A simple predictive scoring system for prolonged mechanical ventilation in severe sepsis and septic shock

Introduction

Prolonged mechanical ventilation (MV) is associated with high morbidity and mortality in septic patients. However, limited data are available on the prediction of prolonged MV. We conducted an observational cohort study aimed at developing a prolonged MV predictive scoring system for severe sepsis and septic shock.

Methods

We retrospectively analyzed 120 consecutive patients with severe sepsis or septic shock who were ventilated for more than 72 hours between January 2005 and October 2009. Clinical features and physiologic parameters were examined for more than 15 days for use as predictors of MV. Patients were divided into two groups: group 1, those requiring MV for <15 days; group 2, those requiring MV >15 days.

Results

The mean (± SD) age and SOFA scores were 65.3 ± 16.7 years and 10.0 ± 3.9, respectively, and 35% required prolonged MV. Univariate analysis indicated that the length of ICU and hospital stays, hospital mortality, the rate of transfusion, incidence of ARDS, ventilator-associated pneumonia (VAP), other nosocomial infection (NI) and drug-resistant bacteria, the ratio of steroid therapy and muscle relaxant use, and the mean PaO₂/FiO₂ ratio during the first 3 days after admission were significantly different between the two groups. The independent predictors for prolonged MV were ARDS (OR 5.24 (P = 0.001; 95% CI: 1.9 to 14.1)), VAP (OR 7.75 (P < 0.001; 95% CI: 2.7 to 22.0)), and transfusion (OR 2.84 (P = 0.036; 95% CI: 1.0 to 7.5)) Using these results, we were able to develop a prolonged MV predictive scoring system. This simplified clinical risk assessment tool was developed from the results of univariate and multivariate analysis, with scoring based on a cut-off point related to the adjusted odds ratio. Prolonged MV score: VAP = 7 points; ARDS = 5 points; transfusion = 2 points; incidence of drug-resistant bacteria, steroid therapy, muscle relaxant use, other NI, the mean PaO₂/FiO₂ ratio during the first 3 days after admission <220 = each 1 point. The area under the receiver operating characteristic curve for prolonged MV in this scoring system was 0.866 (P < 0.001; 95% CI: 0.802 to 0.931).

Conclusions

The simple predictive scoring system for prolonged MV in severe sepsis/septic shock developed here will therefore help in planning the long-term care of such patients.