Format

Send to

Choose Destination
Respir Med. 2004 Jan;98(1):1-8.

The effect of learning on ventilatory responses to inspiratory threshold loading in COPD.

Author information

1
Department of Pulmonary Physiology, Sir Charles Gairdner Hospital, Nedlands, WA 6009, Australia.

Abstract

BACKGROUND:

Progressive threshold loading (PTL) is a common test of respiratory muscle endurance. Healthy naive subjects improve endurance with successive exposures to PTL by altering their breathing responses, thus necessitating a familiarization period before reproducible measures can be obtained. This study sought to determine whether a similar "learning effect" is evident in patients with COPD, and what the mechanism of any such effect may be.

METHODS:

Ten subjects with COPD (FEV1 34+/-13% predicted) underwent PTL on four occasions (>24 h apart). During PTL measurements were obtained of breathing pattern and maximum threshold pressure (Pthmax) achieved. Maximum inspiratory pressure (PImax) was measured on each occasion.

RESULTS:

Over the four tests PImax improved by 21+/-16% (SD) (P<0.05) and Pthmax by 32+/-21% (P<0.05) with a plateau in these measures achieved by test three. Pthmax/PImax was unchanged, being 61+/-11% at test one and 67+/-12% at test four. In contrast to healthy subjects, PTL was not associated with increased expiratory time or decreased end-expiratory lung volume.

CONCLUSIONS:

In contrast to PImax and Pthmax, which changed with successive tests, a single measure of the ratio Pthmax/PImax may present a useful guide to the endurance capacity of the respiratory muscles in patients with COPD.

PMID:
14959807
[Indexed for MEDLINE]
Free full text

Supplemental Content

Full text links

Icon for Elsevier Science
Loading ...
Support Center