Lactate Kinetics in Severe COPD: Implications of an Abnormal Aminopyrine Breath Test

The ability of the 13C aminopyrine breath test (APBT) to reflect hepatocellular metabolic capacity and therefore to predict lactate removal following incremental exercise in male COPD patients was evaluated. Two previous patients with COPD who had histories of heavy alcohol intake but no overt liver disease showed prolonged lactate elevation following exercise. The possibility of subclinical hepatic disease affecting lactate removal was considered. No patient in the present study had clinical evidence of liver disease. Four of 9 patients had an abnormal APBT (mean 5.0% cumulative dose 13CO 2 excreted over 2 h). Patients with a normal APBT (group 1) and with an abnormal APBT (group 2) were compared. The groups did not differ in age or severity of lung disease. An incremental exercise test was performed and lactate samples were collected before, during, and for 90 min following exercise. Exercise parameters (work rate, duration, VO 2 max, VEmax, and peak lactate) did not differ between groups. Comparing group 1 with group 2 mean values, the time to recover to resting lactate values (Trecov 45 vs 76 min, respectively, p 2 was inversely correlated with both Trecov (r = −0.76, p