Patient–ventilator asynchrony is most commonly recognized as a patient who seems to be “fighting” the ventilator, whose efforts, either inspiratory or expiratory, are not in synchrony with the ventilator. It is a mismatch between the patient demand for flow, volume, or pressure as functions of time and what the ventilator is supplying to the patient. Although possibly an oversimplification, asynchrony implies that either the patient wants an inspiration that the ventilator does not adequately deliver, or the ventilator wants to give an inspiration that the patient does not want. Conversely, the patient wants to expire when the ventilator is delivering a breath, or the patient does not want to expire gas when the ventilator has stopped inspiratory support.

Asynchrony is a common problem for both invasive and noninvasive positive pressure mechanical ventilation.1–6  It has been reported...

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