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Medline ® Abstract for Reference 5

of 'Assessment of respiratory distress in the mechanically ventilated patient'

Patient-ventilator asynchrony during assisted mechanical ventilation.
Thille AW, Rodriguez P, Cabello B, Lellouche F, Brochard L
Intensive Care Med. 2006;32(10):1515.
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 amedian 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.
UniversitéParis XII, INSERM U651, Réanimation Médicale, AP-HP Hôpital Henri Mondor, Facultéde Médecine, 51 avenue du Maréchal de Lattre de Tassigny, 94000 Créteil, France. arnaud.thille@wanadoo.fr