What Is Auto-Trigger/False Trigger Asynchrony?

In mechanical ventilation, the trigger refers to the mechanism that initiates a breath. This can be patient-triggered, where the ventilator detects the patient’s inspiratory effort and delivers a breath in response, or ventilator-triggered, where breaths are delivered automatically at a preset frequency.

Trigger dyssynchrony occurs when there is a mismatch between the patient’s effort to initiate a breath and the ventilator’s response. This may happen if the ventilator fails to detect the patient’s effort, delivers a breath without any patient effort (known as auto-triggering), or responds with improper timing, leading to poor patient-ventilator interaction.

Auto-triggering can result from several factors that falsely signal the ventilator to deliver a breath. Common causes include cardiac oscillations, excessively sensitive trigger settings, leaks in the ventilator circuit, condensation in the tubing, and chest wall movements such as tremors or hiccups.

If left uncorrected, auto-triggering can lead to multiple complications. These include patient discomfort, respiratory alkalosis due to hypocapnia from overventilation, increased work of breathing, difficulty weaning from the ventilator, and hemodynamic instability resulting from frequent, unnecessary breaths.