ICU · Respiratory / monitoring

Patient–Ventilator Asynchrony

Also known as Patient-ventilator asynchrony · Asynchrony · Ineffective triggering · Double triggering · Breath stacking · Auto-triggering · Flow starvation · Reverse triggering · Fighting the ventilator · Asynchrony index

Patient-ventilator asynchrony is a mismatch between the patient's neural respiratory drive and the ventilator's delivered breaths, detectable on the waveforms. It is common and associated with longer ventilation and higher mortality. The types fall by the phase of the breath: trigger asynchrony (ineffective triggering, auto-triggering, double triggering/breath stacking), flow asynchrony (starvation, excess), and cycle asynchrony (premature or delayed cycling). An asynchrony index over 10 per cent is significant. Management is to read the waveforms, identify the type, and fix the cause — sedation, the trigger sensitivity, the flow and inspiratory time, and a cycling-off criterion — with NAVA or PAV for refractory cases.