Document Detail

Hypoxia suppresses symptom perception in asthma.
MedLine Citation:
PMID:  15020291     Owner:  NLM     Status:  MEDLINE    
Any factor that inhibits the ability of an individual with asthma to recognize their symptoms appropriately may contribute to treatment delay, "near miss" events, and death during acute severe asthma. The purpose of this study was to investigate the effects of two common features of acute severe asthma--hypoxia and hypercapnia--on respiratory sensation. Sixteen individuals with stable asthma were exposed to three gas conditions (34 minutes each): isocapnic hypoxia (arterial blood O2 saturation of approximately 80%), hypercapnia (increase in end-tidal CO2 of approximately 5-10 Torr), or isocapnic normoxia on 3 separate days. The perceived magnitude of externally applied resistive loads, measured during each gas condition, was reduced throughout hypoxia compared with normoxia, and there was a trend for a progressive decline during hypercapnia. Within the 15-minutes postgas inhalation period, methacholine-induced symptoms of difficult breathing, chest tightness, and breathlessness, measured using modified Borg scales, were 25-30% lower after hypoxia compared with normoxia but were not reduced after hypercapnia. We conclude that 30 minutes of sustained hypoxia and possibly hypercapnia impair sensations of respiratory load and that the effects of hypoxia persist for at least 10 minutes after returning to normoxia.
Danny J Eckert; Peter G Catcheside; Janet H Smith; Peter A Frith; R Doug McEvoy
Publication Detail:
Type:  Comparative Study; Journal Article; Research Support, Non-U.S. Gov't     Date:  2004-03-12
Journal Detail:
Title:  American journal of respiratory and critical care medicine     Volume:  169     ISSN:  1073-449X     ISO Abbreviation:  Am. J. Respir. Crit. Care Med.     Publication Date:  2004 Jun 
Date Detail:
Created Date:  2004-05-26     Completed Date:  2004-08-12     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  9421642     Medline TA:  Am J Respir Crit Care Med     Country:  United States    
Other Details:
Languages:  eng     Pagination:  1224-30     Citation Subset:  AIM; IM    
Adelaide Institute for Sleep Health and Department of Respiratory Medicine, Repatriation General Hospital, Daw Park, South Australia, Australia.
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MeSH Terms
Anoxia / blood,  physiopathology*
Asthma / blood,  physiopathology*
Biological Markers / blood
Blood Gas Analysis
Bronchial Provocation Tests
Bronchoconstriction / physiology
Carbon Dioxide / blood
Forced Expiratory Volume / physiology
Hypercapnia / physiopathology
Inhalation / physiology
Inspiratory Capacity / physiology
Oxygen / blood
Perception / physiology*
Respiration, Artificial
Reg. No./Substance:
0/Biological Markers; 124-38-9/Carbon Dioxide; 7782-44-7/Oxygen

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

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