Respiratory modulation of cardiovagal baroreflex sensitivity

1 Department of Surgery and Anaesthesia, University of Otago, Wellington; 2 Department of Physiology, University of Otago, Dunedin, New Zealand; and 3 Department of Human Kinetics, Faculty of Health and Social Development, University of British Columbia, Kelowna, British Columbia, Canada Submitted 2...

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Published in:Journal of applied physiology (1985) 2009-09, Vol.107 (3), p.718-724
Main Authors: Tzeng, Y. C, Sin, P. Y. W, Lucas, S. J. E, Ainslie, P. N
Format: Article
Language:English
Subjects:
Adult
Airway management
Algorithms
Baroreflex - physiology
Biological and medical sciences
Blood pressure
Blood Pressure - physiology
Electrocardiography
Female
Fundamental and applied biological sciences. Psychology
Heart - physiology
Heart failure
Heart rate
Heart Rate - physiology
Humans
Male
Respiration
Respiratory Mechanics - physiology
Studies
Tidal Volume
Vagus Nerve - physiology
Young Adult
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Summary:1 Department of Surgery and Anaesthesia, University of Otago, Wellington; 2 Department of Physiology, University of Otago, Dunedin, New Zealand; and 3 Department of Human Kinetics, Faculty of Health and Social Development, University of British Columbia, Kelowna, British Columbia, Canada Submitted 20 May 2009 ; accepted in final form 15 July 2009 Emerging evidence has suggested that with minimal prerequisite training, slow deep breathing around 0.10 Hz can acutely enhance cardiovagal baroreflex sensitivity (BRS) in humans. Such reports have led to the speculation that behavioral interventions designed to reduce breathing frequency may serve a therapeutic role in ameliorating depressed baroreflex function in conditions such as chronic heart failure, essential hypertension, and obstructive airway disease. This study sought to test the hypothesis that slow controlled breathing acutely enhances cardiovagal baroreflex function in young healthy volunteers. Distinct from earlier studies, however, baroreflex function was examined ( n = 30) using the classical pharmacological modified Oxford method, which enabled the assessment of cardiovagal BRS through experimentally driven baroreceptor stimulation across a wide range of blood pressures. For a comparison against existing evidence, spontaneous cardiovagal BRS was also assessed using the -index and sequence method. Compared with fast breathing (0.25 Hz), slow breathing (0.10 Hz) was associated with an increase in the -index (8.1 ± 14 ms/mmHg, P < 0.01) and spontaneous up-sequence BRS (10 ± 11 ms/mmHg, P < 0.01). In contrast, BRS derived from spontaneous down sequences and the modified Oxford method were unaltered by slow breathing. The lack of change in BRS derived from the modified Oxford method challenges the concept that slow breathing acutely augments arterial baroreflex function in otherwise healthy humans. Our results also provide further evidence that spontaneous BRS may not reflect the BRS determined by experimentally driven baroreceptor stimulation. baroreceptors; blood pressure; heart rate; parasympathetic Address for reprint requests and other correspondence: Y. C. Tzeng, Dept. of Surgery and Anaesthesia, Univ. of Otago-Wellington, 23A Mein St., PO Box 7343, Newtown, Wellington South, New Zealand (e-mail: shieak.tzeng{at}otago.ac.nz )
ISSN:8750-7587
1522-1601
DOI:10.1152/japplphysiol.00548.2009