Expansion of the medical intensive care unit: clinical consequences in a large urban hospital.

We examined how a permanent expansion of the medical ICU (MICU) affected resource utilization and severity of illness for intensive care admissions within a 700-bed urban teaching hospital. On our 162-bed medical service, construction of a separate cardiac care unit and the expansion of the MICU increased the number of core intensive care beds by 100%. We prospectively analyzed noncardiology MICU admissions 2 months before, immediately after, and 4 months after MICU expansion. Although the volume of MICU patients increased by 51% after MICU expansion, the severity of illness as determined by the Acute Physiology and Chronic Health Evaluation (APACHE II) score and types of admission diagnoses remained the same. Moreover, there was no change in MICU occupancy and length of stay, hospital or MICU mortality, or MICU readmission rate. The increased MICU patient volume came from the ED, transfers from other hospitals, and from other ICUs within our hospital. In contrast, the volume and severity of illness of MICU transfers from the inpatient medical floor service were constant in all time periods. These results suggest that, while MICU expansion increased patient volume, physician utilization of the MICU resources was unchanged. Our physicians used high-intensity ICU beds in a consistent fashion in response to external factors, such as ED activity, intramural ICU transfers, and referrals from other hospitals.