1
|
Gibbons TD, Ainslie PN, Thomas KN, Wilson LC, Akerman AP, Donnelly J, Campbell HA, Cotter JD. Influence of the mode of heating on cerebral blood flow, non-invasive intracranial pressure and thermal tolerance in humans. J Physiol 2021; 599:1977-1996. [PMID: 33586133 DOI: 10.1113/jp280970] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2020] [Accepted: 02/01/2021] [Indexed: 12/22/2022] Open
Abstract
KEY POINTS The human brain is particularly vulnerable to heat stress; this manifests as impaired cognition, orthostatic tolerance, work capacity and eventually, brain death. The brain's limitation in the heat is often ascribed to inadequate cerebral blood flow (CBF), but elevated intracranial pressure is commonly observed in mammalian models of heat stroke and can on its own cause functional impairment. The CBF response to incremental heat strain was dependent on the mode of heating, decreasing by 30% when exposed passively to hot, humid air (sauna), while remaining unchanged or increasing with passive hot-water immersion (spa) and exercising in a hot environment. Non-invasive intracranial pressure estimates (nICP) were increased universally by 18% at volitional thermal tolerance across all modes of heat stress, and therefore may play a contributing role in eliciting thermal tolerance. The sauna, more so than the spa or exercise, poses a greater challenge to the brain under mild to severe heating due to lower blood flow but similarly increased nICP. ABSTRACT The human brain is particularly vulnerable to heat stress; this manifests as impaired cognitive function, orthostatic tolerance, work capacity, and eventually, brain death. This vulnerability is often ascribed to inadequate cerebral blood flow (CBF); however, elevated intracranial pressure (ICP) is also observed in mammalian models of heat stroke. We investigated the changes in CBF with incremental heat strain under three fundamentally different modes of heating, and assessed whether heating per se increased ICP. Fourteen fit participants (seven female) were heated to thermal tolerance or 40°C core temperature (Tc ; oesophageal) via passive hot-water immersion (spa), passive hot, humid air exposure (sauna), cycling exercise, and cycling exercise with CO2 inhalation to prevent heat-induced hypocapnia. CBF was measured with duplex ultrasound at each 0.5°C increment in Tc and ICP was estimated non-invasively (nICP) from optic nerve sheath diameter at thermal tolerance. At thermal tolerance, CBF was decreased by 30% in the sauna (P < 0.001), but was unchanged in the spa or with exercise (P ≥ 0.140). CBF increased by 17% when end-tidal P C O 2 was clamped at eupnoeic pressure (P < 0.001). On the contrary, nICP increased universally by 18% with all modes of heating (P < 0.001). The maximum Tc was achieved with passive heating, and preventing hypocapnia during exercise did not improve exercise or thermal tolerance (P ≥ 0.146). Therefore, the regulation of CBF is dramatically different depending on the mode and dose of heating, whereas nICP responses are not. The sauna, more so than the spa or exercise, poses a greater challenge to the brain under equivalent heat strain.
