Alteration of pulmonary function in intravenous drug abusers. Prevalence, severity, and characterization of gas exchange abnormalities.

We examined the influence of chronic intravenous drug abuse on respiratory function in 512 consecutive drug addicts by obtaining respiratory histories, pulmonary function tests and chest roentgenograms. Two hundred and fourteen (42 per cent) had carbon monoxide-diffusing capacities (DLCO) of less than 75 per cent predicted (mean 65.7 per cent), and in 38 per cent reduced DLCO was the sole pulmonary function test abnormality. Obstructive lung disease attributed to asthma or chronic bronchitis was observed in 6 per cent and a restrictive defect due to interstitial lung disease was observed in 7 per cent. Exercise limitation due to dyspnea among those patients with altered pulmonary function was uncommon except in those with obstructive or restrictive lung disease. Roentgenographic evidence of pulmonary hypertension was not observed in any of the patients. Gas exchange measured at rest and during exercise in 11 patients with a low DLCO and in three patients with restrictive lung disease and a low DLCO revealed an increased alveolar-arterial oxygen difference but normal minute ventilation, dead space-to-tidal volume ratio and absence of abnormal right-to-left shunts. We conclude that alterations in pulmonary function in drug addicts due to foreign particle emboli are very common but that significant respiratory symptoms are unusual and that abnormalities in gas exchange during exercise are mild.