Physiological Response in Lung Transplant Recipients Undergoing Neurally Adjusted Ventilatory Assist

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

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.

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

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