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Froese L, Gomez A, Sainbhi AS, Batson C, Stein K, Alizadeh A, Zeiler FA. Dynamic Temporal Relationship Between Autonomic Function and Cerebrovascular Reactivity in Moderate/Severe Traumatic Brain Injury. FRONTIERS IN NETWORK PHYSIOLOGY 2022; 2:837860. [PMID: 36926091 PMCID: PMC10013014 DOI: 10.3389/fnetp.2022.837860] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/17/2021] [Accepted: 01/28/2022] [Indexed: 12/12/2022]
Abstract
There has been little change in morbidity and mortality in traumatic brain injury (TBI) in the last 25 years. However, literature has emerged linking impaired cerebrovascular reactivity (a surrogate of cerebral autoregulation) with poor outcomes post-injury. Thus, cerebrovascular reactivity (derived through the pressure reactivity index; PRx) is emerging as an important continuous measure. Furthermore, recent literature indicates that autonomic dysfunction may drive impaired cerebrovascular reactivity in moderate/severe TBI. Thus, to improve our understanding of this association, we assessed the physiological relationship between PRx and the autonomic variables of heart rate variability (HRV), blood pressure variability (BPV), and baroreflex sensitivity (BRS) using time-series statistical methodologies. These methodologies include vector autoregressive integrative moving average (VARIMA) impulse response function analysis, Granger causality, and hierarchical clustering. Granger causality testing displayed inconclusive results, where PRx and the autonomic variables had varying bidirectional relationships. Evaluating the temporal profile of the impulse response function plots demonstrated that the autonomic variables of BRS, ratio of low/high frequency of HRV and very low frequency HRV all had a strong relation to PRx, indicating that the sympathetic autonomic response may be more closely linked to cerebrovascular reactivity, then other variables. Finally, BRS was consistently associated with PRx, possibly demonstrating a deeper relationship to PRx than other autonomic measures. Taken together, cerebrovascular reactivity and autonomic response are interlinked, with a bidirectional impact between cerebrovascular reactivity and circulatory autonomics. However, this work is exploratory and preliminary, with further study required to extract and confirm any underlying relationships.
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Affiliation(s)
- Logan Froese
- Biomedical Engineering, Faculty of Engineering, University of Manitoba, Winnipeg, MB, Canada
| | - Alwyn Gomez
- Section of Neurosurgery, Department of Surgery, Rady Faculty of Health Sciences, University of Manitoba, Winnipeg, MB, Canada
- Department of Human Anatomy and Cell Science, Rady Faculty of Health Sciences, University of Manitoba, Winnipeg, MB, Canada
| | - Amanjyot Singh Sainbhi
- Biomedical Engineering, Faculty of Engineering, University of Manitoba, Winnipeg, MB, Canada
| | - Carleen Batson
- Department of Human Anatomy and Cell Science, Rady Faculty of Health Sciences, University of Manitoba, Winnipeg, MB, Canada
| | - Kevin Stein
- Section of Neurosurgery, Department of Surgery, Rady Faculty of Health Sciences, University of Manitoba, Winnipeg, MB, Canada
| | - Arsalan Alizadeh
- Section of Neurosurgery, Department of Surgery, Rady Faculty of Health Sciences, University of Manitoba, Winnipeg, MB, Canada
| | - Frederick A. Zeiler
- Biomedical Engineering, Faculty of Engineering, University of Manitoba, Winnipeg, MB, Canada
- Section of Neurosurgery, Department of Surgery, Rady Faculty of Health Sciences, University of Manitoba, Winnipeg, MB, Canada
- Department of Human Anatomy and Cell Science, Rady Faculty of Health Sciences, University of Manitoba, Winnipeg, MB, Canada
- Centre on Aging, University of Manitoba, Winnipeg, MB, Canada
- Division of Anaesthesia, Department of Medicine, Addenbrooke’s Hospital, University of Cambridge, Cambridge, United Kingdom
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Impact of Respiratory Fluctuation on Hemodynamics in Human Cardiovascular System: A 0-1D Multiscale Model. FLUIDS 2022. [DOI: 10.3390/fluids7010028] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
To explore hemodynamic interaction between the human respiratory system (RS) and cardiovascular system (CVS), here we propose an integrated computational model to predict the CVS hemodynamics with consideration of the respiratory fluctuation (RF). A submodule of the intrathoracic pressure (ITP) adjustment is developed and incorporated in a 0-1D multiscale hemodynamic model of the CVS specified for infant, adolescent, and adult individuals. The model is verified to enable reasonable estimation of the blood pressure waveforms accounting for the RF-induced pressure fluctuations in comparison with clinical data. The results show that the negative ITP caused by respiration increases the blood flow rates in superior and inferior vena cavae; the deep breathing improves the venous return in adolescents but has less influence on infants. It is found that a marked reduction in ITP under pathological conditions can excessively increase the flow rates in cavae independent of the individual ages, which may cause the hemodynamic instability and hence increase the risk of heart failure. Our results indicate that the present 0-1D multiscale CVS model incorporated with the RF effect is capable of providing a useful and effective tool to explore the physiological and pathological mechanisms in association with cardiopulmonary interactions and their clinical applications.
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Porta A, Gelpi F, Bari V, Cairo B, De Maria B, Tonon D, Rossato G, Ranucci M, Faes L. Categorizing the Role of Respiration in Cardiovascular and Cerebrovascular Variability Interactions. IEEE Trans Biomed Eng 2021; 69:2065-2076. [PMID: 34905489 DOI: 10.1109/tbme.2021.3135313] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
OBJECTIVE Respiration disturbs cardiovascular and cerebrovascular controls but its role is not fully elucidated. METHODS Respiration can be classified as a confounder if its observation reduces the strength of the causal relationship from source to target. Respiration is a suppressor if the opposite situation holds. We prove that a confounding/suppression (C/S) test can be accomplished by evaluating the sign of net redundancy/synergy balance in the predictability framework based on multivariate autoregressive modelling. In addition, we suggest that, under the hypothesis of Gaussian processes, the C/S test can be given in the transfer entropy decomposition framework as well. Experimental protocols: We applied the C/S test to variability series of respiratory movements, heart period, systolic arterial pressure, mean arterial pressure, and mean cerebral blood flow recorded in 17 pathological individuals (age: 648 yrs; 17 males) before and after induction of propofol-based general anesthesia prior to coronary artery bypass grafting, and in 13 healthy subjects (age: 278 yrs; 5 males) at rest in supine position and during head-up tilt with a table inclination of 60. RESULTS Respiration behaved systematically as a confounder for cardiovascular and cerebrovascular controls. In addition, its role was affected by propofol-based general anesthesia but not by a postural stimulus of limited intensity. CONCLUSION The C/S test can be fruitfully exploited to categorize the role of respiration over causal variability interactions. SIGNIFICANCE The application of the C/S test could favor the comprehension of the role of respiration in cardiovascular and cerebrovascular regulations.
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Ogilvie LM, Edgett BA, Gray S, Al-Mufty S, Huber JS, Brunt KR, Simpson JA. A new approach to improve the hemodynamic assessment of cardiac function independent of respiratory influence. Sci Rep 2021; 11:17223. [PMID: 34446745 PMCID: PMC8390640 DOI: 10.1038/s41598-021-96050-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2021] [Accepted: 07/19/2021] [Indexed: 01/06/2023] Open
Abstract
Cardiovascular and respiratory systems are anatomically and functionally linked; inspiration produces negative intrathoracic pressures that act on the heart and alter cardiac function. Inspiratory pressures increase with heart failure and can exceed the magnitude of ventricular pressure during diastole. Accordingly, respiratory pressures may be a confounding factor to assessing cardiac function. While the interaction between respiration and the heart is well characterized, the extent to which systolic and diastolic indices are affected by inspiration is unknown. Our objective was to understand how inspiratory pressure affects the hemodynamic assessment of cardiac function. To do this, we developed custom software to assess and separate indices of systolic and diastolic function into inspiratory, early expiratory, and late expiratory phases of respiration. We then compared cardiac parameters during normal breathing and with various respiratory loads. Variations in inspiratory pressure had a small impact on systolic pressure and function. Conversely, diastolic pressure strongly correlated with negative inspiratory pressure. Cardiac pressures were less affected by respiration during expiration; late expiration was the most stable respiratory phase. In conclusion, inspiration is a large confounding influence on diastolic pressure, but minimally affects systolic pressure. Performing cardiac hemodynamic analysis by accounting for respiratory phase yields more accuracy and analytic confidence to the assessment of diastolic function.
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Affiliation(s)
- Leslie M Ogilvie
- Department of Human Health and Nutritional Sciences, University of Guelph, 50 Stone Road East, Guelph, ON, N1G 2W1, Canada
- IMPART Investigator Team Canada, Saint John, Canada
| | - Brittany A Edgett
- Department of Human Health and Nutritional Sciences, University of Guelph, 50 Stone Road East, Guelph, ON, N1G 2W1, Canada
- Department of Pharmacology, Dalhousie Medicine New Brunswick, Saint John, NB, Canada
- IMPART Investigator Team Canada, Saint John, Canada
| | - Simon Gray
- Cambridge Electronic Design Limited, Milton, Cambridge, England
| | - Sally Al-Mufty
- Department of Human Health and Nutritional Sciences, University of Guelph, 50 Stone Road East, Guelph, ON, N1G 2W1, Canada
- IMPART Investigator Team Canada, Saint John, Canada
| | - Jason S Huber
- Department of Human Health and Nutritional Sciences, University of Guelph, 50 Stone Road East, Guelph, ON, N1G 2W1, Canada
| | - Keith R Brunt
- Department of Pharmacology, Dalhousie Medicine New Brunswick, Saint John, NB, Canada
- IMPART Investigator Team Canada, Saint John, Canada
| | - Jeremy A Simpson
- Department of Human Health and Nutritional Sciences, University of Guelph, 50 Stone Road East, Guelph, ON, N1G 2W1, Canada.
- IMPART Investigator Team Canada, Saint John, Canada.
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Nardone M, Teixeira AL, Incognito AV, Vermeulen TD, Shafer BM, Millar PJ, Foster GE. Within-breath sympathetic baroreflex sensitivity is modulated by lung volume but unaffected by acute intermittent hypercapnic hypoxia in men. Am J Physiol Heart Circ Physiol 2020; 319:H213-H221. [DOI: 10.1152/ajpheart.00296.2020] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
In resting spontaneously breathing men, the present study observed that sympathetic baroreflex sensitivity (BRS) was higher during low versus high lung volumes but not different between inspiration and expiration. High- but not low-lung volume BRS was negatively associated with resting muscle sympathetic nerve activity (MSNA). Acute intermittent hypercapnic hypoxia increased resting MSNA and diastolic blood pressure, without altering within-breath BRS. These findings provide novel insight into mechanisms controlling within-breath modulation of MSNA in humans.
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Affiliation(s)
- Massimo Nardone
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada
| | - André L. Teixeira
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada
| | - Anthony V. Incognito
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada
| | - Tyler D. Vermeulen
- Centre for Heart, Lung, and Vascular Health, School of Health and Exercise Sciences, University of British Columbia, Kelowna, British Columbia, Canada
| | - Brooke M. Shafer
- Centre for Heart, Lung, and Vascular Health, School of Health and Exercise Sciences, University of British Columbia, Kelowna, British Columbia, Canada
| | - Philip J. Millar
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada
- Toronto General Research Institute, Toronto General Hospital, Toronto, Ontario, Canada
| | - Glen E. Foster
- Centre for Heart, Lung, and Vascular Health, School of Health and Exercise Sciences, University of British Columbia, Kelowna, British Columbia, Canada
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Relationship between the fall in blood pressure in the standing position and diaphragmatic muscle thickness: proof of concept study. Blood Press Monit 2020; 24:284-288. [PMID: 31567294 DOI: 10.1097/mbp.0000000000000403] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
BACKGROUND The diaphragm is an important muscle of respiration, and regulates the intrathoracic pressure. Blood pressure is regulated by the baroreceptor reflex system, and is also affected by intrathoracic pressure. We examined the relationship between the diaphragmatic muscle thickness and the degree of drop in blood pressure in the standing position. METHODS We prospectively studied 15 healthy subjects. The diaphragmatic muscle thickness was measured using a B-mode ultrasonic imaging device. The blood pressure before and after standing was measured by a head-up tilt test. RESULTS The diastolic blood pressure difference during expiration and inspiration showed a significant correlation with the diaphragmatic muscle thickness (r = 0.578, P = 0.024 and r = 0.518, P = 0.048, respectively). CONCLUSION The diaphragmatic muscle thickness was related to the fall in diastolic blood pressure in the standing position. This indicates that adequate diaphragmatic muscle thickness helps to maintain intrathoracic pressure and prevents excessive drop in blood pressure in the standing position.
