Control of Breathing in Patients with Chronic Pulmonary Obstructive Disease: Response to Bamiphylline

Abstract

In two groups (A and B) of patients with severe chronic obstructive pulmonary disease (COPD), matched for age and routine pulmonary function testing, we evaluated inspiratory muscle strength (MIP), breathing pattern, mouth occlusion pressure (P0.1), inspiratory neural drive, assessed in terms of electromyographic activity of both diaphragm (EMGd) and intercostal (EMGint) muscles, and P0.1/EMGd ratio, an index of inspiratory neuromuscular coupling. Group A (8 patients) was studied before and after a 7-day period of a new oral xanthine derivative (bamiphylline, 1.2 g daily), and group B (7 patients) was given a placebo. Under control conditions, compared with an age-matched normal control group, groups A and B both exhibited a decrease in MIP, more rapid (increase in respiratory frequency RF) and shallower (decrease in tidal volume; VT) breathing (RSB), a marked increase in both EMGd and EMGint and a lower P0.1/EMGd ratio. With bamiphylline FEV1 and PaO2 significantly increased, while a substantial increase in MIP was found in 5 out of the 8 patients. VT and inspiratory time (Ti) also significantly increased, and RF decreased. Both EMGd and EMGint significantly decreased, whereas P0.1/EMGd exhibited a substantial increase in 5 out of the 8 patients. Conversely, no significant changes were observed in group B during the study period. From these data we conclude that in patients with COPD, clinical manifestations, probably associated with inspiratory muscle overloading (decrease in muscle strength, RSB, increase in respiratory neural drive, and derangement in neuromuscular coupling) may benefit from a short-term treatment with bamiphylline.