Does Inhalation of Pentamidine in the Supine Position Increase Deposition in the Upper Part of the Lung?

To assess the effect of posture on the distribution of nebulized pentamidine isethionate deposition in the lung, ten patients with AIDS were studied. Two nebulizer systems, System 22 Mizer (MedicAid) and Respirgard II (Marquest) were modified by adding 40 cm of corrugated tubing (volume 150 ml) to allow the patients to be studied in both the sitting and supine posture. Modification of the nebulizers caused a reduction in lung deposition in the sitting position for the System 22 Mizer but increased deposition in the Respirgard II compared with the unmodified apparatus. The ratio of upper to lower zone deposition (corrected for 133Xe distribution) was increased in the supine position for both devices (p