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What type of asynchrony can you see? #7

Artikel

Autor: Jorge Correia Crespo

Datum: 13.09.2022

Is this a) an ineffective effort, b) delayed cycling, c) a flow asynchrony, or d) double triggering?
What type of asynchrony can you see? #7
Flow waveform showing fast increase followed by exponential decay
Flow waveform showing fast increase followed by exponential decay

Answer

Delayed cycling. This occurs when the mechanical inspiration extends into neural expiration.

How to recognize it

  • Fast decrease in inspiratory flow followed by an exponential decline in inspiratory flow (less steep)
  • Also look for an abrupt increase in Paw near the end of inspiration on the pressure waveform

Common possible causes

In pressure-support ventilation:

  • Cycling criteria (expiratory trigger sensitivity) set too low
  • Pressure support too high
  • Pressure ramp too long


In pressure-controlled ventilation:

  • Cycling criteria (expiratory trigger sensitivity) set too low
  • Inspiratory time too long


In volume-controlled ventilation:

  • Low flow
  • Long inspiratory time
  • High tidal volume

Solution

  • Increase expiratory trigger sensitivity (ETS)
  • Decrease inspiratory time (TI)
  • Decrease ventilation parameters (pressure support [PS], tidal volume [Vt], pressure ramp [P-ramp], etc.)