Determinants of Outcome for Patients in the Medical Intensive Care Unit Requiring Abdominal Surgery

A Prospective, Single-Center Study

¹ From the Department of Internal Medicine, Pulmonary and Critical Care Division, Washington University School of Medicine, St. Louis
² From the Department of Surgery, Pulmonary and Critical Care Division, Washington University School of Medicine, St. Louis

Objective: To identify objective factors, available at the time of surgical evaluation, associated with outcome for patients in the medical ICU undergoing abdominal surgery.

Design: Single-center, prospective observational study.

Setting: An academic tertiary care center.

Patients: The study included 1,617 consecutive patients in the medical ICU.

Intervention: Prospective patient surveillance and data collection.

Measurements: Patient demographics, severity of illness, organ system derangements, abdominal processes requiring surgery, and hospital mortality.

Results: Sixty-seven patients in the medical ICU (4.1 percent) developed an acute abdominal process potentially amenable to surgical intervention. Eleven of these patients (16.4 percent) elected not to undergo surgery (mortality=100 percent). Forty-two of the 56 patients who underwent surgery survived (75.0 percent). Stepwise logistic regression analysis identified two independent objective predictors of mortality for this patient cohort (p<0.05): an organ system failure index (OSFI) >2 (adjusted odds ratio [AOR]=19.5; 95 percent confidence interval [CI], 7.4 to 51.5; p<0.001); and an APACHE II score >18 (AOR=9.4; CI=3.1 to 28.3; p=0.03). The observed mortality following surgery was stratified according to the presence or absence of these two factors: neither present, 5.1 percent; APACHE II>18 present alone, 33 percent; OSFI >2 present alone, 60 percent; and both present, 88.9 percent (p<0.001). Surgical non-survivors and patients electing not to undergo surgery were similar without significant differences for demographics, severity of illness, or organ system derangements at the time of surgical evaluation.

Conclusions: The number of organ system derangements and the severity of illness, as assessed by APACHE II, appear to be useful discriminators of outcome for patients in the medical ICU undergoing abdominal surgery. These data suggest potential outcome predictors for this selected group of patients in the ICU.

Key Words: abdominal surgery • APACHE • critical care • organ system failures • outcomes

Submitted on November 29, 1993
Accepted on March 1, 1994