
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Affiliation(s)
- Kyuhee Lim
- College of Nursing, Yonsei University, Seoul, Republic of Korea.,Severance Hospital, Yonsei University Health System, Seoul, Republic of Korea
| | - Sooah Jung
- Severance Hospital, Yonsei University Health System, Seoul, Republic of Korea.,Graduate School of Public Health, Yonsei University, Seoul, Republic of Korea
| | - Heejung Kim
- College of Nursing, Yonsei University, Seoul, Republic of Korea.,Brain Korea 21 FOUR Project, Seoul, Republic of Korea.,Mo-Im Kim Nursing Research Institute, Seoul, Republic of Korea.,Yonsei Evidence Based Nursing Centre of Korea: a JBI Affiliated Group, Yonsei University, Seoul, Republic of Korea
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6
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Mijatovic G, Antonacci Y, Faes L. Measuring the Rate of Information Transfer in Point-Process Data: Application to Cardiovascular Interactions. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2021; 2021:341-344. [PMID: 34891305 DOI: 10.1109/embc46164.2021.9629688] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
We present the implementation to cardiovascular variability of a method for the information-theoretic estimation of the directed interactions between event-based data. The method allows to compute the transfer entropy rate (TER) from a source to a target point process in continuous time, thus overcoming the severe limitations associated with time discretization of event-based processes. In this work, the method is evaluated on coupled cardiovascular point processes representing the heartbeat dynamics and the related peripheral pulsation, first using a physiologically-based simulation model and then studying real point-process data from healthy subjects monitored at rest and during postural stress. Our results document the ability of TER to detect direction and strength of the interactions between cardiovascular processes, also highlighting physiologically plausible interaction mechanisms.
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Schulz A, Back SN, Schaan VK, Bertsch K, Vögele C. On the construct validity of interoceptive accuracy based on heartbeat counting: Cardiovascular determinants of absolute and tilt-induced change scores. Biol Psychol 2021; 164:108168. [PMID: 34411619 DOI: 10.1016/j.biopsycho.2021.108168] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2021] [Revised: 08/11/2021] [Accepted: 08/11/2021] [Indexed: 12/18/2022]
Abstract
Interoceptive accuracy (IAcc) as assessed with the heartbeat counting task (IAccHBCT) may be affected by a range of factors including (1.) the ability to adequately detect cardiac signals, indicated by IAcc in a heartbeat discrimination task (IAccHBDT), (2.) cardiac signal properties, affected by sympathetic and parasympathetic tone, and (3.) non-interoceptive processes, including time estimation accuracy (TEAcc). In the current study we investigated the contribution of these factors to absolute and Δ IAccHBCT scores, induced by passive head-up and head-down tilt in 49 healthy individuals. A set of hierarchical regression models showed IAccHBDT scores as the strongest and, across different orthostatic (tilt) conditions, most stable (positive) predictor of absolute and Δ IAccHBCT scores. Neither indicators of cardiac signal properties (except for HR in head-down-tilt), nor TEAcc predicted absolute or Δ IAccHBCT scores. These findings support the convergent and discriminant validity of absolute and Δ IAccHBCT scores.
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Affiliation(s)
- André Schulz
- Clinical Psychophysiology Laboratory, Department of Behavioural and Cognitive Sciences, University of Luxembourg, Esch-sur-Alzette, Luxembourg.
| | - Sarah N Back
- Clinical Psychophysiology Laboratory, Department of Behavioural and Cognitive Sciences, University of Luxembourg, Esch-sur-Alzette, Luxembourg; Division of Clinical Psychology and Psychotherapy, Department of Psychology, Ludwig-Maximilians-University Munich, Munich, Germany
| | - Violetta K Schaan
- Clinical Psychophysiology Laboratory, Department of Behavioural and Cognitive Sciences, University of Luxembourg, Esch-sur-Alzette, Luxembourg
| | - Katja Bertsch
- Division of Clinical Psychology and Psychotherapy, Department of Psychology, Ludwig-Maximilians-University Munich, Munich, Germany
| | - Claus Vögele
- Clinical Psychophysiology Laboratory, Department of Behavioural and Cognitive Sciences, University of Luxembourg, Esch-sur-Alzette, Luxembourg
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Booth GJ, Cole J, Geiger P, Adams J, Barnhill J, Hughey S. Pulse Arrival Time Is Associated With Hemorrhagic Volume in a Porcine Model: A Pilot Study. Mil Med 2021; 187:e630-e637. [PMID: 33620076 DOI: 10.1093/milmed/usab069] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2020] [Revised: 11/20/2020] [Accepted: 02/09/2021] [Indexed: 11/14/2022] Open
Abstract
BACKGROUND Hemorrhage is a major cause of preventable death worldwide, and early identification can be lifesaving. Pulse wave contour analysis has previously been used to infer hemodynamic variables in a variety of settings. We hypothesized that pulse arrival time (PAT), a form of pulse wave contour analysis which is assessed via electrocardiography (ECG) and photoplethysmography (PPG), is associated with hemorrhage volume. METHODS Yorkshire-Cross swine were randomized to hemorrhage (30 mL/kg over 20 minutes) vs. control. Continuous ECG and PPG waveforms were recorded with a novel monitoring device, and algorithms were developed to calculate PAT and PAT variability throughout the respiratory cycle, termed "PAT index" or "PAT_I." Mixed effects models were used to determine associations between blood loss and PAT and between blood loss and PAT_I to account for clustering within subjects and investigate inter-subject variability in these relationships. RESULTS PAT and PAT_I data were determined for ∼150 distinct intervals from five subjects. PAT and PAT_I were strongly associated with blood loss. Mixed effects modeling with PAT alone was substantially better than PAT_I alone (R2 0.93 vs. 0.57 and Akaike information criterion (AIC) 421.1 vs. 475.5, respectively). Modeling blood loss with PAT and PAT_I together resulted in slightly improved fit compared to PAT alone (R2 0.96, AIC 419.1). Mixed effects models demonstrated significant inter-subject variability in the relationships between blood loss and PAT. CONCLUSIONS Findings from this pilot study suggest that PAT and PAT_I may be used to detect blood loss. Because of the simple design of a single-lead ECG and PPG, the technology could be packaged into a very small form factor device for use in austere or resource-constrained environments. Significant inter-subject variability in the relationship between blood loss and PAT highlights the importance of individualized hemodynamic monitoring.