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Cross TJ, Kim CH, Johnson BD, Lalande S. The interactions between respiratory and cardiovascular systems in systolic heart failure. J Appl Physiol (1985) 2019; 128:214-224. [PMID: 31774354 DOI: 10.1152/japplphysiol.00113.2019] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Heart failure (HF) is a complex and multifaceted disease. The disease affects multiple organ systems, including the respiratory system. This review provides three unique examples illustrating how the cardiovascular and respiratory systems interrelate because of the pathology of HF. Specifically, these examples outline the impact of HF pathophysiology on 1) respiratory mechanics and the mechanical "cost" of breathing; 2) mechanical interactions of the heart and lungs; and on 3) abnormalities of pulmonary gas exchange during exercise, and how this may be applied to treatment. The goal of this review is to, therefore, raise the awareness that HF, though primarily a disease of the heart, is accompanied by marked pathology of the respiratory system.
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Affiliation(s)
- Troy James Cross
- Department of Cardiovascular Diseases, Mayo Clinic, Rochester Minnesota
| | - Chul-Ho Kim
- Department of Cardiovascular Diseases, Mayo Clinic, Rochester Minnesota
| | - Bruce D Johnson
- Department of Cardiovascular Diseases, Mayo Clinic, Rochester Minnesota
| | - Sophie Lalande
- Department of Kinesiology and Heath Education, University of Texas at Austin, Austin, Texas
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Rickards CA. Vive la résistance! The role of inspiratory resistance breathing on cerebral blood flow. Respir Physiol Neurobiol 2019; 265:76-82. [DOI: 10.1016/j.resp.2018.10.001] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2018] [Revised: 08/22/2018] [Accepted: 10/03/2018] [Indexed: 10/28/2022]
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9
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Convertino VA. Mechanisms of inspiration that modulate cardiovascular control: the other side of breathing. J Appl Physiol (1985) 2019; 127:1187-1196. [PMID: 31225967 DOI: 10.1152/japplphysiol.00050.2019] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The objective of this minireview is to describe the physiology and potential clinical benefits derived from inspiration. Recent animal and clinical studies demonstrate that one of the body's natural mechanisms associated with inspiration is to harness the respiratory pump to enhance circulation to vital organs. There is evidence that large reductions in intrathoracic pressure (>20 cmH2O) caused by some inspiration maneuvers (e.g., Mueller maneuver) or pathophysiology (e.g., heart failure, chronic obstructive lung disease) can result in adverse hemodynamic effects. However, the respiratory pump can improve cardiovascular functions when a "sweet spot" for generation of negative intrathoracic pressure during inspiration can be maintained at or less than 10 cmH2O below normal inspiration. These beneficial physiological effects include greater cardiac filling and output, lower intracranial pressure, cardiac baroreflex resetting, greater cerebral blood flow oscillatory patterns, increased vascular pressure gradients, and promoting sustained feedback between sympathetic nerve activity and arterial pressure. In addition to promoting gas exchange, data obtained from numerous animal and human experiments have provided new insights into "the other side of breathing": the modulation of circulation by reduced intrathoracic pressure generated during inspiration. The translation of these physiological relationships form the basis for the development and application of technologies designed to optimize the intrathoracic pump for treatment of clinical conditions associated with hypovolemia including cardiac arrest, orthostatic hypotension, hemorrhagic shock, and traumatic brain injury. Harnessing these fundamental mechanisms that control cardiopulmonary physiology provides opportunities to use inspiration as a potential tool to help treat significant and often life-threatening circulatory disorders.
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Affiliation(s)
- Victor A Convertino
- Battlefield Health & Trauma Center for Human Integrative Physiology, U.S. Army Institute of Surgical Research, JBSA Fort Sam Houston, Texas
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Kantor DB, Hirshberg EL, McDonald MC, Griffin J, Buccigrosso T, Stenquist N, Smallwood CD, Nelson KA, Zurakowski D, Phipatanakul W, Hirschhorn JN. Fluid Balance Is Associated with Clinical Outcomes and Extravascular Lung Water in Children with Acute Asthma Exacerbation. Am J Respir Crit Care Med 2018; 197:1128-1135. [PMID: 29313715 PMCID: PMC6019929 DOI: 10.1164/rccm.201709-1860oc] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2017] [Accepted: 01/08/2018] [Indexed: 11/16/2022] Open
Abstract
RATIONALE The effects of fluid administration during acute asthma exacerbation are likely unique in this patient population: highly negative inspiratory intrapleural pressure resulting from increased airway resistance may interact with excess fluid administration to favor the accumulation of extravascular lung water, leading to worse clinical outcomes. OBJECTIVES Investigate how fluid balance influences clinical outcomes in children hospitalized for asthma exacerbation. METHODS We analyzed the association between fluid overload and clinical outcomes in a retrospective cohort of children admitted to an urban children's hospital with acute asthma exacerbation. These findings were validated in two cohorts: a matched retrospective and a prospective observational cohort. Finally, ultrasound imaging was used to identify extravascular lung water and investigate the physiological basis for the inferential findings. MEASUREMENTS AND MAIN RESULTS In the retrospective cohort, peak fluid overload [(fluid input - output)/weight] is associated with longer hospital length of stay, longer treatment duration, and increased risk of supplemental oxygen use (P values < 0.001). Similar results were obtained in the validation cohorts. There was a strong interaction between fluid balance and intrapleural pressure: the combination of positive fluid balance and highly negative inspiratory intrapleural pressures is associated with signs of increased extravascular lung water (P < 0.001), longer length of stay (P = 0.01), longer treatment duration (P = 0.03), and increased risk of supplemental oxygen use (P = 0.02). CONCLUSIONS Excess volume administration leading to fluid overload in children with acute asthma exacerbation is associated with increased extravascular lung water and worse clinical outcomes.
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Affiliation(s)
- David B. Kantor
- Division of Critical Care Medicine, Department of Anesthesiology, Critical Care and Pain Medicine
- Department of Anaesthesia
| | - Eliotte L. Hirshberg
- Division of Pulmonary and Critical Care Medicine, Department of Internal Medicine, Intermountain Medical Center, Murray, Utah
- Department of Pediatrics, Division of Pediatric Critical Care, University of Utah, Salt Lake City, Utah; and
| | | | - John Griffin
- Division of Critical Care Medicine, Department of Anesthesiology, Critical Care and Pain Medicine
| | | | - Nicole Stenquist
- Division of Critical Care Medicine, Department of Anesthesiology, Critical Care and Pain Medicine
| | - Craig D. Smallwood
- Division of Critical Care Medicine, Department of Anesthesiology, Critical Care and Pain Medicine
- Department of Anaesthesia
| | - Kyle A. Nelson
- Division of Pediatric Emergency Medicine
- Department of Pediatrics, and
| | - David Zurakowski
- Division of Critical Care Medicine, Department of Anesthesiology, Critical Care and Pain Medicine
- Department of Anaesthesia
| | | | - Joel N. Hirschhorn
- Division of Endocrinology, Boston Children’s Hospital, Boston, Massachusetts
- Department of Genetics, Harvard Medical School, Boston, Massachusetts
- Program in Medical and Population Genetics, Broad Institute of Harvard and Massachusetts Institute of Technology, Cambridge, Massachusetts
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Cheyne WS, Williams AM, Harper MI, Eves ND. Acute volume loading exacerbates direct ventricular interaction in a model of COPD. J Appl Physiol (1985) 2017; 123:1110-1117. [PMID: 28729396 DOI: 10.1152/japplphysiol.01109.2016] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2016] [Revised: 06/28/2017] [Accepted: 07/18/2017] [Indexed: 11/22/2022] Open
Abstract
Volume loading increases left ventricular (LV) stroke volume (LVSV) through series interaction, but may paradoxically reduce LVSV in the presence of large increases in right ventricular (RV) afterload because of direct ventricular interaction (DVI). RV afterload is often increased in chronic obstructive pulmonary disease (COPD) as a result of pathological changes to respiratory mechanics, namely increased negative intrathoracic pressure (nITP), dynamic lung hyperinflation (DH), and increased pulmonary vascular resistance (PVR). These hallmarks of COPD negatively impact LV hemodynamics in normovolemia. However, it is unknown how these heart-lung interactions are impacted by acute volume loading. Twenty healthy subjects (23 ± 2 yr) completed the study protocol, involving acute volume loading via 20° head-down tilt (HDT) in isolation and with 1) inspiratory resistance of -20 cmH2O (HDT+nITP) and 2) nITP, expiratory resistance to induce DH and hypoxic-mediated increases in PVR (HDT+COPD model). LV volumes and geometry were assessed using triplane echocardiography. HDT significantly increased LVSV by 10 ± 10% through an 8 ± 6% increase in LV end-diastolic volume (LVEDV). HDT+nITP paradoxically decreased LVSV by 11 ± 12% and LVEDV by 6 ± 9% from supine baseline, or -14 ± 10% LVSV and -15 ± 13% LVEDV from HDT (P < 0.001). HDT+COPD model decreased LVSV (21 ± 10% and 28 ± 11%) and LVEDV (16 ± 10% and 22 ± 10%) from both supine and HDT, respectively (P < 0.001). Under all conditions, significant septal flattening (increased radius of septal curvature) occurred, indicating DVI. Thus, when RV afterload is increased and/or an external constraint to ventricular filling exists, acute volume loading appears to paradoxically reduce LVSV. These findings have important implications for understanding how volume status impacts cardiopulmonary interactions in COPD.NEW & NOTEWORTHY Volume loading may exacerbate adverse cardiopulmonary interaction in COPD; however, the mechanisms remain unclear. We found that when negative intrathoracic pressure is increased, acute volume loading paradoxically reduces stroke volume. This reduction in stroke volume is considerably greater in a model of COPD, owing to the effects of lung hyperinflation.
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Affiliation(s)
- William S Cheyne
- Centre for Heart, Lung and Vascular Health, School of Health and Exercise Sciences, University of British Columbia, Kelowna, British Columbia, Canada
| | - Alexandra M Williams
- Centre for Heart, Lung and Vascular Health, School of Health and Exercise Sciences, University of British Columbia, Kelowna, British Columbia, Canada
| | - Megan I Harper
- Centre for Heart, Lung and Vascular Health, School of Health and Exercise Sciences, University of British Columbia, Kelowna, British Columbia, Canada
| | - Neil D Eves
- Centre for Heart, Lung and Vascular Health, School of Health and Exercise Sciences, University of British Columbia, Kelowna, British Columbia, Canada
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Bari V, De Maria B, Mazzucco CE, Rossato G, Tonon D, Nollo G, Faes L, Porta A. Cerebrovascular and cardiovascular variability interactions investigated through conditional joint transfer entropy in subjects prone to postural syncope. Physiol Meas 2017; 38:976-991. [DOI: 10.1088/1361-6579/aa638c] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
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13
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Nicia SB, van Veelen TA, Stens J, Koopman MMW, Boer C. Detection of volume loss using the Nexfin device in blood donors. Anaesthesia 2015; 71:163-70. [PMID: 26566706 DOI: 10.1111/anae.13283] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/23/2015] [Indexed: 12/13/2022]
Abstract
We investigated which haemodynamic parameters derived from Nexfin non-invasive continuous arterial blood pressure measurements are optimal to detect controlled volume loss in spontaneously breathing subjects. Haemodynamic monitoring was performed in 40 whole-blood donors. Mean arterial pressure, cardiac index, systemic vascular resistance index and pulse pressure variation were recorded during controlled breathing, and a Valsalva manoeuvre was performed before and after blood donation. Blood donation resulted in a reduction in cardiac index (from 3.96 ± 0.84 l.min(-1) .m(2) to 3.30 ± 0.61 l.min(-1) .m(2) ; p < 0.001), an increase in systemic vascular resistance (from 1811 ± 450 dyn.s.cm(-5) .m(2) to 2137 ± 428 dyn.s.cm(-5) .m(2) ; p < 0.001) and an increase in pulse pressure variation (from 13.4 ± 5.1 to 15.3 ± 5.4%; p = 0.02). The area under the receiver operating characteristic curve to detect volume loss was highest for cardiac index (0.94, 95% CI 0.88-0.99) and systemic vascular resistance (0.90, 95% CI 0.82-0.99). Nexfin is a non-invasive haemodynamic monitor that can feasibly detect volaemic changes in spontaneously breathing subjects.
