Document Detail

Manual assessment of the initial fall in blood pressure after orthostatic challenge at high altitude.
MedLine Citation:
PMID:  19099326     Owner:  NLM     Status:  MEDLINE    
OBJECTIVE: Dizziness is a symptom of acute mountain sickness (AMS). This study tested whether immediate fall in systolic blood pressure (BP) on standing was more severe at altitude and whether this was associated with symptoms of dizziness. METHODS: Eighty-five lowlanders flew into La Paz, Bolivia (3650 m), and after 4 to 5 days of acclimatization ascended in 90 minutes to the Chacaltaya Laboratory (5200 m) by road. Blood pressure was measured on 5 occasions, 3 times at 5200 m and twice at sea level, before and after the expedition using a mercury sphygmomanometer. Both a supine and an erect (within 15 seconds of standing) BP measurement were recorded. Participants recorded whether they felt dizzy on standing. A mixed-effect model was used to test for a difference in the change in BP for time and altitude. RESULTS: The immediate fall in systolic BP observed on standing was significantly greater (P < .001) on all 3 altitude study days (18.2, 23.4, and 20.7 mm Hg) than at sea level (12.2 and 12.4 mm Hg). There was no significant difference in the change in diastolic BP or change in mean arterial BP between sea level and altitude. CONCLUSIONS: The immediate drop in systolic BP observed on standing was greater at altitude. However, mean arterial pressure was maintained, and we found no association between the degree of immediate fall in BP and dizziness or AMS.
Oliver T Mytton; Alistair Simpson; Alfred A R Thompson; Richard A Oram; Adam Darowski; Ly-Mee Yu; David J Collier; Andrew J Pollard
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Wilderness & environmental medicine     Volume:  19     ISSN:  1080-6032     ISO Abbreviation:  Wilderness Environ Med     Publication Date:  2008  
Date Detail:
Created Date:  2008-12-22     Completed Date:  2009-01-29     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  9505185     Medline TA:  Wilderness Environ Med     Country:  United States    
Other Details:
Languages:  eng     Pagination:  225-32     Citation Subset:  IM    
Oxford University Medical School, United Kingdom.
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MeSH Terms
Altitude Sickness
Dizziness / epidemiology*,  etiology*
Hypotension, Orthostatic / complications,  diagnosis*
Grant Support
//Wellcome Trust

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

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