LIVER transplantation is the preferred treatment for end-stage liver disease, but postoperative complications can prolong mechanical ventilation dependency. Risk factors such as fluid administration, transfusion volume, graft size, ascites, and pleural effusion impair cardiac and pulmonary function. Additionally, abdominal muscle transection, pain, and mesh placement hinder respiratory recovery. In paediatric liver transplant recipients, diaphragmatic dysfunction is linked to extended ventilation and longer intensive care stays.
An ideal ventilation support mode should enhance patient-ventilator interaction while minimising asynchronies and haemodynamic disturbances. Pressure Support Ventilation (PSV) is widely used but delivers fixed assistance, increasing asynchronies. Neurally Adjusted Ventilatory Assist (NAVA) adapts positive pressure to diaphragm electrical activity, improving synchronisation and reducing asynchronies. This synchrony helps lower pleural pressure, mitigating cardiovascular stress.
Echocardiography is essential for assessing cardiac function post-transplant, yet the combined effects of NAVA on cardiovascular and respiratory function remain underexplored. This study evaluated patient-ventilator interaction and cardiac performance in paediatric liver transplant recipients transitioning to assisted breathing. Results showed that NAVA reduced asynchronies and improved cardiac performance compared to PSV.
Prior studies in paediatric patients with PARDS, bronchiolitis, and post-cardiac surgery demonstrated enhanced respiratory synchrony with NAVA. In this study, the asynchrony index (AI) was 1.5% with NAVA, lower than previous reports (1.7%-11%). PSV also showed improved AI (8.6%) compared to historical data (8.8%-25%), likely due to expiratory trigger optimisation with EAdi monitoring. However, no significant changes in respiratory exchanges were observed.
NAVA’s advantages are particularly relevant after major abdominal surgery. Surgical factors, including diaphragm elevation and muscle tone reduction, predispose patients to atelectasis. Pain and diaphragmatic dysfunction further reduce residual functional capacity, worsening atelectasis. Unlike ascites, which is drained, pleural effusion may persist, affecting lung function. Other factors, such as postoperative analgesia, graft-to-recipient weight ratio (GRWR), and abdominal mesh, impact ventilatory activity. Large grafts (>4% GRWR) can impair diaphragmatic movement and venous return. In this study, 14% of patients had mesh placement, and 29% had a GRWR >4%.
Fluid balance and transfusion volume also affect ventilation outcomes. Massive transfusions (>40 ml/kg in six hours) and positive fluid balance (10%-20%) correlate with prolonged ventilation and pulmonary complications. NAVA resulted in lower airway pressures, reducing pulmonary stress compared to PSV.
A cross-over A-B-A study design controlled for residual treatment effects, strengthening statistical reliability. However, limitations include its single-centre setting, small sample size, and lack of investigator blinding. Despite these constraints, findings suggest NAVA offers superior patient-ventilator synchrony in paediatric liver transplant recipients.
Reference
Chiusolo F et al. Effect of neurally adjusted ventilator assist versus pressure support ventilation on asynchronies and cardiac function in pediatric liver transplantation. Sci Rep. 2025;15(1):7158.