Collapse
Affiliation(s)
- Travis D Gibbons
- University of Otago, 55/47 Union St. W, Dunedin, Otago, 9016, New Zealand
| | - Philip N Ainslie
- University of British Columbia, Okangan Campus, Kelowna, BC, V1V 1V7, Canada
| | - Kate N Thomas
- University of Otago, 55/47 Union St. W, Dunedin, Otago, 9016, New Zealand
| | - Luke C Wilson
- University of Otago, 55/47 Union St. W, Dunedin, Otago, 9016, New Zealand
| | | | | | - Holly A Campbell
- University of Otago, 55/47 Union St. W, Dunedin, Otago, 9016, New Zealand
| | - Jim D Cotter
- University of Otago, 55/47 Union St. W, Dunedin, Otago, 9016, New Zealand
| |
Collapse
|
2
|
Ewalts M, Dawkins T, Boulet LM, Thijssen D, Stembridge M. The influence of increased venous return on right ventricular dyssynchrony during acute and sustained hypoxaemia. Exp Physiol 2020; 106:925-937. [PMID: 33369788 DOI: 10.1113/ep088657] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2020] [Accepted: 12/19/2020] [Indexed: 11/08/2022]
Abstract
NEW FINDINGS What is the central question of this study? Right ventricular dyssynchrony is a marker of function that is elevated in healthy individuals exposed to acute hypoxia, but does it remain elevated during sustained exposure to high altitude hypoxia, and can it be normalised by augmenting venous return? What is the main finding and its importance? For the first time it is demonstrated that (i) increasing venous return in acute hypoxia restores the synchrony of right ventricular contraction and (ii) dyssynchrony is evident after acclimatisation to high altitude, and remains sensitive to changes in venous return. Therefore, the interpretation of right ventricular dyssynchrony requires consideration the prevailing haemodynamic state. ABSTRACT Regional heterogeneity in timing of right ventricular (RV) contraction (RV dyssynchrony; RVD) occurs when pulmonary artery systolic pressure (PASP) is increased during acute hypoxia. Interestingly, RVD is not observed during exercise, a stimulus that increases both PASP and venous return. Therefore, we hypothesised that RVD in healthy humans is sensitive to changes in venous return, and examined whether (i) increasing venous return in acute hypoxia lowers RVD and (ii) if RVD is further exaggerated in sustained hypoxia, given increased PASP is accompanied by decreased ventricular filling at high altitude. RVD, PASP and right ventricular end-diastolic area (RVEDA) were assessed using transthoracic two-dimensional and speckle-tracking echocardiography during acute normobaric hypoxia ( F i O 2 = 0.12) and sustained exposure (5-10 days) to hypobaric hypoxia (3800 m). Venous return was augmented with lower body positive pressure at sea level (LBPP; +10 mmHg) and saline infusion at high altitude. PASP was increased in acute hypoxia (20 ± 6 vs. 28 ± 7, P < 0.001) concomitant to an increase in RVD (18 ± 7 vs. 38 ± 10, P < 0.001); however, the addition of LBPP during hypoxia decreased RVD (38 ± 0 vs. 26 ± 10, P < 0.001). Sustained hypoxia increased PASP (20 ± 4 vs. 26 ± 5, P = 0.008) and decreased RVEDA (24 ± 4 vs. 21 ± 2, P = 0.042), with RVD augmented (14 ± 5 vs. 31 ± 12, P = 0.001). Saline infusion increased RVEDA (21 ± 2 vs. 23 ± 3, P = 0.008) and reduced RVD (31 ± 12 vs. 20 ± 9, P = 0.001). In summary, an increase in PASP secondary to acute and sustained exposure to hypoxia augments RVD, which can be at least partly reduced via increased venous return.
Collapse
Affiliation(s)
- Michiel Ewalts
- Cardiff School of Sport and Health Sciences, Cardiff Metropolitan University, Cardiff, UK.,Department of Physiology, Radboudumc, Nijmegen, The Netherlands
| | - Tony Dawkins
- Cardiff School of Sport and Health Sciences, Cardiff Metropolitan University, Cardiff, UK
| | - Lindsey M Boulet
- Centre for Heart Lung and Vascular Health, University of British Columbia, Kelowna, British Columbia, Canada
| | - Dick Thijssen
- Department of Physiology, Radboudumc, Nijmegen, The Netherlands
| | - Mike Stembridge
- Cardiff School of Sport and Health Sciences, Cardiff Metropolitan University, Cardiff, UK
| |
Collapse
|
3
|
Garcia MK, Rizzo L, Yazbek-Júnior P, Yutiyama D, da Silva FJ, Matheus D, Mastrocolla LE, Massad E. Cardiorespiratory performance of coronary artery disease patients on land versus underwater treadmill tests: a comparative study. Clinics (Sao Paulo) 2017; 72:667-674. [PMID: 29236912 PMCID: PMC5706058 DOI: 10.6061/clinics/2017(11)04] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/20/2017] [Accepted: 07/21/2017] [Indexed: 11/18/2022] Open
Abstract
