Simplifying Patient-Ventilator Interactions During the Trigger Phase

The following image illustrates four types of patient-ventilator interactions that can occur while triggering a breath

1) Early trigger:

A mechanical breath is initiated before the onset of neural inspiration. Revere trigger is an example of early trigger where passive mechanical inflation triggers diaphragm contraction.

2) Late trigger:

Mechanical inflation begins more than 100 milliseconds after the start of the patient's inspiration.

3) Failed Trigger: 

Also known as an ineffective trigger, a patient's inspiratory effort fails to generate flow or pressure changes needed to reach the trigger sensitivity threshold, preventing the delivery of a mechanical breath.

4) False trigger (Auto trigger):

A non patient signal, such as an air leak, can cause pressure or flow changes that exceed the trigger sensitivity threshold, leading to the initiation of a mechanical breath.

Note- the following image shows pressure trigger as an example to illustrate patient-ventilator interactions