The lung in HIV infection: can pulmonary function testing help?

Simple lung function tests have been used to evaluate respiratory symptoms in human immunodeficiency virus (HIV) infected individuals. Abnormalities of simple lung function tests, in particular decreases in the transfer factor of the lung for carbon monoxide (TL,CO) have been described in patients with acquired immune deficiency syndrome (AIDS) who have respiratory disease. Early studies showed marked reductions in TL,CO in patients with pneumocystis pneumonia but other forms of pulmonary infection or neoplasm also resulted in reductions in TL,CO values. Lung function studies in larger numbers of patients have shown reductions in all lung function measurements, particularly in TL,CO. in all categories of HIV disease. The most marked reductions in TL,CO are seen in patients with pneumocystis pneumonia but reductions also occur in pulmonary bacterial infection, tuberculosis and pulmonary Kaposi's sarcoma. TL,CO values improved following recovery from pneumocystis pneumonia but rarely returned to normal. Zidovudine therapy does not contribute to the abnormalities of lung function but smokers generally have worse lung function tests in all categories of HIV disease. The diagnostic usefulness of simple lung function tests is limited. A reduced TL,CO is a highly sensitive index for the presence of pneumonitis (pneumocystis or otherwise) in HIV-infected individuals but lacks the necessary specificity to be a satisfactory diagnostic tool. Simple lung function tests have limitations but have a value as a simple screening test to determine the presence of underlying organic disease in HIV seropositive patients with respiratory symptoms. The presence of a normal TL,CO value makes the presence of pneumonitis unlikely.