Does Acute Physiologic and Chronic Health Evaluation (APACHE II) Scoring Predict Need for Prolonged Support After Coronary Revascularization?

Significant intensive care unit (ICU) resources are allocated to patients recovering from coronary artery bypass graft (CABG) procedures, suggesting that a system to identify patients at risk for prolonged ICU therapy would help to enhance the use of this resource.To test the hypothesis that post-CABG patients likely to require prolonged ICU stay could be identified at the time of admission using the Acute Physiologic and Chronic Health Evaluation (APACHE II) system for scoring the severity of illness, we retrospectively reviewed the length of ICU stay for all patients recovering from CABG procedures over 1 yr, comparing the APACHE II scores assigned to patients requiring the longest stay with scores for patients with the briefest stay to determine whether a difference in score corresponded with the difference in length of stay. All medical records were reviewed and the physiologic variables (n = 12) used to assess acute physiologic status were recorded. Perioperative therapeutic interventions having significant impact on the physiologic variables used to derive the APACHE II score also were recorded. The study group was defined as patients requiring ICU care lasting between 14 and 84 days (n = 20); a control group of 23 patients was randomly selected from 124 patients having an ICU stay of 48 h or less. The overall APACHE II scores, and the component scores used to derive the overall scores, were calculated for both groups and were compared. The mean APACHE II score for the study group was 23.5 compared with 13.2 (P < 0.001) for the control group. Component scores also were significantly higher in the study group, as was the use of pharmacologic and mechanical support, including inotropic and antiarrhythmic drugs, and intraaortic-assist devices. The higher incidence of therapeutic intervention in the study group was expected to normalize the physiologic variables used to derive the APACHE II score, thereby artifactually reducing both overall and component scores in this group and masking the severity of illness. However, the APACHE II score remained significantly higher in the study group despite normalizing interventions, suggesting that this scoring system may provide a means of assessing physiologic status of post-CABG patients that may help to anticipate ICU utilization. Limitations of the APACHE II scoring system include variations in measurement modalities, criteria for defining acute physiologic derangement, and clinical management techniques. The extent to which these factors influence the data collected, data interpretation, and subsequent physiologic scoring is unclear. Nonetheless, the APACHE system may provide an approximate marker indicating severity of illness for post-CABG patients, and thus may prove useful in stratifying the cardiac surgical population's utilization of ICU resources. (Anesth Analg 1995;81:24-9)