Transplant Anesthesia
Transplantation is the standard of care for many end-stage diseases (Ceste M, Banks D, Manecke G, Glas K. Transplant anesthesia. In: Barash PG, Cullen BF, Stoelting RK, Cahalan MK, Ortega R, Stock MC, eds. Clinical Anesthesia. Philadelphia: Lippincott Williams & Wilkins; 2013:1459–1489). In general, maximum cold ischemic times are 4 to 6 hours for heart or lung grafts, 12 to 24 hours for livers, and up to 72 hours for kidneys. In major transplant centers, specialist anesthesiology teams participate in the preoperative assessment and optimization of patients for major organ transplant procedures.
I. Anesthetic Management of Organ Donors
Brain-Dead Donor. Legal and medical brain death criteria differ from state to state, but all require cessation of both cerebral and brain stem function. Potentially reversible causes of coma or unresponsiveness (hypothermia, hypotension, drugs, toxins) must be ruled out before declaration of brain death. A flat electroencephalogram is consistent with brain death. Transcranial Doppler and traditional or isotope angiography are used to confirm the clinical examination and lack of blood flow to the brain.
Brain-dead patients may have intact spinal reflexes, so they may require neuromuscular blockade during organ procurement.
Brain death is associated with hemodynamic instability, hormonal chaos, systemic inflammation, and oxidant stress, all of which may negatively impact donor organ function. After pituitary failure ensues, hormone therapy may help stabilize patients hemodynamically. Cardiac graft function is likely improved by donor hormone therapy (desmopressin better than norepinephrine).
The mainstay of donor management is maintenance of euvolemia, so central venous pressure (CVP) monitoring is standard. (CVP is maintained at 6–12 mm Hg.)
Efforts should be made to maintain serum sodium below 155 mmol/L. Packed cells are
used to maintain hematocrit of 30%, and fresh-frozen plasma (FFP) is used to maintain the international normalized ratio (INR) below 1.5.
Table 51-1 Characteristics of the Ideal Deceased Lung Donor
Age <55 yrs
ABO compatibility
Clear chest radiographs
PaO2 >300 on FIO2 1.0, PEEP 5 cm H2O
Tobacco history <20 pack-yrs
Absence of chest trauma
No evidence of aspiration or sepsis
Negative sputum Gram stain result
Absence of purulent secretions at bronchoscopy
FIO2 = fraction of inspired oxygen; PEEP = positive end-expiratory pressure.
The anesthesiologist is responsible for maintaining donor oxygenation, perfusion, and normothermia.
Donor lungs are more susceptible to injury in brain-dead patients before procurement than are other organs, likely from contusion, aspiration, or edema with fluid resuscitation (Table 51-1). Patients ventilated with tidal volumes of 6 to 9 mL/kg and 8 to 10 cm H2O positive end-expiratory pressure (PEEP) were more likely to be lung donors than patients managed with tidal volumes of 10 to 15 mg/kg and 3 to 5 cm PEEP.
Donation After Cardiac Death (DCD)
The criteria for death of DCD donors (previously called non–heart-beating donors) are distinct from those of brain-dead donors. DCD donors typically have severe whole-brain dysfunction but have electrical activity in the brain. Death is defined by cessation of circulation and respiration. Life support measures are used to control the timing of death and organ procurement to maximize the function of organs from these donors.
Anesthesiologists do not necessarily have to be involved in DCD donor management. Circulation and respiration must be absent for 2 minutes before the start of organ recovery.
II. Living Kidney Donors
Safety and comfort are the primary considerations in the care of living donors (laparoscopic donor nephrectomy).
Both anesthetics and insufflation of the peritoneum with CO2 decrease renal blood flow (RBF), so fluid repletion is important to maintaining renal perfusion.
Nitrous oxide is contraindicated for laparoscopic donor nephrectomy because bowel distention can impede surgery.
III. Living Liver Donors
Left lobe donation is usually done in the context of parent-to-child donation. Donor right lobectomy is needed for adult-to-adult liver transplantation.
Large liver resections may require virtually complete hepatic venous exclusion (cross-clamping of the hepatic pedicle, usually without cava clamping).
Transesophageal echocardiography is ideal and may obviate placement of central lines.
INR increases significantly after right lobe surgery, peaking a few days after surgery along with a decrease in platelet counts, just when an epidural catheter for postoperative pain management is usually removed.
IV. Immunosuppressive Agents
(Table 51-2). Pharmacologic suppression of the immune response to allografts is associated with major side effects (Table 51-3). Immune-suppressed patients coming to the operating room deserve special attention to sterile technique and maintenance of antibiotic, antifungal, and antiviral regimens during the perioperative period.
Table 51-2 Immunosuppressive Drugs | ||
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Table 51-3 Complications of Chronic Immune Suppression | ||||||||||||||||
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V. Corneal Transplantation
Corneas are the most common organs transplanted in the United States being performed under local anesthesia (often with intravenous sedation) or general anesthesia.
A major anesthetic goal is maintaining low intraocular pressure.
VI. Renal Transplantation
Preoperative Considerations. An enormous variety of diseases are treated with renal transplants (Table 51-4). About 50% of deaths of patients on dialysis are caused by heart failure. Hypercoagulable states are common in patients with renal disease.
All solid organ transplant patients are screened for tumors (mammography, Pap test, colonoscopy, prostate specific antigen) and infection (dental evaluation, viral serologies).
Extended criteria donors (age, creatinine, stroke or cardiac event as a cause of death, hypertension) are often
used for kidney transplantation. (Minimization of cold ischemia times is essential.)
Table 51-4 Diagnoses of Patients on Adult Renal Trnsplant Waiting List
Diagnosis
Patients on List (%)
Type 2 diabetes
30.0
Hypertensive nephrosclerosis
21.5
Glomerular disease
19.7
Polycystic kidney disease
6.6
Tubular/interstitial disease
5.0
Renovascular/other vascular disease
3.6
Congenital or metabolic disease
3.1
Neoplasm
0.3
Other
0.5
Kidney allocations (blood type O kidneys allocated to type O recipients; blood type B kidneys are transplanted only in B recipients) are more complex than liver allocations.
Intraoperative Protocols. Renal transplantation is generally done under general anesthesia. Before incision, antibiotics are given. A central venous catheter (usually triple lumen) is placed for CVP monitoring and drug administration, and a bladder catheter is placed.
The major anesthetic consideration is maintenance of RBF.
Typical hemodynamic goals during renal transplant surgery are systolic pressure >90 mm Hg, mean systemic pressure >60 mm Hg, and CVP >10 mm Hg. Plasmalyte is the crystalloid of choice for kidney transplantation and preserves acid–base balance and electrolytes compared with Ringer’s lactate or normal saline.
After the first anastomosis is started, a diuresis is initiated (mannitol and furosemide are often both given). Dopamine does not reliably improve renal function in this setting.
Tight blood glucose control (80–110 mg/dL) during renal transplantation is a reasonable anesthetic management goal.
Patient-controlled analgesia is a good choice for postoperative pain management perhaps combined with combination blocks (ilioinguinal–iliohypogastric and intercostal nerve blocks). Chronic pain after renal transplantation is a common problem.
Table 51-5 Diagnoses Leading Toliver Transplantation in Adults | |||
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