The early phase of the minute ventilation recovery curve predicts extubation failure better than the minute ventilation recovery time

Abstract

Study objectives: To determine, in patients who had successful outcomes in spontaneous breathing trials (SBTs), whether the analysis of the minute ventilation (Ve) recovery time obtained by minute-by-minute sequential monitoring after placing the patient back on mechanical ventilation (MV) may be useful in predicting extubation outcome.

Design: Twelve-month prospective observational study.

Setting: Medical-surgical ICU of a university hospital.

Patients: Ninety-three patients receiving > 48 h of MV.

Interventions: Baseline respiratory parameters (ie, respiratory rate, tidal volume, and Ve) were measured under pressure support ventilation prior to the SBT. After tolerating the SBT, patients again received MV with their pre-SBT ventilator settings, and respiratory parameters were recorded minute by minute.

Measurements and results: Seventy-four patients (80%) were successfully extubated, and 19 patients (20%) were reintubated. Reintubated patients were similar to non-reintubated patients in baseline respiratory parameters and baseline variables, except for age and COPD diagnosis. The recovery time needed to reduce Ve to half the difference between the Ve measured at the end of a successful SBT and basal Ve (RT50%DeltaVe) was lower in patients who had undergone successful extubation than in those who had failed extubation (mean [+/- SD] time, 2.7 +/- 1.2 vs 10.8 +/- 8.4 min, respectively; p < 0.001). Multiple logistic regression adjusted for age, sex, comorbid status, diagnosis (ie, neurocritical vs other), and severity of illness revealed that neurocritical disease (odds ratio [OR], 7.6; p < 0.02) and RT50%DeltaVe (OR, 1.7; p < 0.01) were independent predictors of extubation outcome. The area under the receiver operating characteristic curve for the predictive model was 0.89 (95% confidence interval, 0.81 to 0.96).

Conclusion: Determination of the RT50%DeltaVe at the bedside may be a useful adjunct in the decision to extubate, with better results found in nonneurocritical patients.