Chapter 25: Bariatric Surgery/Weight Loss in the Liver Transplant Candidate/Recipient

THE OBESITY EPIDEMIC

Obesity is an ever-increasing problem both in the United States and worldwide. In 2014, 6, the World Health Organization reported 13% of adults to be obese and 39% overweight.¹ In the United States, nearly 40% of the adult population suffers from obesity.² The trend of increasing obesity continues to be disproportionately higher with increasing body mass index (BMI), with the highest growth in the super morbidly obese population.³ Obesity-related conditions include diabetes, heart disease, and stroke, which are some of the leading causes of preventable death. Nonalcoholic fatty liver disease (NAFLD) that develops from obesity is associated with a higher mortality and liver-related deaths.⁴95% prevalence of NAFLD in obese patients who had bariatric operations have been reported.4

In 2013, the American Medical Association officially classified obesity as a disease. According to the American Heart Association/American College of Cardiology/The Obesity Society (AHA/ACC/TOS) clinical guidelines on the identification, evaluation, and treatment of overweight and obesity in adults, “overweight” is defined as a BMI of 25 to 29.9 kg/m² and “obesity” is defined as a BMI of ≥30 kg/m². Per their recommendations, the initial therapy for weight loss is lifestyle modification, such as exercise, decreased caloric intake, and counseling. Other interventions include the addition of pharmacologic agents, and bariatric surgery is appropriate for those who fail conservative management.⁵

THE EFFECT OF OBESITY ON THE LIVER

It is well known that obesity and metabolic syndrome lead to the development of NAFLD. In the presence of both conditions, more free fatty acids are delivered to the liver, resulting in steatosis.⁶ Higher BMIs are associated with a greater degree of steatosis and higher insulin resistance. A study by Wolf et al.⁷ showed that steatosis of the liver was found in over 30% of morbidly obese patients who had hyperlipidemia and hyperglycemia. The extent of liver disease ranges from mild fatty liver with steatosis to nonalcoholic steatohepatitis (NASH) with lobar inflammation and fibrosis, which can eventually lead to cirrhosis. The diagnosis of NAFLD can be made on ultrasound and sometimes routine blood work with slight elevations in liver enzymes. The severity of fibrosis associated with NAFLD in obese patients should be evaluated by a fibroscan, which is an examination of the liver similar to an ultrasound. On biopsy, NAFLD is defined as greater than 5% of hepatocytes with steatosis.⁸

EARLY BARIATRIC PROCEDURES THAT LEAD TO LIVER FAILURE

Surgical attempts at treating obesity began in the 1950s when numerous intestinal bypass techniques were published, one of which introduced the jejunoileal bypass. The proximal 40 cm of jejunum was anastomosed to the distal 10 cm of ileum. The malabsorptive procedure was effective in producing weight loss and was initially popular, but was eventually abandoned due to multiple unwanted side effects such as electrolyte abnormalities from diarrhea, renal ...