Focal air trapping in patients with HIV infection: CT evaluation and correlation with pulmonary function test results

OBJECTIVE. HIV-positive individuals commonly have symptoms of airway diseas e. We evaluated thin-section CT scans of HIV-infected individuals during in spiration and expiration for evidence of focal air trapping. We also correl ated imaging findings with pulmonary function test results. SUBJECTS AND METHODS. Fifty-nine subjects, 48 of whom were HIV-positive and 11 of whom were HIV-negative, underwent thin-section CT of the thorax duri ng inspiration and expiration. All subjects also undervent pulmonary functi on tests. Two radiologists, who were unaware of the subjects' HIV status an d smoking history and of the results of pulmonary function tests, evaluated the CT scans for the presence and severity of focal air trapping. RESULTS. Expiratory CT revealed focal air trapping in 33 subjects: 30 were HIV-positive and three were HIV-negative (p = .0338). The mean values of fo rced expiratory volume in 1 sec (FEV1), forced mid expiratory flow, and dif fusion capacity (DLCO) were significantly lower for subjects with focal air trapping (mean = 88.85, 84.52, and 80.80, respectively) than for those wit h normal findings on CT (mean = 100.84, 99.24, and 95.82, respectively; p = .001, p = .021, and p = .003, respectively). We found no significant diffe rences in smoking history between HIV-positive and HIV-negative subjects. S evere air trapping on expiratory CT scans was seen in three subjects: All t hree had HIV infection, low CD4 counts, and abnormally decreased FEV1 and D LCO values. CONCLUSION. Focal air trapping was a common finding on thoracic CT scans ob tained during expiration in HIV-positive subjects. Tn addition, focal air t rapping was associated with significantly lower FEV1, forced mid expiratory flow, and DLCO values than those found for subjects in whom CT revealed no focal air trapping. These results suggest that small airways disease may a ccompany a decline in pulmonary function in HIV-positive individuals.