OBJECTIVE To compare responses to a cardiopulmonary exercise test on land versus on an underwater treadmill, to assess the cardiorespiratory performance of coronary artery disease patients while immersed in warm water and to compare with the performance of healthy individuals. METHODS The sample population consisted of 40 subjects, which included 20 coronary artery disease patients aged 63.7±8.89 years old, functional class I and II, according to the New York Hearth Association, and 20 healthy subjects aged 64.7±7.09 years old. The statistical significances were calculated through an ANOVA test with a (1 - β) power of 0.861. ClinicalTrials.gov: NCT00989248 (22). RESULTS Significant differences were uncovered in coronary artery disease group regarding the variables heart beats (HB), (p>0.01), oxygen consumption (VO2), (p>0.01) and carbon dioxide production (VCO2) (p<0.01). Also, for the same group, in relation to the environment, water versus on land for HB, VO2, VCO2 and oxygen for each heart beat (VO2/HB) all of than (p<0.01). The stages for data collected featured the subject's performance throughout the experiment, and within the given context, variables rating of perceived exertion (RPE), HB, VO2, VCO2 and VO2/HB (p<0.01) showed significant interactions between test stages and environment. Additionally, there was a significant interaction between the etiology and the test stages for the variables HB, VO2 and VCO2 (p<0.01). Electrocardiographic changes compatible with myocardial ischemia or arrhythmia were not observed. The subjects exhibited lower scores on Borg's perceived exertion scale in the water than at every one of the test stages on land (p<0.01). CONCLUSION This study show that a cardiopulmonary exercise test can be safely conducted in subjects in immersion and that the procedures, resources and equipment used yielded replicable and reliable data. Significant differences observed in water versus on land allow us to conclude that coronary artery disease patients are able to do physical exercise in water and that the physiological effects of immersion do not present any risk for such patients, as exercise was well tolerated by all subjects.
Collapse
Affiliation(s)
- Mauricio Koprowski Garcia
- Instituto de Medicina e Reabilitacao, Hospital das Clinicas (HCFMUSP), Faculdade de Medicina, Universidade de Sao Paulo, Sao Paulo, SP, BR
- *Corresponding author. E-mail:
| | - Limanara Rizzo
- Departamento de Medicina Legal e Etica Medica, Faculdade de Medicina (FMUSP), Universidade de Sao Paulo, Sao Paulo, SP, BR
| | - Paulo Yazbek-Júnior
- Instituto de Medicina e Reabilitacao, Hospital das Clinicas (HCFMUSP), Faculdade de Medicina, Universidade de Sao Paulo, Sao Paulo, SP, BR
| | - Daniela Yutiyama
- Instituto de Medicina e Reabilitacao, Hospital das Clinicas (HCFMUSP), Faculdade de Medicina, Universidade de Sao Paulo, Sao Paulo, SP, BR
| | - Fabiola Jomar da Silva
- Instituto de Medicina e Reabilitacao, Hospital das Clinicas (HCFMUSP), Faculdade de Medicina, Universidade de Sao Paulo, Sao Paulo, SP, BR
| | - Denise Matheus
- Instituto de Medicina e Reabilitacao, Hospital das Clinicas (HCFMUSP), Faculdade de Medicina, Universidade de Sao Paulo, Sao Paulo, SP, BR
| | | | - Eduardo Massad
- Departamento de Medicina Legal e Etica Medica, Faculdade de Medicina (FMUSP), Universidade de Sao Paulo, Sao Paulo, SP, BR
| |
Collapse
|
4
|
Sato D, Yamazaki Y, Takahashi A, Uetake Y, Nakano S, Iguchi K, Baba Y, Nara R, Shimoyama Y. Water immersion decreases sympathetic skin response during color-word Stroop test. PLoS One 2017; 12:e0180765. [PMID: 28742137 PMCID: PMC5524402 DOI: 10.1371/journal.pone.0180765] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2016] [Accepted: 06/21/2017] [Indexed: 11/18/2022] Open
Abstract
Water immersion alters the autonomic nervous system (ANS) response in humans. The effect of water immersion on executive function and ANS responses related to executive function tasks was unknown. Therefore, this study aimed to determine whether water immersion alters ANS response during executive tasks. Fourteen healthy participants performed color-word-matching Stroop tasks before and after non-immersion and water immersion intervention for 15 min in separate sessions. The Stroop task-related skin conductance response (SCR) was measured during every task. In addition, the skin conductance level (SCL) and electrocardiograph signals were measured over the course of the experimental procedure. The main findings of the present study were as follows: 1) water immersion decreased the executive task-related sympathetic nervous response, but did not affect executive function as evaluated by Stroop tasks, and 2) decreased SCL induced by water immersion was maintained for at least 15 min after water immersion. In conclusion, the present results suggest that water immersion decreases the sympathetic skin response during the color-word Stroop test without altering executive performance.
