Weaning from mechanical ventilation: Readiness testing
- Scott K Epstein, MD
Scott K Epstein, MD
- Professor of Medicine
- Tufts University School of Medicine
Discontinuing mechanical ventilation is a two-step process:
●Readiness testing – During readiness testing, objective clinical criteria are evaluated to determine whether a patient is ready to begin weaning. Some clinicians also consider physiological tests, known as weaning predictors, because they are hesitant to begin weaning on the basis of clinical criteria alone. The clinical criteria and weaning predictors are defined and described below.
●Weaning – Weaning is the process of decreasing ventilator support and allowing patients to assume a greater proportion of their ventilation. It may involve either an immediate shift from full ventilatory support to a period of breathing without assistance from the ventilator (ie, a spontaneous breathing trial [SBT]) or a gradual reduction in the amount of ventilator support [1,2]. Regardless of which approach is chosen, extubation is considered once the patient demonstrates the ability to breathe without the ventilator and both airway patency and airway protection have been assessed. (See "Extubation management".)
PURPOSE OF READINESS TESTING
Readiness testing has two major purposes. The first is to identify patients who are ready to wean from mechanical ventilation. This is important because clinicians tend to underestimate the capacity of patients to breathe independently. Unnecessary mechanical ventilation needlessly increases the risk of complications related to mechanical ventilation.
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- PURPOSE OF READINESS TESTING
- CLINICAL CRITERIA
- Required criteria
- Optional criteria
- Clinical evidence
- WEANING PREDICTORS
- Rapid shallow breathing index
- Minute ventilation
- Maximal inspiratory pressure
- Occlusion pressure
- Work of breathing
- Gastric mucosal acidosis
- Oxygen cost of breathing
- Integrative indices
- APPROACH TO READINESS TESTING
- Daily screening
- Automated readiness testing
- SUMMARY AND RECOMMENDATIONS