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Affiliation(s)
- S B Nicia
- VU University Medical Centre, Amsterdam, the Netherlands
| | - T A van Veelen
- VU University Medical Centre, Amsterdam, the Netherlands
| | - J Stens
- VU University Medical Centre, Amsterdam, the Netherlands
| | - M M W Koopman
- Sanquin Blood Supply Foundation, Amsterdam, the Netherlands
| | - C Boer
- Institute for Cardiovascular Research, VU University Medical Centre, Amsterdam, the Netherlands
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Porta A, Faes L, Marchi A, Bari V, De Maria B, Guzzetti S, Colombo R, Raimondi F. Disentangling cardiovascular control mechanisms during head-down tilt via joint transfer entropy and self-entropy decompositions. Front Physiol 2015; 6:301. [PMID: 26578973 PMCID: PMC4621422 DOI: 10.3389/fphys.2015.00301] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2015] [Accepted: 10/12/2015] [Indexed: 11/13/2022] Open
Abstract
A full decomposition of the predictive entropy (PE) of the spontaneous variations of the heart period (HP) given systolic arterial pressure (SAP) and respiration (R) is proposed. The PE of HP is decomposed into the joint transfer entropy (JTE) from SAP and R to HP and self-entropy (SE) of HP. The SE is the sum of three terms quantifying the synergistic/redundant contributions of HP and SAP, when taken individually and jointly, to SE and one term conditioned on HP and SAP denoted as the conditional SE (CSE) of HP given SAP and R. The JTE from SAP and R to HP is the sum of two terms attributable to SAP or R plus an extra term describing the redundant/synergistic contribution to the JTE. All quantities were computed during cardiopulmonary loading induced by −25° head-down tilt (HDT) via a multivariate linear regression approach. We found that: (i) the PE of HP decreases during HDT; (ii) the decrease of PE is attributable to a lessening of SE of HP, while the JTE from SAP and R to HP remains constant; (iii) the SE of HP is dominant over the JTE from SAP and R to HP and the CSE of HP given SAP and R is prevailing over the SE of HP due to SAP and R both in supine position and during HDT; (iv) all terms of the decompositions of JTE from SAP and R to HP and SE of HP due to SAP and R were not affected by HDT; (v) the decrease of the SE of HP during HDT was attributed to the reduction of the CSE of HP given SAP and R; (vi) redundancy of SAP and R is prevailing over synergy in the information transferred into HP both in supine position and during HDT, while in the HP information storage synergy and redundancy are more balanced. The approach suggests that the larger complexity of the cardiac control during HDT is unrelated to the baroreflex control and cardiopulmonary reflexes and may be related to central commands and/or modifications of the dynamical properties of the sinus node.
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Affiliation(s)
- Alberto Porta
- Department of Biomedical Sciences for Health, University of Milan Milan, Italy ; Department of Cardiothoracic, Vascular Anesthesia and Intensive Care, IRCCS Policlinico San Donato Milan, Italy
| | - Luca Faes
- BIOtech, Department of Industrial Engineering, University of Trento Trento, Italy ; IRCS PAT-FBK Trento, Italy
| | - Andrea Marchi
- Department of Electronics Information and Bioengineering, Politecnico di Milano Milan, Italy ; Department of Emergency and Intensive Care, San Gerardo Hospital Monza, Italy
| | - Vlasta Bari
- Department of Cardiothoracic, Vascular Anesthesia and Intensive Care, IRCCS Policlinico San Donato Milan, Italy
| | | | | | | | - Ferdinando Raimondi
- Department of Anesthesia and Intensive Care, IRCCS Humanitas Clinical and Research Center Rozzano, Italy
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van Duijvenboden S, Hanson B, Child N, Orini M, Rinaldi CA, Gill JS, Taggart P. Effect of autonomic blocking agents on the respiratory-related oscillations of ventricular action potential duration in humans. Am J Physiol Heart Circ Physiol 2015; 309:H2108-17. [PMID: 26475587 PMCID: PMC4698427 DOI: 10.1152/ajpheart.00560.2015] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/22/2015] [Accepted: 10/14/2015] [Indexed: 12/01/2022]
Abstract
Ventricular action potential repolarization is critical to electrical stability and arrhythmogenesis. Oscillations at the respiratory frequency were investigated in humans by combining endocardial electrophysiological recordings, controlled respiration with adrenergic blocking agents. Results are consistent with a partial role of the sympathetic nervous system combined with additional mechanisms, possibly involving mechano-electric feedback. Ventricular action potential duration (APD) is an important component of many physiological functions including arrhythmogenesis. APD oscillations have recently been reported in humans at the respiratory frequency. This study investigates the contribution of the autonomic nervous system to these oscillations. In 10 patients undergoing treatment for supraventricular arrhythmias, activation recovery intervals (ARI; a conventional surrogate for APD) were measured from multiple left and right ventricular (RV) endocardial sites, together with femoral artery pressure. Respiration was voluntarily regulated and heart rate clamped by RV pacing. Sympathetic and parasympathetic blockade was achieved using intravenous metoprolol and atropine, respectively. Metroprolol reduced the rate of pressure development (maximal change in pressure over time): 1,271 (± 646) vs. 930 (± 433) mmHg/s; P < 0.01. Systolic blood pressure (SBP) showed a trend to decrease after metoprolol, 133 (± 21) vs. 128 (± 25) mmHg; P = 0.06, and atropine infusion, 122 (± 26) mmHg; P < 0.05. ARI and SBP exhibited significant cyclical variations (P < 0.05) with respiration in all subjects with peak-to-peak amplitudes ranging between 0.7 and 17.0 mmHg and 1 and 16 ms, respectively. Infusion of metoprolol reduced the mean peak-to-peak amplitude [ARI, 6.2 (± 1.4) vs. 4.4 (± 1.0) ms, P = 0.008; SBP, 8.4 (± 1.6) vs. 6.2 (± 2.0) mmHg, P = 0.002]. The addition of atropine had no significant effect. ARI, SBP, and respiration showed significant coupling (P < 0.05) at the breathing frequency in all subjects. Directed coherence from respiration to ARI was high and reduced after metoprolol infusion [0.70 (± 0.17) vs. 0.50 (± 0.23); P < 0.05]. These results suggest a role of respiration in modulating the electrophysiology of ventricular myocardium in humans, which is partly, but not totally, mediated by β-adrenergic mechanisms.
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Affiliation(s)
| | - Ben Hanson
- Department of Mechanical Engineering, University College London, London, UK
| | - Nick Child
- Department of Cardiology, Guy's and St. Thomas's Hospital, London, UK; and
| | - Michele Orini
- Institute of Cardiovascular Science, University College London, London, UK
| | | | - Jaswinder S Gill
- Department of Cardiology, Guy's and St. Thomas's Hospital, London, UK; and
| | - Peter Taggart
- Institute of Cardiovascular Science, University College London, London, UK
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16
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Asakawa N, Sakakibara M, Noguchi K, Kamiya K, Yamada S, Yoshitani T, Ono K, Oba K, Tsutsui H. Adaptive Servo-Ventilation Has More Favorable Acute Effects on Hemodynamics Than Continuous Positive Airway Pressure in Patients With Heart Failure. Int Heart J 2015; 56:527-32. [PMID: 26370373 DOI: 10.1536/ihj.15-110] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Adaptive servo-ventilation (ASV) has been attracting attention as a novel respiratory support therapy for heart failure (HF). However, the acute hemodynamic effects have not been compared between ASV and continuous positive airway pressure (CPAP) in HF patients.We studied 12 consecutive patients with stable chronic HF. Hemodynamic measurement was performed by right heart catheterization before and after CPAP 5 cmH2O, CPAP 10 cmH2O, and ASV for 15 minutes each.Heart rate, blood pressure, pulmonary capillary wedge pressure (PCWP), and stroke volume index (SVI) were not changed by any intervention. Right atrial pressure significantly increased after CPAP 10 cmH2O (3.6 ± 3.3 to 6.7 ± 1.6 mmHg, P = 0.005) and ASV (4.1 ± 2.6 to 6.8 ± 1.5 mmHg, P = 0.026). Cardiac index was significantly decreased by CPAP 10 cmH2O (2.3 ± 0.4 to 1.9 ± 0.3 L/minute/m(2), P = 0.048), but was not changed by ASV (2.3 ± 0.4 to 2.0 ± 0.3 L/ minute/m(2), P = 0.299). There was a significant positive correlation between baseline PCWP and % of baseline SVI by CPAP 10 cmH2O (r = 0.705, P < 0.001) and ASV (r = 0.750, P < 0.001). ASV and CPAP 10 cmH2O had significantly greater slopes of this correlation than CPAP 5 cmH2O, suggesting that patients with higher PCWP had a greater increase in SVI by ASV and CPAP 10 cmH2O. The relationship between baseline PCWP and % of baseline SVI by ASV was shifted upwards compared to CPAP 10 cmH2O. Furthermore, based on the results of a questionnaire, patients accepted CPAP 5 cmH2O and ASV more favorably compared to CPAP 10 cmH2O.ASV had more beneficial effects on acute hemodynamics and acceptance than CPAP in HF patients.
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Affiliation(s)
- Naoya Asakawa
- Department of Cardiovascular Medicine, Hokkaido University Graduate School of Medicine
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17
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Porta A, Marchi A, Bari V, Heusser K, Tank J, Jordan J, Barbic F, Furlan R. Conditional symbolic analysis detects nonlinear influences of respiration on cardiovascular control in humans. PHILOSOPHICAL TRANSACTIONS. SERIES A, MATHEMATICAL, PHYSICAL, AND ENGINEERING SCIENCES 2015; 373:rsta.2014.0096. [PMID: 25548269 PMCID: PMC4281867 DOI: 10.1098/rsta.2014.0096] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/19/2023]
Abstract
We propose a symbolic analysis framework for the quantitative characterization of complex dynamical systems. It allows the description of the time course of a single variable, the assessment of joint interactions and an analysis triggered by a conditioning input. The framework was applied to spontaneous variability of heart period (HP), systolic arterial pressure (SAP) and integrated muscle sympathetic nerve activity (MSNA) with the aim of characterizing cardiovascular control and nonlinear influences of respiration at rest in supine position, during orthostatic challenge induced by 80° head-up tilt (TILT) and about 3 min before evoked pre-syncope signs (PRESY). The approach detected (i) the exaggerated sympathetic modulation and vagal withdrawal from HP variability and the increased presence of fast MSNA variability components during PRESY compared with TILT; (ii) the increase of the SAP-HP coordination occurring at slow temporal scales and a decrease of that occurring at faster time scales during PRESY compared with TILT; (iii) the reduction of the coordination between fast MSNA and SAP patterns during TILT and PRESY; (iv) the nonlinear influences of respiration leading to an increased likelihood to observe the abovementioned findings during expiration compared with inspiration one. The framework provided simple, quantitative indexes able to distinguish experimental conditions characterized by different states of the autonomic nervous system and to detect the early signs of a life threatening situation such as postural syncope.
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Affiliation(s)
- Alberto Porta
- Department of Biomedical Sciences for Health, University of Milan, Milan, Italy IRCCS Galeazzi Orthopedic Institute, Milan, Italy
| | - Andrea Marchi
- Department of Anesthesia and Intensive Care Unit, Rozzano, Milan, Italy
| | - Vlasta Bari
- Department of Cardiothoracic-Vascular Anesthesia and Intensive Care, IRCCS Policlinico San Donato, Milan, Italy
| | - Karsten Heusser
- Institut für Klinische Pharmakologie, Medizinische Hochschule Hannover, Hannover, Germany
| | - Jens Tank
- Institut für Klinische Pharmakologie, Medizinische Hochschule Hannover, Hannover, Germany
| | - Jens Jordan
- Institut für Klinische Pharmakologie, Medizinische Hochschule Hannover, Hannover, Germany
| | - Franca Barbic
- Department of Internal Medicine, Humanitas Clinical and Research Center, Rozzano, Milan, Italy
| | - Raffaello Furlan
- Department of Medical Biotechnology and Translational Medicine, University of Milan, Milan, Italy Department of Internal Medicine, Humanitas Clinical and Research Center, Rozzano, Milan, Italy
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18
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Hanson B, Child N, Van Duijvenboden S, Orini M, Chen Z, Coronel R, Rinaldi CA, Gill JS, Gill JS, Taggart P. Oscillatory behavior of ventricular action potential duration in heart failure patients at respiratory rate and low frequency. Front Physiol 2014; 5:414. [PMID: 25389408 PMCID: PMC4211392 DOI: 10.3389/fphys.2014.00414] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2014] [Accepted: 10/07/2014] [Indexed: 12/22/2022] Open
Abstract
Oscillations of arterial pressure occur spontaneously at a frequency of approximately 0.1 Hz coupled with synchronous oscillations of sympathetic nerve activity (“Mayer waves”). This study investigated the extent to which corresponding oscillations may occur in ventricular action potential duration (APD). Fourteen ambulatory (outpatient) heart failure patients with biventricular pacing devices were studied while seated upright watching movie clips to maintain arousal. Activation recovery intervals (ARI) as a measure of ventricular APD were obtained from unipolar electrograms recorded from the LV epicardial pacing lead during steady state RV pacing from the device. Arterial blood pressure was measured non-invasively (Finapress) and respiration monitored. Oscillations were quantified using time frequency and coherence analysis. Oscillatory behavior of ARI at the respiratory frequency was observed in all subjects. The magnitude of the ARI variation ranged from 2.2 to 6.9 ms (mean 5.0 ms). Coherence analysis showed a correlation with respiratory oscillation for an average of 43% of the recording time at a significance level of p < 0.05. Oscillations in systolic blood pressure in the Mayer wave frequency range were observed in all subjects for whom blood pressure was recorded (n = 13). ARI oscillation in the Mayer wave frequency range was observed in 6/13 subjects (46%) over a range of 2.9 to 9.2 ms. Coherence with Mayer waves at the p < 0.05 significance level was present for an average of 29% of the recording time. In ambulatory patients with heart failure during enhanced mental arousal, left ventricular epicardial APD (ARI) oscillated at the respiratory frequency (approximately 0.25 Hz). In 6 patients (46%) APD oscillated at the slower Mayer wave frequency (approximately 0.1 Hz). These findings may be important in understanding sympathetic activity-related arrhythmogenesis.
