Extreme Hypoxia Causing Brady-Arrythmias During Apnea in Elite Breath-Hold Divers

Introduction: The cardiac electrical conduction system is very sensitive to hypoglycemia and hypoxia, and the consequence may be brady-arrythmias. Weddell seals endure brady-arrythmias during their dives when desaturating to 3.2 kPa and elite breath-hold-divers (BHD), who share metabolic and cardiov...

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Autores principales:	Thomas Kjeld, Anders Brenøe Isbrand, Katrine Linnet, Bo Zerahn, Jens Højberg, Egon Godthaab Hansen, Lars Christian Gormsen, Jacob Bejder, Thomas Krag, John Vissing, Hans Erik Bøtker, Henrik Christian Arendrup
Formato:	article
Lenguaje:	EN
Publicado:	Frontiers Media S.A. 2021
Materias:	junctional rhythm brady-arrythmia free-diving invasive blood pressure hypoxia induced factor-1 (HIF-1) atrioventricular block Physiology QP1-981
Acceso en línea:	https://doaj.org/article/9bf5e0c58cbf41e9a56c5e2c60e08606
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spelling	oai:doaj.org-article:9bf5e0c58cbf41e9a56c5e2c60e086062021-12-03T06:21:41ZExtreme Hypoxia Causing Brady-Arrythmias During Apnea in Elite Breath-Hold Divers1664-042X10.3389/fphys.2021.712573https://doaj.org/article/9bf5e0c58cbf41e9a56c5e2c60e086062021-12-01T00:00:00Zhttps://www.frontiersin.org/articles/10.3389/fphys.2021.712573/fullhttps://doaj.org/toc/1664-042XIntroduction: The cardiac electrical conduction system is very sensitive to hypoglycemia and hypoxia, and the consequence may be brady-arrythmias. Weddell seals endure brady-arrythmias during their dives when desaturating to 3.2 kPa and elite breath-hold-divers (BHD), who share metabolic and cardiovascular adaptions including bradycardia with diving mammals, endure similar desaturation during maximum apnea. We hypothesized that hypoxia causes brady-arrythmias during maximum apnea in elite BHD. Hence, this study aimed to define the arterial blood glucose (Glu), peripheral saturation (SAT), heart rhythm (HR), and mean arterial blood pressure (MAP) of elite BHD during maximum apneas.Methods: HR was monitored with Direct-Current-Pads/ECG-lead-II and MAP and Glu from a radial arterial-catheter in nine BHD performing an immersed and head-down maximal static pool apnea after three warm-up apneas. SAT was monitored with a sensor on the neck of the subjects. On a separate day, a 12-lead-ECG-monitored maximum static apnea was repeated dry (n = 6).Results: During pool apnea of maximum duration (385 ± 70 s), SAT decreased from 99.6 ± 0.5 to 58.5 ± 5.5% (∼PaO2 4.8 ± 1.5 kPa, P < 0.001), while Glu increased from 5.8 ± 0.2 to 6.2 ± 0.2 mmol/l (P = 0.009). MAP increased from 103 ± 4 to 155 ± 6 mm Hg (P < 0.005). HR decreased to 46 ± 10 from 86 ± 14 beats/minute (P < 0.001). HR and MAP were unchanged after 3–4 min of apnea. During dry apnea (378 ± 31 s), HR decreased from 55 ± 4 to 40 ± 3 beats/minute (P = 0.031). Atrioventricular dissociation and junctional rhythm were observed both during pool and dry apneas.Conclusion: Our findings contrast with previous studies concluding that Glu decreases during apnea diving. We conclude during maximum apnea in elite BHD that (1) the diving reflex is maximized after 3–4 min, (2) increasing Glu may indicate lactate metabolism in accordance with our previous results, and (3) extreme hypoxia rather than hypoglycemia causes brady-arrythmias in elite BHD similar to diving mammals.Thomas KjeldAnders Brenøe IsbrandKatrine LinnetBo ZerahnJens HøjbergEgon Godthaab HansenLars Christian GormsenJacob BejderThomas KragJohn VissingHans Erik BøtkerHenrik Christian ArendrupFrontiers Media S.A.articlejunctional rhythmbrady-arrythmiafree-divinginvasive blood pressurehypoxia induced factor-1 (HIF-1)atrioventricular blockPhysiologyQP1-981ENFrontiers in Physiology, Vol 12 (2021)
institution	DOAJ
collection	DOAJ
language	EN