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Affiliation(s)
- Gregory J Booth
- Department of Anesthesiology and Pain Medicine, Naval Medical Center Portsmouth, Portsmouth, VA 23708, USA.,Naval Biotechnology Group, Naval Medical Center Portsmouth, Portsmouth, VA 23708, USA
| | - Jacob Cole
- Department of Anesthesiology and Pain Medicine, Naval Medical Center Portsmouth, Portsmouth, VA 23708, USA.,Naval Biotechnology Group, Naval Medical Center Portsmouth, Portsmouth, VA 23708, USA
| | - Phillip Geiger
- Department of Anesthesiology and Pain Medicine, Naval Medical Center Portsmouth, Portsmouth, VA 23708, USA.,Naval Biotechnology Group, Naval Medical Center Portsmouth, Portsmouth, VA 23708, USA
| | - Jacob Adams
- Department of Anesthesiology and Pain Medicine, Naval Medical Center Portsmouth, Portsmouth, VA 23708, USA
| | - Joshua Barnhill
- Department of Anesthesiology and Pain Medicine, Naval Medical Center Portsmouth, Portsmouth, VA 23708, USA
| | - Scott Hughey
- Department of Anesthesiology and Pain Medicine, Naval Medical Center Portsmouth, Portsmouth, VA 23708, USA.,Naval Biotechnology Group, Naval Medical Center Portsmouth, Portsmouth, VA 23708, USA
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Mijatovic G, Pernice R, Perinelli A, Antonacci Y, Busacca A, Javorka M, Ricci L, Faes L. Measuring the Rate of Information Exchange in Point-Process Data With Application to Cardiovascular Variability. FRONTIERS IN NETWORK PHYSIOLOGY 2021; 1:765332. [PMID: 36925567 PMCID: PMC10013020 DOI: 10.3389/fnetp.2021.765332] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/26/2021] [Accepted: 11/26/2021] [Indexed: 02/01/2023]
Abstract
The amount of information exchanged per unit of time between two dynamic processes is an important concept for the analysis of complex systems. Theoretical formulations and data-efficient estimators have been recently introduced for this quantity, known as the mutual information rate (MIR), allowing its continuous-time computation for event-based data sets measured as realizations of coupled point processes. This work presents the implementation of MIR for point process applications in Network Physiology and cardiovascular variability, which typically feature short and noisy experimental time series. We assess the bias of MIR estimated for uncoupled point processes in the frame of surrogate data, and we compensate it by introducing a corrected MIR (cMIR) measure designed to return zero values when the two processes do not exchange information. The method is first tested extensively in synthetic point processes including a physiologically-based model of the heartbeat dynamics and the blood pressure propagation times, where we show the ability of cMIR to compensate the negative bias of MIR and return statistically significant values even for weakly coupled processes. The method is then assessed in real point-process data measured from healthy subjects during different physiological conditions, showing that cMIR between heartbeat and pressure propagation times increases significantly during postural stress, though not during mental stress. These results document that cMIR reflects physiological mechanisms of cardiovascular variability related to the joint neural autonomic modulation of heart rate and arterial compliance.
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Affiliation(s)
- Gorana Mijatovic
- Faculty of Technical Science, University of Novi Sad, Novi Sad, Serbia
| | - Riccardo Pernice
- Department of Engineering, University of Palermo, Palermo, Italy
| | - Alessio Perinelli
- CIMeC, Center for Mind/Brain Sciences, University of Trento, Rovereto, Italy
| | - Yuri Antonacci
- Department of Physics and Chemistry "Emilio Segrè," University of Palermo, Palermo, Italy
| | | | - Michal Javorka
- Department of Physiology and Biomedical Center Martin, Jessenius Faculty of Medicine, Comenius University, Martin, Slovakia
| | - Leonardo Ricci
- Department of Physics, University of Trento, Trento, Italy
| | - Luca Faes
- Department of Engineering, University of Palermo, Palermo, Italy
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10
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Zia J, Kimball J, Rozell C, Inan OT. Harnessing the Manifold Structure of Cardiomechanical Signals for Physiological Monitoring During Hemorrhage. IEEE Trans Biomed Eng 2020; 68:1759-1767. [PMID: 32749958 DOI: 10.1109/tbme.2020.3014040] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
OBJECTIVE Local oscillation of the chest wall in response to events during the cardiac cycle may be captured using a sensing modality called seismocardiography (SCG), which is commonly used to infer cardiac time intervals (CTIs) such as the pre-ejection period (PEP). An important factor impeding the ubiquitous application of SCG for cardiac monitoring is that morphological variability of the signals makes consistent inference of CTIs a difficult task in the time-domain. The goal of this work is therefore to enable SCG-based physiological monitoring during trauma-induced hemorrhage using signal dynamics rather than morphological features. METHODS We introduce and explore the observation that SCG signals follow a consistent low-dimensional manifold structure during periods of changing PEP induced in a porcine model of trauma injury. Furthermore, we show that the distance traveled along this manifold correlates strongly to changes in PEP ( ∆PEP). RESULTS ∆PEP estimation during hemorrhage was achieved with a median R2 of 92.5% using a rapid manifold approximation method, comparable to an ISOMAP reference standard, which achieved an R2 of 95.3%. CONCLUSION Rapidly approximating the manifold structure of SCG signals allows for physiological inference abstracted from the time-domain, laying the groundwork for robust, morphology-independent processing methods. SIGNIFICANCE Ultimately, this work represents an important advancement in SCG processing, enabling future clinical tools for trauma injury management.
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Zia J, Kimball J, Hahn JO, Inan OT. Mitigating Hypovolemia-Induced Miscalibration of Photoplethysmogram-Derived Blood Pressure. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2020; 2020:5288-5291. [PMID: 33019177 DOI: 10.1109/embc44109.2020.9175592] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Pulse transit time (PTT) is a hemodynamic indicator that may be obtained non-invasively using photoplethysmogram (PPG) signals for continuous blood pressure (BP) monitoring. Among the most promising applications of this technology are military and civilian trauma cases, where reduced blood volume due to hemorrhage, or absolute hypovolemia, is the leading preventable cause of death. However, the drawback of this method is that it requires calibration for each patient; additionally, changes in physiological state may affect PTT calibration. In this work, a porcine model (n = 6) was used to demonstrate that changes in blood volume lead to miscalibration of PTT for BP estimation. To mitigate hypovolemia-induced miscalibration, this work first defines a template-based signal quality index (SQI) for characterizing the morphology of PPG signals; it is then shown that the subject-specific calibration of SQI to BP is more robust to changes in blood volume than PTT. Though changes in PPG signal quality are not necessarily specific to changes in BP, these results suggest that PPG-based monitoring systems may benefit from incorporating morphological information for cuffless BP estimation in trauma settings.
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Zia J, Kimball J, Rolfes C, Hahn JO, Inan OT. Enabling the assessment of trauma-induced hemorrhage via smart wearable systems. SCIENCE ADVANCES 2020; 6:eabb1708. [PMID: 32766449 PMCID: PMC7375804 DOI: 10.1126/sciadv.abb1708] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/05/2020] [Accepted: 06/05/2020] [Indexed: 05/08/2023]
Abstract
As the leading cause of trauma-related mortality, blood loss due to hemorrhage is notoriously difficult to triage and manage. To enable timely and appropriate care for patients with trauma, this work elucidates the externally measurable physiological features of exsanguination, which were used to develop a globalized model for assessing blood volume status (BVS) or the relative severity of blood loss. These features were captured via both a multimodal wearable system and a catheter-based reference and used to accurately infer BVS in a porcine model of hemorrhage (n = 6). Ultimately, high-level features of cardiomechanical function were shown to strongly predict progression toward cardiovascular collapse and used to estimate BVS with a median error of 15.17 and 18.17% for the catheter-based and wearable systems, respectively. Exploring the nexus of biomedical theory and practice, these findings lay the groundwork for digital biomarkers of hemorrhage severity and warrant further study in human subjects.
