ORGAN TRANSPLANTATION

Question 1

What are the most commonly transplanted organs?

Answer 1

Organs that may be transplanted in humans include the heart, kidneys, liver, lungs,
pancreas, and intestines. The bone marrow may also be transplanted for certain
forms of cancer

Question 2

How does donation after brain death differ from donation after cardiac death?

Answer 2

○ The diagnosis of brain death is based on the loss of cerebral cortical and brainstem function.
• The loss of cerebral cortical function is implied from unconsciousness, the lack of spontaneous movement, and unresponsiveness to external stimuli.
• The loss of brainstem function is implied from apnea and absent cranial nerve reflexes.
○ Clinical studies that may be performed to provide supporting evidence include an electroencephalogram or cerebral blood flow studies.
○ Irreversibility of the diagnosis of brain death should also be established.
• This is usually achieved by the lack of any improvement in 12 to 24 hours after the diagnosis.
• Other derangements that must be excluded include central drug effects, postictal states, cardiovascular or metabolic instability, or hypothermia. ⊙ ○ The diagnosis of brain death is always made before a donor procedure and never in the operating room.
○ However, in the absence of brain death, but in the presence of a devastating and irreversible brain injury, the patient’s family may elect to withdraw life support.
○ In the event the family consents to organ donation, withdrawal of support is typically done in the operating room.
○ If the patient succumbs as a result of the withdrawal of life support—experiences cardiac death—organs may be harvested.
○ Under these conditions, the organs undergo a period of ischemia at normal body temperature (termed “warm ischemia”), a condition which necessitates rapid cooling, preservative administration, and procurement to minimize ischemic injury

Question 3

What conditions preclude transplantation?

Answer 3

○ Untreated systemic infection, incurable malignancy, untreated substance abuse, and lack of sufficient social support to comply with post-transplant care are contraindications to transplantation

Question 4

What is the most common cause of death in organ transplant recipients?

Answer 4

○ The most common cause of death in transplant recipients is infections due to chronic immunosuppression.
○ All physicians, including anesthesiologists, caring for the transplant patient should adhere to strict aseptic technique

Question 5

Most transplant candidates are screened for comorbidities prior to being waitlisted.
What additional beneficial preoperative measures can be undertaken once a donor is identified?

Answer 5

○ Because of the long wait times between listing and transplantation (not infrequently a year or more), preoperative screening tests may need to be repeated particularly when prior results are equivocal.
○ Most important are tests for ischemic heart disease (postoperative cardiovascular mortality is second in frequency to infection), assessment of laboratory results such as electrolytes and
hemoglobin, and, if needed, preoperative dialysis.

Question 6

Who is a candidate for renal transplantation?

Answer 6

○ Kidneys are the most commonly transplanted major organ.
○ Patients who have end-stage renal disease and are being considered for (or are currently receiving)
dialysis are candidates for renal transplantation.
○ Transplantation has led to lower overall morbidity and mortality than dialysis and to improved survival.
○ The most common cause of end-stage renal disease leading to chronic dialysis dependence is diabetes mellitus, followed by hypertension

Question 7

What is the major cause of death in dialysis patients?

Answer 7

Cardiovascular disease is responsible for over 50% of deaths in patients receiving dialysis.

Question 8

What differs between an extended criteria donor kidney and a standard criteria donor graft?

Answer 8

○ Extended criteria donors are older donors, donors with diabetes, and grafts with prolonged preservation times (acceptable times vary by organ; for the kidney >24 to 36 hours of cold ischemia is considered prolonged, for the liver >8 to 12 hours).
○ Organs donated after cardiac death incur additional warm ischemia and are considered as a subcategory of extended criteria grafts

Question 9

Where is the donor kidney transplanted in the recipient patient? From where does it
derive its vascular supply? Where is the ureter anastomosed?

Answer 9

○ The kidney is transplanted on one side of the recipient’s iliac fossa.
○ The vascular supply for the transplanted kidney is derived from the iliac vessels.
○ The ureter of the transplanted kidney is anastomosed directly to the recipient’s bladder.

