Discontinuation of mechanical ventilation is a two step process, consisting of readiness testing and weaning:
- Readiness testing – Readiness testing is the evaluation of objective criteria to determine whether a patient might be able to successfully and safely wean from mechanical ventilation.
- Weaning – Weaning is the process of decreasing the amount of support that the patient receives from the mechanical ventilator, so the patient assumes a greater proportion of the ventilatory effort. The purpose is to assess the probability that mechanical ventilation can be successfully discontinued. Weaning may involve either an immediate shift from full ventilatory support to a period of breathing without assistance from the ventilator or a gradual reduction in the amount of ventilator support [1,2]. Weaning has also been referred to as the discontinuation of mechanical ventilation or liberation from the mechanical ventilator.
Patients who wean successfully have less morbidity, mortality, and resource utilization than patients who require prolonged mechanical ventilation or the reinstitution of mechanical ventilation [3-6]. The most successful weaning strategies include a daily assessment of the patient’s readiness to wean and the careful use of sedatives [7,8].
Weaning methods are reviewed here. Assessment of a patient’s readiness to wean and the extubation process are described separately. (See "Weaning from mechanical ventilation: Readiness testing" and "Extubation management".)
CHOOSING A WEANING METHOD
Traditional methods of weaning include spontaneous breathing trials (SBTs), progressive decreases in the level of pressure support during pressure support ventilation (PSV), and progressive decreases in the number of ventilator-assisted breaths during intermittent mandatory ventilation (IMV). Newer weaning methods include computer-driven automated PSV weaning and early extubation with immediate use of post-extubation noninvasive positive pressure ventilation (NPPV).