Post-Operative Care After Liver Transplantation

Hemodynamic Management

The target is to keep mean arterial pressure (MAP) in the normal range for patient age, and this means finding equilibrium between hypotension and hypertension both of which are frequent following pediatric LT. Monitoring tools include echocardiogram, aortic flow variability using transesophageal Doppler and Near Infrared Spectroscopy (NIRS). Hemodynamic targets include: Stroke Volume Index (SVi) >25 ml/m ² , Cardiac Index (CI) > 3,5 L/min/m ² , and Stroke Volume Variation (SVV) < 10% using a trans-esophageal aortic Doppler. Important therapeutic objectives of adequate hemodynamic management include decreasing blood lactate upon Pediatric Intensive Care Unit (PICU) admission and its normalization within the first hours. Use of fluid boluses and/or vasopressive drugs is standard of care. Fluid replacement should be guided using fluid responsiveness criteria (e.g., minimum urine output: 0.5-1 ml/kg/h very low central venous pressure [CVP], or small telesystolic left ventricular surface area).

Systemic hypertension is a classic side effect of both calcineurin inhibitors and volume overload. In addition, pain contributes to blood pressure (BP) elevation in the post-operative period. Systemic hypertension should be treated to reach normal range ± 2SD for recipient age.

Fluid overload is well recognized as a factor associated with adverse events in PICU. However, excessive fluid restriction may impair graft perfusion and renal function (vascular thrombosis, pre-renal azotemia). In the first days after transplantation, ongoing drain losses need to be compensated, usually with crystalloids. In case of significant drain losses or hypoalbuminemia (below 3 g/dl), use of 5% or 20% albumin may contribute to maintaining intravascular volume while mitigating fluid overload. Fresh frozen plasma (FFP) is seldom used as compensation fluid, as there is no evidence that it is beneficial. What more, it carries the combined risk of allo-sensitization and masking early graft dysfunction. In the absence of vascular anomalies, a negative fluid balance should be sought starting on post-operative day 2 or 3. This is attainable either by using diurectics or by limiting fluid loss replacement.

Respiratory Management

The post-operative period is characterized by the risk for frequent respiratory complications. Prompt extubation is the goal of early post-operative management. There is no benefit to prolonged mechanical ventilation. Contraindications to rapid wean from respiratory support include: active bleeding, hemodynamic instability, respiratory failure, or severe neurological impairment precluding endotracheal tube removal.

Typical respiratory complications include atelectasis, pleural effusion, and occasionally right phrenic nerve palsy. Pleural effusion is often associated with ascites and mandates assessment of hepatic venous outflow. It may require percutaneous drainage. Right phrenic nerve involvement is much rarer and can be suspected clinically, or when an elevated right hemi-diaphragm is observed on X-ray. Diagnosis is confirmed using ultrasound or fluoroscopy to assess diaphragm movement during spontaneous breathing. Diaphragmatic training through neurally adjusted ventilation may be of some benefit. Diaphragmatic plication may be warranted in case of repeated failure to wean from ventilator support.

Surgical Management

Particular care should be given to avoiding hypovolemia because of the associated risk of vascular thrombosis. Therefore, continuous follow-up of drain losses is essential. Drain losses must be initially fully compensated with colloids and/or crystalloids, and adapted thereafter to mitigate fluid overload. The drain fluid should be routinely checked for bilirubin, amylase and trigyceride levels to ascertain the origin of the leak. In case of massive ascites and hypoalbuminemia, albumin may be of benefit to compensate losses.

Color and composition of fluid is relevant for management. For example, in case persistently high ascites output, the following should be ruled out: portal vein thrombosis, Budd-Chiari syndrome, intestinal perforation, and chylous ascites. In case of loss of more than once the circulating blood volume despite medical management or drainage of > 5 ml/kg/h of blood-stained fluid, surgical hemostatic procedures should be considered. Only once bleeding is under control, anticoagulation according to local protocol should be initiated. Both bleeding and thrombosis are feared complications following LT. While active bleeding warrants immediate cessation of anticoagulation, correction of severe hemostasis anomalies, and discussion with the surgical team, it is crucial to remember that platelet transfusion can result in vascular thrombosis during disseminated intravascular coagulation (DIC). Both in case of resuscitation and in routine management, it is generally accepted that target hemoglobin should be in the 8-10 g/dL range in the early post-operative phase. Therefore, daily abdominal ultrasound with Doppler is valuable to monitor for thrombosis during the early post-operative phase. Evidence of thrombosis warrants immediate discussion with the transplant surgeon. Vascular complications are further described in Chapter 20 .

Abdominal compartment syndrome (ACS) is another complication that should be sought and anticipated. ACS is a major concern because it is associated with high risk of vascular thrombosis and mortality. Invasive bladder pressure monitoring is necessary both to diagnose and monitor ACS. Intra-abdominal hypertension (IAH) with an intravesical pressure > 20 mmHg is a critical sign of ACS, warranting aggressive management.