Question 10

What are the preoperative considerations for the patient scheduled to undergo renal
transplantation?

Answer 10

○ Preoperative considerations for the patient scheduled to undergo a renal transplant are similar to any other surgical procedure in which the patient has chronic renal failure.
○ This includes scheduling of hemodialysis prior to surgery to optimize the patient’s volume status, electrolytes (particularly potassium), and acid-base balance.
○ The serum glucose levels of the patient with diabetes mellitus
should also be evaluated before and during surgery.

Question 11

How is preoperative ischemic heart disease ruled out prior to transplant listing?0

Answer 11

○ Preoperative ischemic heart disease should be ruled out preoperatively.
○ Stress echocardiography is probably better than thallium imaging in predicting postoperative cardiac events.
○ Coronary angiography should be considered in high-risk patients.

Question 12

What is the usual general anesthetic regimen administered for renal
transplantation?

Answer 12

The usual general anesthetic regimen for renal transplant procedures is
balanced anesthesia: a combination of volatile anesthetic and short-acting opioid.
○ Nitrous oxide is avoided because it causes bowel distention

Question 13

What consideration must be made when selecting a neuromuscular blocking drug
for patients undergoing renal transplantation?

Answer 13

. When selecting a neuromuscular blocking (NMB) drug, consideration should
be given to the method of clearance. A NMB that does not rely primarily on renal
clearance should be selected. Cisatracurium is particularly attractive because
its metabolism is independent of both the kidney and liver

Question 14

Why is optimal hydration important during renal transplantation? What type
of crystalloid solution should be used for hydration? What monitoring
method may be used to help guide hydration intraoperatively for renal
transplantation?

Answer 14

○ Optimal hydration is important to improve the early function of the transplanted kidney.
○ The crystalloid solution used for hydration intraoperatively should not contain potassium (e.g., normal saline).
○ Monitoring the patient’s central venous pressure may be a useful guide to the patient’s state of hydration.

Question 15

Is dopamine of benefit during renal transplant procedures?

Answer 15

○ Dopamine is often administered intraoperatively during renal transplant in an effort to increase renal blood flow and kidney perfusion.
○ However, no studies support this practice.
○ Other methods of ensuring adequate renal perfusion
are the maintenance of systemic blood pressure near normal and the provision of adequate hydration

Question 16

Why is mannitol administered intraoperatively during renal transplant procedures?

Answer 16

Mannitol is often administered intraoperatively during renal transplant procedures
to facilitate an osmotic diuresis. However, controlled studies supporting an improved outcome are lacking

Question 17

Cardiac arrest after completion of the renal artery anastomosis is thought to be secondary to what?

Answer 17

○ Reperfusion of the newly transplanted graft can lead to hyperkalemia; however, this life-threatening complication is less frequently seen during kidney
transplantation than with liver graft reperfusion.
○ A potassium-containing solution is used to preserve the kidney before transplantation.
○ The washout of this solution and accumulated acid metabolites is believed to be the cause of the
hyperkalemia.

Question 18

Who is a candidate for liver transplantation?

Answer 18

Patients with acute hepatic failure, chronic end-stage liver disease, tumors (in the absence of extrahepatic spread), and metabolic abnormalities affecting their liver are candidates for liver transplantation.

Question 19

How are liver transplant recipients prioritized for organ allocation?

Answer 19

Patient acuity, as determined by the MELD score, is used to allocate organs.
The MELD score predicts 90-day mortality in the absence of transplantation.

Question 20

What is the 1-month mortality for a waitlisted candidate with a high model for
end-stage liver disease (MELD) score (score >30)?

Answer 20

A patient with a MELD score greater than 30 has a 30% probability of dying or
becoming too ill for transplant within a 30-day period.

Question 21

What physiologic disturbances are often present in patients before liver
transplantation?

