Document Detail


Intrapulmonary and intracardiac shunting with exercise at altitude.
MedLine Citation:
PMID:  18715120     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
Recent studies in normal participants have shown that right to left shunt blood vessels in the lung open up during exercise. We describe the first field study to investigate this phenomenon at altitude. This study aimed to assess the effect of altitude and partial acclimatization on inducible right to left shunting at rest and with exercise. A contrast-enhanced transcranial Doppler imaging technique to detect microbubbles after injection of blood and saline agitated with air was used to measure right to left shunting in 10 normal participants at rest and immediately after exercising to maximum oxygen consumption (VO(2max)) at 80 m, on acute exposure to 3450 m, and finally after a week above 3450 m. At 80 m, exercising resulted in right to left shunting via patent foramen ovale in 2 participants, but there was no evidence of shunting in the remaining 8 participants. Cerebral microbubbles were detected at rest in the 2 participants with patent foramen ovale on acute exposure to 3450 m, and the shunting increased on exercise (P = .04). In 5 of the remaining 8 participants without patent foramen ovale, cerebral microbubbles were detected on exercise (P = .04) but not at rest. Partial acclimatization had minimal effect on the prevalence or magnitude of the intrapulmonary or intracardiac shunts. Oxygenation was similar in those with shunts compared with those without shunts. Intrapulmonary shunting occurs on exercise at altitude, but the clinical and physiologic significances have yet to be determined. Despite the occurrence of shunting in most participants, our results suggest that this phenomenon is not a significant factor in altitude and exercise-induced hypoxia.
Authors:
Chris H E Imray; Kyle T S Pattinson; Steve Myers; Colin W Chan; Helen Hoar; Steve Brearey; Phil Collins; Alex D Wright;
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:  2008-08-21     Completed Date:  2008-12-29     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  9505185     Medline TA:  Wilderness Environ Med     Country:  United States    
Other Details:
Languages:  eng     Pagination:  199-204     Citation Subset:  IM    
Affiliation:
Coventry and Warwickshire County Vascular Unit, and Warwick Medical School, UHCW NHS Trust, Coventry, UK. chrisimray@aol.com
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MeSH Terms
Descriptor/Qualifier:
Adult
Aged
Altitude*
Anoxia / etiology,  physiopathology*
Blood Flow Velocity
Cerebral Arteries / ultrasonography
Coronary Circulation
Exercise / physiology*
Female
Foramen Ovale, Patent / physiopathology*
Humans
Lung / blood supply*,  physiology
Male
Middle Aged
Oxygen Consumption / physiology
Pulmonary Circulation
Rest / physiology*
Ultrasonography, Doppler, Transcranial
Young Adult
Grant Support
ID/Acronym/Agency:
//Medical Research Council

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


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