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Affiliation(s)
- Jonathan Zia
- Department of Electrical and Computer Engineering, Georgia Institute of Technology, Atlanta, GA 30332, USA
- Emory University School of Medicine, Atlanta, GA 30322, USA
| | - Jacob Kimball
- Department of Electrical and Computer Engineering, Georgia Institute of Technology, Atlanta, GA 30332, USA
| | - Christopher Rolfes
- Translational Training and Testing Laboratories Inc., Atlanta, GA 30313, USA
| | - Jin-Oh Hahn
- Department of Mechanical Engineering, University of Maryland, College Park, MD 20742, USA
| | - Omer T. Inan
- Department of Electrical and Computer Engineering, Georgia Institute of Technology, Atlanta, GA 30332, USA
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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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Comparison of short-term heart rate variability indexes evaluated through electrocardiographic and continuous blood pressure monitoring. Med Biol Eng Comput 2019; 57:1247-1263. [PMID: 30730027 DOI: 10.1007/s11517-019-01957-4] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2018] [Accepted: 01/28/2019] [Indexed: 10/27/2022]
Abstract
Heart rate variability (HRV) analysis represents an important tool for the characterization of complex cardiovascular control. HRV indexes are usually calculated from electrocardiographic (ECG) recordings after measuring the time duration between consecutive R peaks, and this is considered the gold standard. An alternative method consists of assessing the pulse rate variability (PRV) from signals acquired through photoplethysmography, a technique also employed for the continuous noninvasive monitoring of blood pressure. In this work, we carry out a thorough analysis and comparison of short-term variability indexes computed from HRV time series obtained from the ECG and from PRV time series obtained from continuous blood pressure (CBP) signals, in order to evaluate the reliability of using CBP-based recordings in place of standard ECG tracks. The analysis has been carried out on short time series (300 beats) of HRV and PRV in 76 subjects studied in different conditions: resting in the supine position, postural stress during 45° head-up tilt, and mental stress during computation of arithmetic test. Nine different indexes have been taken into account, computed in the time domain (mean, variance, root mean square of the successive differences), frequency domain (low-to-high frequency power ratio LF/HF, HF spectral power, and central frequency), and information domain (entropy, conditional entropy, self entropy). Thorough validation has been performed using comparison of the HRV and PRV distributions, robust linear regression, and Bland-Altman plots. Results demonstrate the feasibility of extracting HRV indexes from CBP-based data, showing an overall relatively good agreement of time-, frequency-, and information-domain measures. The agreement decreased during postural and mental arithmetic stress, especially with regard to band-power ratio, conditional, and self-entropy. This finding suggests to use caution in adopting PRV as a surrogate of HRV during stress conditions.
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15
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Kortekaas MC, van Velzen MHN, Grüne F, Niehof SP, Stolker RJ, Huygen FJPM. Small intra-individual variability of the pre-ejection period justifies the use of pulse transit time as approximation of the vascular transit. PLoS One 2018; 13:e0204105. [PMID: 30304059 PMCID: PMC6179208 DOI: 10.1371/journal.pone.0204105] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2017] [Accepted: 09/03/2018] [Indexed: 12/15/2022] Open
Abstract
Background Vascular transit time (VTT) is the propagation time of a pulse wave through an artery; it is a measure for arterial stiffness. Because reliable non-invasive VTT measurements are difficult, as an alternative we measure pulse transit time (PTT). PTT is defined as the time between the R-wave on electrocardiogram and arrival of the resulting pulse wave in a distal location measured with photoplethysmography (PPG). The time between electrical activation of the ventricles and the resulting pulse wave after opening of the aortic valve is called the pre-ejection period (PEP), a component of PTT. The aim of this study was to estimate the variability of PEP at rest, to establish how accurate PTT is as approximation of VTT. Methods PTT was measured and PEP was assessed with echocardiography (gold standard) in three groups of 20 volunteers: 1) a control group without cardiovascular disease aged <50 years and 2) aged >50 years, and 3) a group with cardiovascular risk factors, defined as arterial hypertension, dyslipidemia, kidney failure and diabetes mellitus. Results Per group, the mean PEP was: 1) 58.5 ± 13.0 ms, 2) 52.4 ± 11.9 ms, and 3) 57.6 ± 11.6 ms. However, per individual the standard deviation was much smaller, i.e. 1) 2.0–5.9 ms, 2) 2.8–5.1 ms, and 3) 1.6–12.0 ms, respectively. There was no significant difference in the mean PEP of the 3 groups (p = 0.236). Conclusion In conclusion, the intra-individual variability of PEP is small. A change in PTT in a person at rest is most probably the result of a change in VTT rather than of PEP. Thus, PTT at rest is an easy, non-invasive and accurate approximation of VTT for monitoring arterial stiffness.
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Affiliation(s)
- Minke C. Kortekaas
- Department of Anesthesiology, Erasmus University Medical Centre, Rotterdam, the Netherlands
- * E-mail:
| | - Marit H. N. van Velzen
- Department of Anesthesiology, Erasmus University Medical Centre, Rotterdam, the Netherlands
| | - Frank Grüne
- Department of Anesthesiology, Erasmus University Medical Centre, Rotterdam, the Netherlands
| | - Sjoerd P. Niehof
- Department of Anesthesiology, Erasmus University Medical Centre, Rotterdam, the Netherlands
| | - Robert J. Stolker
- Department of Anesthesiology, Erasmus University Medical Centre, Rotterdam, the Netherlands
| | - Frank J. P. M. Huygen
- Department of Anesthesiology, Erasmus University Medical Centre, Rotterdam, the Netherlands
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KROHOVA J, CZIPPELOVA B, TURIANIKOVA Z, LAZAROVA Z, TONHAJZEROVA I, JAVORKA M. Preejection Period as a Sympathetic Activity Index: a Role of Confounding Factors. Physiol Res 2017; 66:S265-S275. [DOI: 10.33549/physiolres.933682] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
In previous studies, one of the systolic time intervals – preejection period (PEP) – was used as an index of sympathetic activity reflecting the cardiac contractility. However, PEP could be also influenced by several other cardiovascular variables including preload, afterload and diastolic blood pressure (DBP). The aim of this study was to assess the behavior of the PEP together with other potentially confounding cardiovascular system characteristics in healthy humans during mental and orthostatic stress (head-up tilt test – HUT). Forty-nine healthy volunteers (28 females, 21 males, mean age 18.6 years (SD=1.8 years)) participated in the study. We recorded finger arterial blood pressure by volume-clamp method (Finometer Pro, FMS, Netherlands), PEP, thoracic fluid content (TFC) – a measure of preload, and cardiac output (CO) by impedance cardiography (CardioScreen® 2000, Medis, Germany). Systemic vascular resistance (SVR) – a measure of afterload – was calculated as a ratio of mean arterial pressure and CO. We observed that during HUT, an expected decrease in TFC was accompanied by an increase of PEP, an increase of SVR and no significant change in DBP. During mental stress, we observed a decrease of PEP and an increase of TFC, SVR and DBP. Correlating a change in assessed measures (delta values) between mental stress and previous supine rest, we found that ΔPEP correlated negatively with ΔCO and positively with ΔSVR. In orthostasis, no significant correlation between ΔPEP and ΔDBP, ΔTFC, ΔCO, ΔMBP or ΔSVR was found. We conclude that despite an expected increase of sympathetic activity during both challenges, PEP behaved differently indicating an effect of other confounding factors. To interpret PEP values properly, we recommend simultaneously to measure other variables influencing this cardiovascular measure.
