Weaning from mechanical ventilation

For many critically ill patients admitted to an intensive care unit, the insertion of an endotracheal tube and the initiation of mechanical ventilation (MV) can be lifesaving procedures. Subsequent patient care often requires intensivists to manage the complex interaction of multiple failing organ systems. The shift in the intensivists' focus toward the discontinuation of MV can thus occur late in the course of critical illness. The dangers of MV, however, make it imperative to wean patients at the earliest possible time. Premature weaning trials, however, trigger significant respiratory distress, which can cause setbacks in the patient's clinical course. Premature extubation is also risky. To reduce delayed weaning and premature extubation, a three-step diagnostic strategy is suggested: measurement of weaning predictors, a trial of unassisted breathing (T-tube trial), and a trial of extubation. Since each step constitutes a diagnostic test, clinicians must not only command a thorough understanding of each test but must also be aware of the principles of clinical decision making when interpreting the information generated by each step. Many difficult aspects of pulmonary pathophysiology encroach on weaning management. Accordingly, weaning commands sophisticated, individualized care. Few other responsibilities of an intensivist require a more analytical effort and carry more promise for improving patient outcome than the application of physiologic principles in the weaning of patients.