Weaning predictors are often incorporated in protocols to predict weaning outcome for patients on mechanical ventilation. The predictors are used as a decision point in protocols to determine whether a patient may advance to a spontaneous breathing trial. The impact of including predictors in a weaning protocol has not been previously studied. We designed a study to determine the effect of including a weaning predictor (frequency-tidal volume ratio, or ƒ/Vt) in a weaning protocol.
Randomized, blinded controlled trial.
Academic teaching hospitals.
Three hundred and four patients admitted to intensive care units at three academic teaching hospitals.
Patients were screened daily for measures of oxygenation, cough and secretions, adequate mental status, and hemodynamic stability. Patients were randomized to two groups; in one group the ƒ/Vt was measured but not used in the decision to wean (n = 151), but in the other group, ƒ/Vt was measured and used, using a threshold of 105 breaths/min/L (n = 153). Patients passing the screen received a 2-hr spontaneous breathing trial. Patients passing the spontaneous breathing trial were eligible for an extubation attempt.
Measurements and Main Results:
Groups were similar with regard to gender, age, and Acute Physiology and Chronic Health Evaluation II score. The median duration for weaning time was significantly shorter in the group where the weaning predictor was not used (2.0 vs. 3.0 days, p = .04). There was no difference with regard to the extubation failure, in-hospital mortality rate, tracheostomy, or unplanned extubation.
Including a weaning predictor (ƒ/Vt) in a protocol prolonged weaning time. In addition, the predictor did not confer survival benefit or reduce the incidence of extubation failure or tracheostomy. The results of this study indicate that ƒ/Vt should not be used routinely in weaning decision making.