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

Introduction

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

Methods

Patients who were admitted to our 8-bed surgical-ICU and stayed more than 24 hours on MV were prospectively evaluated from June 1999 to June 2000. Demographics, ARF etiology, APACHE II and gas exchange and mechanical parameters were assessed. Weaning failure was defined as reintubation within 48 hours after extubation. Weaning failure (WF) patients were compared with those who were successfully extubated (SE) and the total group (TG = SE + WF). Outcome measures were mortality, MV and ICU length of stay and MV free days.

Results

155 patients required MV for more than 24 hours, of which 103 (66%) were successfully extubated, 19 (12%) had weaning failure, and 33 (21%) died before weaning could be attempted. There were no differences in age, sex, APACHE II scores, or etiology between WF and other groups. However, WF patients had longer ICU and MV length of stay than TG (14 ± 6.2 vs. 9.2 ± 7.4 days, P = 0.005; and 9.1 ± 4.8 vs. 5.5 ± 5.6, P = 0.002, respectively) and SE patients (8.8 ± 6.4, P = 0.003; and 4.6 ± 4.3, P = 0.001). WF patients had also less MV free days than SE patients (15 ± 11.2 vs. 25 ± 5.5, P = 0.001).

There was no difference in mortality between WF and GT patients (32% vs. 26%, P = NS). However, SE patients had 2% mortality, which was lower than WF and GT patients (P < 0.05).

Conclusion

Weaning failure is associated with longer MV and ICU length of stay, but does not increase mortality compared with the total group of patients. Weaning failure patients had the same risk of death as patients being connected for the first time to mechanical ventilation.