Early Trigger Leading to Double Triggering – Stacked Tidal Volumes and Target Variable
Impact of limit or target variable on size of double triggered breaths.
On pressure-limited modes, it is frequent that one of the stacked breaths generates very little volumes. Volumes can be inferred from the area under the curve of the flow vs time graph. Here, the first breath of each pair of stacked breaths delivers small volumes since the ventilator is only giving 3cmH2O (minimum amount that can be applied on this ventilator) of pressure above PEEP with each breath (right lower corner, under Pinsp). This happens because the other breaths produce larger volumes than target, so the ventilator decreases the amount of pressure it delivers on APV (APV is an adaptive mode). This amount of pressure cannot inflate the lungs to a significant degree in a passive patient and the first breath in early trigger is, at least initially, passive.
Early triggered fixed with decreased respiratory rate.
