Weaning from mechanical ventilation

The best strategy to shorten the total time on mechanical ventilation is to determine at least on a daily basis the patient’s ability to tolerate unassisted spontaneous breathing. Under this approach, a screening test (respiratory rate to tidal volume ratio) should be performed as early as possible; if this test is positive (f/VT <105), then a confirmatory spontaneous breathing trial (30-120 minutes in duration) should be performed in order to assess tolerance to spontaneous breathing. In patients who fail the screening or the confirmatory test, different techniques for progressive withdrawal of mechanical ventilation can be applied, the most common being pressure support ventilation. Automated systems seem to perform at least as well as usual care and may even perform better. Noninvasive ventilation and high-flow nasal oxygen may be useful to hasten the weaning process and avoid reintubation in selected populations. Patients with a long weaning duration (>7 days from the first attempt to separation of the ventilator) have poor outcomes. Extubation failure is still not properly understood and is associated with a high mortality rate.