Anaesthesia for paediatric liver transplantation

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32

Anaesthesia for paediatric liver transplantation

NICHOLAS WASSON AND BABETTE HORN

32.1  Historical aspects

32.2  Introduction

32.3  Preoperative evaluation

32.4  Preoperative preparation

32.5  Induction of Anaesthesia

32.6  Lines and monitoring

32.7  Case flow

32.8  Transfer to intensive care unit

References

32.1  HISTORICAL ASPECTS

The first paediatric liver transplant was performed in 1963 by Thomas E. Starzl in Denver, Colorado, on a baby with biliary atresia [1]. With the development of cyclosporine and other immunosuppressive agents [2] since that time, as well as the development of new surgical techniques, there are now more than 140 transplant centres in the United States alone. Several hundred transplants are now performed each year both in the United States and abroad, all with significantly reduced morbidity and mortality [3].

32.2  INTRODUCTION

No one individual can take credit for a successful outcome when a child is undergoing liver transplantation, as it requires a multidisciplinary team. This consists of surgeons, anaesthesiologists, operating room nurses, scrub technicians, hepatology advanced practice nurses (APNs), fellows, attending faculty members, intensive care unit (ICU) fellows, ICU nurses and other ancillary personnel, among many others. All of these people are vitally important for ensuring good outcomes in these medically complex children. Anaesthesiologists play an integral part of this team. Developing an anaesthetic plan for these patients involves careful preoperative evaluation, close intraoperative monitoring and frequent communication with the surgeon and other specialties involved in the care of this child.

32.3  PREOPERATIVE EVALUATION

It is imperative that a careful preoperative assessment be performed when a child presents for liver transplantation. This begins with a thorough history and physical examination. The anaesthesiologist should focus on the extent of liver disease and any comorbidities, including but not limited to

Cause of liver failure and reason for transplant

Coagulation status (prothrombin time [PT]/partial thromboplastin time [PTT]/international normalised ratio [INR], fibrinogen, platelets)

Sequelae of portal hypertension (oesophageal varices, significant ascites, etc.)

Current liver and renal function

Cardiopulmonary comorbidities

Review of recent cardiology evaluation and any imaging studies (e.g. echocardiography)

Acid/base status

Electrolytes and blood glucose (especially any existing hyperkalaemia)

Temperature irregularities

Prior surgeries or procedures

Any other existing comorbidities and their anaesthetic implications

In addition to the preoperative evaluation, the anaesthesiologist should discuss with the patient and family members the preoperative plan, as well as the risks and benefits of the anaesthesia associated with the procedure. Liver transplantation is a high-risk surgery. As with any other high-risk procedure, possible complications, including massive haemorrhage; risks of blood transfusion, death or major neurologic, cardiac or pulmonary complications; and the need for reoperation, should be discussed.

It is important to be aware of the patient–family unit’s ability to hear and understand the conversations that are taking place. The discussion can also be tailored to the developmental level of the patient. Unnecessary anxiety and fear can thus be avoided.

32.4  PREOPERATIVE PREPARATION

Liver transplants are commonly performed at all hours of the day or night. However, there is usually a 6- to 8-hour lead time between the notification of a transplant to the operating room staff and the actual transplant for deceased donor transplants, and living donor transplants are often scheduled weeks in advance. Ample time therefore exists for preanaesthetic planning, including establishing initial intravenous (IV) access or preoperative central access (e.g. peripherally inserted central catheters or PICC lines), preoperative laboratory evaluation and review of any and all of the patient’s history. Blood products are ordered by the surgical team and are included in the preoperative orders.

For preoperative lab evaluation, serum electrolytes (specifically Na/K+), renal function, complete blood count (CBC) and platelet count, coagulation status (PT/PTT/INR) and type and cross-match of blood products should be performed. In addition, it is common practice to notify the blood banking services of these cases, so that adequate personnel are available and blood products are in ample supply in the event of a massive transfusion requirement. This of upmost importance in patients with a very high risk of haemorrhage, including but not limited to redo liver transplants, patients with a history of prior abdominal surgery with adhesions, patients with significant coagulation abnormalities and patients receiving a reduced-size graft with a cut liver edge.

Upon arrival in the preoperative holding area, a final assessment should take place prior to proceeding to the operating room. This includes identification of any airway abnormalities, loose teeth or anything (facial hair, facial dysmorphism, etc.) that could potentially make mask ventilation and intubation difficult, as well as any underlying ascites or positional respiratory compromise. Fasting status should also be verified, as well as any other aspiration risk. The need for initial IV access should be noted. Perioperative anxiety is often present in these patients, since stranger anxiety has its onset at about 9 months of age. This can be treated with oral midazolam 0.25–1.0 mg/kg or IV/intramuscular (IM) midazolam 0.1–0.2 mg/kg. Preoperative anxiolysis is acceptable in these patients, despite significant liver dysfunction, as the clearance in these patients of a one-time dose of midazolam is only slightly impaired [4].

32.5  INDUCTION OF ANAESTHESIA

The standard preoperative check should be performed by the anaesthesia and nursing staff upon arrival to the operating room. Close attention when moving the patient on the operating room table will prevent dislodging of any IVs or indwelling catheters. Patients who are already intubated and coming from an ICU should be transported to the operating room with emergency drugs and airway supplies should the patient be inadvertently extubated or become acutely unstable on transport.

Once in the operating room, the standard monitors are attached with the assistance of the nursing staff so as to avoid the operative field. As there is a risk for life-threatening hyperkalaemia upon reperfusion, the application of defibrillation or pacing pads on the patient prior to incision is advisable.

The use of induction agent and technique should be individualised for each patient after careful consideration of underlying liver pathology, haemodynamic abnormalities, electrolyte abnormalities, presence of ascites, history of gastrointestinal bleeding from any gastric varices and so forth. Sevoflurane is commonly used for the induction of younger and healthy vigorous patients who lack IV access and who do not have severe ascites, vomiting or any other aspiration concerns. Propofol (2–3 mg/kg IV) is often well tolerated in haemodynamically stable patients, even in liver failure; however, etomidate (0.2–0.3 mg/kg IV) and ketamine (1–2 mg/kg IV) are suitable alternatives.

For rapid sequence induction in normokalaemic patients, succinylcholine (1–2 mg/kg IV) is acceptable. Otherwise, high-dose rocuronium (1.2 mg/kg IV) is preferable. For anaesthetic maintenance, isoflurane is often selected, as this has been shown to preserve splanchnic blood flow [5] and vasodilate hepatic vasculature for improved perfusion [6]. Also, we advocate low fresh gas flows for maintenance during the procedure to also help maintain normothermia. Additional intraoperative analgesia is provided by narcotics, often given by infusion. Fentanyl is most often chosen, as its metabolism is mostly unchanged in liver disease [7]. Cisatracurium is often then chosen via infusion as the mode of muscle relaxation, as it is metabolised independent of liver metabolism [8].

Orotracheal intubation with a cuffed tube is utilised for most patients, even small infants. If the patient is already intubated, a recent chest X-ray should be reviewed for ideal tube placement. In some cases, it may be prudent to replace the endotracheal tube (ETT) altogether if a cuffed ETT or different-sized ETT is desired.

32.6  LINES AND MONITORING

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