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Affiliation(s)
- J. KROHOVA
- Department of Physiology, Jessenius Faculty of Medicine in Martin, Comenius University in Bratislava, Martin, Slovakia
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17
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Boubaker H, Grissa MH, Beltaief K, Dridi Z, Najjar MF, Bouida W, Boukef R, Marghli S, Nouira S. Systolic time intervals combined with Valsalva maneuver for the diagnosis of left ventricular dysfunction in COPD exacerbations. Int J Chron Obstruct Pulmon Dis 2016; 11:2237-2243. [PMID: 27695311 PMCID: PMC5029838 DOI: 10.2147/copd.s96280] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
Background The goal of this study was to determine the value of systolic time intervals and their change during Valsalva maneuver (VM) in the diagnosis of left ventricular dysfunction (LVD) in patients with acute exacerbation of chronic obstructive pulmonary disease (AECOPD). Methods We included 166 patients admitted to the emergency department for AECOPD. Measurement of systolic time intervals included electromechanical activation time (EMAT), left ventricular ejection time (LVET), and EMAT/LVET ratio. These were performed at baseline and during the first strain phase of the VM using a computerized phonoelectrocardiographic method. The diagnosis of LVD was determined on the basis of clinical examination, echocardiography, and brain natriuretic peptide. The values of systolic time intervals were compared between patients with and without LVD; their diagnostic performance was assessed using the area under receiver operating characteristic (ROC) curve. Results Patients with LVD (n=95) had a significantly higher EMAT and lower LVET and EMAT/LVET ratio compared to patients without LVD (n=71); the area under ROC curve was 0.79, 0.88, and 0.90, respectively, for EMAT, LVET, and EMAT/LVET ratio. All baseline systolic time intervals changed significantly during VM in patients without LVD but they did not change in patients with LVD. The area under ROC curve increased to 0.84 and 0.93, respectively, for EMAT and EMAT/LVET ratio but did not change for LVET. Conclusion Simple and noninvasive measurements of systolic time intervals combined with VM could be helpful to detect or rule out LVD in patients admitted to the emergency room for COPD excacerbation. The EMAT/LVET ratio seems to have the best diagnostic value.
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Affiliation(s)
- Hamdi Boubaker
- Department of Emergency, Fattouma Bourguiba University Hospital; Research Laboratory (LR12SP18), University of Monastir
| | - Mohamed Habib Grissa
- Department of Emergency, Fattouma Bourguiba University Hospital; Research Laboratory (LR12SP18), University of Monastir
| | - Kaouther Beltaief
- Department of Emergency, Fattouma Bourguiba University Hospital; Research Laboratory (LR12SP18), University of Monastir
| | | | | | - Wahid Bouida
- Department of Emergency, Fattouma Bourguiba University Hospital; Research Laboratory (LR12SP18), University of Monastir
| | - Riadh Boukef
- Department of Emergency, Sahloul University Hospital, Sousse
| | - Soudani Marghli
- Department of Emergency, Tahar Sfar University Hospital, Mahdia, Tunisia
| | - Semir Nouira
- Department of Emergency, Fattouma Bourguiba University Hospital; Research Laboratory (LR12SP18), University of Monastir
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18
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van Velzen MHN, Loeve AJ, Kortekaas MC, Niehof SP, Mik EG, Stolker RJ. Effect of heat-induced pain stimuli on pulse transit time and pulse wave amplitude in healthy volunteers. Physiol Meas 2015; 37:52-66. [PMID: 26641656 DOI: 10.1088/0967-3334/37/1/52] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Pain is commonly assessed subjectively by interpretations of patient behaviour and/or reports from patients. When this is impossible the availability of a quantitative objective pain assessment tool based on objective physiological parameters would greatly benefit clinical practice and research beside the standard self-report tests. Vasoconstriction is one of the physiological responses to pain. The aim of this study was to investigate whether pulse transit time (PTT) and pulse wave amplitude (PWA) decrease in response to this vasoconstriction when caused by heat-induced pain. The PTT and PWA were measured in healthy volunteers, on both index fingers using photoplethysmography and electrocardiography. Each subject received 3 heat-induced pain stimuli using a Temperature-Sensory Analyzer thermode block to apply a controlled, increasing temperature from 32.0 °C to 50.0 °C to the skin. After reaching 50.0 °C, the thermode was immediately cooled down to 32.0 °C. The study population was divided into 2 groups with a time-interval between the stimuli 20s or 60s. The results showed a significant (p < 0.05) decrease of both PTT and PWA on the stimulated and contralateral side. Moreover, there was no significant difference between the stimulated and contralateral side. The time-interval of 20s was too short to allow PTT and PWA to return to baseline values and should exceed 40s in future studies. Heat-induced pain causes a decrease of PTT and PWA. Consequently, it is expected that, in the future, PTT and PWA may be applied as objective indicators of pain, either beside the standard self-report test, or when self-report testing is impossible.
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Affiliation(s)
- Marit H N van Velzen
- Department of Anesthesiology, Laboratory of Experimental Anesthesiology, Erasmus University Medical Center Rotterdam, The Netherlands
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Thomas SS, Nathan V, Zong C, Soundarapandian K, Shi X, Jafari R. BioWatch: A Noninvasive Wrist-Based Blood Pressure Monitor That Incorporates Training Techniques for Posture and Subject Variability. IEEE J Biomed Health Inform 2015. [PMID: 26208369 DOI: 10.1109/jbhi.2015.2458779] [Citation(s) in RCA: 61] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Noninvasive continuous blood pressure (BP) monitoring is not yet practically available for daily use. Challenges include making the system easily wearable, reducing noise level and improving accuracy. Variations in each person's physical characteristics, as well as the possibility of different postures, increase the complexity of continuous BP monitoring, especially outside the hospital. This study attempts to provide an easily wearable solution and proposes training to specific posture and individual for further improving accuracy. The wrist watch-based system we developed can measure electrocardiogram and photoplethysmogram. From these two signals, we measure pulse transit time through which we can obtain systolic and diastolic blood pressure through regression techniques. In this study, we investigate various functions to perform the training to obtain blood pressure. We validate measurements on different postures and subjects, and show the value of training the device to each posture and each subject. We observed that the average RMSE between the measured actual systolic BP and calculated systolic BP is between 7.83 to 9.37 mmHg across 11 subjects. The corresponding range of error for diastolic BP is 5.77 to 6.90 mmHg. The system can also automatically detect the arm position of the user using an accelerometer with an average accuracy of 98%, to make sure that the sensor is kept at the proper height. This system, called BioWatch, can potentially be a unified solution for heart rate, SPO2 and continuous BP monitoring.
