Persistent reduction in lung function after Pneumocystis carinii pneumonia in AIDS patients.

By means of serial lung function tests we examined the changes in lung function and possible pulmonary long-term sequelae in AIDS patients with a primary episode of Pneumocystis carinii pneumonia (PCP). A total of 19 patients had lung function tests performed prospectively from the time of PCP diagnosis, at 7 days, 14 days, 1, 2, 3, 4.5, 6 and 9 months after PCP. Forced vital capacity (FVC) and forced expiratory volume in 1 second (FEV1) were both reduced to a median of 61% of predicted at PCP diagnosis, and were normalized within 1 month and 1 week respectively. The median pulmonary diffusing capacity for carbon monoxide (DLCO) was severely reduced to 43% of predicted during the acute infection. Although DLCO improved significantly during the first 2 months, it remained reduced at a median DLCO of 64% of predicted 9 months after PCP. We conclude that despite a general improvement in lung function during the first 2 months following the PCP diagnosis, ther was a persistent reduction in DLCO up to 9 months following PCP. The pathological mechanisms causing this reduction remain to be established.