Résumé
A spontaneous breathing trial (SBT) is a test performed in mechanically ventilated patients to assess the respiratory effort needed after extubation. Despite the widespread use of these tests, there is still a significant extubation failure rate of 10% to 20%. The objective of this study was to assess the efficiency of three SBTs to predict post extubation effort to breathe. Materials and methods: this is a post-hoc analysis of three multicenter randomized cross-over physiological study. A total of 504 measures of inspiratory efforts (pressure time product per minute, PTPmin) from 126 adult intensive care unit patients were performed. Each realized 15-minute of three SBTs in a random order before extubation: pressure support ventilation level of 7cmH2O with positive en expiratory pressure level of 0cmH2O (PSV7PEEP0), T-Piece trial, and PSV 0cmH2O PEEP 0cmH2O (PSV0PEEP0). Inspiratory effort was recorder after each SBT and after extubation. Primary outcome was the rate of patients with a post extubation effort to breathe similar to the effort required during the SBT. We consider similar an effort withing a bilateral range of 20% of the post extubation effort to breathe. Results: inspiratory effort after extubation was similar to the effort required during the SBT in 32% of the patients with the PSV7PEEP0 trial, in 48% with the T-Piece trial and in 49% with the PSV0PEEP0 trial (Figure 1). In patients whose effort was not similar between after extubation and SBT, the effort to breathe after extubation was more often higher than during the PSV7PEEP0 trial (p<0.01), higher or lower in the same proportion compared with the T-Piece trial (p=0.63), and more often lower than during the PSV0PEEP0 trial (p=0.01). Conclusion: the post extubation effort to breathe was replicated by SBT in less than half of patients. Unassisted SBTs, T-piece and PSV0PEEP0 trials, are the most appropriate to replicate the inspiratory effort after extubation. Customizing the trials (by selecting the trials requiring the closest effort to the post extubation effort), permits to replicate the effort in 75% of the patients.