Ethane in the exhalate of subjects with pneumonia

Exhaled ethane results from free radical peroxidation of lipids. The amount of exhaled ethane may depend on local factors in the lung. To test this hypothesis, exhaled ethane production was measured in a group of patients with bacterial pneumonia. Seventeen patients hospitalized with pneumonia were studied when they presented with their disease and then post recovery, 2-11 weeks later. For the ethane measurements, subjects breathed ethane-free air for 10 minutes. The last two minutes of exhalate was collected in mylar bags. Ethane was concentrated on cold charcoal and then quantified by gas chromatography against a known standard. There was no difference between acute and convalescent ethane values (Wilcoxon signed rank test: median of acute group =2.36 pmoles/min/kg, median of convalescent group = 2.64 pmoles/min/kg, P=.0739). No significant correlation between ethane levels and WBC counts (r=.376, p=0.137) during the acute illness was evident. Eliminating current smokers did not alter these results. Interestingly, ethane levels in 12/17 subjects increased after recovery from the acute illness including all 4 of the current smokers. These results indicate that acute inflamation in the lung does not alter exhaled ethane levels.