ZuWallack R, Hashim A, McCusker C, Normandin E, Benoit-Connors ML, Lahiri B

Chron Respir Dis. 2006;3(1):11-18.

The Section of Pulmonary and Critical Care Medicine, St Francis Hospital and Medical Center, Hartford, CT 06105. [email protected]

Although pulmonary rehabilitation has proven effectiveness in multiple outcome areas, the optimum duration of this intervention is not clear. We evaluated in an observational study the trajectory of change in upper and lower extremity exercise performance, exertional dyspnea and health status over the course of 12 weeks (24 sessions) of pulmonary rehabilitation in individuals with chronic obstructive pulmonary disease. Demonstrating a plateau in response in these areas might be of practical use for pulmonary rehabilitation programs. We measured outcomes at baseline and at four-session (two week) intervals over the course of our comprehensive outpatient pulmonary rehabilitation program. These included treadmill endurance time at approximately 85% of initial maximal work rate, the number of arm lifts per minute, dyspnea at isotime during treadmill walking and the Chronic Respiratory Disease Questionnaire (CRQ) total score. Thirteen patients with chronic obstructive pulmonary disease (COPD) (five male, eight female) were studied; their age was 66 +/- 8 years and their FEV1 was 34 +/- 11% of predicted. Improvement was noted in all four outcome areas very early in the course of pulmonary rehabilitation. Treadmill endurance time and arm lifts increased significantly over baseline by the fourth and eighth session, respectively, and both increased in a near-linear fashion throughout pulmonary rehabilitation. Exertional dyspnea and CRQ also improved very early, with each showing a significant change from baseline by the fourth session. Their improvement, however, appeared to plateau relatively early during the course of pulmonary rehabilitation. Although the numbers studied are small and the applicability of these results to other programs is undetermined, this study does suggest that 20 or more sessions are needed for optimal acute changes in exercise performance, but improvement in dyspnea and quality of life may occur earlier.

PMID: 16509173 [PubMed-in process]

Commentary:

In this study, the optimum duration of PR was addressed from another point of view. Specifically, the investigators analyzed the trajectory of change (at 2-week intervals) in outcomes indices of exercise tolerance, dyspnea, and health status among COPD patients undergoing PR, to determine the time frame within which most of the benefits occurred in their 12-week outpatient PR program. Interestingly, in this study, the noted improvements in treadmill walking and arm lifts were evident after the first several training sessions but continued to increase progressively over the full 12 courses of PR. In contrast, a plateau was reached in gains in health status and dyspnea earlier in the course of PR. The findings of continued improvement in exercise tolerance over 12 weeks in this study contrast somewhat with the findings of the study noted above by Sewell and colleagues (see Abstract 1 above), wherein comparable gains in exercise tolerance were reached after 4 versus 7 weeks of training in PR. The differences noted with regard to timing and trajectory of gains in exercise tolerance between these studies may reflect differing patient populations and study group size, differences in training regimens, use of different outcomes measures of exercise tolerance, and differing healthcare systems in which the PR was conducted. Further studies of larger cohorts of patients undergoing PR are needed to clarify this issue further.

CR