The short-term effects of intermittent positive pressure breathing treatments on ventilation in patients with neuromuscular disease.

BACKGROUND The effects of intermittent positive-pressure breathing (IPPB) and abdominal belt on regional lung ventilation in neuromuscular patients are unknown. We conducted a prospective physiologic short-term study in stable neuromuscular patients to determine the effects of IPBB, with and without abdominal belt, on regional lung ventilation. METHODS IPPB was performed as 30 consecutive deep breaths up to 30 cm H(2)O face-mask pressure each: 10 in supine position, 10 in left-lateral position, and 10 in right-lateral position. Each patient received IPPB sessions with and without an abdominal belt, in a random order, at one-day intervals. Patients were then followed-up to 3 hours after IPPB. Lung ventilation was measured via electrical-impedance tomography (tidal volume via electrical-impedance tomography [electrical-impedance V(T)], which is reported in arbitrary units) in 4 lung quadrants. Baseline V(T) and exhaled V(T) after each deep breath were also measured. The primary outcome was maintenance of regional ventilation after 3 hours. RESULTS Global electrical-impedance V(T) remained significantly higher than at baseline as long as 3 hours after the IPPB sessions. Global and regional electrical-impedance V(T) at the end of the 3-hour study period was significantly higher with the abdominal belt in place. Regional ventilation did not change significantly. With IPPB in the supine position, electrical-impedance V(T) was significantly greater in the anterior than the posterior lung regions (P < .001). With IPPB in supine position, median and interquartile range V(T) values increased from 0.25 L (0.20-0.30) to the exhaled V(T) of 1.50 L (1.08-1.96) (P < .001). There were no differences in regional ventilation. CONCLUSIONS In patients with neuromuscular disease, supine IPPB treatments, with or without abdominal belt, increased ventilation to anterior lungs regions, compared to the left-lateral and right-lateral positions. Global ventilation 3 hours after IPPB treatments remained higher than at baseline and was best preserved with the use of an abdominal belt.