Document Detail

Haemodynamic effects of proportional assist ventilation during high-intensity exercise in patients with chronic obstructive pulmonary disease.
MedLine Citation:
PMID:  20920126     Owner:  NLM     Status:  In-Process    
BACKGROUND AND OBJECTIVE: Proportional assist ventilation (PAV) has been proposed as a more physiological modality of non-invasive ventilation, thereby reducing the potential for deleterious cardio-circulatory effects during exercise, in patients with COPD. We therefore evaluated whether PAV modulates the kinetic and 'steady-state' haemodynamic responses to exercise in patients with moderate-to-severe COPD.
METHODS: Twenty patients underwent constant-load (75-80% peak work rate) cycle ergometer exercise testing to the limit of tolerance (T(lim)), while receiving PAV or breathing spontaneously. Stroke volume (SV), heart rate (HR) and cardiac output (CO) were monitored by impedance cardiography.
RESULTS: Compared with unassisted breathing, PAV increased T(lim) in 8/20 patients (median improvement 113% (range 8 to 212) vs -20% (range -40 to -9)). PAV had no significant effects on 'steady-state' haemodynamic responses either in patients with or those without increased T(lim) (P > 0.05). However, at the onset of exercise, SV kinetics were slowed with PAV, in 13/15 patients with analysable data. HR dynamics remained unaltered or failed to accelerate sufficiently in nine of these patients, thereby slowing CO kinetics (T(1/2) 61 s (range 81-30) vs 89 s (range 100-47)). These deleterious effects were not, however, associated with PAV-induced changes in T(lim) (P > 0.05).
CONCLUSIONS: PAV slowed the SV and CO kinetics at the onset of high-intensity exercise in selected patients with moderate-to-severe COPD. However, these adverse effects of PAV disappeared during the stable phase of exercise, and were not related to the ergogenic potential of PAV in this patient population.
Cláudia R Carrascossa; Cristino C Oliveira; Audrey Borghi-Silva; Eloara M V Ferreira; Joyce Maya; Fernando Queiroga; Danilo C Berton; Luiz E Nery; J Alberto Neder
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Respirology (Carlton, Vic.)     Volume:  15     ISSN:  1440-1843     ISO Abbreviation:  Respirology     Publication Date:  2010 Nov 
Date Detail:
Created Date:  2010-10-27     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  9616368     Medline TA:  Respirology     Country:  Australia    
Other Details:
Languages:  eng     Pagination:  1185-91     Citation Subset:  IM    
Copyright Information:
© 2010 The Authors; Respirology © 2010 Asian Pacific Society of Respirology.
Pulmonary Function and Clinical Exercise Physiology Unit, Division of Respiratory Diseases, Department of Medicine, Federal University of Sao Paulo (UNIFESP), São Paulo, Brazil.
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