Effects of almitrine on the regional distribution of ventilation and perfusion in chronic bronchitis.

A double-blind, placebo-controlled, crossover study of the effects on regional lung function of oral almitrine bismesylate at a dose of 3 mg X kg-1, was carried out in six patients with severe chronic airflow obstruction. Oxygen saturation (SaO2) was measured by ear-lobe oximetry and ventilation (VE) by inductance plethysmography. Radionuclide ventilation images of the lungs were obtained using krypton-81m by inhalation and perfusion images using both krypton-81m, by i.v. infusion, and technetium-99m human serum albumin macro-aggregates. The images of ventilation, blood flow and VA/Q ratios were analysed in several ways to see if distributional changes explained the improvement in oxygen saturation. SaO2 improved by 6% and VE was 19% greater after almitrine than after placebo. There was no significant change in the distribution of ventilation, perfusion or VA/Q between any of 10 horizontal slices through the left lung. The average position of ventilation distribution was shifted towards the top of the lung compared to placebo (p less than 0.05). No significant changes in distribution of perfusion were observed. We conclude that almitrine is not associated with any change in the inter-regional distribution of perfusion, but may have a slight effect on the distribution of ventilation.