Breathing patterns and cardiovascular autonomic modulation during hypoxia induced by simulated altitude

Bernardi, Luciano, Passino, Claudio, Wilmerding, Virginia, Dallam, George M., Parker, Daryl L., Robergs, Robert A., & Appenzeller, Otto (2001) Breathing patterns and cardiovascular autonomic modulation during hypoxia induced by simulated altitude. Journal of Hypertension, 19(5), pp. 947-958.

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Abstract

Objective

  • To assess the influence of different breathing patterns on autonomic cardiovascular modulation during acute exposure to altitude-induced hypoxia.

Design

  • We measured relative changes in minute ventilation (VE), oxygen saturation (% SaO2), spectral analysis of RR interval and blood pressure, and response to stimulation of carotid baroreceptors (neck suction) at baseline and after acute (1 h) hypobaric hypoxia (equivalent to 5000 m, in a hypobaric chamber).

Methods

  • We studied 19 human subjects: nine controls and 10 Western yoga trainees of similar age, while breathing spontaneously, at 15 breaths/min (controlled breathing) and during 'complete yogic breathing' (slow diaphragmatic + thoracic breathing, ∼5 breaths/min) in yoga trainees, or simple slow breathing in controls.

Results

  • At baseline %SaO2, VE and autonomic pattern were similar in both groups; simulated altitude increased VE in controls but not in yoga trainees; %SaO2 decreased in all subjects (P < 0.0001), but more in controls than in yoga trainees (17 versus 12%, 14 versus 9%, 14 versus 8%, all P < 0.05 or better, during spontaneous breathing, controlled breathing and yogic or slow breathing, respectively). Simulated altitude decreased RR interval (from 879 ± 45 to 770 ± 39, P < 0.01) and increased indices deducted from spectral analysis of heart rate variability (low frequency/high frequency (LF/HF) ratio from 1.6 ± 0.5 to 3.2 ± 1.1, P < 0.05) and systolic blood pressure (low-frequency fluctuations from 2.30 ± 0.31 to 3.07 ± 0.24 In-mmHg2, P < 0.05) in controls, indicating sympathetic activation; these changes were blunted in yoga trainees, and in both groups during slow or yogic breathing. No effect of altitude was seen on stimulation of carotid baroreceptors in both groups.

Conclusions

  • Well-performed slow yogic breathing maintains better blood oxygenation without increasing VE (i.e. seems to be a more efficient breathing) and reduces sympathetic activation during altitude-induced hypoxia.

Impact and interest:

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ID Code: 96929
Item Type: Journal Article
Refereed: Yes
Additional URLs:
Keywords: adult; altitude; article; autonomic nervous system; blood oxygenation; blood pressure; breathing pattern; breathing rate; cardiovascular autoregulation; carotid sinus pressoreceptor reflex; clinical article; controlled study; female; heart rate variabilit, Adult; Altitude; Anoxia; Autonomic Nervous System; Blood Pressure; Cardiovascular System; Female; Heart Rate; Humans; Male; Neck; Oxygen; Pressoreceptors; Respiration; Suction; Yoga
DOI: 10.1097/00004872-200105000-00016
ISSN: 0263-6352
Divisions: Current > QUT Faculties and Divisions > Faculty of Health
Current > Schools > School of Exercise & Nutrition Sciences
Deposited On: 19 Jul 2016 02:02
Last Modified: 19 Jul 2016 02:02

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