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Affiliation(s)
- Ben Hanson
- Department of Mechanical Engineering, University College London London, UK
| | - Nick Child
- Cardiovascular (Imaging) Department, King's College London London, UK
| | | | - Michele Orini
- Institute of Cardiovascular Science, University College London London, UK
| | - Zhong Chen
- Cardiovascular (Imaging) Department, King's College London London, UK
| | - Ruben Coronel
- Department of Experimental Cardiology, Academic Medical Center Amsterdam, Netherlands
| | | | - Jaspal S Gill
- Division of Medicine, University College London London, UK
| | - Jaswinder S Gill
- Cardiovascular (Imaging) Department, King's College London London, UK
| | - Peter Taggart
- Institute of Cardiovascular Science, University College London London, UK
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Prinsloo GE, Rauch HGL, Derman WE. A brief review and clinical application of heart rate variability biofeedback in sports, exercise, and rehabilitation medicine. PHYSICIAN SPORTSMED 2014; 42:88-99. [PMID: 24875976 DOI: 10.3810/psm.2014.05.2061] [Citation(s) in RCA: 65] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
CONTEXT An important component of the effective management of chronic noncommunicable disease is the assessment and management of psychosocial stress. The measurement and modulation of heart rate variability (HRV) may be valuable in this regard. OBJECTIVE To describe the measurement and physiological control of HRV; to describe the impact of psychosocial stress on cardiovascular disease, metabolic syndrome, and chronic respiratory disease, and the relationship between these diseases and changes in HRV; and to describe the influence of biofeedback and exercise on HRV and the use of HRV biofeedback in the management of chronic disease. DATA SOURCES AND STUDY SELECTION The PubMed, Medline, and Embase databases were searched (up to August 2013). Additional articles were obtained from the reference lists of relevant articles and reviews. Articles were individually selected for further review based on the quality and focus of the study, and the population studied. RESULTS Heart rate variability is reduced in stress and in many chronic diseases, and may even predict the development and prognosis of some diseases. Heart rate variability can be increased with both exercise and biofeedback. Although the research on the effect of exercise is conflicting, there is evidence that aerobic training may increase HRV and cardiac vagal tone both in healthy individuals and in patients with disease. Heart rate variability biofeedback is also an effective method of increasing HRV and cardiac vagal tone, and has been shown to decrease stress and reduce the morbidity and mortality of disease. CONCLUSION The assessment and management of psychosocial stress is a challenging but important component of effective comprehensive lifestyle interventions for the management of noncommunicable disease. It is, therefore, important for the sports and exercise physician to have an understanding of the therapeutic use of HRV modulation, both in the reduction of stress and in the management of chronic disease.
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Affiliation(s)
- Gabriell E Prinsloo
- MRC/UCT Research Unit for Exercise Science and Sports Medicine, University of Cape Town, Cape Town, South Africa.
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20
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Porta A, Faes L, Bari V, Marchi A, Bassani T, Nollo G, Perseguini NM, Milan J, Minatel V, Borghi-Silva A, Takahashi ACM, Catai AM. Effect of age on complexity and causality of the cardiovascular control: comparison between model-based and model-free approaches. PLoS One 2014; 9:e89463. [PMID: 24586796 PMCID: PMC3933610 DOI: 10.1371/journal.pone.0089463] [Citation(s) in RCA: 73] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2013] [Accepted: 01/20/2014] [Indexed: 12/19/2022] Open
Abstract
The proposed approach evaluates complexity of the cardiovascular control and causality among cardiovascular regulatory mechanisms from spontaneous variability of heart period (HP), systolic arterial pressure (SAP) and respiration (RESP). It relies on construction of a multivariate embedding space, optimization of the embedding dimension and a procedure allowing the selection of the components most suitable to form the multivariate embedding space. Moreover, it allows the comparison between linear model-based (MB) and nonlinear model-free (MF) techniques and between MF approaches exploiting local predictability (LP) and conditional entropy (CE). The framework was applied to study age-related modifications of complexity and causality in healthy humans in supine resting (REST) and during standing (STAND). We found that: 1) MF approaches are more efficient than the MB method when nonlinear components are present, while the reverse situation holds in presence of high dimensional embedding spaces; 2) the CE method is the least powerful in detecting age-related trends; 3) the association of HP complexity on age suggests an impairment of cardiac regulation and response to STAND; 4) the relation of SAP complexity on age indicates a gradual increase of sympathetic activity and a reduced responsiveness of vasomotor control to STAND; 5) the association from SAP to HP on age during STAND reveals a progressive inefficiency of baroreflex; 6) the reduced connection from HP to SAP with age might be linked to the progressive exploitation of Frank-Starling mechanism at REST and to the progressive increase of peripheral resistances during STAND; 7) at REST the diminished association from RESP to HP with age suggests a vagal withdrawal and a gradual uncoupling between respiratory activity and heart; 8) the weakened connection from RESP to SAP with age might be related to the progressive increase of left ventricular thickness and vascular stiffness and to the gradual decrease of respiratory sinus arrhythmia.
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Affiliation(s)
- Alberto Porta
- Department of Biomedical Sciences for Health, University of Milan, Milan, Italy
- Galeazzi Orthopedic Institute, Milan, Italy
- * E-mail:
| | - Luca Faes
- Department of Physics and BIOtech, University of Trento, Trento, Italy
| | - Vlasta Bari
- Gruppo Ospedaliero San Donato Foundation, Milan, Italy
- Department of Electronics Information and Bioengineering, Politecnico di Milano, Milan, Italy
| | - Andrea Marchi
- Department of Electronics Information and Bioengineering, Politecnico di Milano, Milan, Italy
- Department of Anesthesia and Intensive Care, Humanitas Clinical and Research Center, Rozzano, Italy
| | - Tito Bassani
- Humanitas Clinical and Research Center, Rozzano, Italy
| | - Giandomenico Nollo
- BIOtech, Department of Industrial Engineering, University of Trento, Trento, Italy
- IRCS PAT-FBK, Trento, Italy
| | - Natália Maria Perseguini
- Department of Physiotherapy, Federal University of São Carlos, São Carlos, São Paulo State, Brazil
| | - Juliana Milan
- Department of Physiotherapy, Federal University of São Carlos, São Carlos, São Paulo State, Brazil
| | - Vinícius Minatel
- Department of Physiotherapy, Federal University of São Carlos, São Carlos, São Paulo State, Brazil
| | - Audrey Borghi-Silva
- Department of Physiotherapy, Federal University of São Carlos, São Carlos, São Paulo State, Brazil
| | - Anielle C. M. Takahashi
- Department of Physiotherapy, Federal University of São Carlos, São Carlos, São Paulo State, Brazil
| | - Aparecida M. Catai
- Department of Physiotherapy, Federal University of São Carlos, São Carlos, São Paulo State, Brazil
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21
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Porta A, Castiglioni P, Di Rienzo M, Bassani T, Bari V, Faes L, Nollo G, Cividjan A, Quintin L. Cardiovascular control and time domain Granger causality: insights from selective autonomic blockade. PHILOSOPHICAL TRANSACTIONS. SERIES A, MATHEMATICAL, PHYSICAL, AND ENGINEERING SCIENCES 2013; 371:20120161. [PMID: 23858489 DOI: 10.1098/rsta.2012.0161] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
We studied causal relations among heart period (HP), systolic arterial pressure (SAP) and respiration (R) according to the definition of Granger causality in the time domain. Autonomic pharmacological challenges were used to alter the complexity of cardiovascular control. Atropine (AT), propranolol and clonidine (CL) were administered to block muscarinic receptors, β-adrenergic receptors and centrally sympathetic outflow, respectively. We found that: (i) at baseline, HP and SAP interacted in a closed loop with a dominant causal direction from HP to SAP; (ii) pharmacological blockades did not alter the bidirectional closed-loop interactions between HP and SAP, but AT reduced the dominance of the causal direction from HP to SAP; (iii) at baseline, bidirectional interactions between HP and R were frequently found; (iv) the closed-loop relation between HP and R was unmodified by the administration of drugs; (v) at baseline, unidirectional interactions from R to SAP were often found; and (vi) while AT induced frequently an uncoupling between R and SAP, CL favoured bidirectional interactions. These results prove that time domain measures of Granger causality can contribute to the description of cardiovascular control by suggesting the temporal direction of the interactions and by separating different causality schemes (e.g. closed loop versus unidirectional relations).
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Affiliation(s)
- Alberto Porta
- Department of Biomedical Sciences for Health, Galeazzi Orthopaedic Institute, University of Milan, 20161 Milan, Italy.
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22
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Lucas SJE, Lewis NCS, Sikken ELG, Thomas KN, Ainslie PN. Slow breathing as a means to improve orthostatic tolerance: a randomized sham-controlled trial. J Appl Physiol (1985) 2013; 115:202-11. [DOI: 10.1152/japplphysiol.00128.2013] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Endogenous oscillations in blood pressure (BP) and cerebral blood flow have been associated with improved orthostatic tolerance. Although slow breathing induces such responses, it has not been tested as a therapeutic strategy to improve orthostatic tolerance. With the use of a randomized, crossover sham-controlled design, we tested the hypothesis that breathing at six breaths/min (vs. spontaneous breathing) would improve orthostatic tolerance via inducing oscillations in mean arterial BP (MAP) and cerebral blood flow. Sixteen healthy participants (aged 25 ± 4 yr; mean ± SD) had continuous beat-to-beat measurements of middle cerebral artery blood velocity (MCAv), BP (finometer), heart rate (ECG), and end-tidal carbon dioxide partial pressure during an incremental orthostatic stress test to presyncope by combining head-up tilt with incremental lower-body negative pressure. Tolerance time to presyncope was improved (+15%) with slow breathing compared with spontaneous breathing (29.2 ± 5.4 vs. 33.7 ± 6.0 min; P < 0.01). The improved tolerance was reflected in elevations in low-frequency (LF; 0.07-0.2 Hz) oscillations of MAP and mean MCAv, improved metrics of dynamic cerebrovascular control (increased LF phase and reduced LF gain), and a reduced rate of decline for MCAv (−0.60 ± 0.27 vs. −0.99 ± 0.51 cm·s−1·min−1; P < 0.01) and MAP (−0.50 ± 0.37 vs. −1.03 ± 0.80 mmHg/min; P = 0.01 vs. spontaneous breathing) across time from baseline to presyncope. Our findings show that orthostatic tolerance can be improved within healthy individuals with a simple, nonpharmacological breathing strategy. The mechanisms underlying this improvement are likely mediated via the generation of negative intrathoracic pressure during slow and deep breathing and the related beneficial impact on cerebrovascular and autonomic function.