Collapse
Affiliation(s)
- Daisuke Sato
- Institute for Human Movement and Medical Sciences, Niigata University of Health and Welfare, Niigata city, Niigata, Japan
- Graduate school for Major in Health Science, Niigata University of Health and Welfare, Niigata city, Niigata, Japan
- Department of Health and Sports, Niigata University of Health and Welfare, Niigata city, Niigata, Japan
- * E-mail:
| | - Yudai Yamazaki
- Institute for Human Movement and Medical Sciences, Niigata University of Health and Welfare, Niigata city, Niigata, Japan
- Graduate school for Major in Health Science, Niigata University of Health and Welfare, Niigata city, Niigata, Japan
| | - Akari Takahashi
- Department of Health and Sports, Niigata University of Health and Welfare, Niigata city, Niigata, Japan
| | - Yoshihito Uetake
- Graduate school for Major in Health Science, Niigata University of Health and Welfare, Niigata city, Niigata, Japan
| | - Saki Nakano
- Department of Health and Sports, Niigata University of Health and Welfare, Niigata city, Niigata, Japan
| | - Kaho Iguchi
- Department of Health and Sports, Niigata University of Health and Welfare, Niigata city, Niigata, Japan
| | - Yasuhiro Baba
- Department of Health and Sports, Niigata University of Health and Welfare, Niigata city, Niigata, Japan
| | - Rio Nara
- Department of Health and Sports, Niigata University of Health and Welfare, Niigata city, Niigata, Japan
| | - Yoshimitsu Shimoyama
- Graduate school for Major in Health Science, Niigata University of Health and Welfare, Niigata city, Niigata, Japan
- Department of Health and Sports, Niigata University of Health and Welfare, Niigata city, Niigata, Japan
| |
Collapse
|
5
|
Boldt LH, Fraszl W, Röcker L, Schefold JC, Steinach M, Noack T, Gunga HC. Changes in the haemostatic system after thermoneutral and hyperthermic water immersion. Eur J Appl Physiol 2007; 102:547-54. [PMID: 18043935 DOI: 10.1007/s00421-007-0620-7] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/12/2007] [Indexed: 11/29/2022]
Abstract
Warm water bathing is a popular recreational activity and is frequently used in rehabilitation medicine. Although well tolerated in most cases, there are reports indicating an increased risk of thrombotic events after hot tub bathing. The effects of a 45 min thermoneutral bath followed by a 50 min bath with increasing water temperature (maximum 41 degrees C) until reaching a body core temperature of 39 degrees C on factors of blood coagulation and fibrinolysis were studied in eight healthy male volunteers. Blood was obtained after a 45-min resting period as control and after the thermoneutral and hyperthermic bath as well as after another 45 min recovery period at the end of the study. Hyperthermic immersion (HI) lead to a shortening of activated partial thromboplastin time (aPTT) (P < 0.05). Fibrinogen concentration decreased immediately after HI (P < 0.05) but increased during recovery (P < 0.05). Plasminogen activator inhibitor (PAI) activity decreased during HI (P < 0.05), D-dimer concentration was not found to change. Thrombocyte count increased (P < 0.05) during HI. The increases in tissue-type plasminogen activator concentration as well as leucocyte count during HI were due to haemoconcentration. Prothrombin time, PAI-activity and granulocyte count decreased during thermoneutral immersion (P < 0.05). Warm water bathing leads to haemoconcentration and minimal activation of coagulation. The PAI-1 activity is decreased. A marked risk for thrombotic or bleeding complications during warm water bathing in healthy males could not be ascertained.
