Relationship between abdominal pressure and diaphragmatic movement in abdominal breathing

Abstract

Background: Abdominal breathing is a breathing method used to increase inspiratory tidal volumes, by using a quickly forced expiration with contraction of the abdominal muscles;it is an effective breathing method for increasing tidal volume in patients with COPD. It is hypothesized that forced expiration may increase abdominal pressure and improve diaphragmatic movement. However, very few studies have investigated changes in diaphragmatic movement,or abdominal and pleural pressures during these breathing maneuvers.

Objectives: To examine the change in intraabdominal and intrapleural pressures and associated diaphragmatic movement during abdominal and normal breathing;to clarify the mechanism of abdominal breathing in healthy volunteer subjects.

Methods: Eight males were instructed to perform rapid inspiration with and without quickly contracting their abdominal muscles. Gastric pressure (Pga) and esophageal pressure (Pes) during both breathing maneuvers were measured by nasal-gastric balloon catheter with pressure sensors. Transverse abdominal muscle thickness and respiratory muscle activity, measured as the distance of diaphragmatic movement (Ddi),were both measured by ultrasound imaging.

Results: The change in distance of diaphragmatic movement during abdominal breathing correlated significantly and positively with changes in Pga (r=0.69,P=0.028). Changes in Pga correlated significantly and negatively with Ddi (r=0.72,P=0.021). Further, a significant correlation between ⊿Pga and ⊿Pes was observed (r=0.60,P=0.03).

Conclusions: Abdominal breathing increases abdominal pressure,which can increase diaphragmatic movement and inspiratory negative pressure,to improve inspiratory tidal volume.