Increases in intra-abdominal pressure affect pulmonary compliance
F. Obeid, A. Saba, J. Fath, B. Guslits, R. Chung, V. Sorensen, J. Buck and M. Horst
Department of Surgery, Henry Ford Hospital, Detroit, Mich, USA.
OBJECTIVES: To determine the effect of increased intra-abdominal pressure
(IAP) on pulmonary compliance and to determine an effective means to
measure IAP. DESIGN: A prospective study. SETTING: An urban tertiary care
hospital. PATIENTS: Twenty-six adult patients undergoing laparoscopic
cholecystectomy. INTERVENTIONS: Intra-operative management of laparoscopic
cholecystectomy requiring endotracheal intubation with general anesthesia,
nasogastric and urinary bladder catheters, and position changes. Additional
interventions included use of a rectal manometer and a respiratory pressure
module inserted within the ventilator circuit. MAIN OUTCOME MEASURES:
Correlation of changes in IAP with changes in dynamic pulmonary compliance,
measured as tidal volume/(end inspiratory pressure--end expiratory
pressure) and comparison of three different measurement techniques
(bladder, rectal, and gastric) with a standard technique (insufflation
pressure) in three different positions (supine, Trendelenburg's, and
reverse Trendelenburg's). RESULTS: Compliance was significantly related to
insufflation pressure (P < .001) by analysis of variance. In the gas
insufflation model, the mean increment in bladder pressure reflected most
closely the IAP increment in the supine position (5.7 vs 6 mm Hg) but not
in the Trendelenburg (2.1 vs 6 mm Hg) and reverse Trendelenburg positions
(3.4 vs 6 mm Hg). Rectal and gastric pressures were also position dependent
and technically less reliable. CONCLUSIONS: Increased IAP has a major
influence on pulmonary compliance (50% decrease at 16 mm Hg). Measurements
of IAP by intraorgan manometry are position dependent and may not
accurately reflect the intraperitoneal pressure.
