Regional deposition of aerosolized pentamidine: Effects of body position and breathing pattern

Objective: To evaluate the effects of varying body position and breathing pattern on overall lung distribution of aerosolized pentamidine. Design: Nonrandomized control trial with four weekly inhalational treatments. Setting: The nuclear medicine department of a voluntary hospital. Patients: Sixteen men with the acquired immunodeficiency syndrome (AIDS) or positive serology for the human immunodeficiency virus (HIV). Thirteen patients (81%) completed the study. Interventions: Patients inhaled a solution of either saline and technetiurn-99m bound to diethylenetriamine penta-acetic acid or sterile water, pentamidine (60 mg), and technetium-99m bound to human serum albumin. On weekly visits, the patients inhaled the aerosol solution using four methods: sitting, supine, sitting with an abdominal binder, and sitting and breathing from residual volume with a shallow inspiration. Measurements and Main Results: Deposition scans, obtained after each aerosol inhalation, were superimposed on each patient's equilibrium xenon scan, and a frequency distribution histogram was constructed. An asymmetry index was determined from this histogram. The lower the asymmetry index, the more homogeneous the aerosol distribution. Only use of the supine position showed a significant decrease in the asymmetry index (mean, 0.34 ± 0.02 in the supine position, 0.48 ± 0.03 in the sitting position; P < 0.001). Aerosol distribution in the lungs was more uniform when administered to patients in the supine position. Patients receiving aerosolized pentamidine may benefit from inhalation in the supine position; these results should be verified by clinical study.