Document Detail

Pattern of breathing during exercise in patients with interstitial lung disease.
MedLine Citation:
PMID:  6648857     Owner:  NLM     Status:  MEDLINE    
The responses to exercise were studied in 41 patients with pulmonary fibrosis, in whom vital capacity (VC) was reduced to 62% of predicted normal values. Maximum power output (POmax) was 53% predicted; there was a significant relationship between POmax and VC (r = 0.564). The maximum ventilation achieved during exercise was also related to VC (r = 0.614). Although arterial oxygen saturation (SaO2) fell by more than 5% in 13 of 31 patients, there was no relationship between either SaO2 at POmax or the exercise related fall in SaO2 and POmax. Heart rate responses were higher than normal predicted values in seven patients, all of whom showed a low POmax (36% predicted); this finding was due only in part to a fall in SaO2. The ventilatory response to exercise was within normal limits for the patients as a whole; those subjects with the lowest POmax showed relatively higher ventilatory responses to exercise but the difference was not significant. The pattern and timing of breathing was studied in 32 patients and compared with control subjects matched by sex, age, and size. Tidal volume (VT) was low in the patients; maximum VT was related to VC (r = 0.761), but at low values of VC VTmax was higher than in healthy subjects with comparable VC. The total breathing cycle time (Ttot) fell with progressive exercise in patients and controls; Ttot for a given ventilation was shorter in the patients. Inspiratory time (Ti) was shorter in patients than controls, as was Ti/Ttot. In most patients with diffuse pulmonary fibrosis exercise is limited by a reduced ventilatory capacity, despite the adoption of a short Ti and high inspiratory flow rate, both of which serve to optimise tidal volume and breathing frequency and presumably reduce both the force developed by inspiratory muscles and the sensation of breathlessness.
J G Burdon; K J Killian; N L Jones
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Thorax     Volume:  38     ISSN:  0040-6376     ISO Abbreviation:  Thorax     Publication Date:  1983 Oct 
Date Detail:
Created Date:  1984-01-27     Completed Date:  1984-01-27     Revised Date:  2009-11-18    
Medline Journal Info:
Nlm Unique ID:  0417353     Medline TA:  Thorax     Country:  ENGLAND    
Other Details:
Languages:  eng     Pagination:  778-84     Citation Subset:  IM; S    
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MeSH Terms
Exercise Test
Middle Aged
Oxygen / blood
Physical Exertion*
Pulmonary Fibrosis / blood,  physiopathology*
Tidal Volume
Time Factors
Vital Capacity
Reg. No./Substance:

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