THE USE OF TONOMETRY TO PREDICT MORTALITY IN PATIENTS UNDERGOING ABDOMINAL AORTIC-ANEURYSM REPAIR

Objective: To assess the reliability of intramucosal pH (pHi) of the s igmoid colon, IL-6 concentration and the APACHE II score in predicting outcome in patients undergoing elective abdominal aortic aneurysm rep air. Design: Prospective study. Methods: In 42 patients, measurements were made of the sigmoid pHi with the silicone tonometer and plasma IL -6 by enzyme linked immuno-sorbent assay (ELISA). The daily postoperat ive APACHE II scores were also calculated. In 29 patients a preoperati ve left ventricular ejection fraction was determined by gated radionuc lide angiography. Results: Four out of 42 patients who were studied di ed. The lowest perioperative pHi, the peak postoperative IL-6 concentr ation and APACHE II scores were significantly different in the survivo rs in comparison to the non-survivors. In the non-survivors, the fall in pHi preceded the time of patient's demise by at least 4 days. Signi ficant correlations were observed between changes in pHi, IL-6 and APA CHE II. Using receiver operating characteristic curves, pi-Ii was show n to be the most predictive of mortality compared to the other variabl es. The simplicity, speed and practicality of using the tonometer adds to its superiority over the latter measurements. No relationship was found between ventricular ejection fraction, pHi and outcome. Conclusi on: Although the number of patients is small, these results support pH i as a valuable predictor of outcome and also suggest a role for the g ut in initiating the IL-6 and physiological responses.