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.