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This Article Full Text Full Text (PDF) All Versions of this Article: 289/6/H2364    most recent 00004.2005v1 Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in ISI Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via ISI Web of Science (2) Citing Articles via Google Scholar Google Scholar Articles by Lanfranchi, P. A. Articles by Giannuzzi, P. Search for Related Content PubMed PubMed Citation Articles by Lanfranchi, P. A. Articles by Giannuzzi, P.

Autonomic cardiovascular regulation in subjects with acute mountain sickness

¹Centre de Recherche, Hôpital du Sacré-Coeur, Montreal, Quebec, Canada; ²Division of Cardiology, ³Service of Bioengineering, ⁵Division of Respiratory Medicine, and ⁷Department of Radiology, Salvatore Maugeri Foundation, Istituto Scientifico IRCCS Veruno, Verona; and ⁴Unit of Respiratory Medicine, San Raffaele University Hospital, Milan, Italy; and ⁶Division of Physiology, Department of Medicine, University of California, San Diego, California

Submitted 4 January 2005 ; accepted in final form 25 July 2005

The aims of this study were 1) to evaluate whether subjects suffering from acute mountain sickness (AMS) during exposure to high altitude have signs of autonomic dysfunction and 2) to verify whether autonomic variables at low altitude may identify subjects who are prone to develop AMS. Forty-one mountaineers were studied at 4,559-m altitude. AMS was diagnosed using the Lake Louise score, and autonomic cardiovascular function was explored using spectral analysis of R-R interval and blood pressure (BP) variability on 10-min resting recordings. Seventeen subjects (41%) had AMS. Subjects with AMS were older than those without AMS (P < 0.01). At high altitude, the low-frequency (LF) component of systolic BP variability (LF_SBP) was higher (P = 0.02) and the LF component of R-R variability in normalized units (LF_RRNU) was lower (P = 0.001) in subjects with AMS. After 3 mo, 21 subjects (43% with AMS) repeated the evaluation at low altitude at rest and in response to a hypoxic gas mixture. LF_RRNU was similar in the two groups at baseline and during hypoxia at low altitude but increased only in subjects without AMS at high altitude (P < 0.001) and did not change between low and high altitude in subjects with AMS. Conversely, LF_SBP increased significantly during short-term hypoxia only in subjects with AMS, who also had higher resting BP (P < 0.05) than those without AMS. Autonomic cardiovascular dysfunction accompanies AMS. Marked LF_SBP response to short-term hypoxia identifies AMS-prone subjects, supporting the potential role of an exaggerated individual chemoreflex vasoconstrictive response to hypoxia in the genesis of AMS.

hypoxia; autonomic nervous system; heart rate; blood pressure