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20
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Effects of trunk posture in Fowler's position on hemodynamics. Auton Neurosci 2015; 189:56-9. [PMID: 25600883 DOI: 10.1016/j.autneu.2015.01.002] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2014] [Revised: 10/10/2014] [Accepted: 01/06/2015] [Indexed: 11/23/2022]
Abstract
We speculated that stroke volume would be higher and heart rate would be lower when the head and upper trunk were mainly upright in the Fowler's position. We therefore analyzed the effects of three trunk postures in Fowler's position on heart rate, blood pressure and circulatory volume. Heart rate (HR), blood pressure (BP), stroke volume (SV), cardiac output (Q), systemic vascular resistance (SVR), ejection time (ET) and pre-ejection period (PEP) were measured in 10 healthy male volunteers (mean age ± SEM, 20.7 ± 0.5 y; range, 19-23 y) while in three trunk postures in Fowler's position. Stroke volume and Q were measured using impedance cardiography. The three trunk postures were 30° of lower and upper trunk inclination (WT30°), 30° and 60° of lower and upper trunk inclination (UT 60°), respectively and 60° of upper and lower trunk inclination (WT60°). Both SV and ET were significantly higher and HR and PEP were lower at UT60° than at WT60° (p < 0.01) whereas these values did not significantly differ between WT30° and UT60° (p > 0.05). None of Q, SVR and BP significantly differed among the three conditions (p > 0.05). These findings suggested that SV and preload are higher when the upper trunk is upright (UT60°) than when the entire trunk is upright (WT60°) while in Fowler's position. In addition, Q might be maintained without increasing HR through vagal withdrawal when only the upper trunk is upright in healthy young males in Fowler's position.
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Couderc JP, Kyal S, Mestha LK, Xu B, Peterson DR, Xia X, Hall B. Detection of atrial fibrillation using contactless facial video monitoring. Heart Rhythm 2014; 12:195-201. [PMID: 25179488 DOI: 10.1016/j.hrthm.2014.08.035] [Citation(s) in RCA: 65] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/18/2014] [Indexed: 11/17/2022]
Abstract
BACKGROUND It is estimated that 33.5 million people in the world have developed atrial fibrillation (AF), and an estimated 30% of patients with AF are unaware of their diagnosis (silent AF). OBJECTIVE The purpose of this study was to test a new technology for contactless detection of AF based on facial video recordings. METHODS The proposed technique uses a camera to record an individual's face and extract the subtle beat-to-beat variations of skin color reflecting the cardiac pulsatile signal. In a group of adults referred for electrical cardioversion, we recorded the ECG and the video of the subjects' face before and after electrical cardioversion. We extracted the beat-to-beat pulse rates expressed as pulses per minute (ppm) from the videoplethysmographic (VPG) signal acquired using a standard web camera. We introduce a novel quantifier of pulse variability called the pulse harmonic strength (PHS) and report its ability to detect the presence of AF. RESULTS Eleven subjects (8 male; age 65 ± 6 years) were included in the study. The VPG and ECG-based rates were statistically different between the AF and sinus rhythm periods: 72 ± 9 ppm vs 57 ± 7 ppm (P < .0001) for VPG and 80 ± 17 bpm vs 56 ± 7 bpm (P < .0001) for ECG signals. Among the 407 epochs of 15 seconds of synchronized ECG and VPG signals, PHS was associated with a 20% detection error rate, and the error rates of the automatic ECG-based measurements ranged between 17% and 29%. CONCLUSION Our preliminary results support the concept that contactless video-based monitoring of the human face for detection of abnormal pulse variability due to AF is feasible.
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Affiliation(s)
- Jean-Philippe Couderc
- Heart Research Follow-up Program, Cardiology Department, University of Rochester Medical Center, University of Rochester, New-York.
| | - Survi Kyal
- Palo Alto Research Center-A Xerox Company, Webster, New York
| | - Lalit K Mestha
- Palo Alto Research Center-A Xerox Company, Webster, New York
| | - Beilei Xu
- Palo Alto Research Center-A Xerox Company, Webster, New York
| | - Derick R Peterson
- Department of Biostatistics and Computational Biology, University of Rochester Medical Center, Rochester, New York
| | - Xiaojuan Xia
- Heart Research Follow-up Program, Cardiology Department, University of Rochester Medical Center, University of Rochester, New-York
| | - Burr Hall
- Heart Research Follow-up Program, Cardiology Department, University of Rochester Medical Center, University of Rochester, New-York
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Heathers JAJ. Everything Hertz: methodological issues in short-term frequency-domain HRV. Front Physiol 2014; 5:177. [PMID: 24847279 PMCID: PMC4019878 DOI: 10.3389/fphys.2014.00177] [Citation(s) in RCA: 178] [Impact Index Per Article: 17.8] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2013] [Accepted: 04/17/2014] [Indexed: 11/22/2022] Open
Abstract
Frequency analysis of the electrocardiographic RR interval is a common method of quantifying autonomic outflow by measuring the beat-to-beat modulation of the heart (heart rate variability; HRV). This review identifies a series of problems with the methods of doing so—the interpretation of low-frequency spectral power, the multiple use of equivalent normalized low frequency (LFnu), high frequency (HFnu) and ratio (LF/HF) terms, and the lack of control over extraneous variables, and reviews research in the calendar year 2012 to determine their prevalence and severity. Results support the mathematical equivalency of ratio units across studies, a reliance on those variables to explain autonomic outflow, and insufficient control of critical experimental variables. Research measurement of HRV has a substantial need for general methodological improvement.
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Affiliation(s)
- James A J Heathers
- Psychophysiology Group, Department of Psychology, University of Sydney Sydney, NSW, Australia
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Pulse wave transit time measurements of cardiac output in patients undergoing partial hepatectomy: a comparison of the esCCO system with thermodilution. Anesth Analg 2014; 117:1307-12. [PMID: 24257379 DOI: 10.1213/ane.0b013e3182a44c87] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
BACKGROUND Measuring cardiac output accurately during anesthesia is thought to be helpful for safely controlling hemodynamics. Several minimally invasive methods to measure cardiac output have been developed as alternatives to thermodilution with pulmonary artery catheterization. We evaluated the reliability of a novel pulse wave transit time method of cardiac output assessment to trend with thermodilution cardiac output in patients undergoing partial hepatectomy. METHODS Thirty-one patients (ASA physical status II or III) undergoing partial hepatectomy under general anesthesia were evaluated. Cardiac output measurements by pulse wave transit time method and by thermodilution were recorded after induction of anesthesia, after a change in body positioning to 20° head up, after a change to 20° head down, after volume challenge with 10 mL·kg hydroxyethyl starch 6%, during the Pringle maneuver, and immediately after Pringle maneuver release. Trending was assessed using Bland-Altman analysis and concordance analysis. RESULTS The direction of change between consecutive pulse wave transit time measurements and the corresponding thermodilution measurements showed a concordance rate of 96.0% (lower 95% confidence interval = 64%), with limits of agreement -1.51 and 1.61 L·min. CONCLUSIONS The pulse wave transit time method had good concordance but fairly wide limits of agreement with regard to trending in patients with changes in preload and systemic vascular resistance. There are potential inaccuracies when vasopressors are used to treat hypotension associated with decreased systemic vascular resistance. The study limitations are that the cardiac output data were collected in a nonblinded fashion, and an existing intraarterial catheter was used, although the system requires only routine, noninvasive cardiovascular monitors. This is a promising technique that currently has limitations and will require further improvements and clinical assessment.
