CHAPTER 60

### KEY POINTS

• Patients are candidates for liberation from mechanical ventilation when gas exchange or circulatory disturbances which precipitated respiratory failure have been reversed.

• More than half of all critically ill patients can be successfully liberated from mechanical ventilation after a brief trial of spontaneous breathing on the first day that reversal of precipitating factors is recognized. Gradual reduction of mechanical support, termed weaning, is frequently unnecessary and can prolong the duration of mechanical ventilation.

• Once a patient has been liberated from the ventilator, extubation should follow if mechanisms of airway maintenance (cough, gag, swallow) are sufficient to protect the airway from secretions. Whether to extubate is a decision which follows successful liberation from the ventilator.

• In patients who fail their first trial of spontaneous breathing, attention should turn to defining and treating the pathophysiologic processes underlying failure.

• One weaning regimen, the gradual reduction of intermittent mandatory breaths, prolongs patients’ time on mechanical ventilation.

• Liberation from mechanical ventilation is achieved most expeditiously if patients are given a trial of spontaneous breathing (T-Piece or pressure support ≤7 cm H2O) each day. Patients remain on ventilators unnecessarily when clinicians do not put this simple plan in place.

• Patients who have had most correctable factors addressed and remain marginal with regard to ventilatory capacity should in most circumstances undergo a trial of extubation rather than remain intubated for protracted periods of time. Noninvasive positive pressure ventilation may be useful in these patients to transition them to fully spontaneous breathing following extubation.

Positive pressure ventilation can be lifesaving, but is also associated with many complications (Table 60-1). Most studies have demonstrated that earlier withdrawal of mechanical ventilatory support, when feasible, is associated with better outcomes. We will outline principles and approaches to the withdrawal of mechanical ventilation in a way to achieve this milestone at the earliest possible time and in a safe fashion.

TABLE 60-1

Complications Associated With Endotracheal Intubation and Mechanical Ventilation

### LIBERATION STRATEGIES

Many intensivists have reasoned that by gradually reducing ventilatory support, the respiratory muscles exercise at subfatiguing loads, leading to gradual improvement of function. Some studies have suggested that respiratory exercises (repetitions of low-load resistive breathing) can lead to successful extubation in patients who have previously failed.1 However, no studies have established that respiratory muscle training, through the use of graded withdrawal of ventilatory support, hastens the recovery ...

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