Early-Phase Recovery of Cardiorespiratory Measurements after Maximal Cardiopulmonary Exercise Testing in Patients with Chronic Obstructive Pulmonary Disease.

Background . This study investigated respiratory gas exchanges and heart rate (HR) kinetics during early-phase recovery after a maximal cardiopulmonary exercise test (CPET) in patients with chronic obstructive pulmonary disease (COPD) grouped according to airflow limitation. Methods . Thirty control individuals (control group: CG) and 81 COPD patients (45 with "mild" or "moderate" airflow limitation, COPDI-II , versus 36 with "severe" or "very severe" COPD, COPDIII-IV ) performed a maximal CPET. The first 3 min of recovery kinetics was investigated for oxygen uptake ([Formula: see text]O2 ), minute ventilation ([Formula: see text]), respiratory equivalence, and HR. The time for [Formula: see text]O2 to reach 25% (T1/4 [Formula: see text]O2 ) of peak value was also determined and compared. Results . The [Formula: see text]O2 , [Formula: see text], and HR recovery kinetics were significantly slower in both COPD groups than CG ( p < 0.05). Moreover, COPDIII-IV group had significantly higher [Formula: see text]O2 and [Formula: see text] during recovery than COPDI-II group ( p < 0.05). T1/4 [Formula: see text]O2 significantly differed between groups ( p < 0.01; 58 ± 18 s in CG, 79 ± 26 s in COPDI-II group, and 121 ± 34 s in COPDIII-IV ) and was significantly correlated with forced expiratory volume in one second in COPD patients ( p < 0.001, r = 0.53) and with peak power output ( p < 0.001, r = 0.59). Conclusion . The COPD groups showed slower kinetics in the early recovery period than CG, and the kinetics varied with severity of airflow obstruction.