Patient-ventilator Asynchrony During Assisted Mechanical Ventilation

Intensive Care Med. 2006 Oct;32(10):1515-22. doi: 10.1007/s00134-006-0301-8. Epub 2006 Aug 1.

Abstract

Objective: 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.

Methods: 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.

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

Results: 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 cmH(2)O, 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).

Conclusions: 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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aged
  • Chi-Square Distribution
  • Female
  • Humans
  • Intensive Care Units
  • Lung / physiopathology*
  • Male
  • Middle Aged
  • Monitoring, Physiologic / instrumentation
  • Monitoring, Physiologic / methods
  • Prospective Studies
  • Respiration, Artificial / methods*
  • Respiration, Artificial / statistics & numerical data
  • Signal Processing, Computer-Assisted
  • Statistics, Nonparametric