Preoperative risk stratification of critically ill patients

Abstract

Study objective: Risk assessment historically emphasized cardiac morbidity and mortality in elective, outpatient, non-cardiac surgery. However, critically ill patients increasingly present for therapeutic interventions. Our study investigated the relationship of American Society of Anesthesiologists (ASA) class, revised cardiac risk index (RCRI), and sequential organ failure assessment (SOFA) score with survival to discharge in critically ill patients with respiratory failure.

Design: Retrospective cohort analysis over a 21-month period.

Setting: Five adult intensive care units (ICUs) at a single tertiary medical center.

Patients: Three hundred fifty ICU patients in respiratory failure, who underwent 501 procedures with general anesthesia.

Measurements: Demographic, clinical, and surgical variables were collected from the pre-anesthesia evaluation forms and preoperative ICU charts. The primary outcome was survival to discharge.

Main results: Ninety-six patients (27%) did not survive to discharge. There were significant differences between survivors and non-survivors for ASA (3.7 vs. 3.9, p=0.001), RCRI (1.6 vs. 2.0, p=0.003), and SOFA score (8.1 vs. 11.2, p<0.001). Based on the area under the receiver operating characteristic curve for these relationships, there was only modest discrimination between the groups, ranging from the most useful SOFA (0.68) to less useful RCRI (0.60) and ASA (0.59).

Conclusions: This single center retrospective study quantified a high perioperative risk for critically ill patients with advanced airways: one in four did not survive to discharge. Preoperative ASA score, RCRI, and SOFA score only partially delineated survivors and non-survivors. Given the existing limitations, future research may identify assessment tools more relevant to discriminating survival outcomes for critically ill patients in the perioperative environment.

Keywords: Critical care outcomes; Organ dysfunction scores; Postoperative complications; Risk assessment.