John F. McConville, M.D., and John P. Kress, M.D. N Engl J Med 2012; 367:2233-2239 December 6,
In the United States, almost 800,000 patients who are hospitalized each year require mechanical ventilation.1 This estimate excludes neonates, and there is little doubt that mechanical ventilation will be increasingly used as the number of patients 65 years of age or older continues to increase.2,3 The majority of patients who receive mechanical ventilation have acute respiratory failure in the postoperative period, pneumonia, congestive heart failure, sepsis, trauma, or the acute respiratory distress syndrome (ARDS).4
Our discussion below assumes that physicians have addressed metabolic, inflammatory, and infectious conditions that may be present and have corrected them to the extent possible. As soon as the condition that caused respiratory failure has started to improve, the transition from full ventilatory support to spontaneous breathing may be initiated. This transition requires sufficient respiratory-muscle strength to sustain breathing and maintain acceptable gas exchange. In most patients, this transition also includes the removal of the endotracheal tube. In patients with prolonged respiratory failure, the term “weaning” may be apropos, since it describes a gradual process of improving the strength-to-load ratio of the respiratory system to enable spontaneous respiration. Unfortunately, although this term is widely used, it is somewhat misleading in the vast majority of patients with acute respiratory failure. “Liberation” from mechanical ventilation is a better description, since it implies rapid removal of a burden that is no longer necessary.
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