NAVA vs PSV Ventilation During Weaning From Mechanical Ventilation in Children After Liver Transplantation

Study Overview
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Brief Summary
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Liver transplantation is the treatment of choice for acute and chronic end-stage liver disease. Neurally Adjusted Ventilator Assist (NAVA) may be a feasible solution to guide the liberation from mechanical ventilation reducing asynchronies between patient and ventilator, and optimizing ventilator cycling. Cardiovascular and respiratory effects during NAVA ventilation are very limited after major abdominal surgery. The purpose of this application is to explore the efficacy of NAVA to reduce the asynchronies between the ventilator and pediatric patient admitted in Pediatric Intensive Care Unit (PICU) after major abdominal surgery, and the relationship between an optimal level of NAVA and cardiac and pulmonary function.

Detailed Description
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Twelve pediatric patients underwent liver transplantation and admitted during postoperative period in PICU will be studied. They will be endotracheally intubated and spontaneously triggering the mechanical ventilator. In each patient enrolled a specially manufactured nasogastric tube will be inserted. This nasogastric tube is equipped with ten electrodes. The correct position of the nasogastric tube (and of electrodes) will be confirmed checking the good quality of Edi trace with the P waves displayed by the central electrodes on monitor of Servo I Ventilator (Maquet). All the patients will be ventilated using ventilators with NAVA option (Servo-I, Maquet Critical Care, Sweden). After a stabilization period in Pressure Support Ventilation (PSV) according with the attending physician, each patient will be studied for a duration of 2 hours, divided in three trials of 40-minutes (first 30 minutes to washout from the effects of previous ventilation mode and during the last 10 minutes the results will be recorded). Each patient will be randomized for ventilation mode sequence (PSV/NAVA/PSV or NAVA/PSV/NAVA). The patient tracings of flow, airway pressure, electrical activity of diaphragm for the patient-ventilator interaction analysis, blood gas analysis and cardiovascular parameters will be recorded during each trial.

Official Title
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The Use of Neurally Adjusted Ventilator Assist Versus Pressure Support Ventilation durIng weaninG From Mechanical ventilAtion in pediaTric Patients After livEr Transplantation. A Physiologic Cross-over Controlled Trial. NAVIGATE Study

Conditions
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Pediatric Liver Transplantation, Weaning From Mechanical Ventilation

Intervention / Treatment
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* Procedure: Weaning from mechanical ventilation


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Liver recipients (from cadaveric or living donor) Invasive Mechanical ventilation Exclusion Criteria: Neurological impairment Neuromuscular, mitochondrial, metabolic, or chromosomal diseases with baby hypotonia Lesions of medulla Hemodynamic instability requiring inotropes/vasopressors (dopamine > 6 mcg/kg/min, norepinephrine, epinephrine, dobutamine, milrinone) or volume load. Congenital cardiovascular disease Patient extubated Need of controlled mechanical ventilation Intravenous infusion of benzodiazepines or propofol Pneumonia, pneumothorax, massive pleural effusion Patient placed on extracorporeal circuit Contraindications to insert nasogastric tube Not expected to survive beyond 24 hours Parental/legal guardian refusal

Ages Eligible for Study
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Minimum Age: 1 Month
Maximum Age: 10 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: Treatment
Allocation: Randomized
Intervention Model: Crossover Assignment
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Active Comparator: NAVA/PSV/NAVA<br>6 patients | Procedure: Weaning from mechanical ventilation<br>* Cross over study: 3 periods of 40 minutes in ventilation mode (NAVA or PSV); to register ventilator traces and cardiopulmonary parameters during the last 10 minutes of each period.<br>|
| Active Comparator: PSV/NAVA/PSV<br>6 patients | Procedure: Weaning from mechanical ventilation<br>* Cross over study: 3 periods of 40 minutes in ventilation mode (NAVA or PSV); to register ventilator traces and cardiopulmonary parameters during the last 10 minutes of each period.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Asynchrony Index | Asynchrony Index (ratio between the number of asynchronous breathing events and the total respiratory rate, expressed as percentage) will be measured in the last 10 minutes of each ventilatory trial of 40 minutes. | last 10 minutes of each ventilatory trial, NAVA or PSV | 
| Left and right ventricle function | Evaluation of left and right ventricular function variation during each ventilation mode. It will be measured by trans-thoracic echocardiogram in the last 10 minutes of each ventilatory trial of 40 minutes. | last 10 minutes of each ventilatory trial, NAVA or PSV | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| arterial partial pressure of oxygen (PaO2) | millimeters of mercury (mm Hg) | last 10 minutes of each ventilatory trial, NAVA or PSV | 
| arterial partial pressure of carbon dioxide | mm Hg | last 10 minutes of each ventilatory trial, NAVA or PSV | 
| oxygen index | {[mean airway pressure in centimeters of water × fraction of inspired oxygen × 100] ÷ PaO2 in mm Hg} | last 10 minutes of each ventilatory trial, NAVA or PSV | 
| respiratory rate | breaths per minute | last 10 minutes of each ventilatory trial, NAVA or PSV | 
| lactate | millimole/liter | last 10 minutes of each ventilatory trial, NAVA or PSV | 
| heart rate | beats per minute (bpm) | last 10 minutes of each ventilatory trial, NAVA or PSV | 
| cardiac index | {cardiac output [stroke volume (milliliter) x heart rate (bpm)] / body surface area (BSA; weight in kilograms and height in centimeters will be combined to report BSA in m^2)} in liters/minute/m^2 | last 10 minutes of each ventilatory trial, NAVA or PSV | 
| mean arterial pressure | mm Hg | last 10 minutes of each ventilatory trial, NAVA or PSV | 
| central venous pressure | mm Hg | last 10 minutes of each ventilatory trial, NAVA or PSV | 
| systemic vascular resistance | [(mean arterial pressure - central venous pressure) x 79.92 / cardiac index] in dynes/seconds/cm^-5 | last 10 minutes of each ventilatory trial, NAVA or PSV | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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mechanical ventilation, liver transplantation, pediatric, neurally adjusted ventilatory assist, weaning, pressure support ventilation