Liberation from Mechanical Ventilation in Acute Hypoxemic Respiratory Failure or Adult Respiratory Distress Syndrome: A Review.

Efforts to liberate patients from invasive mechanical ventilation (MV) begin when the underlying cause of acute hypoxemic respiratory failure (AHRF) or adult respiratory distress syndrome (ARDS) that led to use of invasive ventilation has resolved or improved and patients can initiate spontaneous breaths. In preparation for liberation, clinicians transition patients to spontaneous modes of ventilation as soon as possible while ensuring that patients' respiratory effort is not insufficient or excessive during weaning attempts. Concurrently, clinicians aim to minimize the effects of sedative and analgesic agents, screen daily to identify patients who are ready to undergo a spontaneous breathing trial (SBT), and conduct SBTs to help assess patients' readiness for extubation. Extubation failure is rarely the consequence of a single physiological abnormality. Rather, it reflects the interaction of multiple mechanisms that often coexist, including an imbalance between respiratory system load and capacity, ineffective cough, and secretion burden among others. For these reasons, single weaning parameters and SBTs may fail to identify some patients who are at risk for extubation failure. Conversely, indices and scores that combine two or more parameters and newer techniques may provide mechanistic insights into the pathways that lead to extubation failure, help to characterize 'at-risk' phenotypes, and identify patients who may benefit from closer monitoring, targeted therapeutic strategies, and/or early application of noninvasive respiratory support strategies such as high-flow nasal cannula (HFNC) and bilevel noninvasive positive pressure ventilation (NIV).