1996 OPEN FORUM Abstracts
When Should Difficult Weaning Be Done?
Neil R. Maclntyre, MD Monday, November 4, 1996
Many patients receiving mechanical ventilatory support receive this support during an acute, transient episode of respiratory failure. As such, they often can be rapidly removed as their lung disease resolves. Under these circumstances, the ventilatory muscles are strong and the rapid resolution of the excessive muscle loads allows prompt return of the work of breathing back to the patient. Aggressive weaning approaches such as t-piece trials are appropriate in this setting.
In the minority of patients, the resolution of disease is much slower and the respiratory muscle function recovery may also be impaired. These are patients in whom rapid removal of ventilatory support is impossible. These patients probably constitute the minority of patients in the ICU but, because of their ventilator course, may actually constitute the majority of patient ventilator days.
Weaning these patients is a balance between aggressiveness (rapid removal of support) and avoidance of fatigue (too rapid reduction of support). Partial support techniques (IMV, pressure support, pressure assist) are helpful in this setting. These partial support approaches offer the advantage of lower ventilator pressures and some patient muscle activity to forestall atrophy. Careful monitoring of muscle load tolerance (e.g. respiratory frequency) is critical in balancing aggressiveness with safety in this setting.