Introduction and management of patient-ventilator asynchrony

The most frequent reason for instituting mechanical ventilation is to decrease a patient's work of breathing. For the most effective unloading of the inspiratory muscles, the ventilator should cycle in synchrony with the activity of a patient's own respiratory rhythm. However, imperfect patient-ventilator interaction is common during assisted ventilation and direct evaluation of ventilator graphics may serve as a tool to guide the physicians to take the appropriate action to improve the asynchrony. Failure to achieve this synchrony may cause various complications including prolonged weaning and longer hospital stay. The present article introduces asynchrony relative to the 4 phases of a breath and illustrates how asynchrony can be identified with two conventional ventilatory waveforms: pressure and flow. Besides, it also reviews different illustrations of waveforms and clinical management to improve asynchrony.