patient-ventilator asynchrony during mechanical invasive assisted-ventilation in pediatric patients

Conditions: Respiration, Artificial

Summary: the purpose of this study is to document the prevalence and type of asynchronies incidence during invasive mechanical ventilation in pediatric patients breathing under pressure support. and to observe the impact of adjusting the expiratory trigger setting on asynchronies, and compare these incidences with asynchronies measured in pediatric patient breathing under nava system (neurally adjusted ventilatory assist).

two sessions will be recorded, one in psv, one with nava, delivered in a random order after being sure the infant is calm and comfortable, according to his parents and/or the nurse in charge. criteria for initiating invasive ventilation and to start psv will follow the usual practice guidelines of the unit. ventilation parameters in ps will be adjusted by the clinician in charge of the patient, as usual based on clinical observation. investigators will not interfere with ventilator settings. ventilation will be applied via an endotracheal tube, uncuffed for the majority (if infant \< 5 years), according to commonly applied guidelines in this unit. one 15 minutes session will be recorded, after being sure the infant is calm and comfortable according to the parents and/or the nurse in charge. then the clinician in charge of the patient will modify the ets, first decreasing it of 10% below the initial set value, and will be recorded the following 5 minutes after stabilization and secondly increasing it of 10% above the initial set value, and will be recorded the following 5 minutes after stabilization. nava will be set to deliver initially the same peak pressure (comparable level of assist) than during the initial ps period. same peep will be delivered in both modes. this is possible with a pre-visualization window, allowing adjustments before switching to the nava mode. nava ventilation will be recorded during 20 minutes. the 2 sessions, pressure support and nava, will be recorded consecutively.

Eligibility criteria:
inclusion criteria: * all consecutive patients from 4 weeks to 12 years (post natal interm infants) admitted to the pediatric intensive care unit (picu) and receiving mechanical ventilation in pressure support ventilation exclusion criteria: * non treated pneumothorax * hemodynamic instability * at least 2 hours following the admission in the picu in post cardiac surgery * fio2 \> 0.6 * poor short term prognosis (defined as a high risk of death in the next seven days) * contraindication for gastric tube or obtention of a reliable emgdi signal * known esophageal problem (hiatal hernia, esophageal varicosities) * active upper gastro-intestinal bleeding or any other contraindication to the insertion of a naso-gastric tube * neuromuscular disease * patients with a pacemaker

Keywords: prospective studies humans, pediatric positive-pressure respiration/methods* respiration, artificial/methods* intensive care intensive care units/statistics & numerical data* respiration, artificial/statistics & numerical data* patients/statistics & numerical data* prevalence respiratory muscles/innervation