Answer 21

○ Physiologic disturbances in patients with end-stage liver disease affect virtually every organ system.
○ The patient may have encephalopathy, ranging from mild
confusion to coma; hyperdynamic circulation due to decreased systemic vascular resistance and an increased cardiac output; decreased plasma volume; and ascites.
○ Arterial hypoxemia may be due to pulmonary effusions, atelectasis, or
hepatopulmonary syndrome.
○ Renal dysfunction and oliguria may be present.
○ Patients may have anemia, thrombocytopenia, and coagulopathy.
○ Electrolyte abnormalities that may be present include hypokalemia, hypocalcemia, and hyponatremia. ○ Finally, these patients may have glucose intolerance or frank diabetes. ○ As the age of patients undergoing liver transplantation increases, the
proportion with coronary artery disease has increased

Question 22

What is the best screening test for portopulmonary hypertension?

Answer 22

○ Portopulmonary hypertension is defined as pulmonary hypertension (mean pulmonary artery pressure >25 mm Hg) in the presence of portal hypertension.
○ Resting echocardiography is a useful screening test because it identifies nearly all patients with the condition.
○ In patients with an estimated right ventricular systolic pressure greater than 50 mm Hg on echo, right heart catheterization is used to confirm or rule out the diagnosis.
○ There is significant perioperative mortality associated with mean preoperative PA pressure greater than 35 mm Hg.

Question 23

23. What is hepatopulmonary syndrome? Why is it significant?

Answer 23

○ Hepatopulmonary syndrome (HPS) consists of arterial hypoxemia (PaO2 <70 mmHg on room air) in the presence of an intrapulmonary shunt.
○ Liver transplantation cures HPS, albeit over a variable time course.
○ There is, however, an increased risk of perioperative mortality in patients with significant HPS (PaO2 <50 mm Hg on room air)

Question 24

What types of monitoring may be used intraoperatively during liver
transplantation?

Answer 24

○ Monitors that facilitate the anesthetic management of patients undergoing liver transplant procedures include invasive arterial blood pressure monitoring and
monitoring of cardiac filling pressures using a pulmonary artery catheter.
○ These monitors are useful because major shifts in the intravascular volume and hemodynamic instability almost always occur.
○ Arterial blood pressure is best
monitored from an artery above the level of the diaphragm because the aorta may be cross-clamped during the portion of the procedure in which anastomosis of the hepatic artery takes place.
○ Transesophageal echocardiograms are useful to monitor the volume status and cardiac function, and to detect emboli.
○ A Foley catheter isused to measure urine output

Question 25

What types of intravenous access are typically established preoperatively
for liver transplant procedures? Why should placement be
supradiaphragmatic?

Answer 25

Peripheral intravenous access should be established preoperatively using several
large-bore catheters to allow for the ability to transfuse blood products rapidly.
Intravenous catheters should be placed above the level of the diaphragm because
the inferior vena cava is typically cross-clamped during the procedure.

Question 26

Why are cell-saver devices used intraoperatively for liver transplantation?

Answer 26

Cell-saver devices are often used intraoperatively during liver transplant procedures because of the massive amounts of blood loss and massive fluid requirements during the procedure.

Question 27

Why is calcium administration often required during liver transplantation?

Answer 27

○ Calcium administration is often required during liver transplantation because of the frequency of citrate toxicity, caused when the citrate in banked blood binds with ionized calcium, which can cause myocardial depression.
○ This condition is more frequent during liver transplantation, particularly the anhepatic stage,
as the liver is unavailable to metabolize citrate

Question 28

What are the three stages of liver transplant procedures?

Answer 28

○ The preanhepatic, anhepatic, and neohepatic stage comprise the stages of the surgical procedure.
○ The preanhepatic stage involves the dissection of the portal venous structures and mobilization of the native liver.
○ The anhepatic stage begins when the native liver’s blood supply is interrupted by clamping of the
suprahepatic and infrahepatic inferior vena cava and the portal vein.
○ The neohepatic stage begins with the return of vascular supply to the graft, usually via the inferior vena cava and portal vein

Question 29

What are the characteristic physiologic derangements of the preanhepatic stage of liver transplant procedures?

