PEEP and prone ventilation in liver transplantation: consideration or contraindication?

Introduction

Acute respiratory distress syndrome (ARDS) can complicate liver transplantation (LT). Positive end expiratory pressure (PEEP) and prone ventilation (PV) have theoretical adverse hepatic effects. An adult paracetamol overdose required super-urgent LT. Immediate postoperative hypoxaemia due to ARDS developed (Table 1, i), as supported by FiO₂/PaO₂ ratio, bilateral pulmonary infiltrates, and normal pulmonary artery occlusion pressures. PEEP (15 cm H₂O) and PV improved gas exchange immediately (Table 1, ii) and at 18 hours (Table 1, iii). Doppler examination of hepatic vessels was normal. Discharge home was on day 41.

Table 1

Methods

A telephone questionnaire to British LT intensive care units about using PEEP and PV postoperatively after emergency LT.

Results

Completed questionnaires were obtained from the six other British LT intensive care units. All responders were consultant intensivists. Four routinely set PEEP on the ventilator. Three stated levels depended on oxygen requirements. One routinely used PEEP irrespectively. Two used PEEP depending on oxygen requirements. Two felt PV was 'absolutely contraindicated', quoting an evidence base, alternative available measures, and concerns regarding hepatic perfusion. No responder could recall PV being used in this context.

Discussion

Opinions regarding the use of PEEP post emergency LT are mixed. Opinions of PV appear polarised. No units appear to have used it in this context. Potential detrimental effects of PEEP and PV in LT include reduced cardiac output and hepatic blood flow. Increased intra-abdominal pressure with PV may compound this. However, restoring cardiac output maintains normal liver function and blood flow [1, 2]. Positioning to allow abdominal excursion minimises risk [2]. Concerns raised in the questionnaire may be overstated. We suggest both modalities can be used effectively, without detriment to donor liver or patient outcome. Further research is required.