The Use of Neurally Adjusted Ventilatory Assist (NAVA) Versus Pressure Support During Asynchrony in Children

Study Overview
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Brief Summary
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The aim of the current study is to compare the application neurally adjusted ventilatory assist (NAVA) to optimize pressure support ventilation in 12 pediatric patients.

Detailed Description
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Asynchrony during assisted ventilation in children is common because of the presence of uncuffed artificial airways and their rapid ventilatory rate with small volumes compared to adults.As a result, the most common approach to ventilatory support in children is pressure ventilation, since pressure targeted ventilation allows gas delivery to vary based on patient demand. In addition, many manufacturers have incorporated adjuncts designed to improve synchrony in pressure targeted ventilation. Most of today's ICU ventilators incorporate rise time and control of the breath termination criteria in pressure ventilation by either altering inspiratory time directly or adjusting the inspiratory flow termination criteria in pressure support ventilation. In addition, careful adjustment of trigger sensitivity, and insuring driving pressure is appropriately set to avoid large tidal volumes improves synchrony in many patients. However, in spite of all of these potential adjustments many pediatric patients are still asynchronous. A recently released new mode of ventilation, NAVA (neurally adjusted ventilatory assist) is designed to reduce the asynchrony that exists between the ventilator and the patient. With NAVA, gas delivery from the mechanical ventilator is triggered, controlled and cycled by the diaphragmatic EMG signal (Edi). The ventilator is aware of the change in diaphragmatic EMG by the insertion of a specially designed nasogastric tube (NGT) with EMG electrodes that cross the diaphragm. This NGT also functions similar to any standard NGT. NAVA is used to control all aspects of assisted ventilatory support. A number of preliminary studies in neonates and pediatric patients have demonstrated that patient ventilator synchrony is improved with the application of NAVA. In general, tidal volumes delivered by the ventilator are decreased, respiratory rates increased and peak inspiratory pressures decreased. In these studies, triggering and cycling of the ventilator are controlled by the diaphragmatic EMG in more than 70 % of the time. If the EMG signal does not activate or terminate positive pressure backup flow/pressure/time signal, control gas delivery -as is customary in standard modes of ventilatory support- takes over. We hypothesize that the use of NAVA will improve trigger and flow synchrony in children and insure that tidal volumes are normalized (6 to 8 ml/kg) in these patients. Asynchrony will be studied in 12 mechanically ventilated pediatric patients in the Pediatric ICU at Hospital Universitario Materno-Infantil La Paz in Madrid, Spain. The study protocol has 5 phases Phase 0: patient asynchrony documentation and 10 min recording Phase 1: NAVA catheter insertion and 10 min recording in basal ventilatory mode after 20 min stabilization Phase 2: Pressure support is optimized and 10 min recording after 20 min stabilization Phase 3: NAVA mode ventilation and 10 min recording after 20 min stabilization Phase 4: Pressure support ventilation and 10 min recording after 20 min stabilization

Official Title
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The Use of NAVA vs. Pressure Support During Asynchrony in Children

Conditions
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Patient/Ventilator Asynchrony

Intervention / Treatment
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* Other: Pressure Support Ventilation
* Other: Neurally adjusted ventilatory assist (NAVA)


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Trigger asynchrony Breath initiation asynchrony Breath termination asynchrony Patient ventilated by Servo i (Maquet Critical Care AB,Solna,Sweden) Patients breathing spontaneously with no control breaths Exclusion Criteria: Shock Agitation Asynchrony caused by pain Abundant tracheal secretions

Ages Eligible for Study
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Minimum Age: 1 Month
Maximum Age: 18 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Diagnostic
Intervention Model: Crossover Assignment
Masking: None (Open Label)


Arms and Interventions

| Intervention/Treatment |
| --- |
|Other: Pressure Support Ventilation|Spontaneous mode of ventilation whereby the patient initiates the breath and the ventilator delivers support with the preset pressure value|
|Other: Neurally adjusted ventilatory assist (NAVA)|Gas delivery from the mechanical ventilator is triggered, controlled and cycled by the diaphragmatic EMG signal (Edi). The ventilator is aware of the change in diaphragmatic EMG by the insertion of a specially designed nasogastric tube with EMG electrodes that cross the diaphragm.|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Level of asynchrony | Number of each defined forms of asynchrony per minute during pressure support and during NAVA Six forms of asynchrony will be identified during optimal pressure support and optimal NAVA: trigger asynchrony, breath initiation asynchrony and breath termination asynchrony, demand asynchrony, inspiratory asynchrony and neuro-asynchrony | 3 hours | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Positive Pressure Ventilation, Neurally Adjusted Ventilatory Assist, Patient/ventilator Asynchrony, Pediatric patient, Infant