Answer 29

○ The preanhepatic stage of liver transplant procedures is characterized by cardiovascular instability due to sudden decreases in the intraabdominal pressure,
and the exacerbation of chronic hypovolemia due to loss of ascites and hemorrhage.
○ Metabolic and electrolyte abnormalities can occur during this stage, including metabolic acidosis and hypocalcemia.
○ Hemorrhage, often requiring the rapid infusion of fluids and blood products, is related to the degree of portal hypertension and adhesions from prior abdominal surgery.

Question 30

What are the characteristic physiologic derangements of the anhepatic stage of liver transplant procedures?

Answer 30

○ The anhepatic stage of liver transplant procedures is characterized by precipitous
decreases in venous return and cardiac output.
○ For this reason, cardiac inotropic
drugs and sympathomimetic drugs are often administered during this portion of the liver transplant procedure to maintain cardiac output.
○ Hypocalcemia and metabolic acidosis commonly occur during this stage.

Question 31

What is the “piggy-back” technique and why is it used in some patients?

Answer 31

○ The piggy-back technique involves the anastomosis of the donor hepatic veins to the recipient vena cava, followed by portal anastomosis.
○ The piggy-back technique is preferred by some centers because it avoids transection of the inferior
vena cava, which may preserve venous return.
○ An alternative to the piggy-back
technique is the use of venovenous bypass, which involves rerouting blood from the inferior vena cava to the superior vena cava, which can augment venous return.
○ It is not universally used as it prolongs surgery and has unique
complications, including air embolism.

Question 32

What are the characteristic physiologic derangements that occur with reperfusion of the donor graft during liver transplant procedures?

Answer 32

○ The neohepatic stage of liver transplant procedures is characterized by the potential
for precipitous hyperkalemia, acidosis, and hypothermia due to the cold ischemic effluent from the graft entering the central circulation.
○ The systemic vascular resistance drops, and emboli of blood or air can occur.
○ Hyperkalemia is exacerbated
by the washout of the potassium-containing solution used to preserve the liver, in addition to unclamping of the inferior vena cava and portal vein.
○ Hypotension, arrhythmias, and cardiac arrest may potentially occur during this time

Question 33

Which coagulopathies can occur during liver transplantation

Answer 33

Coagulopathies that can occur during a liver transplant procedure include
thrombocytopenia, decreased levels of multiple coagulation factors (due to decreased synthesis and dilution), and fibrinolysis

Question 34

Why is nitrous oxide avoided for maintenance anesthesia during liver
transplantation?

Answer 34

○ Nitrous oxide is often avoided for maintenance anesthesia during liver
transplantation because it may cause bowel distention.
○ Additionally, nitrous oxide may increase the size of embolized air, and it may increase pulmonary vascular resistance in a population prone to pulmonary hypertension.

Question 35

Why do some anesthesiologists prefer cisatracurium as the nondepolarizing neuromuscular blocking drug for liver transplantation?

Answer 35

○ Cisatracurium is often selected as the nondepolarizing neuromuscular blocking drug, because its elimination is by spontaneous Hofmann elimination and ester hydrolysis, which are independent of liver function

Question 36

What signs of donor graft function can be assessed intraoperatively after graft reperfusion?

Answer 36

○ Signs of graft function include improvement in metabolic acidosis (due to metabolism of citrate to bicarbonate), a reduced calcium requirement (again, due to the liver’s ability to metabolize citrate), and a rising body temperature (due to exothermic reactions in the liver).
○ Hepatorenal syndrome may occur, as noted, by increasing urine output

Question 37

When is extubation of the trachea after liver transplant surgery performed?

Answer 37

The trachea generally remains intubated at the conclusion of the transplant until the patient is hemodynamically stable, bleeding is controlled, and the graft appears to be functioning well

Question 38

Who is a candidate for heart transplantation? What ejection fraction is commonly
seen in patients undergoing heart transplantation?

