Early Cycling: A Common Cause of Double Triggering

Pic 1: The first image shows an upward deformation of the early portion of expiratory flow-time scalar (decreased expiratory flow) becuase of continuation of neural inspiration afte the end of mechanical inflation. 

Pic 2: There are two breaths separated by a small gap (incomplete expiration) which is known as double trigger. Early cycle can lead to double trigger if neural inspiration continues beyond mechanical inspiratory phase and reaches the trigger sensitivity threshold.

Pic 3: Shows comparison of early cycle with and without double trigger. Early cycling occurs when the neural inspiratory time is longer than the mechanical inflation time. 

Pic 4: You can see a larger pressure drop in the esophageal pressure waveform (reaches trigger sensitivity threshold during early expiration) in early cycling with double trigger compared to early cycling without double trigger.

Pic 5: Prolongation of inspiratory time by selecting a lower percentage of flow termination criteria in pressure support mode can correct the early cycle dyssynchrony. In this case end inspiration setting was changed from 30% to 10%.