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Vistisen ST, Andersen KK, Frederiksen CA, Kirkegaard H. Variations in the pre-ejection period induced by ventricular extra systoles may be feasible to predict fluid responsiveness. J Clin Monit Comput 2013; 28:341-9. [PMID: 24203263 DOI: 10.1007/s10877-013-9528-4] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2013] [Accepted: 10/31/2013] [Indexed: 11/28/2022]
Abstract
Monitoring that can predict fluid responsiveness is an unsettled matter for spontaneously breathing patients. Based on the convincing results with dynamic monitoring based on preload variations induced by mechanical ventilation, we hypothesised that the extra systolic post-ectopic beat could constitute a similar intermittent preload shift inducing a brief variation in blood pressure and that the magnitude of this variation could predict the hemodynamic response to volume expansion in sedated pigs. Ten pigs were sedated and hemodynamically monitored and four intravascular volume shifts were made: blood depletion (25% of estimated blood volume; 660 ml), retransfusion (of 500 ml depleted blood), and two sequential volume expansions (500 ml colloid each). Between volume shifts, supraventricular and ventricular extra systoles were induced by a pacemaker. Hemodynamic variables such as pulse pressure (PP) and pre-ejection period (PEP) were determined for each heart beat and the hemodynamic changes in the post-ectopic beats compared to sinus beats was extracted (e.g. ∆PP and ∆PEP) and used to predict fluid responsiveness of subsequent volume expansions which was determined by receiver operating characteristic (ROC) curves. Ventricular extra systoles were generally useful for fluid responsiveness prediction (ROC areas >0.65). ∆PEP variables best predicted fluid responsiveness: ∆PEP derived from arterial pressure curve and ECG had ROC area of 0.84 and sensitivity of 0.77 and specificity of 0.71; ∆PEP derived from plethysmographic curve and ECG had ROC area of 0.79 and sensitivity of 0.71 and specificity of 0.70. However, ∆PP was not a useful variable in this study (ROC area <0.65). Hemodynamic analysis of post ectopic beats may be a feasible method for fluid responsiveness prediction.
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Affiliation(s)
- Simon Tilma Vistisen
- Research Centre for Emergency Medicine, Institute of Clinical Medicine, Aarhus University, Nørrebrogade 44, Building 30, 1st Floor, 8000, Århus C, Denmark,
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Vistisen ST, Juhl-Olsen P, Frederiksen CA, Kirkegaard H. Variations in the pre-ejection period induced by deep breathing do not predict the hemodynamic response to early haemorrhage in healthy volunteers. J Clin Monit Comput 2013; 28:233-41. [DOI: 10.1007/s10877-013-9526-6] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2013] [Accepted: 10/24/2013] [Indexed: 11/24/2022]
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VETTORELLO M, SANTAMBROGIO SM, CALINI AR, TIZZONI L, MARCONI G, LIPPI MG, SESANA G, CHIARA O, FUMAGALLI R. Predicting haemorrhage in pre-hospital traumatic patients: evaluation of the novel heart-to-arm time index. Acta Anaesthesiol Scand 2013; 57:929-35. [PMID: 23701337 DOI: 10.1111/aas.12135] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/25/2013] [Indexed: 01/10/2023]
Abstract
BACKGROUND Early recognition of hypovolaemia in trauma patients is very important. However, the most often used clinical signs, such as hypotension and tachycardia, lack specificity and sensitivity. METHODS We propose a non-invasive index of hypovolaemia, the heart to arm time (iHAT), based on a modified pulse transit time indexed to heart rate. Pulse transit time is the sum of pre-ejection period and vascular transit time. Following pre-load reductions due to hypovolaemia, ventricular diastolic filling time increases causing an increase in pre-ejection-period, pulse transit time, and hence iHAT. One hundred and four consecutive patients with suspected major trauma were enrolled. The primary aim was to evaluate the use of the iHAT for detecting haemorrhage in major trauma. The secondary end point was to compare the specificity and sensitivity of iHAT compared to commonly used indexes. RESULTS iHAT was calculated in 84 subjects, 11 of whom were haemorrhagic. iHAT discriminated haemorrhagic from non-haemorrhagic group (46.8% vs. 66.9%, P < 0.0001). The cut-off for iHAT with the best compromise between sensitivity (90.9%) and specificity (100%) was reached at the 58.78% level. Comparing haemorrhagic and non-haemorrhagic patients, the area under the ROC curve was 0.952 for iHAT, 0.835 for heart rate, and 0.911 for systolic blood pressure, showing no significant differences. CONCLUSIONS iHAT is a non-invasive index that can identify haemorrhage in trauma patients with high sensitivity and specificity. These data should be considered as an exploration, but any conclusion should be validated in a new set of consecutive patients.
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Affiliation(s)
| | - S. M. SANTAMBROGIO
- Anesthesia and Intensive Care Unit I; Department of Perioperative Medicine and Intensive Care; ‘Niguarda Ca' Granda’ Hospital; Milan; Italy
| | - A. R. CALINI
- Anesthesia and Intensive Care Unit I; Department of Perioperative Medicine and Intensive Care; ‘Niguarda Ca' Granda’ Hospital; Milan; Italy
| | - L. TIZZONI
- Anesthesia and Intensive Care Unit Department; San Gerardo University Hospital; Monza; Italy
| | - G. MARCONI
- AAT 118 Milano; Italy Emergency Operations Center and Helicopter Emergency Medical System; AREU; Lombardia; Italy
| | - M. G. LIPPI
- Anesthesia and Intensive Care Unit I; Department of Perioperative Medicine and Intensive Care; ‘Niguarda Ca' Granda’ Hospital; Milan; Italy
| | - G. SESANA
- AAT 118 Milano; Italy Emergency Operations Center and Helicopter Emergency Medical System; AREU; Lombardia; Italy
| | - O. CHIARA
- Emergency Department and Trauma Team; ‘Niguarda Cà Granda’ Hospital; Milan; Italy
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Muehlsteff J, Ritz A, Drexel T, Eickholt C, Carvalho P, Couceiro R, Kelm M, Meyer C. Pulse Arrival Time as surrogate for systolic blood pressure changes during impending neurally mediated syncope. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2013; 2012:4283-6. [PMID: 23366874 DOI: 10.1109/embc.2012.6346913] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Blood pressure regulation failures cause neurally mediated syncope often resulting in a fall. A warning device might help to make patients aware of an impending critical event or even trigger the patient to perform countermeasures such as lying down or isometric exercises. We previously demonstrated that the Pulse Arrival Time (PAT) methodology is a potential approach to enable early detection of impending faints. The aim of the present study was to evaluate whether PAT can be used as an easy to measure beat-to-beat surrogate for systolic blood pressure (SBP) changes during a passive standing exercise (head-up tilt table testing (HUTT)). A significant PAT increase of more than 10 % was accompanied with a critical SBP decrease in syncope patients. Although PAT is in general not considered as a good measure of absolute blood pressure we found strong correlations (R>0.89, P<0.01) of SBP and PAT after PAT began to increase. Therefore, our data suggest that the pulse arrival time is useful to monitor blood pressure changes in patients with neurally mediated syncope. This might open up new avenues to prevent falls in these patients.