Collapse
Affiliation(s)
- Leif-Hendrik Boldt
- Department of Physiology, Center for Space Medicine Berlin, Charité, University Medicine Berlin, Campus Benjamin Franklin, Arnimallee 22, 14195, Berlin, Germany.
| | | | | | | | | | | | | |
Collapse
|
6
|
Weiler-Ravell D, Shupak A, Goldenberg I, Halpern P, Shoshani O, Hirschhorn G, Margulis A. Pulmonary oedema and haemoptysis induced by strenuous swimming. BMJ (CLINICAL RESEARCH ED.) 1995; 311:361-2. [PMID: 7640542 PMCID: PMC2550430 DOI: 10.1136/bmj.311.7001.361] [Citation(s) in RCA: 81] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
|
7
|
Convertino VA, Thompson CA, Benjamin BA, Keil LC, Savin WM, Gordon EP, Haskell WL, Schroeder JS, Sandler H. Haemodynamic and ADH responses to central blood volume shifts in cardiac-denervated humans. CLINICAL PHYSIOLOGY (OXFORD, ENGLAND) 1990; 10:55-67. [PMID: 2302936 DOI: 10.1111/j.1475-097x.1990.tb00083.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Haemodynamic responses and antidiuretic hormone (ADH) were measured during body position changes designed to induce blood volume shifts in 10 cardiac transplant recipients to assess the contribution of cardiac and vascular volume receptors in the control of ADH secretion. Each subject underwent 15 min of a control period in the seated posture, then assumed a lying posture for 30 min at 6 degrees head-down tilt (HDT) followed by 30 min of seated recovery. Venous blood samples and cardiac dimensions (echocardiography) were taken at 0 and 15 min before HDT, 5, 15 and 30 min of HDT, and 5, 15 and 30 min of seated recovery. Blood samples were analysed for haematocrit, plasma osmolality, plasma renin activity (PRA) and ADH. Resting plasma volume (PV) was measured by Evans blue dye and per cent changes in PV during posture changes were calculated from changes in haematocrit. Heart rate (HR) and blood pressure (BP) were recorded every 2 min. In the cardiac transplant subjects, mean HR decreased (BP less than 0.05) from 102 b.p.m. pre-HDT to 94 b.p.m. during HDT and returned to 101 b.p.m. in seated recovery while BP was slightly elevated (P less than 0.05). PV was increased by 6.3% (P less than 0.05) by the end of 30 min of HDT but returned to pre-HDT levels following seated recovery. Plasma osmolality was not altered by posture changes. Mean left ventricular end-diastolic volume increased (P less than 0.05) from 90 +/- 5 ml pre-HDT to 105 +/- 4 ml during HDT and returned to 88 +/- 5 ml in seated recovery. Plasma ADH was reduced by 28% (P less than 0.05) by the end of HDT and returned to pre-HDT levels with seated recovery. PRA was also reduced by 28% (P less than 0.05) with HDT. These responses were similar to those of six normal cardiac-innervated control subjects and one heart-lung recipient. Therefore, cardiac volume receptors are not the only mechanism for the control of ADH release during acute blood volume shifts in man.
Collapse
Affiliation(s)
- V A Convertino
- Life Sciences Research Office, National Aeronautics and Space Administration, Kennedy Space Center, Florida 32899
| | | | | | | | | | | | | | | | | |
Collapse
|