Abdominal pressure transmission in humans during slow breathing maneuvers

H. LORING. Abdominal pressure transmission in humans during slow breathing maneuvers. J. Appl. Physiol. 68(5): 1850-1853, 1990.-Pressure transmission within the abdomen was studied in four subjects standing and supine, breathing slowly and performing slow breathing maneuvers. Pressures were meas-ured in the stomach and rectum with air-containing balloon-catheter systems Pga(air) and Prec and in the stomach with a water-filled catheter system Pga(liq). Changes in Pga(air), Pga(liq), and Prec were nearly in phase and linearly related. The changes in Pga(liq) and Prec were nearly equal in all maneuvers, whereas the changes in Pga(air) were systemati-cally greater than those of Pga(liq) and Prec during quiet breathing and relaxation maneuvers in the upright position. During expulsive maneuvers in either posture the abdominal shape and stomach position were relatively constant, and th