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Wang CH, Lu CW, Lin TY, Abbod MF, Shieh JS. An assessment of pulse transit time for detecting heavy blood loss during surgical operation. Open Biomed Eng J 2012; 6:104-11. [PMID: 23304244 PMCID: PMC3537113 DOI: 10.2174/1874120701206010104] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2012] [Revised: 09/07/2012] [Accepted: 10/05/2012] [Indexed: 11/25/2022] Open
Abstract
The main contribution of this paper is the use of non-invasive measurements such as electrocardiogram (ECG) and photoplethysmographic (PPG) pulse oximetry waveforms to develop a new physiological signal analysis technique for detecting blood loss during surgical operation. Urological surgery cases were considered as the control group due to its generality, and cardiac surgery as experimental group since it involves blood loss and water supply. Results show that the control group has the tendency of a reduction of the pulse transient time (PTT), and this indicates an increment in the blood flow velocity changes from slow to fast. While for the experimental group, the PTT indicates high values during blood loss, and low values during water supply. Statistical analysis shows considerable differences (i.e., P <0.05) between both groups leading to the conclusion that PTT could be a good indicator for monitoring patients' blood loss during a surgical operation.
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Affiliation(s)
- Chien-Hao Wang
- Department of Mechanical Engineering, Yuan Ze University, Taiwan, R.O.C
| | - Cheng-Wei Lu
- Department of Mechanical Engineering, Yuan Ze University, Taiwan, R.O.C
- Department of Anesthesiology, Far Eastern Memorial Hospital, Taiwan, R.O.C
| | - Tzu-Yu Lin
- Department of Mechanical Engineering, Yuan Ze University, Taiwan, R.O.C
- Department of Anesthesiology, Far Eastern Memorial Hospital, Taiwan, R.O.C
| | - Maysam F Abbod
- School of Engineering and Design, Brunel University, London, UK
| | - Jiann-Shing Shieh
- Department of Mechanical Engineering, Yuan Ze University, Taiwan, R.O.C
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Sugo Y, Sakai T, Terao M, Ukawa T, Ochiai R. The comparison of a novel continuous cardiac output monitor based on pulse wave transit time and echo Doppler during exercise. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2012; 2012:236-239. [PMID: 23365874 DOI: 10.1109/embc.2012.6345913] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
A new technology called estimated continuous cardiac output (esCCO) uses pulse wave transit time (PWTT) obtained from an electrocardiogram and pulse oximeter to measure cardiac output (CO) non-invasively and continuously. This study was performed to evaluate the accuracy of esCCO during exercise testing. We compared esCCO with CO measured by the echo Doppler aortic velocity-time integral (VTIao_CO). The correlation coefficient between esCCO and VTIao_CO was r= 0.87 (n= 72). Bias and precision were 0.33 ± 0.95 L/min and percentage error was 31%. The esCCO could detect change in VTIao_CO larger than 1 L/min with a concordance rate of 88%. In polar plot, 83% of data are within 0.5 L/min, and 100% of data are within 1 L/min. Those results show the acceptable accuracy and trend ability of esCCO. Change in pre-ejection period (PEP) measured by using M-mode of Diagnostic Ultrasound System accounted for approximately half of change in PWTT. This indicates that PEP included in PWTT has an impact on the accuracy of esCCO measurement. In this study, the validity of esCCO during exercise testing was assessed and shown to be acceptable. The result of this study suggests that we can expand its application.
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Affiliation(s)
- Yoshihiro Sugo
- Nihon Kohden Corp., 1-31-4 Nishi-Ochiai, Shinjuku-ku, Tokyo, Japan.
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MEYER CHRISTIAN, MORREN GEERT, MUEHLSTEFF JENS, HEISS CHRISTIAN, LAUER THOMAS, SCHAUERTE PATRICK, RASSAF TIENUSH, PURERFELLNER HELMUT, KELM MALTE. Predicting Neurally Mediated Syncope Based on Pulse Arrival Time: Algorithm Development and Preliminary Results. J Cardiovasc Electrophysiol 2011; 22:1042-8. [DOI: 10.1111/j.1540-8167.2011.02030.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Tang CHH, Chan GSH, Middleton PM, Cave G, Harvey M, Javed F, Savkin AV, Lovell NH. Pulse transit time variability analysis in an animal model of endotoxic shock. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2010; 2010:2849-52. [PMID: 21095708 DOI: 10.1109/iembs.2010.5626072] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The use of non-invasively measured pulse transit time (PTT) to monitor the cardiovascular systems in critically ill patients, like sepsis, can be of significant clinical value. In this study, the potential of PTT and its variability in cardiovascular system monitoring in a mechanically ventilated and anesthetized rabbit model of endotoxic shock was assessed. Eight adult New Zealand white rabbits, which were treated with endotoxin bolus infusion, were studied. Measurements of PTT, pre-ejection period (PEP), and vascular transit time (VTT) were obtained in pre- and post-intervention stages (before and 90 minutes after the administration of endotoxin). The decrease in mean PTT (p < 0.05) and PEP (p < 0.01) in the post-intervention stage reflected sympathetic activation, whilst the increase in respiratory variation in PTT (p < 0.01), PEP (p 〈 0.01), and VTT (p < 0.01) could be attributed to an enhancement of respiratory variation in stroke volume associated with hypovolemia in endotoxic shock. The relationship between beat-to-beat variability in PTT and all other cardiovascular time series were further investigated through linear regression analysis, which revealed that PTT was most strongly correlated with VTT (R(2) ≥ 0.84 with positive slope). Computation of coherence and phase shift in the ventilating frequency band (HF: 0.50 - 0.75 Hz) showed that the respiratory variation in PTT was synchronized with both PEP and VTT (coherence > 0.84 with phase shift less than one cardiac beat). These results highlighted the potential value of PTT and its respiratory variation in characterizing the pathophysioloigcal hemodynamic change in endotoxic shock.
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Affiliation(s)
- Collin H H Tang
- School of Electrical Engineering and Telecommunications, UNSW, Sydney, NSW 2052, Australia
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Relationship between pulse transit time and blood pressure is impaired in patients with chronic heart failure. Clin Res Cardiol 2010; 99:657-64. [DOI: 10.1007/s00392-010-0168-0] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/04/2009] [Accepted: 04/14/2010] [Indexed: 12/13/2022]
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Tang CHH, Middleton PM, Savkin AV, Chan GSH, Bishop S, Lovell NH. Non-invasive classification of severe sepsis and systemic inflammatory response syndrome using a nonlinear support vector machine: a preliminary study. Physiol Meas 2010; 31:775-93. [PMID: 20453293 DOI: 10.1088/0967-3334/31/6/004] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Sepsis has been defined as the systemic response to infection in critically ill patients, with severe sepsis and septic shock representing increasingly severe stages of the same disease. Based on the non-invasive cardiovascular spectrum analysis, this paper presents a pilot study on the potential use of the nonlinear support vector machine (SVM) in the classification of the sepsis continuum into severe sepsis and systemic inflammatory response syndrome (SIRS) groups. 28 consecutive eligible patients attending the emergency department with presumptive diagnoses of sepsis syndrome have participated in this study. Through principal component analysis (PCA), the first three principal components were used to construct the SVM feature space. The SVM classifier with a fourth-order polynomial kernel was found to have a better overall performance compared with the other SVM classifiers, showing the following classification results: sensitivity = 94.44%, specificity = 62.50%, positive predictive value = 85.00%, negative predictive value = 83.33% and accuracy = 84.62%. Our classification results suggested that the combinatory use of cardiovascular spectrum analysis and the proposed SVM classification of autonomic neural activity is a potentially useful clinical tool to classify the sepsis continuum into two distinct pathological groups of varying sepsis severity.
