The Impact of a ‘‘Low-Intensity’’ Versus ‘‘High-Intensity’’ Medical Intensive Care Unit on Patient Outcomes in Critically Ill Veterans

Abstract

To determine whether a low-intensity versus high-intensity medical intensive care unit (MICU) format in a Veterans Affairs (VA) hospital setting improves patient outcomes, as measured by duration of mechanical ventilation (MV), ventilator-free days (VFDs), and hospital mortality. Retrospective cohort study. Medical intensive care unit at the San Francisco Veterans Affairs Medical Center (SFVAMC). On July 1, 2004, the SFVAMC transitioned from a low-intensity MICU to a high-intensity MICU. All patients admitted to the MICU who required MV for 18 months before (n = 96) and 18 months after (n = 131) the transition were included in the analysis. We prospectively defined the primary outcome measure as the difference in the median duration of MV between groups. Secondary outcomes included VFDs and hospital mortality. Continuous variables were compared using the Wilcoxon rank sum test; dichotomous variables were compared using Fisher exact test. The low-intensity and high-intensity MICU groups were similar in age, gender, weight, and admitting diagnosis (P > .27 in all cases). Acute Physiology and Chronic Health Evaluation II (APACHE II) scores were 22.0 in the low-intensity era and 20.0 in the high-intensity era (P = .048). Median duration of MV was significantly lower in the high-intensity MICU format compared to the low-intensity MICU format (102 vs 61 hours, P for log-rank test = .0052). After controlling for covariates, there were 4.2 more VFDs in the high-intensity era (95% CI 1.9 to 6.6 days). The high-intensity era was associated with a reduced hospital mortality rate (27% vs 40%) and an adjusted odds ratio of 0.34 (95% CI 0.15 to 0.74). For critically ill veterans admitted to an MICU requiring MV, a high-intensity ICU structure is associated with more favorable mechanical ventilatory outcomes and lower mortality.