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Affiliation(s)
- Samuel J. E. Lucas
- Department of Physiology, University of Otago, Dunedin, New Zealand
- School of Physical Education, University of Otago, Dunedin, New Zealand
- School of Sport and Exercise Sciences, College of Life and Environmental Sciences, University of Birmingham, Birmingham, United Kingdom
| | - Nia C. S. Lewis
- Centre of Heart, Lung and Vascular Health, School of Health and Exercise Sciences, Faculty of Health and Social Development, University of British Columbia, Okanagan Campus, Vancouver, British Columbia, Canada
- Research Institute of Sport and Exercise Science, Liverpool John Moores University, Liverpool, United Kingdom; and
| | - Elisabeth L. G. Sikken
- Department of Physiology, University of Otago, Dunedin, New Zealand
- Department of Physiology, Radboud University, Nijmegen Medical Centre, Nijmegen, the Netherlands
| | - Kate N. Thomas
- Department of Physiology, University of Otago, Dunedin, New Zealand
- School of Physical Education, University of Otago, Dunedin, New Zealand
| | - Philip N. Ainslie
- Centre of Heart, Lung and Vascular Health, School of Health and Exercise Sciences, Faculty of Health and Social Development, University of British Columbia, Okanagan Campus, Vancouver, British Columbia, Canada
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23
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Cross TJ, Kavanagh JJ, Breskovic T, Zubin Maslov P, Lojpur M, Johnson BD, Dujic Z. The Effects of Involuntary Respiratory Contractions on Cerebral Blood Flow during Maximal Apnoea in Trained Divers. PLoS One 2013; 8:e66950. [PMID: 23840561 PMCID: PMC3694127 DOI: 10.1371/journal.pone.0066950] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2013] [Accepted: 05/14/2013] [Indexed: 11/26/2022] Open
Abstract
The effects of involuntary respiratory contractions on the cerebral blood flow response to maximal apnoea is presently unclear. We hypothesised that while respiratory contractions may augment left ventricular stroke volume, cardiac output and ultimately cerebral blood flow during the struggle phase, these contractions would simultaneously cause marked ‘respiratory’ variability in blood flow to the brain. Respiratory, cardiovascular and cerebrovascular parameters were measured in ten trained, male apnoea divers during maximal ‘dry’ breath holding. Intrathoracic pressure was estimated via oesophageal pressure. Left ventricular stroke volume, cardiac output and mean arterial pressure were monitored using finger photoplethysmography, and cerebral blood flow velocity was obtained using transcranial ultrasound. The increasingly negative inspiratory intrathoracic pressure swings of the struggle phase significantly influenced the rise in left ventricular stroke volume (R2 = 0.63, P<0.05), thereby contributing to the increase in cerebral blood flow velocity throughout this phase of apnoea. However, these contractions also caused marked respiratory variability in left ventricular stroke volume, cardiac output, mean arterial pressure and cerebral blood flow velocity during the struggle phase (R2 = 0.99, P<0.05). Interestingly, the magnitude of respiratory variability in cerebral blood flow velocity was inversely correlated with struggle phase duration (R2 = 0.71, P<0.05). This study confirms the hypothesis that, on the one hand, involuntary respiratory contractions facilitate cerebral haemodynamics during the struggle phase while, on the other, these contractions produce marked respiratory variability in blood flow to the brain. In addition, our findings indicate that such variability in cerebral blood flow negatively impacts on struggle phase duration, and thus impairs breath holding performance.
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Affiliation(s)
- Troy J. Cross
- Griffith Health Institute and Heart Foundation Research Centre, Griffith University, Gold Coast Campus, Queensland, Australia
- Division of Cardiovascular Diseases, Mayo Clinic, Rochester, Minnesota, United States of America
- * E-mail:
| | - Justin J. Kavanagh
- Griffith Health Institute and Heart Foundation Research Centre, Griffith University, Gold Coast Campus, Queensland, Australia
| | - Toni Breskovic
- Department of Physiology, University of Split School of Medicine, Split, Croatia
| | - Petra Zubin Maslov
- Department of Physiology, University of Split School of Medicine, Split, Croatia
| | - Mihajlo Lojpur
- Department of Anaesthesiology, Clinical Hospital Center Split, Split, Croatia
| | - Bruce D. Johnson
- Division of Cardiovascular Diseases, Mayo Clinic, Rochester, Minnesota, United States of America
| | - Zeljko Dujic
- Department of Physiology, University of Split School of Medicine, Split, Croatia
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24
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Lalande S, Luoma CE, Miller AD, Johnson BD. Expiratory loading improves cardiac output during exercise in heart failure. Med Sci Sports Exerc 2013; 44:2309-14. [PMID: 22776881 DOI: 10.1249/mss.0b013e318267bb5a] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
PURPOSE The objective of this study was to investigate the effect of changes in expiratory intrathoracic pressure on stroke volume (SV) at rest and during moderate exercise in patients with heart failure versus healthy individuals. METHODS SV was obtained by echocardiography during spontaneous breathing and during expiratory loads of 5 and 10 cm H2O produced by a ventilator in 11 patients with heart failure (61 ± yr, ejection fraction: 32 ± 4%, New York Heart Association, 32% ± 4%; NYHA class I-II) and 11 age-matched healthy individuals at rest and during exercise at 60% of aerobic capacity on a semirecumbent cycle ergometer. RESULTS At rest, expiratory loading did not change HR, SV index (SVI), or cardiac index (CI) in either group. During moderate exercise, expiratory loading increased SVI and CI in patients with heart failure but decreased SVI and CI in healthy individuals. There was a negative correlation between changes in gastric pressure and SVI (r = -0.51, P < 0.05) in healthy individuals, whereas there was a positive correlation between changes in gastric pressure accompanying expiratory loading and CI (r = 0.83, P < 0.01) in patients with heart failure. CONCLUSION Expiratory loading during moderate exercise elicited increases in SVI and CI in patients with heart failure but decreased SVI and CI in healthy individuals. Improvements in cardiac function during submaximal exercise in patients with heart failure may be caused by a beneficial reduction in left ventricular preload.
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Affiliation(s)
- Sophie Lalande
- Division of Cardiovascular Diseases, Department of Medicine, Mayo Clinic, Rochester, MN 55905, USA.
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25
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Bassani T, Bari V, Marchi A, Wu MA, Baselli G, Citerio G, Beda A, de Abreu MG, Güldner A, Guzzetti S, Porta A. Coherence analysis overestimates the role of baroreflex in governing the interactions between heart period and systolic arterial pressure variabilities during general anesthesia. Auton Neurosci 2013; 178:83-8. [PMID: 23578373 PMCID: PMC3820040 DOI: 10.1016/j.autneu.2013.03.007] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2012] [Revised: 01/07/2013] [Accepted: 03/19/2013] [Indexed: 11/28/2022]
Abstract
During general anesthesia positive pressure mechanical ventilation (MV) profoundly affects intrathoracic pressure and venous return, thus soliciting cardiopulmonary reflexes and modifying stroke volume. As a consequence heart period, approximated as the temporal distance between two consecutive R peaks on the ECG (RR), and systolic arterial pressure (SAP) variability series are usually highly correlated at the MV frequency (MVF) and this significant correlation is commonly taken as an indication of an active baroreflex. In this study the involvement of baroreflex was tested according to a time-domain linear Granger causality approach accounting explicitly for MV in two experimental protocols. In the first protocol volatile (VA) or intravenous (IA) anesthetic was administered in humans during pressure controlled MV (PCMV). In the second protocol IA was administered in pigs during PCMV or pressure support MV (PSMV). Causality analysis was contrasted with RR-SAP squared coherence. Significant coherence values at MVF were always found in both protocols. On the contrary, a significant causal link from SAP to RR was less frequently found in humans independently of the anesthesiological strategy and in animals during PCMV. PSMV was superior to PCMV in animals because it was able to better preserve a link from SAP to RR. During general anesthesia the involvement of baroreflex in governing RR-SAP variability interactions is largely overestimated by RR-SAP squared coherence and causality analysis can be exploited to rank anesthesiological strategies and MV modes according to the ability of preserving a working baroreflex.
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Affiliation(s)
- Tito Bassani
- Department of Biomedical Sciences for Health, Galeazzi Orthopedic Institute, University of Milan, Milan, Italy
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Georgiopoulou VV, Kalogeropoulos AP, Borlaug BA, Gheorghiade M, Butler J. Left Ventricular Dysfunction With Pulmonary Hypertension. Circ Heart Fail 2013; 6:344-54. [DOI: 10.1161/circheartfailure.112.000095] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Affiliation(s)
- Vasiliki V. Georgiopoulou
- From the Division of Cardiology, Emory University, Atlanta, GA (V.V.G., A.P.K., J.B.); Division of Cardiology, Mayo Clinic, Rochester, MN (B.A.B.); and Center for Cardiovascular Innovation, Northwestern University, Feinberg School of Medicine, Chicago, IL (M.G.)
| | - Andreas P. Kalogeropoulos
- From the Division of Cardiology, Emory University, Atlanta, GA (V.V.G., A.P.K., J.B.); Division of Cardiology, Mayo Clinic, Rochester, MN (B.A.B.); and Center for Cardiovascular Innovation, Northwestern University, Feinberg School of Medicine, Chicago, IL (M.G.)
| | - Barry A. Borlaug
- From the Division of Cardiology, Emory University, Atlanta, GA (V.V.G., A.P.K., J.B.); Division of Cardiology, Mayo Clinic, Rochester, MN (B.A.B.); and Center for Cardiovascular Innovation, Northwestern University, Feinberg School of Medicine, Chicago, IL (M.G.)
| | - Mihai Gheorghiade
- From the Division of Cardiology, Emory University, Atlanta, GA (V.V.G., A.P.K., J.B.); Division of Cardiology, Mayo Clinic, Rochester, MN (B.A.B.); and Center for Cardiovascular Innovation, Northwestern University, Feinberg School of Medicine, Chicago, IL (M.G.)
| | - Javed Butler
- From the Division of Cardiology, Emory University, Atlanta, GA (V.V.G., A.P.K., J.B.); Division of Cardiology, Mayo Clinic, Rochester, MN (B.A.B.); and Center for Cardiovascular Innovation, Northwestern University, Feinberg School of Medicine, Chicago, IL (M.G.)
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Hanson B, Gill J, Western D, Gilbey MP, Bostock J, Boyett MR, Zhang H, Coronel R, Taggart P. Cyclical modulation of human ventricular repolarization by respiration. Front Physiol 2012; 3:379. [PMID: 23055983 PMCID: PMC3457072 DOI: 10.3389/fphys.2012.00379] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2012] [Accepted: 09/06/2012] [Indexed: 11/13/2022] Open
Abstract
BACKGROUND Respiratory modulation of autonomic input to the sinus node results in cyclical modulation of heart rate, known as respiratory sinus arrhythmia (RSA). We hypothesized that the respiratory cycle may also exert cyclical modulation on ventricular repolarization, which may be separately measurable using local endocardial recordings. METHODS AND RESULTS The study included 16 subjects with normal ventricles undergoing routine clinical electrophysiological procedures for supraventricular arrhythmias. Unipolar electrograms were recorded from 10 right and 10 left ventricular endocardial sites. Breathing was voluntarily regulated at 5 fixed frequencies (6, 9, 12, 15, and 30 breaths per min) and heart rate was clamped by RV pacing. Activation-recovery intervals (ARI: a surrogate for APD) exhibited significant (p < 0.025) cyclical variation at the respiratory frequency in all subjects; ARI shortened with inspiration and lengthened with expiration. Peak-to-peak ARI variation ranged from 0-26 ms; the spatial pattern varied with subject. Arterial blood pressure also oscillated at the respiratory frequency (p < 0.025) and lagged behind respiration by between 1.5 s and 0.65 s from slowest to fastest breathing rates respectively. Systolic oscillation amplitude was significantly greater than diastolic (14 ± 5 vs. 8 ± 4 mm Hg ± SD, p < 0.001). CONCLUSIONS Observations in humans with healthy ventricles using multiple left and right ventricular endocardial recordings showed that ARI action potential duration (APD) varied cyclically with respiration.
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Affiliation(s)
- Ben Hanson
- Department of Mechanical Engineering, University College LondonLondon, UK
| | - Jaswinder Gill
- Department of Cardiology, Guys and St. Thomas's Hospital and Kings College LondonLondon, UK
| | - David Western
- Department of Mechanical Engineering, University College LondonLondon, UK
| | - Michael P. Gilbey
- Department of Neuroscience, Physiology and Pharmacology, University College LondonLondon, UK
| | - Julian Bostock
- Department of Cardiology, Guys and St. Thomas's Hospital and Kings College LondonLondon, UK
| | - Mark R. Boyett
- Division of Cardiovascular Medicine, University of ManchesterManchester, UK
| | - Henggui Zhang
- Biological Physics Group, University of ManchesterManchester, UK
| | - Ruben Coronel
- Experimental Cardiology Group, Academic Medical CenterAmsterdam, Netherlands
| | - Peter Taggart
- Neurocardiology Unit, University College London HospitalsLondon, UK
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Anavekar NS, Wong BF, Foley TA, Bishu K, Kolipaka A, Koo CW, Khandaker MH, Oh JK, Young PM. Index of biventricular interdependence calculated using cardiac MRI: a proof of concept study in patients with and without constrictive pericarditis. Int J Cardiovasc Imaging 2012; 29:363-9. [DOI: 10.1007/s10554-012-0101-x] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/03/2012] [Accepted: 07/12/2012] [Indexed: 11/28/2022]
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Pedersen LM, Nielsen J, Østergaard M, Nygård E, Nielsen HB. Increased intrathoracic pressure affects cerebral oxygenation following cardiac surgery. Clin Physiol Funct Imaging 2012; 32:367-71. [DOI: 10.1111/j.1475-097x.2012.01138.x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2011] [Accepted: 03/13/2012] [Indexed: 11/29/2022]
Affiliation(s)
| | - Jonas Nielsen
- Department of Anaesthesia; Rigshospitalet; University of Copenhagen; Copenhagen; Denmark
| | - Morten Østergaard
- Department of Anaesthesia; Rigshospitalet; University of Copenhagen; Copenhagen; Denmark
| | - Eigil Nygård
- Department of Thoracic Anaesthesia; Varde Heart Center; Varde; Denmark
| | - Henning B. Nielsen
- Department of Anaesthesia; Rigshospitalet; University of Copenhagen; Copenhagen; Denmark
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Porta A, Bassani T, Bari V, Pinna GD, Maestri R, Guzzetti S. Accounting for Respiration is Necessary to Reliably Infer Granger Causality From Cardiovascular Variability Series. IEEE Trans Biomed Eng 2012; 59:832-41. [DOI: 10.1109/tbme.2011.2180379] [Citation(s) in RCA: 91] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Meredith DJ, Clifton D, Charlton P, Brooks J, Pugh CW, Tarassenko L. Photoplethysmographic derivation of respiratory rate: a review of relevant physiology. J Med Eng Technol 2011; 36:1-7. [PMID: 22185462 DOI: 10.3109/03091902.2011.638965] [Citation(s) in RCA: 103] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
An abnormal respiratory rate is often the earliest sign of critical illness. A reliable estimate of respiratory rate is vital in the application of remote telemonitoring systems, which may facilitate early supported discharge from hospital or prompt recognition of physiological deterioration in high-risk patient groups. Traditional approaches use analysis of respiratory sinus arrhythmia from the electrocardiogram (ECG), but this phenomenon is predominantly limited to the young and healthy. Analysis of the photoplethysmogram (PPG) waveform offers an alternative means of non-invasive respiratory rate monitoring, but further development is required to enable reliable estimates. This review conceptualizes the challenge by discussing the effect of respiration on the PPG waveform and the key physiological mechanisms that underpin the derivation of respiratory rate from the PPG.
