Assessment of Respiratory Mechanics and Inspiratory Effort During Spontaneous Breathing Trials to Predict Extubation Failure in High-Risk Patients

Rationale: Conventional parameters to determine the success of spontaneous breathing trials (SBTs) may fail to detect impending respiratory distress. Objectives: To assess whether SBT-induced changes in respiratory system compliance, inspiratory effort, and respiratory drive measured as occlusion pressure during the first 100 milliseconds (P0.1), all assessed noninvasively through airway occlusions, are associated with extubation outcomes. Methods: We conducted a multicenter study on patients at high risk of extubation failure who successfully passed a 30-minute SBT on the basis of conventional parameters. The SBT was reproduced using a specific ventilator immediately before extubation to continuously monitor respiratory system compliance, inspiratory effort, and P0.1. Extubation failure was defined as reintubation within 72 hours. Measurements and Main Results: Forty-six (19%) of 238 extubated patients required reintubation. No differences in VT or respiratory rate were observed between successfully extubated and reintubated patients at any time. In the success group, inspiratory effort and normalized compliance (i.e., scaled to predicted body weight) remained unchanged throughout the SBT. In the failure group, normalized compliance declined (1.0 [0.8-1.21 to 0.7 [0.6-0.91 ml/cm H2O/kg; P < 0.001), whereas inspiratory effort increased (12 [10-151 to 18 [15-201 cm H2O; P <0.001) during the SBT. P0.1 increased in both groups but more markedly in reintubated patients (2 [1.5-2.41 to 3.2 [2.9-3.51 cm H2O; P < 0.001). SBT-induced normalized compliance reduction less than or equal to-0.2 ml/cm H2O/kg (less than or equal to-0.1; less than or equal to-0.2) and inspiratory effort increase >2 cm H2O (>1, >3) were the most accurate predictors of extubation failure (area under the curve, 0.90 [0.84-0.931; sensitivity, 80%; specificity, 83%; area under the curve, 0.94 [0.90-0.971; sensitivity, 89%; specificity, 93%, respectively). Conclusions: In high-risk patients, SBT-induced declines in respiratory system compliance and increases in inspiratory effort are associated with extubation failure.