Monday, March 16, 2009

Waveform of the week: Double-triggering

video

Double triggering is when a breath is initiated before the previous breath has time to end. 
Double triggering results from vigorous inspiratory demand or effort exceeding the volume or flow delivery settings on the ventilator. 










Double triggering highlighted in yellow, notice how another breath is initiated before the previous breath has time to end. 

Conditions which contribute to double-triggering:
  • Sighs.
  • Coughing.
  • Volume or flow settings set inappropriately low. 
  • Inadequate sedation.
  • ARDS low Vt strategy.
  • High ventilatory demand:
-High metabolic rate.
-High PaCO2.
-Reduced ventilatory assistance. 

Double triggering is not really a issue with trigger threshold/sensitivity it has more to due with inspiratory flow synchrony.
So any effort to reduce double-triggering should focus on matching inspiratory flow to the patients demands.

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