Failed Trigger: Also Known as Missed or Ineffective Effort

A failed or ineffective trigger can be identified by analysing the ventilator waveforms. Here’s how to recognize it:

Pressure-Time Scalar:

Baseline Pressure Drop: When the patient makes an inspiratory effort, there will be a drop in the baseline pressure. This is because the patient is trying to inhale, creating negative pressure.

No Triggered Breath: Despite this drop, the ventilator does not deliver a breath. This indicates the effort was insufficient to meet the trigger sensitivity threshold.

Flow-Time Scalar:

Upward Deformation of expiratory flow-time scalar: The inspiratory effort by the patient will reduce the expiratory flow. This manifests as an upward deflection or deformation of the expiratory flow curve. Instead of a smooth return to the baseline, you’ll see a bump indicating the patient’s attempt to inhale.

The following example shows failed/ineffective trigger when pressure trigger is used