Postoperative utilization of critical care services by cardiac surgery: a multicenter study in the Canadian healthcare system

To describe patterns of critical care services used after cardiac surgery and to evaluate whether variations in the process of care influence outcome.

Multicenter, prospective study.

A convenience sample of four cardiac surgical units: three in university-affiliated (teaching) hospitals and one in a nonteaching regional referral center.

A "consecutive sample" of 335 patients after cardiac surgery in four hospitals.

Data were collected regarding all cardiac surgery patients admitted to the critical care units in the four test hospitals.

The critical care unit and hospital lengths of stay and survival were followed. The Therapeutic Intervention Scoring System (TISS) was used to assess the intensive care unit (ICU) interventions used during the first 24 hrs in the ICU and for the final 24 hrs before discharge from the ICU. The severity of illness on admission was assessed using the Acute Physiology and Chronic Health Evaluation (APACHE) scoring system. For patients having similar procedures (e.g., aortocoronary bypass and nonaortocoronary bypass procedures) and with similar outcome (mortality/total hospital length of stay), we found significant differences in the pattern of ICU resource utilization among hospitals. Significant (p < .05) differences in unit length of stay were related to varying factors in different hospitals. In hospital unit A, the type of procedure and preoperative chronic health status influenced unit length of stay (aortocoronary bypass 2.8 +/- 1.7 days; nonaortocoronary bypass 8.7 +/- 8.9 days) because length of stay was different for differing procedure groups. In hospital unit B, the critical care management system and lack of step-down (intermediate care) unit availability resulted in an increased unit length of stay for aortocoronary bypass patients (5.1 +/- 4.5 days) as compared with the other units (mean ICU lengths of stay of 2.8, 2.3, and 3.0 days, respectively). Unit B kept patients for monitoring purposes and had a reduced need for critical care nursing on the day of discharge (TISS = 7.5 +/- 5.5) as compared with the other units (mean TISS scores of 27.4, 23.2, and 21.5).

Significant differences exist among hospitals in the same healthcare system in the utilization of critical care services for cardiac surgery. In spite of these differences, for similar patient "input," the outcome (mortality and hospital lengths of stay) appeared similar. Assessments of utilization of critical care must focus on more detailed specific issues than unit length of stay, and must include factors such as availability of intermediate care areas, the unit management system, chronic health status, and the operative procedures performed, if a utilization management process is to effect improved resource use in critical care.