Monday, April 20, 2009

Waveform of the week: Auto-PEEP

Auto-PEEP indicated by the expiratory flow (red arrow) waveform not returning to baseline (pink arrow).

Auto-PEEP/Intrinsic PEEP (PEEP i)

PEEP-i is actually expiratory asynchrony however, it has a effect on patient triggering. 
The pressure associated with the trapped volume acts as a inspiratory load to be over come by the patient during spontaneous breathing. 

Increased Risks of PEEP-i
  • Minute ventilation greater than 15 lpm.
  • Airway resistance greater than 15 cmH2O.
  • Evidence of expiratory flow obstruction (e.g. expiratory time constant > 1.2 seconds).
Strategies to Reduce PEEP i
  • Increase expiratory time.
  • decrease respiratory rate.
  • Decrease expiratory resistance.