Document Detail

Initial orthostatic hypotension at high altitude.
MedLine Citation:
PMID:  20586601     Owner:  NLM     Status:  MEDLINE    
There are several reports on syncope occurring following standing at high altitude (HA), yet description of the detailed physiological responses to standing at HA are lacking. We examined the hypothesis that appropriate physiological adjustments to upright posture would be compromised at HA (5050 m). Ten healthy volunteers stood up rapidly from supine rest, for 3 min, at sea level and at 5050 m. Beat-to-beat mean arterial blood pressure (MAP, Finometer), middle cerebral artery blood velocity (MCAv, Transcranial Doppler), end-tidal PCO(2) and PO(2), and heart rate (ECG) were recorded continuously. After 14 days at HA, baseline MAP and MCAv were not different to sea level, although HR was elevated. Neither the magnitude of initial (<15 s) responses to standing, nor the time course of initial recovery differed at HA compared with sea level (p > 0.05). By 3 min of standing, MAP was restored to supine values both at sea level (-3 +/- 12 mmHg) and HA (4 +/- 10 mmHg), although there was more complete recovery of HR at sea level (+13 +/- 10 b.min(-1), p = 0.02 vs. + 23 +/- 10 b.min(-1), p = 0.01). Reduced MCAv at 3 min was comparable at sea level and altitude (both -16%). These data indicate that initial cardiovascular and cerebrovascular responses to standing are unaltered when partially acclimatized to HA.
Kate N Thomas; Keith R Burgess; Rishi Basnyat; Samuel J E Lucas; James D Cotter; Jui-Lin Fan; Karen C Peebles; Rebekah A I Lucas; Philip N Ainslie
Publication Detail:
Type:  Controlled Clinical Trial; Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  High altitude medicine & biology     Volume:  11     ISSN:  1557-8682     ISO Abbreviation:  High Alt. Med. Biol.     Publication Date:  2010  
Date Detail:
Created Date:  2010-06-30     Completed Date:  2010-10-21     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  100901183     Medline TA:  High Alt Med Biol     Country:  United States    
Other Details:
Languages:  eng     Pagination:  163-7     Citation Subset:  IM; S    
University of Otago, Dunedin, New Zealand.
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MeSH Terms
Acclimatization / physiology*
Adaptation, Physiological / physiology
Blood Flow Velocity / physiology
Blood Pressure / physiology
Cerebrovascular Circulation / physiology
Hemodynamics / physiology
Hypotension, Orthostatic / complications,  physiopathology*
Oxygen Consumption / physiology
Posture / physiology*
Syncope / diagnosis*,  etiology
Young Adult

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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