Bedside measurement of intra-abdominal pressure (IAP) via an indwelling naso-gastric tube: clinical validation of the technique.

OBJECTIVES

To compare measurements of intraabdominal pressure (IAP) via a naso-gastric tube with the previously validated technique of IAP measurement via a urinary bladder catheter. To examine an association between elevated IAP and oliguric acute renal failure.

DESIGN

Simultaneous paired measurements of gastric and urinary bladder pressures in supine patients.

SETTING

The general intensive care units of two London hospitals.

PATIENTS

141 Paired measurements of intragastric and urinary bladder pressures were obtained in 26 general intensive care patients.

MEASUREMENTS AND RESULTS

With the patient lying supine, 50 ml of sterile water were instilled via manometer tubing into the stomach and bladder following drainage of each viscera. The mid-axillary line was used as the zero reference, and cavity pressures noted in centimeters of water (cmH2O) at end expiration. The results were compared using the technique of Bland and Altman.

RESULTS

Gastric pressure may be approximately 2.5 cmH2O above or below urinary bladder pressure. Manometric measurement of the gastric pressure via a naso-gastric tube provides a simple, reliable, non-invasive technique of IAP measurement. IAP should be regularly monitored in patients with abdominal distension at risk of acute renal failure.