Characteristics and factors associated with mortality in patients receiving mechanical ventilation: first Chilean multicenter study

Abstract

The outcome of mechanically ventilated patients can be influenced by factors such as the indication of mechanical ventilation (MV) and ventilator parameters. To describe the characteristics of patients receiving MV in Chilean critical care units. Prospective cohort of consecutive adult patients admitted to 19 intensive care units (ICU) from 9 Chilean cities who received MV for more than 12 hours between September lst, 2003, and September 28th, 2003. Demographic data, severity of illness, reason for the initiation of MV, ventilation modes and settings as well as weaning strategies were registered at the initiation and then, daily throughout the course of MV for up to 28 days. ICU and hospital mortality were recorded. Of 588 patients admitted, 156 (26.5%) received MV (57% males). Mean age and Simplified Acute Physiology Score-II (SAPS II) were 54.6+/-18 years and 40.6+/-16.4 points respectively The most common indications for MV were acute respiratory failure (71.1%) and coma (22.4%). Assist-control mode (71.6%) and synchronized intermittent mandatory ventilation (SIMV) (14,2%) were the most frequently used. T-tube was the main weaning strategy. Mean duration of MV and length of stay in ICU were 7.8+/-8.7 and 11.1+/- 14 days respectively. Overall ICU mortality was 33.9% (53 patients). The main factors independently associated with increased mortality were (1) SAPS II > or =60 points (Odds Ratio (OR), 10.5; 95% CI, 1.04-106.85) and (2) plateau pressure > or =30 cm H2O at second day (OR, 3.9; 95% CI, 1.17-12.97). Conditions present at the onset of MV and ventilator management were similar to those reported in the literature. Magnitude of multiorgan dysfunction and high plateau pressures are the most important factors associated with mortality.