EFFECT OF SPUTUM INDUCTION ON ARTERIAL OXYGEN-SATURATION AND SPIROMETRY IN HIV-INFECTED PATIENTS

We wanted to study the effect of sputum induction on forced expiratory volume in one second (FEV1) and on oxygen saturation in normal contro ls, asymptomatic human immunodeficiency virus (HIV)-seropositive indiv iduals, and HIV-seropositive patients under investigation for suspecte d Pneumocystis carinii pneumonia (PCP). Over a five month period, sput um induction with ultrasonically nebulized 3% saline was performed on 110 HIV-seropositive patients with suspected PCP, 10 asymptomatic HIV- seropositive patients, and 15 normal controls. Oxygen saturation (peak , trough and change in oxygen saturation (DELTAO2)) was measured throu ghout the procedure using pulse oximetry, and these results compared w ith the chest radiograph and the final pulmonary diagnosis. In additio n, the effect of sputum induction on FEV1 was measured in the 15 contr ol subjects and 10 asymptomatic HIV-seropositive patients. Compared wi th bronchoalveolar lavage, sputum induction had a diagnostic sensitivi ty for PCP of 76%. Chest radiography was 79% sensitive, and had specif icity of 83%. Patients with PCP had lower peak and trough oxygen satur ation values compared with the non-PCP group (mean peak 95 vs 97%; mea n trough 88 vs 91%), and greater falls in O2 saturation during the pro cedure (mean DELTAO2 7.6 vs 5.5%). One subject desaturated to 76%, req uiring supplemental oxygen. Sputum induction caused significant but te mporary falls in FEV1 both in control and HIV-seropositive groups (mea n maximum fall in FEV1 10.4 vs 12.5%) We conclude that although sputum induction causes significant falls in oxygen saturation and FEV1, it remains sensitive and safe, and provides a useful alternative to bronc hoscopy for the diagnosis of PCP.