topic	junctional rhythm brady-arrythmia free-diving invasive blood pressure hypoxia induced factor-1 (HIF-1) atrioventricular block Physiology QP1-981
spellingShingle	junctional rhythm brady-arrythmia free-diving invasive blood pressure hypoxia induced factor-1 (HIF-1) atrioventricular block Physiology QP1-981 Thomas Kjeld Anders Brenøe Isbrand Katrine Linnet Bo Zerahn Jens Højberg Egon Godthaab Hansen Lars Christian Gormsen Jacob Bejder Thomas Krag John Vissing Hans Erik Bøtker Henrik Christian Arendrup Extreme Hypoxia Causing Brady-Arrythmias During Apnea in Elite Breath-Hold Divers
description	Introduction: The cardiac electrical conduction system is very sensitive to hypoglycemia and hypoxia, and the consequence may be brady-arrythmias. Weddell seals endure brady-arrythmias during their dives when desaturating to 3.2 kPa and elite breath-hold-divers (BHD), who share metabolic and cardiovascular adaptions including bradycardia with diving mammals, endure similar desaturation during maximum apnea. We hypothesized that hypoxia causes brady-arrythmias during maximum apnea in elite BHD. Hence, this study aimed to define the arterial blood glucose (Glu), peripheral saturation (SAT), heart rhythm (HR), and mean arterial blood pressure (MAP) of elite BHD during maximum apneas.Methods: HR was monitored with Direct-Current-Pads/ECG-lead-II and MAP and Glu from a radial arterial-catheter in nine BHD performing an immersed and head-down maximal static pool apnea after three warm-up apneas. SAT was monitored with a sensor on the neck of the subjects. On a separate day, a 12-lead-ECG-monitored maximum static apnea was repeated dry (n = 6).Results: During pool apnea of maximum duration (385 ± 70 s), SAT decreased from 99.6 ± 0.5 to 58.5 ± 5.5% (∼PaO2 4.8 ± 1.5 kPa, P < 0.001), while Glu increased from 5.8 ± 0.2 to 6.2 ± 0.2 mmol/l (P = 0.009). MAP increased from 103 ± 4 to 155 ± 6 mm Hg (P < 0.005). HR decreased to 46 ± 10 from 86 ± 14 beats/minute (P < 0.001). HR and MAP were unchanged after 3–4 min of apnea. During dry apnea (378 ± 31 s), HR decreased from 55 ± 4 to 40 ± 3 beats/minute (P = 0.031). Atrioventricular dissociation and junctional rhythm were observed both during pool and dry apneas.Conclusion: Our findings contrast with previous studies concluding that Glu decreases during apnea diving. We conclude during maximum apnea in elite BHD that (1) the diving reflex is maximized after 3–4 min, (2) increasing Glu may indicate lactate metabolism in accordance with our previous results, and (3) extreme hypoxia rather than hypoglycemia causes brady-arrythmias in elite BHD similar to diving mammals.
format	article
author	Thomas Kjeld Anders Brenøe Isbrand Katrine Linnet Bo Zerahn Jens Højberg Egon Godthaab Hansen Lars Christian Gormsen Jacob Bejder Thomas Krag John Vissing Hans Erik Bøtker Henrik Christian Arendrup
author_facet	Thomas Kjeld Anders Brenøe Isbrand Katrine Linnet Bo Zerahn Jens Højberg Egon Godthaab Hansen Lars Christian Gormsen Jacob Bejder Thomas Krag John Vissing Hans Erik Bøtker Henrik Christian Arendrup
author_sort	Thomas Kjeld
title	Extreme Hypoxia Causing Brady-Arrythmias During Apnea in Elite Breath-Hold Divers
title_short	Extreme Hypoxia Causing Brady-Arrythmias During Apnea in Elite Breath-Hold Divers
title_full	Extreme Hypoxia Causing Brady-Arrythmias During Apnea in Elite Breath-Hold Divers
title_fullStr	Extreme Hypoxia Causing Brady-Arrythmias During Apnea in Elite Breath-Hold Divers
title_full_unstemmed	Extreme Hypoxia Causing Brady-Arrythmias During Apnea in Elite Breath-Hold Divers
title_sort	extreme hypoxia causing brady-arrythmias during apnea in elite breath-hold divers
publisher	Frontiers Media S.A.
publishDate	2021
url	https://doaj.org/article/9bf5e0c58cbf41e9a56c5e2c60e08606
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Extreme Hypoxia Causing Brady-Arrythmias During Apnea in Elite Breath-Hold Divers

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