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Contrasting pressure-support ventilation and helium-oxygen during exercise in severe COPD.
MedLine Citation:
PMID:  20851591     Owner:  NLM     Status:  In-Data-Review    
Abstract/OtherAbstract:
Helium-oxygen mixtures and pressure-support ventilation have been used to unload the respiratory muscles and increase exercise tolerance in COPD. Considering the different characteristics of these techniques, we hypothesized that helium-oxygen would be more effective in reducing exercise-induced dynamic hyperinflation than pressure-support. We also hypothesized that patients would experience greater increases in respiratory rate and minute ventilation with helium-oxygen than with pressure-support. The hypotheses were tested in ten patients with severe COPD (FEV(1) = 28 ± 3% predicted [mean ± SE]) during constant-load cycling (80% maximal workrate) while breathing 30% oxygen-alone, helium-oxygen, and pressure-support in randomized order. As hypothesized, helium-oxygen had greater impact on dynamic hyperinflation than did pressure-support (end-exercise; p = 0.03). For the most part of exercise, respiratory rate and minute ventilation were greater with helium-oxygen than with pressure-support (p ≤ 0.008). During the initial phases of exercise, helium-oxygen caused less rib-cage muscle recruitment than did pressure-support (p < 0.03), and after the start of exercise it caused greater reduction in inspiratory reserve volume (p ≤ 0.02). Despite these different responses, helium-oxygen and pressure-support caused similar increases in exercise duration (oxygen-alone: 6.9 ± 0.8 min; helium-oxygen: 10.7 ± 1.4 min; pressure-support: 11.2 ± 1.6 min; p = 0.003) and similar decreases in inspiratory effort (esophageal pressure-time product), respiratory drive, pulmonary resistance, dyspnea and leg effort (p < 0.03). In conclusion, helium-oxygen reduced exercise-induced dynamic hyperinflation by improving the relationship between hyperinflation and minute ventilation. In contrast, pressure-support reduced hyperinflation solely as a result of lowering ventilation. Helium-oxygen was more effective in reducing exercise-induced dynamic hyperinflation in severe COPD, and was associated with greater increases in respiratory rate and minute ventilation than pressure-support.
Authors:
Omar Hussain; Eileen G Collins; Nalan Adiguzel; W Edwin Langbein; Martin J Tobin; Franco Laghi
Publication Detail:
Type:  Journal Article     Date:  2010-09-18
Journal Detail:
Title:  Respiratory medicine     Volume:  105     ISSN:  1532-3064     ISO Abbreviation:  Respir Med     Publication Date:  2011 Mar 
Date Detail:
Created Date:  2011-01-25     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  8908438     Medline TA:  Respir Med     Country:  England    
Other Details:
Languages:  eng     Pagination:  494-505     Citation Subset:  IM    
Copyright Information:
Copyright © 2010 Elsevier Ltd. All rights reserved.
Affiliation:
Edward Hines, Jr. Veterans Affairs Hospital, 111N, 5th Avenue and Roosevelt Road, Hines, IL 60141, USA; Loyola University, Maywood, IL, USA.
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