Answer 38

○ Patients with end-stage heart disease are candidates for heart transplantation.
○ Patients with pulmonary hypertension and end-stage heart disease are candidates for heart-lung transplant procedures.
○ Patients undergoing a heart transplant procedure usually have heart disease secondary to coronary artery disease or a cardiomyopathy. ○ The ejection fraction generally seen in these patients is less than 20%

Question 39

What are the goals for the induction and maintenance of anesthesia for heart transplant patients?

Answer 39

○ The induction of anesthesia for cardiac transplantation may include a benzodiazepine and an opioid.
○ The maintenance of anesthesia may be opioid based as well.
○ The goal of the anesthetic induction and maintenance is to provide good endotracheal intubating conditions while preserving cardiac function.
○ The potential risk of volatile anesthetics during a heart transplant procedure is myocardial depression, vasodilation, or both.

Question 40

What vessels are transected and anastomosed during heart transplant surgery?
What does this mean with regard to a central venous or pulmonary artery catheter?

Answer 40

○ Vessels that are transected and anastomosed during heart transplant procedures include the aorta, pulmonary artery, and left and right atria.
○ These are done during cardiopulmonary bypass.
○ A central venous or pulmonary artery catheter that is in place at the onset of surgery must be pulled back into the internal jugular vein when the patient’s heart is excised

Question 41

What is the indication for isoproterenol during heart transplantation?

Answer 41

○ Isoproterenol is indicated for the maintenance of myocardial contractility and heart rate in the denervated donor heart during and after weaning from cardiopulmonary bypass.
○ Isoproterenol also decreases pulmonary vasculature resistance.

Question 42

Does the transplanted heart react better to catecholamines that are direct or indirect acting?

Answer 42

○ The transplanted heart reacts better to direct-acting catecholamines.
○ Indirect acting drugs including atropine, which work via the autonomic nervous system, are
ineffective due to denervation of the graft

Question 43

Name the physiologic conditions that should be optimized prior to weaning from cardiopulmonary bypass

Answer 43

○ Prior to weaning from cardiopulmonary bypass, patients should be normothermic, and free from acid-base and electrolyte disturbances.
○ The lungs are ventilated and the cardiac chambers free from air

Question 44

Name three conditions that may worsen pulmonary hypertension.

Answer 44

Pulmonary hypertension is exacerbated by hypoxemia, hypercarbia, and elevated
cardiac output, pulmonary vessel spasm, and emboli.

Question 45

What type of endotracheal tube is used in lung transplant procedures?

Answer 45

Double-lumen endotracheal tubes are used for intubation of the trachea for
lung transplant surgery. This allows isolated ventilation of either the left or right lung, so that one lung may be ventilated while the other is being
transplanted.

Question 46

What are some intraoperative problems the anesthesiologist may encounter during
lung transplant procedures?

Answer 46

○ Intraoperative problems during lung transplant procedures may include arterial hypoxemia and pulmonary hypertension.
○ Arterial hypoxemia may occur
during one-lung ventilation.
○ Pulmonary hypertension may occur secondary to pulmonary artery clamping, particularly in patients with preexisting elevation of pulmonary pressure.

Question 47

Why are lung transplant patients predisposed to developing pneumonia in the transplanted lung?

Answer 47

○ Lung transplant patients are predisposed to pneumonia due to disruption of lymphatic drainage, poor mucociliary function, obstruction of bronchi from clots in
the bronchial suture lines, and loss of the cough reflex.
○ Immunosuppression
exacerbates the risk of infection.

Question 48

Who is a candidate for pancreas transplantation?

Answer 48

Patients with diabetes mellitus are candidates for pancreas transplantation

Question 49

What other organ is often transplanted simultaneously along with the pancreas?

Answer 49

○ Most (65%) pancreas transplants are performed simultaneously with kidney transplants because of the advanced nature of the diabetes, which is associated with renal failure. ○ Simultaneous pancreas-kidney transplant recipients experience the best graft survival rates.
○ The success of a pancreas transplant is measured by monitoring blood glucose levels after surgery; blood glucose concentrations may return to normal within hours.