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Affiliation(s)
- D J Meredith
- Nuffield Department of Medicine, University of Oxford, Oxford, OX3 7BN, UK.
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Lalande S, Luoma CE, Miller AD, Johnson BD. Effect of changes in intrathoracic pressure on cardiac function at rest and during moderate exercise in health and heart failure. Exp Physiol 2011; 97:248-56. [PMID: 22080485 DOI: 10.1113/expphysiol.2011.061945] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
This study investigated the effect of changes in inspiratory intrathoracic pressure on stroke volume at rest and during moderate exercise in patients with heart failure and reduced ejection fraction (HFREF) as well as healthy individuals. Stroke volume was obtained by echocardiography during 2 min of spontaneous breathing (S), two progressive levels of inspiratory unloading (UL1 and UL2) using a ventilator, and two progressive levels of inspiratory loading using resistors in 11 patients with HFREF (61 ± 9 years old; ejection fraction 32 ± 4%; NYHA class I-II) and 11 age-matched healthy individuals at rest and during exercise at 60% of maximal aerobic capacity on a semi-recumbent cycle ergometer. At rest, inspiratory unloading progressively decreased stroke volume index (SVI; S, 35.2 ± 5.4 ml m(-2); UL1, 33.3 ± 5.1 ml m(-2); and UL2, 32.2 ± 4.4 ml m(-2)) in healthy individuals, while it increased SVI (S, 31.4 ± 4.6 ml m(-2); UL1, 32.0 ± 5.9 ml m(-2); and UL2, 34.0 ± 7.2 ml m(-2)) in patients with HFREF (P = 0.04). During moderate exercise, inspiratory unloading decreased SVI in a similar manner (S, 43.9 ± 7.1 ml m(-2); UL1, 40.7 ± 4.7 ml m(-2); and UL2, 39.9 ± 3.7 ml m(-1)) in healthy individuals, while it increased SVI (S, 40.8 ± 6.5 ml m(-2); UL1, 42.8 ± 6.9 ml m(-2); and UL2, 44.1 ± 4. ml m(-2)) in patients with HFREF (P = 0.02). Inspiratory loading did not significantly change SVI at rest or during moderate exercise in both groups. It is concluded that inspiratory unloading improved SVI at rest and during moderate exercise in patients with HFREF, possibly due to a reduction in left ventricular afterload.
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Affiliation(s)
- Sophie Lalande
- Division of Cardiovascular Diseases, Mayo Clinic, Rochester, MN 55905, USA.
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Faes L, Nollo G, Porta A. Information domain approach to the investigation of cardio-vascular, cardio-pulmonary, and vasculo-pulmonary causal couplings. Front Physiol 2011; 2:80. [PMID: 22069390 PMCID: PMC3209583 DOI: 10.3389/fphys.2011.00080] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2011] [Accepted: 10/15/2011] [Indexed: 11/13/2022] Open
Abstract
The physiological mechanisms related to cardio-vascular (CV), cardio-pulmonary (CP), and vasculo-pulmonary (VP) regulation may be probed through multivariate time series analysis tools. This study applied an information domain approach for the evaluation of non-linear causality to the beat-to-beat variability series of heart period (t), systolic arterial pressure (s), and respiration (r) measured during tilt testing and paced breathing (PB) protocols. The approach quantifies the causal coupling from the series i to the series j (Cij) as the amount of information flowing from i to j. A measure of directionality is also obtained as the difference between two reciprocal causal couplings (Di,j = Cij − Cji). Significant causal coupling and directionality were detected respectively when the median of Cij over subjects was positive (Cij > 0), and when Di,j was statistically different from zero (Di,j > 0 or Di,j < 0). The method was applied on t, s, and r series measured in 15 healthy subjects (22–32 years, 8 males) in the supine (su) and upright (up) positions, and in further 15 subjects (21–29 years, 7 males) during spontaneous (sp) and paced (pa) breathing. In the control condition (su, sp), a significant causal coupling was observed for Crs, Crt, Cst, and Cts, and significant directionality was present only from r to t (Dr,t > 0). During head-up tilt (up, sp), Crs was preserved, Crt decreased to zero median, and Cst and Cts increased significantly; directionality vanished between r and t (Dr,t = 0) and raised from s to t (Ds,t > 0). During PB (su, pa), Crs increased significantly, Crt and Cts were preserved, and Cst decreased to zero median; directionality was preserved from r to t (Dr,t > 0), and raised from r to s (Dr,s > 0). These results suggest that the approach may reflect modifications of CV, CP, and VP mechanisms consequent to altered physiological conditions, such as the baroreflex engagement and the dampening of respiratory sinus arrhythmia induced by tilt, or the respiratory driving on arterial pressure induced by PB. Thus, it could be suggested as a tool for the non-invasive monitoring of CV and cardiorespiratory control systems in normal and impaired conditions.
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Affiliation(s)
- Luca Faes
- Department of Physics and BIOtech, University of Trento Trento, Italy
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Beda A, Carvalho NC, Güldner A, Koch T, de Abreu MG. Mechanical ventilation during anaesthesia: challenges and opportunities for investigating the respiration-related cardiovascular oscillations. ACTA ACUST UNITED AC 2011; 56:195-206. [PMID: 21728908 DOI: 10.1515/bmt.2011.015] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
The vast majority of the available literature regarding cardiovascular oscillations refers to spontaneously breathing subjects. Only a few studies investigated cardiovascular oscillations, and especially respiration-related ones (RCVO), during intermittent positive pressure mechanical ventilation (IPPV) under anaesthesia. Only a handful considered assisted IPPV, in which spontaneous breathing activity is supported, rather than replaced as in controlled IPPV. In this paper, we review the current understanding of RCVO physiology during IPPV, from literature retrieved through PubMed website. In particular, we describe how during controlled IPPV under anaesthesia respiratory sinus arrhythmia appears to be generated by non-neural mechano-electric feedback in the heart (indirectly influenced by tonic sympathetic regulation of vascular tone and heart contractility) and not by phasic vagal modulation of central origin and/or baroreflex mechanisms. Furthermore, assisted IPPV differs from controlled IPPV in terms of RCVO, reintroducing significant central respiratory vagal modulation of respiratory sinus arrhythmia. This evidence indicates against applying to IPPV interpretative paradigms of RCVO derived from spontaneously breathing subjects, and against considering together IPPV and spontaneously breathing subjects for RCVO-based risk assessment. Finally, we highlight the opportunities that IPPV offers for future investigations of RCVO genesis and interactions, and we indicate several possibilities for clinical applications of RCVO during IPPV.
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Affiliation(s)
- Alessandro Beda
- Pulmonary Engineering Group, Clinic of Anaesthesiology and Intensive Care Therapy, University Clinic Dresden, Germany
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The Finometer can function as a standalone instrument in blood pressure variability studies and does not require support equipment to determine breathing frequency. Blood Press Monit 2010; 15:220-4. [PMID: 20543665 DOI: 10.1097/mbp.0b013e328339e198] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
OBJECTIVE The Finometer records the beat-to-beat finger pulse contour and has been recommended for research studies assessing short-term changes of blood pressure and its variability. Variability measured in the frequency domain using spectral analysis requires the impact of breathing be restricted to high frequency spectra (>0.15 Hz) so that the data from participants need to be excluded when the breathing impact occurs in the low frequency spectra (0.04-0.15 Hz). This study tested whether breathing frequency can be estimated from standard Finometer recordings using either stroke volume oscillation frequency or spectral stroke volume variability maximum scores. METHODS Twenty-two healthy volunteers were tested for 270 s in the supine and upright positions. Finometer recorded the finger pulse contour and a respiratory transducer recorded breathing. Stoke volume oscillation frequency was calculated manually whereas the stroke volume spectral maximums were obtained using the software Cardiovascular Parameter Analysis. These estimates were compared with the breathing frequency using the Bland-Altman procedures. RESULTS Stroke volume oscillation frequency estimated breathing frequency to less than +/-10% and 95% levels of agreement in both supine (-7.7 to 7.0%) and upright (-6.7 to 5.4%) postures. Stroke volume variability maximum scores did not accurately estimate breathing frequency. CONCLUSION Breathing frequency can be accurately derived from standard Finometer recordings using stroke volume oscillations for healthy individuals in both supine and upright postures. The Finometer can function as a standalone instrument in blood pressure variability studies and does not require support equipment to determine the breathing frequency.
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Porta A, Catai AM, Takahashi ACM, Magagnin V, Bassani T, Tobaldini E, van de Borne P, Montano N. Causal relationships between heart period and systolic arterial pressure during graded head-up tilt. Am J Physiol Regul Integr Comp Physiol 2010; 300:R378-86. [PMID: 20962207 DOI: 10.1152/ajpregu.00553.2010] [Citation(s) in RCA: 85] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
In physiological conditions, heart period (HP) affects systolic arterial pressure (SAP) through diastolic runoff and Starling's law, but, the reverse relation also holds as a result of the continuous action of baroreflex control. The prevailing mechanism sets the dominant temporal direction in the HP-SAP interactions (i.e., causality). We exploited cross-conditional entropy to assess HP-SAP causality. A traditional approach based on phases was applied for comparison. The ability of the approach to detect the lack of causal link from SAP to HP was assessed on 8 short-term (STHT) and 11 long-term heart transplant (LTHT) recipients (i.e., less than and more than 2 yr after transplantation, respectively). In addition, spontaneous HP and SAP variabilities were extracted from 17 healthy humans (ages 21-36 yr, median age 29 yr; 9 females) at rest and during graded head-up tilt. The tilt table inclinations ranged from 15 to 75° and were changed in steps of 15°. All subjects underwent recordings at every step in random order. The approach detected the lack of causal relation from SAP to HP in STHT recipients and the gradual restoration of the causal link from SAP to HP with time after transplantation in the LTHT recipients. The head-up tilt protocol induced the progressive shift from the prevalent causal direction from HP to SAP to the reverse causality (i.e., from SAP to HP) with tilt table inclination in healthy subjects. Transformation of phases into time shifts and comparison with baroreflex latency supported this conclusion. The proposed approach is highly efficient because it does not require the knowledge of baroreflex latency. The dependence of causality on tilt table inclination suggests that "spontaneous" baroreflex sensitivity estimated using noncausal methods (e.g., spectral and cross-spectral approaches) is more reliable at the highest tilt table inclinations.
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Affiliation(s)
- Alberto Porta
- Department of Technologies for Health, University of Milan, Milan, Italy.
