A recursive partitioning model showed that disability is determined by age and ICU length of stay (LOS) based on the Functional Independence Measure (FIM) at 7 days post ICU discharge, independent of admitting diagnosis and severity of illness. Four distinct disability risk groups were identified [Young Short LOS (age <42 years, ICU stay <2 weeks); Mixed-age Variable LOS (≥42 years, <2 weeks and ≤45 years, ≥2 weeks); Older Long LOS (46-66 years, ≥2 weeks), and Oldest Long LOS (> 66 years, ≥14 days)]. These groups were characterised by different outcomes and post-ICU healthcare utilisation, with increasing disability from the Young Short LOS to the Oldest Long LOS. In the latter group, only 19% were discharged home directly from hospital, and over one-third required hospital readmission in the year after ICU discharge. Forty percent of this group died within the first 12 months after ICU discharge, and the surviving patients had severe and persistent functional dependency. Cognitive dysfunction, including problem solving and memory, was affected uniformly across risk groups.

Results Of the 15 757 patients admitted, a total of 5183 (33%) received mechanical ventilation for a mean (SD) duration of 5.9 (7.2) days. The mean (SD) length of stay in the intensive care unit was 11.2 (13.7) days. Overall mortality rate in the intensive care unit was 30.7% (1590 patients) for the entire population, 52% (120) in patients who received ventilation because of acute respiratory distress syndrome, and 22% (115) in patients who received ventilation for an exacerbation of chronic obstructive pulmonary disease. Survival of unselected patients receiving mechanical ventilation for more than 12 hours was 69%. The main conditions independently associated with increased mortality were (1) factors present at the start of mechanical ventilation (odds ratio [OR], 2.98; 95% confidence interval [CI], 2.44-3.63; P<.001 for coma), (2) factors related to patient management (OR, 3.67; 95% CI, 2.02-6.66; P<.001 for plateau airway pressure >35 cm H2O), and (3) developments occurring over the course of mechanical ventilation (OR, 8.71; 95% CI, 5.44-13.94; P<.001 for ratio of PaO2 to fraction of inspired oxygen <100).

Conclusion Survival among mechanically ventilated patients depends not only on the factors present at the start of mechanical ventilation, but also on the development of complications and patient management in the intensive care unit.

Procedure: We reviewed a 5-year experience with mechanical ventilation in 383 men with acute respiratory failure and studied the impact of patient age, cause of acute respiratory failure, and duration of mechanical ventilation on survival. Survival rates were 66.6 percent to weaning, 61.1 percent to ICU discharge, 49.6 percent to hospital discharge, and 30.1 percent to 1 year after hospital discharge. When our data were combined with 10 previously reported series, mean survival rates were calculated to be 62 percent to ventilator weaning, 46 percent to ICU discharge, 43 percent to hospital discharge, and 30 percent to 1 year after discharge. Of 255 patients weaned from mechanical ventilation, 44 (17.3 percent) required an additional period of mechanical ventilation during the same hospitalization