Timing Matters: Identifying Early & Late Trigger Dyssynchronies

In mechanical ventilation, there is typically a delay of a few milliseconds between the onset of a patient's neural inspiration and the ventilator's delivery of flow. When this delay exceeds 100 milliseconds, it is referred to as late triggering. Late triggering increases the patient's work of breathing because the ventilator does not assist during the initial phase of inspiration. Conversely, in early triggering, the ventilator delivers a breath before the patient initiates neural inspiration. This results in passive mechanical inflation preceding neural inspiration. A specific form of early trigger-related patient-ventilator dyssynchrony is reverse triggering, where passive mechanical inflation triggers a reflex diaphragmatic contraction.