Objective: To analyse the recovery of oxygen consumption (VO2), ventilation (VE) and carbon dioxide production (VCO2) after maximal cardiopulmonary exercise testing, and to assess the possibility of recovery parameters becoming new markers of functional impairment.
Methods: Thirty-eight patients (30 males, mean age 56 +/- 11 years) with dilated cardiomyopathy performed maximal, symptom limited, treadmill exercise test with breath-by-breath respiratory gas analysis. The patients were divided in two groups, according to maximal oxygen consumption above or below 14 ml/kg/min (group I and group II, respectively). During the recovery, we analyzed the time to reach 50% of the maximal values of VO2 (T1/2 r VO2), VE (T1/2 e VE) and VCO2 (T1/2 r VCO2) in each group.
Results: Twenty-seven patients had a VO2max above 14 ml/kg/min (group I) and 11 had a VO2max below 14 ml/kg/min (group II). The results were as follows: T1/2 r VO2max 109 +/- 21 sec in group I versus 177 +/- 79 sec in group II (p = 0.0001). T1/2 r VCO2max 124 +/- 28 sec in group I versus 201 +/- 88 sec in group II (p = 0.0001) and T1/2 rVEmax 146 +/- 47 sec in group I versus 229 +/- 47 sec in group II (p = 0.0002).
Conclusions: Patients with a poor functional capacity show a delay in the half recovery times of oxygen consumption, ventilation and carbon dioxide production. These data suggest that these parameters may be used as new markers of the level of functional impairment.