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Seidl H, Tuerck J, Schepp W, Schneider AR. Splanchnic arterial blood flow is significantly influenced by breathing-assessment by duplex-Doppler ultrasound. ULTRASOUND IN MEDICINE & BIOLOGY 2010; 36:1677-1681. [PMID: 20800960 DOI: 10.1016/j.ultrasmedbio.2010.07.017] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/27/2010] [Revised: 06/10/2010] [Accepted: 07/20/2010] [Indexed: 05/29/2023]
Abstract
Duplex ultrasound is established for the assessment of mesenteric ischemia but potential influences of breathing on mesenteric arterial blood velocity have not been investigated so far. In 100 patients without abdominal diseases (39 men; age 59.4 ± 18.0 years), peak systolic (PSV), end diastolic velocity (EDV) and resistance index (RI) were assessed in the celiac trunk (CT) and the superior mesenteric artery (SMA) by Doppler ultrasound during expiration and deep inspiration. Expiratory PSVs in the CT and the SMA (153.4 ± 42.5 and 145.3 ± 39.5 cm/s) were significantly higher than inspiratory velocities (135.4 ± 36.8 and 131.9 ± 42.2 cm/s, p < 0.0001 and p = 0.0002), with expiratory PSVs exceeding inspiratory PSVs in more than 75% of patients. The mean percentage of PSV-variation was 21.5% ± 15.3% and 24.6% ± 19.1%, respectively. The study demonstrates that breathing may exert considerable periodic effects on splanchnic arterial hemodynamics. We, therefore, recommend that to prevent an underestimation of arterial stenosis, mesenteric Doppler ultrasound should be performed during expiration.
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Affiliation(s)
- Holger Seidl
- Department of Gastroenterology, Hepatology and Gastroenterological Oncology, Bogenhausen Academic Teaching Hospital, Klinikum Muenchen GmbH, Munich, Germany
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Van de Louw A, Médigue C, Papelier Y, Landrain M, Cottin F. Role of brainstem centers in cardiorespiratory phase difference during mechanical ventilation. Respir Physiol Neurobiol 2010; 174:119-27. [PMID: 20434593 DOI: 10.1016/j.resp.2010.04.014] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2010] [Revised: 04/07/2010] [Accepted: 04/14/2010] [Indexed: 01/31/2023]
Abstract
During mechanical ventilation, large inter-patient and intra-patient variations of the phase of respiratory sinus arrhythmia (RSA) were described. To determine whether these variations were neurally mediated, we compared the RSA phase between: (1) 12 control subjects, (2) 23 mechanically ventilated patients without brain injury (MV group) and (3) 12 brain dead, mechanically ventilated patients, whose central nervous functions were abolished (BD group). ECG and ventilatory flow were recorded during 15 min and the RSA phase was then continuously computed by complex demodulation. Control group exhibited RSA phases between 180° and 250° whereas an opposite pattern, between 0° and 90°, was observed in the BD group. For the two groups, the phase was stable over time. In the MV group, the RSA phases were distributed between 0° and 260°, with a greater variability over time than the other groups. Therefore, during mechanical ventilation, brainstem centers may induce large variations of the RSA phase, not synchronous with the mechanical effect of ventilation.
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Affiliation(s)
- Andry Van de Louw
- Unité de Biologie Intégrative des Adaptations à l'Exercice (INSERM 902/EA 3872, Genopole), ZAC du Bras de Fer, Evry, France.
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Lalande S, Johnson BD. Breathing strategy to preserve exercising cardiac function in patients with heart failure. Med Hypotheses 2009; 74:416-21. [PMID: 19800746 DOI: 10.1016/j.mehy.2009.09.030] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2009] [Accepted: 09/11/2009] [Indexed: 11/30/2022]
Abstract
The heart and lungs are closely linked as they lie in series, share a common surface area and compete for space within the thoracic cavity. The heart and lungs are exposed to the similar changes in intrathoracic pressure, and reflexes within one organ can influence the other (i.e. vagal influence of lung inflation on heart rate). In patients with heart failure, these cardiopulmonary interactions may be altered due to decreased lung and left ventricular compliance, increased cardiac size, high cardiac filling pressure and altered receptor sensitivity to neural activation. Exercise further affects the cardiopulmonary interactions by stimulating an increase in the depth and frequency of breathing which accentuates the fluctuations in intrathoracic pressure, and by requiring large increases in stroke volume and heart rate in order to respond to the increased metabolic demand. Previous work from our laboratory suggested that patients with heart failure avoid high lung volumes during exercise, often at the expense of unnecessary large positive expiratory intrathoracic pressures resulting in significant wasted effort. Moreover, we also observed that voluntarily increases in lung volume in patients with heart failure induced a mild relative bradycardia, a response not observed in similar aged healthy individuals. Thus, we hypothesized that the rapid shallow low lung volume breathing, in combination with positive expiratory intrathoracic pressure, often adopted by patients with heart failure during exercise is an attempt to preserve, or even enhance, the cardiac response to exercise.
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Affiliation(s)
- S Lalande
- Division of Cardiovascular Diseases, Department of Internal Medicine, Mayo Clinic, Rochester, Minnesota 55905, USA.
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Julien C, Parkes MJ, Tzeng SYC, Sin PYW, Ainslie PN, van de Borne P, Fortrat JO, Custaud MA, Gharib C, Porta A, Vallais F, Baselli G, Pagani M, Lucini D, Hughson RL, Taylor JA, Tan CO, Baekey DM, Dick TE, Paton JFR, Taha B. Comments on point:counterpoint: respiratory sinus arrhythmia is due to a central mechanism vs. respiratory sinus arrhythmia is due to the baroreflex mechanism. J Appl Physiol (1985) 2009; 106:1745-9. [PMID: 19414628 DOI: 10.1152/japplphysiol.00196.2009] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
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Abstract
Modern rapid magnetic resonance (MR) imaging techniques have led to widespread use of the modality in cardiac imaging. Despite this progress, many MR studies suffer from image degradation due to involuntary motion during the acquisition. This review describes the type and extent of the motion of the heart due to the cardiac and respiratory cycles, which create image artifacts. Methods of eliminating or reducing the problems caused by the cardiac cycle are discussed, including electrocardiogram gating, subject-specific acquisition windows, and section tracking. Similarly, for respiratory motion of the heart, techniques such as breath holding, respiratory gating, section tracking, phase-encoding ordering, subject-specific translational models, and a range of new techniques are considered.
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Affiliation(s)
- Andrew D Scott
- Cardiovascular Magnetic Resonance Unit, the Royal Brompton Hospital, London, England.
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Keyl C, Stockinger J, Laule S, Staier K, Schiebeling-Römer J, Wiesenack C. Changes in pulse pressure variability during cardiac resynchronization therapy in mechanically ventilated patients. Crit Care 2007; 11:R46. [PMID: 17445270 PMCID: PMC2206474 DOI: 10.1186/cc5779] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2007] [Revised: 03/20/2007] [Accepted: 04/19/2007] [Indexed: 11/10/2022] Open
Abstract
INTRODUCTION The respiratory variation in pulse pressure (PP) has been established as a dynamic variable of cardiac preload which indicates fluid responsiveness in mechanically ventilated patients. The impact of acute changes in cardiac performance on respiratory fluctuations in PP has not been evaluated until now. We used cardiac resynchronization therapy as a model to assess the acute effects of changes in left ventricular performance on respiratory PP variability without the need of pharmacological intervention. METHODS In 19 patients undergoing the implantation of a biventricular pacing/defibrillator device under general anesthesia, dynamic blood pressure regulation was assessed during right ventricular and biventricular pacing in the frequency domain (power spectral analysis) and in the time domain (PP variation: difference between the maximal and minimal PP values, normalized by the mean value). RESULTS PP increased slightly during biventricular pacing but without statistical significance (right ventricular pacing, 33 +/- 10 mm Hg; biventricular pacing, 35 +/- 11 mm Hg). Respiratory PP fluctuations increased significantly (logarithmically transformed PP variability -1.27 +/- 1.74 ln mm Hg2 versus -0.66 +/- 1.48 ln mm Hg2; p < 0.01); the geometric mean of respiratory PP variability increased 1.8-fold during cardiac resynchronization. PP variation, assessed in the time domain and expressed as a percentage, showed comparable changes, increasing from 5.3% (3.1%; 12.3%) during right ventricular pacing to 6.9% (4.7%; 16.4%) during biventricular pacing (median [25th percentile; 75th percentile]; p < 0.01). CONCLUSION Changes in cardiac performance have a significant impact on respiratory hemodynamic fluctuations in ventilated patients. This influence should be taken into consideration when interpreting PP variation.
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Affiliation(s)
- Cornelius Keyl
- Department of Anesthesiology, Heart Centre Bad Krozingen, Suedring 15, 79189 Bad Krozingen, Germany
| | - Jochem Stockinger
- Department of Rhythmology, Heart Centre Bad Krozingen, Suedring 15, 79189 Bad Krozingen, Germany
| | - Sven Laule
- Department of Anesthesiology, Heart Centre Bad Krozingen, Suedring 15, 79189 Bad Krozingen, Germany
| | - Klaus Staier
- Department of Anesthesiology, Heart Centre Bad Krozingen, Suedring 15, 79189 Bad Krozingen, Germany
| | - Jochen Schiebeling-Römer
- Department of Rhythmology, Heart Centre Bad Krozingen, Suedring 15, 79189 Bad Krozingen, Germany
| | - Christoph Wiesenack
- Department of Anesthesiology, University Hospital Regensburg, Franz-Josef-Strauss-Allee 11, 93042 Regensburg, Germany
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Berberian G, Quinn TA, Kanter JP, Curtis LJ, Cabreriza SE, Weinberg AD, Spotnitz HM. Optimized Biventricular Pacing in Atrioventricular Block After Cardiac Surgery. Ann Thorac Surg 2005; 80:870-5. [PMID: 16122446 DOI: 10.1016/j.athoracsur.2005.03.111] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/06/2005] [Revised: 03/22/2005] [Accepted: 03/28/2005] [Indexed: 11/29/2022]
Abstract
BACKGROUND Temporary pacing is required after open-heart surgery for treatment of heart block. Atrioventricular delay and ventricular pacing site might be manipulated to increase cardiac output. We hypothesized that by optimizing both atrioventricular delay and ventricular pacing site a 10% improvement in cardiac output would be observed compared with a standard pacing protocol. METHODS Seven patients in first or third degree heart block after valve replacement surgery had temporary wires sewn to the right atrium, right ventricle, and left ventricle. Cardiac output was measured by integrating flow velocity from an ultrasonic aortic flow probe. After optimization of atrioventricular delays during atrial synchronous right ventricular pacing, the effects of ventricular pacing site were tested at the optimum atrioventricular delay for 10-second intervals. RESULTS Biventricular pacing was beneficial in all patients with a mean increase of 22% in cardiac index over right ventricular pacing (1.95 L/min/m2 +/- 0.27 standard error of the mean (SEM) to 2.38 L/min/m2 +/- 0.27 SEM, p = 0.0012) and 14% over left ventricular pacing (2.08 L/min/m2 +/- 0.22 SEM to 2.38 L/min/m2 +/- 0.27 SEM, p = 0.0133). Comparing optimized with standard pacing for 30-second intervals yielded a mean increase of 10% in cardiac index over three respiratory cycles (2.87 L/min/m2 +/- 0.33 SEM to 2.60 L/min/m2 +/- 0.37 SEM, p = 0.009) and 17% at the corresponding end-expiratory beats (2.76 L/min/m2 +/- 0.33 SEM to 2.36 L/min/m2 +/- 0.36 SEM, p = 0.011). CONCLUSIONS Biventricular pacing at optimum atrioventricular delay improves cardiac output in patients with postoperative heart block by at least 10% compared with standard pacing.
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Affiliation(s)
- George Berberian
- Department of Surgery, Columbia University, College of Physicians and Surgeons, New York, New York 10032, USA
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Lee DL, Lee H, Chang HW, Chang AYW, Lin SL, Huang YCT. Heliox improves hemodynamics in mechanically ventilated patients with chronic obstructive pulmonary disease with systolic pressure variations. Crit Care Med 2005; 33:968-73. [PMID: 15891322 DOI: 10.1097/01.ccm.0000163403.42842.fe] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
OBJECTIVE To test the hypothesis that, compared with air-oxygen, heliox would improve cardiac performance in mechanically ventilated patients with severe chronic obstructive pulmonary disease and systolic pressure variations >15 mm Hg and to determine clinical variables associated with favorable hemodynamic responses to heliox. DESIGN A prospective interventional study. SETTING Medical and respiratory intensive care units at a university-affiliated tertiary medical center. PATIENTS Twenty-five consecutive mechanically ventilated patients with severe chronic obstructive pulmonary disease and acute respiratory failure who had systolic pressure variations >15 mm Hg. INTERVENTIONS Respiratory and hemodynamic measurements were taken at the following time with the same ventilator setting: a) baseline; b) after 30 mins with heliox; and c) 30 mins after return to air-oxygen. MEASUREMENTS AND MAIN RESULTS Heliox ventilation decreased intrinsic positive end-expiratory pressure (air-oxygen vs. heliox [mean +/- sd] 13 +/- 4 cm H2O vs. 5 +/- 2 cm H2O, p < .05), trapped lung volume (air-oxygen vs. heliox 362 +/- 67 mL vs. 174 +/- 86 mL, p < .05), and respiratory changes in systolic pressure variations (DeltaPP) (air-oxygen vs. heliox 29 +/- 5% vs. 13 +/- 7%, p < .05). In the ten patients with pulmonary arterial catheters, heliox decreased mean pulmonary arterial pressure, right atrial pressure, and pulmonary arterial occlusion pressure and increased cardiac index. Preheliox DeltaPP correlated with the magnitude of reduction in intrinsic positive end-expiratory pressure during heliox ventilation. Age, preheliox Paco2, and ratio of forced expiratory volume at first second to forced vital capacity correlated inversely, whereas preheliox DeltaPP correlated positively with increases in cardiac index. CONCLUSIONS Heliox may be a useful adjunct therapy in patients with severe chronic obstructive pulmonary disease during acute respiratory failure who have persistent intrinsic positive end-expiratory pressure-induced hemodynamic changes despite ventilator management.
