Patient-ventilator asynchronies during mechanical ventilation

Patient-ventilator asynchronies are a mismatch between the inspiratory and expiratory times of the patient and the ventilator.


  • Increased work of breathing
  • Ineffective effort
  • Air trapping
  • Respiratory alkalosis and hyperinflation of the lungs (Auto-triggering)
  • Dynamic Hyperinflation
  • Auto PEEP (also known as intrinsic PEEP (PEEPi))
  • Alters the outcome of Weaning
  • Increased levels of sedation
  • Confusion about the actual condition of the patient
  • Sleep disorders
  • Longer ICU stay and mechanical ventilation

Trigger asynchronies

  • occurring during the beginning of inspiration
  • Delayed-triggering
    • time interval between inspiratory effort and the delivery of a mechanical breath is increased
  • Ineffective effort:
    • inspiratory effort fails to trigger mechanical breath delivery
  • Auto-triggering:
    • a mechanical breath is delivered without a patient inspiratory effort

Flow asynchronies

  • occurring during the gas delivery
  • Double-triggering:
    • two (or more) mechanical breaths are delivered during one single inspiratory effort
  • Flow asynchrony:
    • delivered flow does not meet inspiratory flow demands
  • Early cycling:
    • mechanical breath duration is shorter than inspiratory effort duration
  • Delayed cycling:
    • mechanical breath duration is longer than inspiratory effort duration


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