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Affiliation(s)
- Collin H H Tang
- School of Electrical Engineering and Telecommunications, The University of New South Wales, Sydney, NSW 2052, Australia
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Tang CHH, Chan GSH, Middleton PM, Savkin AV, Lovell NH. Spectral analysis of heart period and pulse transit time derived from electrocardiogram and photoplethysmogram in sepsis patients. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2010; 2009:1781-4. [PMID: 19964557 DOI: 10.1109/iembs.2009.5334005] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Sepsis is a potentially lethal condition, and is one of the major causes of death in non-coronary intensive care units. Sepsis syndrome progresses through a number of increasingly severe stages, from systemic inflammatory response syndrome (SIRS) through sepsis, severe sepsis and septic shock. Each stage of sepsis is potentially characterized by differing autonomic nervous system responses. Spectral analysis of cardiovascular variability has been regarded as a possible non-invasive method to study this autonomic regulation, and in this study, the variabilities of heart period (RRi) and pulse transit time (PTT) derived from electrocardiogram and photoplethys-mogram were investigated in three different groups: normal subjects (n = 11), SIRS (n = 7) and severe sepsis patients (n = 16), by computing spectral and cross-spectral measures in the low-frequency (LF) and the high-frequency (HF) ranges. SIRS and severe sepsis patients were found to have lower RRi (p < 0.01), augmented LF power in PTT (p < 0.01) and a lower RRi-PTT ratio (alpha(PTT)) in the LF and HF bands (p < 0.01) as compared with the normal subjects, which might indicate a suppression of baroreflex-mediated autonomic control of heart rate and an increased sympathetic influence on ventricular contractility in sepsis. The results have highlighted the potential value of spectral analysis of RRi and PTT variabilities as a non-invasive tool for clinical evaluation of cardiac autonomic regulation in sepsis patients.
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Affiliation(s)
- Collin H H Tang
- School of Electrical Engineering and Telecommunications, The University of New South Wales, Sydney, NSW 2052, Australia.
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Bezemer R, Karemaker JM, Klijn E, Martin D, Mitchell K, Grocott M, Heger M, Ince C. Simultaneous multi-depth assessment of tissue oxygen saturation in thenar and forearm using near-infrared spectroscopy during a simple cardiovascular challenge. CRITICAL CARE : THE OFFICIAL JOURNAL OF THE CRITICAL CARE FORUM 2009; 13 Suppl 5:S5. [PMID: 19951389 PMCID: PMC2786107 DOI: 10.1186/cc8003] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Introduction Hypovolemia and hypovolemic shock are life-threatening conditions that occur in numerous clinical scenarios. Near-infrared spectroscopy (NIRS) has been widely explored, successfully and unsuccessfully, in an attempt to use it as an early detector of hypovolemia by measuring tissue oxygen saturation (StO2). In order to investigate the measurement site dependence and probe dependence of NIRS in response to hemodynamic changes, such as hypovolemia, we applied a simple cardiovascular challenge: a posture change from supine to upright, causing a decrease in stroke volume (as in hypovolemia) and a heart rate increase in combination with peripheral vasoconstriction to maintain adequate blood pressure. Methods Multi-depth NIRS was used in nine healthy volunteers to assess changes in StO2 in the thenar and forearm in response to the hemodynamic changes associated with a posture change from supine to upright. Results A posture change from supine to upright resulted in a significant increase (P < 0.001) in heart rate. Thenar StO2 did not respond to the hemodynamic changes following the posture change, whereas forearm StO2 did. Forearm StO2 was significantly lower (P < 0.001) in the upright position compared to supine for all probing depths. Conclusions The primary findings in this study were that forearm StO2 is a more sensitive parameter to hemodynamic changes than thenar StO2 and that the depth at which StO2 is measured is of minor influence. Our data support the use of forearm StO2 as a sensitive parameter for the detection of central hypovolemia and hypovolemic shock in (trauma) patients.
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Affiliation(s)
- Rick Bezemer
- Department of Translational Physiology, Academic Medical Center, University of Amsterdam, Meibergdreef 9, 1105 AZ Amsterdam, the Netherlands.
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Avolio AP, Butlin M, Walsh A. Arterial blood pressure measurement and pulse wave analysis-–their role in enhancing cardiovascular assessment. Physiol Meas 2009; 31:R1-47. [DOI: 10.1088/0967-3334/31/1/r01] [Citation(s) in RCA: 202] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
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Middleton PM, Chan GS, O’Lone E, Steel E, Carroll R, Celler BG, Lovell NH. Changes in left ventricular ejection time and pulse transit time derived from finger photoplethysmogram and electrocardiogram during moderate haemorrhage. Clin Physiol Funct Imaging 2009; 29:163-9. [DOI: 10.1111/j.1475-097x.2008.00843.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Vistisen ST, Struijk JJ, Larsson A. Automated pre-ejection period variation indexed to tidal volume predicts fluid responsiveness after cardiac surgery. Acta Anaesthesiol Scand 2009; 53:534-42. [PMID: 19239409 DOI: 10.1111/j.1399-6576.2008.01893.x] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
BACKGROUND Reliable continuous monitoring of fluid responsiveness is an unsolved issue in patients ventilated with low tidal volume. We hypothesised that variations in the pre-ejection period (PEP) defined as the time interval between electrocardiogram (ECG) R-wave and onset of systolic upstroke in arterial blood pressure could reliably predict fluid responsiveness in patients ventilated with moderately low tidal volume. Furthermore, we hypothesised that indexing dynamic parameters to tidal volume would improve their prediction. The aim was to refine and automate a previously suggested algorithm for PEP variation (DeltaPEP) and to test this new parameter indexed to tidal volume (PEPV), as a marker of fluid responsiveness along with central venous pressure (CVP), pulse pressure variation (PPV) and DeltaPEP. Additionally, the aim was to evaluate the concept of indexing dynamic parameters to tidal volume. METHODS Arterial pressure, CVP, ECG and cardiac index (CI) were acquired from 23 mechanically ventilated post-cardiac surgery patients scheduled for volume expansion. PEPV, PPV and DeltaPEP were extracted. RESULTS Using responder/non-responder classification (response=change in CI>+15%), sensitivity and specificity were 100% and 83%, respectively, for PEPV, 94% and 83% for DeltaPEP, and 94% and 83% for PPV. CVP offered no relevant information. Tidal volume indexing improved sensitivity for DeltaPEP to 100%. CONCLUSION In this study in post-cardiac surgery patients, a refined parameter, PEPV, predicted fluid responsiveness better than PPV and DeltaPEP. Our results suggest that dynamic parameters using variations in PEP should be indexed to tidal volume.
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Affiliation(s)
- S T Vistisen
- Cardiothoracic Intensive Care Unit, Department of Anaesthesia and Intensive Care, Aalborg Hospital-Aarhus University Hospitals, Nørrebrogade 44, bygning 1C, 1. sal, Aarhus C, Denmark.
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Bendjelid K. Pre-ejection period, contractility and preload. a fascinating riddle. J Clin Monit Comput 2007; 21:387. [DOI: 10.1007/s10877-007-9098-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2007] [Accepted: 10/05/2007] [Indexed: 11/24/2022]
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