Intensive Care Medicine

, Volume 32, Issue 10, pp 1515–1522 | Cite as

Patient-ventilator asynchrony during assisted mechanical ventilation

  • Arnaud W. Thille
  • Pablo Rodriguez
  • Belen Cabello
  • François Lellouche
  • Laurent Brochard



The incidence, pathophysiology, and consequences of patient-ventilator asynchrony are poorly known. We assessed the incidence of patient-ventilator asynchrony during assisted mechanical ventilation and we identified associated factors.


Sixty-two consecutive patients requiring mechanical ventilation for more than 24 h were included prospectively as soon as they triggered all ventilator breaths: assist-control ventilation (ACV) in 11 and pressure-support ventilation (PSV) in 51.


Gross asynchrony detected visually on 30-min recordings of flow and airway pressure was quantified using an asynchrony index.


Fifteen patients (24%) had an asynchrony index greater than 10% of respiratory efforts. Ineffective triggering and double-triggering were the two main asynchrony patterns. Asynchrony existed during both ACV and PSV, with a median number of episodes per patient of 72 (range 13–215) vs. 16 (4–47) in 30 min, respectively (p = 0.04). Double-triggering was more common during ACV than during PSV, but no difference was found for ineffective triggering. Ineffective triggering was associated with a less sensitive inspiratory trigger, higher level of pressure support (15 cmH2O, IQR 12–16, vs. 17.5, IQR 16–20), higher tidal volume, and higher pH. A high incidence of asynchrony was also associated with a longer duration of mechanical ventilation (7.5 days, IQR 3–20, vs. 25.5, IQR 9.5–42.5).


One-fourth of patients exhibit a high incidence of asynchrony during assisted ventilation. Such a high incidence is associated with a prolonged duration of mechanical ventilation. Patients with frequent ineffective triggering may receive excessive levels of ventilatory support.


Mechanical ventilation Patient-ventilator interaction Ineffective triggering Pressure-support ventilation 


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Copyright information

© Springer-Verlag 2006

Authors and Affiliations

  • Arnaud W. Thille
    • 1
  • Pablo Rodriguez
    • 1
  • Belen Cabello
    • 1
  • François Lellouche
    • 1
  • Laurent Brochard
    • 1
  1. 1.Réanimation Médicale, AP-HP Hôpital Henri Mondor, Faculté de MédecineUniversité Paris XII, INSERM U651CréteilFrance

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