Pulmonary dysfunction in 'freebase' cocaine users.

Of 19 consecutive smokers of cocaine, "freebase" cocaine users, admitted to a chemical dependence program, 12 (63%) had respiratory symptoms and ten (58%) noted dyspnea. Abnormalities of carbon monoxide diffusing capacity were also seen in ten of the subjects, although responses to steady-state exercise testing were normal in subjects undergoing exercise. We believe that freebase cocaine use frequently produces pulmonary gas exchange abnormalities that appear after relatively brief periods of abuse. These abnormalities may persist after cessation of freebase cocaine use. A history of this form of drug abuse should be sought when evaluating patients with appropriate symptoms or abnormalities of diffusing capacity.