Predictors of weaning after acute respiratory failure.

Although weaning predictors have been extensively explored in weaning research, their use is currently under debate. From all the stages of mechanical ventilation, the measurements of weaning predictors have been considered by some authors as imperative in order to progress weaning and initiate a weaning trial. However, this practice is rejected by other authors who considered that these tests are not necessary to perform a weaning trial, based in a meta-analysis study from the American College of Chest Physicians. Among all the weaning predictors, the frequency-to-tidal volume ratio (f/VT) remains the most important predictor of weaning. Other predictors have been defined, but their narrow predictive capacity or the requirement of specific technology, have limited their use. The variability of the results obtained by the efficacy of f/VT is probably explained because in most cases weaning is initiated late, when pre-test probability of weaning success is high. In order to reduce weaning duration, weaning strategies must be performed earlier, when a failed weaning trial probably is poor tolerated and the use of f/VT could have a role. New applications of weaning predictors must be clarified in future research, in order to progress in weaning in the context of new studies. Weaning is still a challenging period during mechanical ventilation.