Predictors of mortality in mechanically ventilated patients

Objectives: There are scarce data from India validating scoring systems used to predict outcome in patients requiring mechanical ventilation. This study prospectively compared the organ system failure (OSF), the acute physiology and chronic health evaluation (APACHE) II, and the APACHE III, scores on patients requiring mechanical ventilation in the medical intensive care unit, to predict outcome. Methods: 200 consecutive patients requiring mechanical ventilation in a medical intensive care unit were recruited. OSF, APACHE II, and APCHE III scores were calculated at admission and daily for one week or until discharge in all patients. Other variables recorded include age, sex, diagnosis, oxygen therapy before ventilation, complications on ventilation, duration in hospital before ventilation, duration of ventilation, type of respiratory failure, alveolar arterial oxygen gradient, P/F ratio, use of tracheostomy, time on ventilator before tracheostomy, muscle relaxant used, fluid balance, inotrope support. Logistic regression analysis and area under the curve were computed to determine which variables independently predict outcome. Results: Of the 200 patients, at discharge 143 patients (71.5%) had died. The factors that independently predicted outcome among these patients on mechanical ventilation were the type of respiratory failure (type I) OR= 2.7 (p = 0.02), the use of inotropes OR 2.4 (p = 0.04), and the APACHE II score OR = 1.8 (p = 0.008) for every five point increase in APACHE II score. Conclusions: Type 1 respiratory failure, the use of inotropes, and the APACHE II score measured at admission are significant independent predictors of mortality in the patients on mechanical ventilation.