Disclaimer
This is the expanded content of a lecture that I gave in 1998. I do not claim that this material is composed entirely of original content - rather, it is a review of some of the classic textbooks and other lectures that I have attended on the subject. Think of it as a traditional medical student or resident lecture

Read part ONE of this three part article first...

Read part TWO of this three part article first...

INTRODUCTION
Having discussed normal physiology, laboratory evaluation of liver function, general principles in evaluation of postoperative liver dysfunction and specific disease entities - it is now time to review anesthetic management of patients with liver and biliary tract disease.

Specifically we will cover the patient with cirrhosis, the patient for cholecystectomy and briefly mention anesthesia for liver transplant. The discussion on liver transplantation is woefully inadequate but is presented more as an example of the clinical concerns involved in a patient with hepatic disease than as a comprehensive discussion of the procedure.

ANESTHESIA FOR THE PATIENT WITH CIRRHOSIS
These patients represent a population in which postoperative morbidity is increased. Problems can occur with wound healing, bleeding, infection, decreased hepatic function and development of encephalopathy.

In the patient with acute hepatic failure, only truly emergency surgery should be undertaken. Preoperatively, administration of fresh frozen plasma may be necessary to correct coagulation defects. These patients will be more susceptible to sedatives - in fact sedatives and depressant drugs are probably not needed and nitrous oxide may be sufficient for analgesia and amnesia. Any intravenous drugs that are utilized may have prolonged action if they depend on hepatic metabolism.Muscle relaxants are appropriate - keep in mind which ones are metabolized by the liver. Cholinesterase should not decrease in acute liver failure (plasma half-life of 14 days) so the use of succinylcholine is possible without risk of prolonged effect.

Glucose levels probably should be measured to avoid hypoglycemia. These patients are also prone to acidosis, hypoxemia and electrolyte abnormalities - appropriate laboratory tests should be utilized to guide therapy.

Obviously, avoid hypotension and maintain urine output. Remember that these patients are more susceptible to infection and encephalopathy may occur if the ammonia load is too high (prevent or treat with lactulose).

For both acute and chronic liver disease there is no optimal anesthetic drug or technique - the overriding concern is that perfusion (i.e. blood pressure) and oxygenation myst be maintained. Regardless of what choice is made, postoperative liver dysfunction is more likely and more severe when compared to normal patients. Regional anesthetic techniques are acceptable as well assuming that coagulation is normal and the same considerations for maintaining blood pressure and oxygenation are followed.

Remember that in the chronic patient plasma proteins may be decreased leading to increased effects of protein-bound drugs. There may be increased susceptibility to cardiac depression, decreased responsiveness to catecholamines, and alterations in anesthetic requirement (increased in the sober alcoholic, decreased in the intoxicated patient, etc.).

ANESTHESIA FOR CHOLECYSTECTOMY
This is most often performed under general anesthesia with muscle relaxation. Regional anesthesia is unlikely since a high sensory level is needed and the area of surgical attention and surgical technique could interfere with spontaneous ventilation.

If performed laparoscopically, insufflation introduces additional concerns including increased abdominal pressure that may interfere with spontaneous ventilation and decreased venoud return. For mechanical ventilation and prevention of aspiration during surgery, endotracheal intubation is a must. A nasogastric or orogastric tube will decompress the stomach and decrease the risk of puncture of the viscera while also improving visualization for the surgeon.

The use of opioids in these patients present a theoretical concern due to the fact that these drugs are known to cause spasm of the sphincter of Oddi. It is likely that the incidence of this is extremely low, that spasm can be caused by surgical manipulation alone, and that antagonism of this opioid effect is effectively antagonized with naloxobne or glucagon. Therefore, it is my opinion that opioids can be used in these patient without difficulty.

Postoperative pain can limit ventilation so attention should be paid to pain relief in these patients. Patient controlled analgesia is often sufficient. Intercostal blockade on the right side has also been advocated in patients for incisional pain.

ANESTHESIA FOR LIVER TRANSPLANT
Liver transplant is the only curative treatment presently available for hepatic failure. Preoperatively these patients may already exhibit hypoxemia, anemia, thrombocytopenia, coagulation defects, electrolyte disturbances (hypokalemia and hypocalcemia), heart failure and encephalopathy. Time to correct these problems may be limited prior to surgery due to the emergent nature of the operation.

Invasive monitoring is routinely utilized in these patients (arterial pressure, cardiac filling pressures) and large bore intravenous access is important for rapid volume replacement. Sites for arterial and venous access are placed above the diaphragm if at all possible because of inferior vena cava clamping and possible abdominal aorta clamping. Blood and fluid requirements are massive. Calcium administration is often required. Decreased venous return during cross-clamping often requires inotropic support. Hypothermia should be avoided.

Hypotension is often seen upon unclamping of the vena cava - this may be due to factors released in the ischemic tissues that are washed out when blood flow is resumed. Many different etiologies of coagulation problems can occur and thromboelastography is often utilized to guide component therapy. Acid-base status, electrolytes, glucose levels, and urine output should all be closely monitored.

Co-existing pulmonary hypertension may require vasodilator therapy (this is the subject of another lecture). When considering whether to use nitrous oxide, the largest concern is the risk of venous air embolism in these patients - most practitioners avoid nitrous. Muscle relaxants are chosen that do not depend upon the liver for metabolism. Postoperative ventilation is frequently necessary.

This discussion is overly simplified. It merely represents an example of the clinical concerns that accompany a patient in liver failure and is presented here more as a learning mechanism than a "guide to anesthesia for liver transplants". Most of you will never take part in a transplant but the lessons learned can be applied each time you administer anesthesia to a patient with hepatic disease.