Predictors of prolonged weaning and survival during ventilator weaning in a respiratory ICU

Abstract

Purpose: An International Consensus Conference proposed classifying weaning into simple, difficult, and prolonged weaning. However, the usefulness of this classification in a respiratory intensive care unit (ICU) is unknown. The aims of the study were: (1) to compare the clinical characteristics and outcomes of patients from the three weaning groups in a respiratory ICU; and (2) to assess predictors for prolonged weaning and survival.

Methods: We prospectively studied 181 mechanically ventilated patients (131, 72% with chronic respiratory disorders) in whom weaning had been initiated, divided into simple (78, 43%), difficult (70, 39%), and prolonged (33, 18%) weaning. We compared the characteristics and outcomes among the three groups and determined the factors associated with prolonged weaning and survival in multivariate analysis.

Results: Patients with simple and difficult weaning had similar characteristics and outcomes. A higher proportion of patients with prolonged weaning had chronic obstructive pulmonary disease, and these patients also had more complications, a longer stay and lower survival. Increased heart rate (≥105 min(-1), p < 0.001) and PaCO(2) (≥ 54 mmHg, p = 0.001) during the spontaneous breathing trial independently predicted prolonged weaning. In addition, the need for reintubation (p < 0.001) and hypercapnia during the spontaneous breathing trial (p = 0.003) independently predicted a decreased 90-day survival.

Conclusion: Because of the similar characteristics and outcomes, the differentiation between simple and difficult weaning had no relevant clinical consequences in a respiratory ICU. Patients with prolonged weaning had the worst outcomes. For the overall population, hypercapnia at the end of spontaneous breathing predicts prolonged weaning and a worse survival, and clinicians should implement measures aimed at improving weaning outcome.