Chapter 56: Perioperative Anesthetic Management of Patients for Liver Transplantation

LIVER TRANSPLANT STATISTICS

• Nearly 6000 liver transplants are performed annually in the United States.

• As available figures show, the waiting list for liver transplant has nearly 16,000 patients, and the numbers continue to grow.

HISTORICAL DEVELOPMENTS AND CHALLENGES

• Surgical techniques evolved from canine models dating from 1955 by Stuart Welch in Albany and Jack Cannon at the UCLA.

• Pioneer preservation solutions formulated at the University of Wisconsin allow liver preservation up to 18 to 24 hours.

• In 1944 Medawar recognized the role of immunity in transplant rejection.

• Immunosuppression was a major challenge, and experiences from renal transplant (synergistic use of azathioprine + prednisone) formed the basis of the present immunotherapy regimen.

• Initial attempts at liver transplants (since 1963) were plagued by immediate surgical failures and intractable bleeds.

• Eventually the first successful transplant was achieved by Starzl et al. in 1967 in a 1-year-old child with hepatoblastoma.

• Survival rates were significantly enhanced by the introduction of antithymocyte globulin (1967) and tacrolimus (1989).

PREOPERATIVE CONCERNS WITH LIVER TRANSPLANTS

Preanesthetic evaluation:

• A 2-stage evaluation is preferred, the first at the time of reporting the need for a transplantation and the second as a re-evaluation after donor identification, just prior to the actual transplantation.

• The gap between these 2 evaluations can be used to improve nutritional status, treat any active infections, and manage associated coagulopathies and reversible organ system damages.

COMMON SYSTEMS INVOLVED AND ANESTHETIC-RELEVANT EVALUATIONS

Cardiopulmonary system (Fig. 56-1 and Table 56-1):

• Conventional noninvasive functional status evaluation – 6-minute walk test.

• Any suspicion of coronary artery disease must be evaluated – Improves long-term outcomes posttransplant.¹

• If significant coronary artery stenosis (>70% stenosis) is detected, revascularization may be attempted prior to transplant.

• Pulmonary hypertension should be ruled out, and patients with right ventricular systolic pressure >45 mm Hg should undergo further evaluation (e.g., cardiac catheterization).

• Dobutamine stress test

  • Preferred in patients with poor/limited functional status, as it quantifies the risk.

  • Rationalized as simulation of cardiovascular stress comparable to surgical stages of liver transplant.

  • High negative predictive value (75% to 100%).

  • Poor positive predictive value (0% to 33%).

• Cardiopulmonary exercise testing (CPET)

  • Physiologically superior in evaluating cardiac and respiratory system reserves in coordination.

  • Some centers have included CPET in the routine evaluation.

  • Patients with an anaerobic threshold >9.0 mL/min/kg predicts complications, with sensitivity and specificity 90.7% and 83.3%, respectively.²

• Hepatopulmonary syndrome (HPS)

  • Intrapulmonary vasodilation leading to blood shunting and hypoxemia.

  • Routine evaluation using room air. Arterial blood gas analysis with PO₂values below 80 mm Hg need further investigation.

  • Transthoracic echocardiography visualizing transpulmonary air bubble appearance into the left heart is fairly sensitive.

  • HPS has high predictive value for need for prolonged postoperative mechanical ventilation.

• Portopulmonary hypertension

  • Portopulmonary hypertension is characterized by a mean pulmonary artery pressure greater than 25 mm Hg ...