Weaning parameters.

Numerous weaning parameters have been studied over the past three decades. These tests range from easily performed maneuvers such as determining the breathing pattern to complex measurements requiring special equipment such as the mechanical work of breathing. Based on the available evidence, it seems that a negative weaning parameter may not be sufficient justification for delaying weaning trials. Clinicians wishing to use weaning parameters must be aware of the testing methodology and should consider adjusting the thresholds used based on individual patients' characteristics, including the estimated risks of each additional day of mechanical ventilation and the perceived risk of a failed trial of weaning. In a patient repeatedly failing weaning trials, parameters may help elucidate the mechanism for failure thereby providing a target for therapeutic intervention, leading to successful liberation.