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Abstract

Introduction: Patients who receive prolonged mechanical ventilation (PMV, =96 hours) have high mortality and are costly. Identifying PMV patients on intensive care unit (ICU) day 1 may facilitate targeting of patients for quality improvement and cost reduction strategies. Hypothesis: Patient characteristics on ICU day 1 identify patients at high risk for PMV. Methods: Adults admitted to 46 ICUs at 34 U.S. hospitals from Jan 2008 through June 2012 were analyzed. Patients receiving mechanical ventilation (MV) at any time were stratified into two groups: those ventilated for <96 hours vs. those receiving PMV. Spearman rank correlation, chi-square, and multivariable logistic regression were used to compare groups. Results: Of 127,373 ICU admissions, 34.2% received MV with median duration 40 hrs (IQR: 15, 110). There were 12,111 (28% of MV) PMV admissions with median duration 188 hrs (IQR: 134, 298). Patients receiving PMV had a longer median ICU stay (11 vs. 3 days), longer hospital stay (19 vs. 8 days), higher ICU mortality (22.3% vs. 17.6%), and higher hospital mortality (30.9% vs. 22.3%) compared with those receiving shorter duration MV. All differences were significant at p<0.001. After multivariable adjustment, severity of illness (as measured by the Acute Physiology Score) was associated with increased likelihood of PMV, but age and being Caucasian were inversely associated. Patients with a hematologic diagnosis had the greatest likelihood of PMV (Odds Ratio (OR) 1.90, 95% CI 1.37-2.63 compared with cardiovascular patients), followed by trauma (OR 1.37, 95% CI 1.24-1.50) and respiratory illness (OR 1.32, 95% CI 1.25-1.40). Patients with a PaO2 to FIO2 ratio <200 in the first 24 hrs of ICU admission (odds ratio (OR) 1.75 (95% CI 1.67-1.84) and patients readmitted to the ICU (OR 1.21, 95% CI 1.11-1.32) were more likely to receive PMV. Patients with a prior diagnosis of COPD did not have an increased risk of PMV (OR 1.02, 95% CI 0.97-1.09). Conclusions: Almost 30% of patients who are ventilated in the ICU require PMV. Identifiable patient characteristics at ICU admission are associated with an increased likelihood of PMV when ventilation is required.