Respiratory Muscle Performance in Normal Elderly Subjects and Patients with COPD: Methods


11 Oct 2014

In our laboratory, Martyn et al used a device similar to that of Nickerson and Keens but with the ability to add weights externally. Martyn et al started with low inspiratory loads which were increased at 2-min intervals so that subjects could develop strategies for managing progressively greater loads. This test was found to be relatively simple and reproducible in normal young subjects.
Many patients with diseases affecting respiratory muscle function are elderly. Therefore, in this study we determine normal values for elderly subjects for RM strength and the 2-min incremental loading test, and their reproducibility. In addition, we compare RM performance in the normal elderly with RM performance in patients who have COPD.
Volunteers who had no history of respiratory or cardiac disease and who had a normal physical examination, normal ECC and normal spirometry formed the study population of normal elderly subjects. Each gave informed consent. All eight subjects had never had tests of respiratory muscle function and had not had prior experience with the weighted plunger apparatus.

The COPD patients were recruited from the respiratory clinic at St. Pauls Hospital, Vancouver, Canada. The eight patients chosen had no previous experience with tests of RM performance. Results of studies on these patients previously have been published.
All subjects and patients had spirometry measured. The FEV, and FVC were measured and expressed as percent predicted (from Morris et al).
In each group, respiratory muscle strength and endurance were measured. The MIP and the MEP at the mouth were measured after maximal expiration, near RV, and after maximal inspiration, near TLC, respectively, according to the method of Black and Hyatt. The maximum pressure taken was the highest of several attempts sustained for a minimum of 1 s.
Maximal voluntary ventilation was measured through a one-way valve (Hans-Rudolph No. 1400). The inspired volume was measured by a turbine transducer (Alpha Technologies, 110-500, Laguna Hills, CA). Maximum ventilation over 15 s was measured and the highest volume for 12 s was used and expressed as liters per minute. Predicted values were taken from Kory et al for men and from Lindall et al for women.

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