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Affiliation(s)
- David Lin Lee
- Department of Medicine, Kaohsiung Veterans General Hospital and School of Medicine, National Yang-Ming Medical University, Taiwan, ROC
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Stark-Leyva KN, Beck KC, Johnson BD. Influence of expiratory loading and hyperinflation on cardiac output during exercise. J Appl Physiol (1985) 2004; 96:1920-7. [PMID: 14729724 DOI: 10.1152/japplphysiol.00756.2003] [Citation(s) in RCA: 76] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Patients with obstructive lung disease are exposed to expiratory loads (ELs) and dynamic hyperinflation as a consequence of expiratory flow limitation. To understand how these alterations in lung mechanics might affect cardiac function, we examined the influence of a 10-cmH2O EL, alone and in combination with voluntary hyperinflation (ELH), on pulmonary pressures [esophageal (Pes) and gastric (Pg)] and cardiac output (CO) in seven healthy subjects. CO was determined by using an acetylene method at rest and at 40 and 70% of peak work. At rest and during exercise, EL resulted in an increase in Pes and Pg (7-18 cmH2O; P < 0.05) and a decrease in CO (from 5.3 ± 1.8 to 4.5 ± 1.4, 12.2 ± 2.2 to 11.2 ± 2.2, and 16.3 ± 3.3 to 15.2 ± 3.2 l/min for rest, 40% peak work, and 70% peak work, respectively; P < 0.05), which remained depressed after an additional 2 min of EL. With ELH, CO increased at rest and both exercise loads (relative to EL only) but remained below control values. The changes in CO were due to a reduction in stroke volume with a tendency for stroke volume to fall further with prolonged EL. There was a negative correlation between CO and the increase in expiratory Pes and Pg with EL ( R = -0.58 and -0.60; P < 0.01), whereas the rise in CO with subsequent hyperinflation was related to a more negative Pes ( R = 0.72; P < 0.01). In conclusion, EL leads to a reduction in CO, which appears to be primarily related to increases in expiratory abdominal and intrathoracic pressure, whereas ELH resulted in an improved CO, suggesting that lung inflation has little impact on cardiac function.
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Affiliation(s)
- Kristy N Stark-Leyva
- Department of Internal Medicine, Mayo Clinic and Foundation, Rochester, Minnesota 55905, USA
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Cooper HE, Clutton-Brock TH, Parkes MJ. Contribution of the respiratory rhythm to sinus arrhythmia in normal unanesthetized subjects during positive-pressure mechanical hyperventilation. Am J Physiol Heart Circ Physiol 2004; 286:H402-11. [PMID: 12958033 DOI: 10.1152/ajpheart.00504.2003] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The precise contribution of the CO2-dependent respiratory rhythm to sinus arrhythmia in eupnea is unclear. The respiratory rhythm and sinus arrhythmia were measured in 12 normal, unanesthetized subjects in normocapnia and hypocapnia during mechanical hyperventilation with positive pressure. In normocapnia (41 +/- 1 mmHg), the respiratory rhythm was always detectable from airway pressure and inspiratory electromyogram activity. The amplitude of sinus arrhythmia (138 +/- 21 ms) during mechanical hyperventilation with positive pressure was not significantly different from that in eupnea. During the same mechanical hyperventilation pattern but in hypocapnia (24 +/- 1 mmHg), the respiratory rhythm was undetectable and the amplitude of sinus arrhythmia was significantly reduced (to 40 +/- 5 ms). These results show a greater contribution to sinus arrhythmia from the respiratory rhythm during hypocapnia caused by mechanical hyperventilation than previously indicated in normal subjects during hypocapnia caused by voluntary hyperventilation. We discuss whether the respiratory rhythm provides the principal contribution to sinus arrhythmia in eupnea.
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Affiliation(s)
- H E Cooper
- School of Sport and Exercise Sciences, Univ. of Birmingham, Edgbaston, Birmingham B15 2TT, UK
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Cohen MA, Taylor JA. Short-term cardiovascular oscillations in man: measuring and modelling the physiologies. J Physiol 2002; 542:669-83. [PMID: 12154170 PMCID: PMC2290446 DOI: 10.1113/jphysiol.2002.017483] [Citation(s) in RCA: 220] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2002] [Accepted: 04/26/2002] [Indexed: 11/08/2022] Open
Abstract
Research into cardiovascular variabilities intersects both human physiology and quantitative modelling. This is because respiratory and Mayer wave (or 10 s) cardiovascular oscillations represent the integrated control of a system through both autonomic branches by systemic haemodynamic changes within a fluid-filled, physical system. However, our current precise measurement of short-term cardiovascular fluctuations does not necessarily mean we have an adequate understanding of them. Empirical observation suggests that both respiratory and Mayer wave fluctuations derive from mutable autonomic and haemodynamic inputs. Evidence strongly suggests that respiratory sinus arrhythmia both contributes to and buffers respiratory arterial pressure fluctuations. Moreover, even though virtual abolition of all R-R interval variability by cholinergic blockade suggests that parasympathetic stimulation is essential for expression of these variabilities, respiratory sinus arrhythmia does not always reflect a purely vagal phenomenon. The arterial baroreflex has been cited as the mechanism for both respiratory and Mayer wave frequency fluctuations. However, data suggest that both cardiac vagal and vascular sympathetic fluctuations at these frequencies are independent of baroreflex mechanisms and, in fact, contribute to pressure fluctuations. Results from cardiovascular modelling can suggest possible sources for these rhythms. For example, modelling originally suggested low frequency cardiovascular rhythms derived from intrinsic delays in baroreceptor control, and experimental evidence subsequently corroborated this possibility. However, the complex stochastic relations between and variabilities in these rhythms indicate no single mechanism is responsible. If future study of cardiovascular variabilities is to move beyond qualitative suggestions of determinants to quantitative elucidation of critical physical mechanisms, both experimental design and model construction will have to be more trenchant.
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Affiliation(s)
- Michael A Cohen
- Department of Cognitive and Neural Systems, Boston University, Boston, MA, USA
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Magosso E, Cavalcanti S, Ursino M. Theoretical analysis of rest and exercise hemodynamics in patients with total cavopulmonary connection. Am J Physiol Heart Circ Physiol 2002; 282:H1018-34. [PMID: 11834500 DOI: 10.1152/ajpheart.00231.2001] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The objective of this study was to determine the impact of a total cavopulmonary connection on the main hemodynamic quantities, both at rest and during exercise, when compared with normal biventricular circulation. The analysis was performed by means of a mathematical model of the cardiovascular system. The model incorporates the main parameters of systemic and pulmonary circulation, the pulsating heart, and the action of arterial and cardiopulmonary baroreflex mechanisms. Furthermore, the effect of changes in intrathoracic pressure on venous return is also incorporated. Finally, the response to moderate dynamic exercise is simulated, including the effect of a central command, local metabolic vasodilation, and the "muscle pump" mechanism. Simulations of resting conditions indicate that the action of baroreflex regulatory mechanisms alone can only partially compensate for the absence of the right heart. Cardiac output and mean systemic arterial pressure at rest show a large decrease compared with the normal subject. More acceptable hemodynamic quantity values are obtained by combining the action of regulatory mechanisms with a chronic change in parameters affecting mean filling pressure. With such changes assumed, simulations of the response to moderate exercise show that univentricular circulation exhibits a poor capacity to increase cardiac output and to sustain aerobic metabolism, especially when the oxygen consumption rate is increased above 1.2-1.3 l/min. The model ascribes the poor response to exercise in these patients to the incapacity to sustain venous return caused by the high resistance to venous return and/or to exhaustion of volume compensation reserve.
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Affiliation(s)
- Elisa Magosso
- Department of Electronics, Computer Science and Systems, University of Bologna, 40136 Bologna, Italy.
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Dempsey JA, Sheel AW, St Croix CM, Morgan BJ. Respiratory influences on sympathetic vasomotor outflow in humans. Respir Physiol Neurobiol 2002; 130:3-20. [PMID: 12380012 DOI: 10.1016/s0034-5687(01)00327-9] [Citation(s) in RCA: 115] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
We have attempted to synthesize findings dealing with four types of respiratory system influences on sympathetic outflow in the human. First, a powerful lung volume-dependent modulation of muscle sympathetic nerve activity (MSNA) occurs within each respiratory cycle showing late-inspiratory inhibition and late-expiratory excitation. Secondly, in the intact human, neither reductions in spontaneous respiratory motor output nor voluntary near-maximum increases in central respiratory motor output and inspiratory effort, per sec, influence MSNA modulation within a breath, MSNA total activity or limb vascular conductance. Thirdly, carotid chemoreceptor stimuli markedly increase total MSNA; but most of the MSNA response to chemoreceptor activation appears to be mediated independently of increased central respiratory motor output. Fourthly, repeated fatiguing contractions of the diaphragm or expiratory muscles in the human show a metaboreflex mediated time-dependent increase in MSNA and reduced vascular conductance and blood flow in the resting limb. Recent evidence suggests that these respiratory influences contribute significantly to sympathetic vasomotor outflow and to the distribution of systemic vascular conductances and blood flow in the exercising human.
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Affiliation(s)
- Jerome A Dempsey
- John Rankin Laboratory of Pulmonary Medicine, Department of Population Health Sciences, University of Wisconsin, 504 N. Walnut Street, Madison, WI 53706, USA.
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Abdalla IA, Murray RD, Awad HE, Stewart WJ, Thomas JD, Klein AL. Reversal of the pattern of respiratory variation of Doppler inflow velocities in constrictive pericarditis during mechanical ventilation. J Am Soc Echocardiogr 2000; 13:827-31. [PMID: 10980085 DOI: 10.1067/mje.2000.105336] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
BACKGROUND Spontaneous inspiration causes a characteristic decrease of the mitral valve (MV) and pulmonary venous (PV) flow velocities obtained by Doppler echocardiography in patients with constrictive pericarditis (CP). This has been explained by the decrement it causes in the intrathoracic pressure. Positive pressure ventilation (PPV) causes an increment of intrathoracic pressure with mechanical inspiration. Therefore the pattern of respiratory variation produced during PPV may differ from that seen during spontaneous breathing. OBJECTIVE Our goal was to describe the effect of PPV on the pattern and magnitude of respiratory variation of MV and PV flow velocities in CP. METHODS We performed intraoperative pulsed Doppler transesophageal echocardiography on 15 patients (13 men, mean age 52+/-15 years) with CP after general anesthesia and before sternotomy and pericardial stripping. The peak velocity and time-velocity integral (TVI) of the mitral inflow E and A waves and the PV systolic and diastolic waves were measured at onset of inspiration and expiration for 3 to 6 respiratory cycles. Respiratory phase was monitored with a heat-sensitive nasal thermistor. The percent change in Doppler flow velocities from mechanical inspiration (INS) to mechanical expiration (EXP) was calculated with the formula %change = INS - EXP / INS x 100. RESULTS The peak velocity of the mitral inflow E wave was significantly higher during mechanical inspiration than expiration (57 +/-14.5 versus 47+/-13.9 cm/s, P<.001). This represented a percent change of 18%+/-7.9% from expiration to inspiration. The mean TVI of the mitral inflow E was also higher during mechanical inspiration than expiration (P = .02). The peak velocity of the PV D wave was higher during mechanical inspiration than expiration (39+/-17.8 versus 28+/-14.7 cm/s, P<.001). This represented a mean percent change of 28%+/-13.8%. The mean value of the TVI for the PV D wave was also significantly greater during mechanical inspiration than expiration (P <.05). CONCLUSIONS Positive pressure ventilation reverses the pattern of respiratory variation of the MV and PV flow velocities in CP. The percent change in the peak velocities of the MV and PV flows produced by PPV is the same range reported in CP during spontaneous breathing.
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Affiliation(s)
- I A Abdalla
- Section of Cardiovascular Imaging, Department of Cardiology, The Cleveland Clinic Foundation, Cleveland, OH 44195, USA
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