To document and compare the prevalence of asynchrony events during invasive-assisted mechanical ventilation in pressure support mode and in neurally adjusted ventilatory assist in children.
Prospective, randomized, and crossover study.
Pediatric and Neonatal Intensive Care Unit, University Hospital of Geneva, Switzerland.
Intubated and mechanically ventilated children, between 4 weeks and 5 years old.
Two consecutive ventilation periods (pressure support and neurally adjusted ventilatory assist) were applied in random order. During pressure support, three levels of expiratory trigger setting were compared: expiratory trigger setting as set by the clinician in charge (PSinit), followed by a 10% (in absolute values) increase and decrease of the clinician’s expiratory trigger setting. The pressure support session with the least number of asynchrony events was defined as PSbest. Therefore, three periods were compared: PSinit, PSbest, and neurally adjusted ventilatory assist. Asynchrony events, trigger delay, and inspiratory time in excess were quantified for each of them.
Data from 19 children were analyzed. Main asynchrony events during PSinit were autotriggering (3.6 events/min [0.7–8.2]), ineffective efforts (1.2/min [0.6–5]), and premature cycling (3.5/min [1.3–4.9]). Their number was significantly reduced with PSbest: autotriggering 1.6/min (0.2–4.9), ineffective efforts 0.7/min (0–2.6), and premature cycling 2/min (0.1–3.1), p < 0.005 for each comparison. The median asynchrony index (total number of asynchronies/triggered and not triggered breaths ×100) was significantly different between PSinit and PSbest: 37.3% [19–47%] and 29% [24–43%], respectively, p < 0.005). With neurally adjusted ventilatory assist, all types of asynchrony events except double-triggering and inspiratory time in excess were significantly reduced resulting in an asynchrony index of 3.8% (2.4–15%) (p < 0.005 compared to PSbest).
Asynchrony events are frequent during pressure support in children despite adjusting the cycling off criteria. Neurally adjusted ventilatory assist allowed for an almost ten-fold reduction in asynchrony events. Further studies should determine the clinical impact of these findings.
1Cardio-respiratory Physiotherapy Department, University Hospital, Geneva, Switzerland.
2Peritox EA 4284-UMI01 INERIS, UPJV, Amiens, France.
3Neonatal and Pediatric Intensive Care Unit, University Hospital, Geneva, Switzerland.
4Intensive Care and Burns Unit, University Hospital, Lausanne, Switzerland.
5Pediatric Intensive Care Unit, University Hospital North, Amiens, France.
* See also p. 728.
Current address for Dr. Vignaux: Cardio-Respiratory Physiotherapy Department, La TourHospital, Geneva, Switzerland.
This work was performed at Neonatal and Pediatric Intensive Care Unit, Department of Pediatrics, University Hospital of Geneva.
Part of this study has been previously reported as an abstract (ATS meeting, May 13-18; 2011, Denver, CO.).
At the time of the study, Mr. Laurence Vignaux was working in the lab run by Philippe Jolliet, Intensive Care Unit, University Hospital of Geneva, Switzerland.
The authors have disclosed that they do not have any conflicts of interest.
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