Impact of weaning failure in the evolution of patients under mechanical ventilation

Introduction

Weaning is a critical period in the evolution acute respiratory failure (ARF) patients. Weaning failure has been associated with increased morbidity and mortality. We evaluated the impact of weaning failure on mortality, and morbidity.

Methods

Patients who were admitted to our eight-bed surgical-ICU and stayed more than 24 h on MV were prospectively evaluated from June 1999 to June 2000. Demographics, ARF etiology, APACHEII, and gas exchange and mechanical parameters were assessed. A protocol-directed weaning consisting in a 2-h trial of low levels of pressure support ventilation and PEEP was used before extubation. Weaning failure was defined as reintubation within 48 h after extubation. Weaning failure (WF) patients were compared with those who were successfully extubated (SE), and also with the total group (TG=SE+WF+patients who died before attempting weaning). Outcome measures were mortality, MV and ICU length of stay, and MV-free days (30-days on MV).

Results

A total of 155 patients required MV for more than 24 h (TG), of which 33 (21%) died before weaning could be attempted. Of the remaining 122 patients, 19 (16%) had weaning failure and were reintubated (WF), and 103 (84%) were successfully extubated (SE). There were no differences in age, sex, APACHEII scores, or etiology between WF and other groups. However, WF patients had longer ICU and MV length of stay than TG and SE patients. WF patients had also fewer MV-free days than SE patients, but not compared with TG. There was no difference in mortality between WF and TG patients.

Discussion

We found that patients who failed weaning do not have a higher mortality rate than all mechanically ventilated patients, although do worse in terms of days on mechanical ventilation and ICU length of stay. This may seem to be in contrast with several previous studies that addressed that extubation failure increases mortality. The explanation for this difference could be that we compared weaning failure (WF) with all mechanically ventilated patients, while the other studies have compared WF only with successfully extubated (SE) patients.