[Oxygen cost of breathing in the prediction of successful weaning from mechanical ventilation].

OBJECTIVE: To determine whether the oxygen cost of breathing (VO2 resp) may predict successful weaning from mechanical ventilation.

DESIGN: A prospective clinical study.

SETTING: A polyvalent intensive care unit of a teaching hospital.

PATIENTS: Thirty non-consecutive mechanically ventilated patients ready to wean. Successful weaning was considered when reintubation was not needed for 48 h after extubation.

INTERVENTIONS: Spontaneous breathing test with a t-tube. VO2 resp was measured with the Douglas bag method.

RESULTS: Successful weaning was present in 20 (67%) of 30 patients. No patient with successful weaning needed tracheal reintubation. A cut-off value for VO2 resp <or= 10% had the highest value for the ROC curve (0.96 +/- 0.03) and +LR (9.5; 95% CI: 1.5 - 61) and -LR (0.1; 95% CI: 0.01 - 0.4) to distinguish between success or failure of weaning. A misclassification error of 7% was present to predict successful weaning.

CONCLUSION: The oxygen cost of breathing has no clinical utility in predicting weaning outcome.