Failed or Ineffective Trigger in a Patient with Neuromuscular Weakness

⤢

Note three instances (one between the 1st and 2nd breaths and two between 2nd and 3rd breaths) of positive deflections on the expiratory portion of the flow-time waveform accompanied by negative deflections of the pressure-time waveform. These are due to patient inspiratory effort. The patient is, however, unable to generate enough flows to meet the trigger sensitivity threshold (set to default of 5L/min on this ventilator) in this case due to neuromuscular weakness. Treatment is to decrease both the sensitivity threshold and depth of sedation.

⤢

Although we still have a few positive deflections in the expiratory portion of the flow vs time waveform for the first couple of breaths, we see a large improvement in failed triggering as evidenced by an increase in patient-triggered breaths (marked with purple arrowhead) and higher actual rate (on the left side, now 17 breaths/min).