Pulmonary rehabilitation for COPD improves exercise time rather than exercise tolerance: effects and mechanisms.

BACKGROUND: COPD patients undergoing pulmonary rehabilitation (PR) show various responses. The purpose of this study was to investigate the possible mechanisms and predictors of the response to PR in COPD patients. METHODS: Thirty-six stable COPD patients underwent PR including a 4-week high-intensity exercise training program, and they were evaluated by cardiopulmonary exercise testing. All patients (mean age 69 years, severe and very severe COPD 94%) were classified into four groups by whether the exercise time (Tex) or the peak oxygen uptake [Formula: see text] increased after PR: two factors increased (both the Tex and the peak [Formula: see text] increased); two factors decreased; time only increased (the Tex increased, but the peak [Formula: see text] economized); and [Formula: see text] only increased (the Tex decreased, but the peak [Formula: see text] increased). Within all patients, the relationships between baseline variables and the post-to-pre-change ratio of the time-slope, Tex/(peak minus resting [Formula: see text]), were investigated. RESULTS: Compared with the two factors increased group (n=11), in the time only increased group (n=18), the mean differences from pre-PR at peak exercise in 1) minute ventilation [Formula: see text] (P=0.004), [Formula: see text] (P<0.0001), and carbon dioxide output [Formula: see text] (P<0.0001) were lower, 2) [Formula: see text]/ [Formula: see text] (P=0.034) and [Formula: see text]/ [Formula: see text] (P=0.006) were higher, and 3) the dead space/tidal volume ratio (VD/VT) and the dyspnea level were similar. After PR, there was no significant difference in the ratio of the observed peak heart rate (HR) to the predicted peak HR (220 - age [years]) between the two groups. A significant negative correlation with the baseline time-slope (r=-0.496, P=0.002) and a positive correlation with the baseline body mass index (BMI) (r=0.496, P=0.002) were obtained. CONCLUSIONS: PR in COPD patients improves Tex rather than exercise tolerance, economizing oxygen requirements, resulting in reduced ventilatory requirements without cardiac loads followed by reduced exertional dyspnea. In addition, the time-slope and BMI could be used to predict PR responses beforehand.

Personalized pulmonary rehabilitation and occupational therapy based on cardiopulmonary exercise testing for patients with advanced chronic obstructive pulmonary disease.

TAKE-HOME SUMMARY: Personalized pulmonary rehabilitation including occupational therapy improves the prognosis of patients with advanced COPD. PURPOSE: We previously reported that patients with chronic obstructive pulmonary disease (COPD) exhibit three exercise-induced life-threatening conditions: hypoxemia, sympathetic overactivity, and respiratory acidosis. We aimed to verify whether mortality in patients with advanced COPD could be reduced by a personalized pulmonary rehabilitation (PPR) program in hospital, which determines individual safe ranges and includes occupational therapy (PPR-OT), to prevent desaturation and sympathetic nerve activation during daily activities. PATIENTS AND METHODS: The novel PPR-OT program was evaluated in a retrospective study of patients with COPD (Global Initiative for Chronic Obstructive Lung Disease [GOLD] Grade D) who underwent cardiopulmonary exercise testing (CPET) between April 1990 and December 1999. They received regular treatment without the proposed therapy (control group: n=61; male-to-female ratio [M:F] =57:4; mean age: 68.5±6.7 years) or with the proposed therapy (PPR-OT group: n=46; M:F =44:2; mean age: 68.7±7.1 years). A prospective observational study included patients with COPD receiving home oxygen therapy (HOT) between April 1995 and March 2007 to compare the survival rates of the control group (n=47; M:F ratio =34:13; mean age: 71.3±10.0 years) and the PPR-OT group (n=85; M:F =78:7; mean age: 70.7±6.1 years) who completed the proposed therapy. Survival after CPET or HOT was analyzed using Cox proportional-hazards regression and Kaplan-Meier analyses. RESULTS: In both studies, the program significantly improved all-cause mortality (retrospective study: risk ratio =0.389 [range: 0.172-0.800]; P=0.0094; log-rank test, P=0.0094; observational study: risk ratio =0.515 [range: 0.296-0.933]; P=0.0291; log-rank test, P=0.0232]. At 5 years and 7 years, all-cause mortality was extremely low in patients in the PPR-OT group receiving HOT (18.8% and 28.2%, respectively), compared to that in the control group (34.0% and 44.7%, respectively). Survival of patients with life-threatening pathophysiological conditions also greatly improved. CONCLUSION: The PPR-OT program improved the survival of patients with advanced COPD probably because it modified life-threatening conditions.