Chapter 13. Liberation From Mechanical Ventilation

John F McConville, MD
DOI: 10.1378/critcare.21.13
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  • Recognize criteria used to assess readiness for spontaneous breathing trials (SBT).

  • List criteria for successful SBT.

  • Identify nonventilator strategies for reducing duration of mechanical ventilation.

  • Identify risk factors for extubation failure despite passing a SBT.

  • Understand how/when to use NIPPV in the postliberation period.


Liberation from mechanical ventilation, rather than weaning, is a better description of the transition from assisted ventilation requiring an endotracheal tube to spontaneous breathing. Earlier liberation from mechanical ventilation (MV) reduces ICU-related complications and, thus, clinicians are often motivated to minimize the duration of MV. Trials of spontaneous breathing with minimal ventilator assistance remain the best method of determining which patients might be ready for liberation. Clinicians should assess a patient's readiness for spontaneous breathing every day and, when appropriate, conduct a spontaneous breathing trial (SBT). This approach results in a decreased duration of MV. Studies have demonstrated that SBTs performed on pressure support or T-piece are equally effective at identifying patients able to breathe spontaneously, and a 30-min SBT has been shown to be as effective longer trials. Importantly, there is increasing evidence that sedation strategies, timing of SBTs, and possibly early mobilization of mechanically ventilated patients may be essential components of an overall strategy to minimize the duration of MV. Because patients requiring reintubation after extubation failure have an increased risk of death, several recent studies have started to tease out the difference between liberation readiness and SBT success. For those patients who are at risk of developing respiratory distress in the postextubation period, early use of noninvasive positive pressure ventilation appears effective at reducing the need for reintubation.


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