Physiological Response in Lung Transplant Recipients Undergoing Neurally Adjusted Ventilatory Assist

Study Overview
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Brief Summary
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Primary Graft Dysfunction (PGD) respresents the leading cause of mortality in early post-operative period of Lung Tranplantation (LTx). Protective ventilatory strategy could potentially reduce the risk of PGD in these patients. Neurally Adjusted Ventilatory Assist (NAVA) is an assisted ventilation mode that could allow to adopt this strategy. Aim of the study is to assess the feasibility of NAVA in the early post-LTx phase and to describe the breathing pattern and the physiological relationship between neural respiratory drive and different levels of ventilatory assist, in the absence of pulmonary vagal afferent feedback.

Detailed Description
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Lung transplantation (LTx) is an important treatment option for select patients with end-stage pulmonary disease. Primary Graft Dysfunction (PGD) is the main cause of death; in the early period following LTx a protective ventilatory strategy (tidal volume - Vt of 6 mL/Kg + Positive End Expiratory Pressure) could potentially reduce the risk of PGD in these patients. Neurally Adjusted Ventilatory Assist (NAVA) is an assisted ventilation mode in which neural inspiratory activity is monitored through the continuous recording of electrical activity of the diaphragm (EAdi). Actually, Guidelines about the adoption of a protective ventilatory strategy in the early post-opeartive period are lacking. NAVA, because of its intrinsic properties (proportionality between respiratory drive and level of assist, prevention of diaphragm atrophy), could allow to reach the afore mentioned ventilatory strategy. So, aim of the study, is the evaluation of patients' neural breathing pattern during NAVA, in early post-operative period of LTx

Official Title
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Physiological Response to Different Levels of Support in Lung Transplant Recipients Undergoing Neurally Adjusted Ventilatory Assist (NAVA)

Conditions
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Neurally Adjusted Ventilatory Assist, Ventilator-Induced Lung Injury, Work of Breathing, Lung Transplant; Complications

Intervention / Treatment
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* Device: NAVA ventilation


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Age > 18 y.o. Admission to ICU for post-operative monitoring after LTx Presence of spontaneous breathing activity Sedation titrated to a target RASS between 0 and -2 Written informed consent obtained Exclusion Criteria: Contraindication to nasogastric tube insertion (gastroesophageal surgery in the previous 3 months, gastroesophageal bleeding in the previous 30 days, history of esophageal varices, facial trauma) Increased risk of bleeding with nasogastric tube insertion, due to severe coagulation disorders and severe thrombocytopenia ( i.e., INR > 2 and platelets count < 70.000/mm3) Severe hemodynamic instability (noradenaline > 0.3 μg/kg/min and/or use of vasopressin) Postoperative extracorporeal respiratory support (ECMO) Pre-operative reconditioning of the transplanted lungs by means of ex-vivo lung perfusion (EVLP) Lung retransplantation Failure to obtain a stable EAdi signal

Ages Eligible for Study
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Minimum 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: Treatment
Intervention Model: Single Group Assignment
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: NAVA group<br>NAVA ventilation | Device: NAVA ventilation<br>* Assisted Ventilation Mode, synchronized, through EAdi catheter, with patient's inspiratory effort and proportional to respiratory drive<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Evaluation of the variations of Electrical Activity of the Diaphragm in response to different levels of ventilatory assist at different degrees of lung inflation (different Positive End Expiratory Pressure values) | Electrical Activity of the Diaphragm (EAdi) (microVolt) | One hour after the recovery of spontaneous breathing | 
| Evaluation of the variations of Neuro-Mechanical Coupling (expressed as microVolt of EAdi /cmH2O of airway pressure Ratio) in response to different levels of ventilatory assist at different degrees of lung inflation | Neuro-Mechanical Coupling (NMC) (microvolt/cmH2O) | One hour after the recovery of spontaneous breathing | 
| Evaluation of the variations of Neuro-ventilatory Efficiency (expressed as microvolt of EAdi / mL of Tidal Volume Ratio) in response to different levels of ventilatory assist at different degree of lung inflation | Neuro-Ventilatory Efficiency (NVE) (microvolt/mL) | One hour after the recovery of spontaneous breathing | 
| Evaluation of the changes in the patient's neural breathing pattern (expressed as mL of Tidal Volume) at different levels of ventilatory assist | Tidal Volume (mL) | One hour after the recovery of spontaneous breathing | 
| Evaluation of the changes in the patient's neural breathing pattern (expressed as respiratory rate) at different levels of ventilatory assist | Respiratory rate (Breaths/min) | One hour after the recovery of spontaneous breathing | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Evaluation of the feasibility of Plateau Pressure during NAVA | Plateau Pressure (Pplat) | One hour after the recovery of spontaneous breathing, with inspiratory hold manoeuvres | 
| Ultrasound assessment of the changes of Diaphragm's Thickening Fraction at different levels of Positive End Expiratory Pressure and at different NAVA gains | Diaphragm's Thickening Fraction (TF) | One hour after the recovery of spontaneous breathing | 
| Assesment of the total asynchrony index (double triggering + missed efforts + inspiratory trigger delay +short cycling + prolonged cycling) | Total Asinchrony Index | One hour after the recovery of spontaneous breathing |