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

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

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.

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.

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