Kidney Support and Perioperative Care in Kidney Transplantation

Pretransplant Evaluation

Perioperative management of kidney transplant recipients begins when they initially are admitted for the transplant. At that time, a complete review of the patient's prior history, current medical conditions, and any recent events that could increase the risk of transplantation should be assessed. A complete physical examination should be performed searching for active illnesses, which could prevent surgery. If no active problems are present, attention should be directed to laboratory studies drawn preoperatively. In particular, the serum potassium (K) should be normal, which at most centers is usually serum K <5.5 mEq/L. A careful assessment for preoperative dialysis need should be undertaken.

Typically, routine dialysis is avoided on the day of renal transplantation except in urgent scenarios, such as hyperkalemia and volume overload. Mild hyperkalemia is common in patients with end-stage kidney failure. Peritoneal dialysis (PD) patients tend to be hypokalemic and seldom require preoperative dialysis. We generally dialyze patients on chronic maintenance hemodialysis (HD) if serum potassium is at least 5.5 mEq/L. A heparin-free dialysis is recommended to reduce risk of bleeding. Duration of dialysis is usually 2 hours because maximum potassium removal is achieved satisfactorily in this time period, and prolongation of cold ischemia time in the donor kidney can be avoided. Alternatively, if the patient will be undergoing preemptive kidney transplant and does not have established access, a trial of intravenous (IV) administration of 10 units of regular insulin together with 50 mL of 50% glucose (i.e., 25 g of glucose) is usually successful. This modality can be repeated intraoperatively as needed. Sodium polystyrene sulfonate should be avoided in pre- and postoperative settings to treat hyperkalemia because of its known association with intestinal necrosis and perforation. Significant volume overload before transplantation is also an indication for dialysis to best optimize for surgery. Usually, ultrafiltration modality is used, and the patient is left about 2 kg above preoperative dry weight. A relatively low ultrafiltration goal (such as 5 to 10 mL/kg per hour) may be reasonable to allow for sufficient plasma reequilibration and thus avoid intraoperative hypotension commonly encountered with anesthesia induction. With the standard use of biocompatible dialysis filters (polyacrylonitrile and others), there is less concern about complement and cytokine activation hampering graft recovery.

It is not uncommon to encounter uncontrolled blood pressure in the preoperative setting because of NPO status resulting in mild hypoglycemia and catecholamine release. These patients may have missed medications and may experience sympathetic stimulation from anticipated surgical stress or anxiety. If blood pressure (BP) remains unacceptably high (e.g., more than 200/120) and volume overload is absent, then an intraoperative antihypertensive agent such as nicardipine, hydralazine, or labetalol with cautious titration can be used to aim for slow and modest BP reduction to the range of 160 to 180/90 to 100. Overzealous treatment should be avoided to minimize risk of intraoperative hypotension with anesthesia induction, which happens because of decreased sympathetic tone, depressed cardiac contractility, and reduced venous return.

Hypertension usually can be managed intraoperatively. Intraoperative IV labetalol is popular but can pose a risk of severe hyperkalemia in HD patients with long cold ischemia times and low intra- and postoperative urine outputs. Labetalol is a nonselective beta blocker and should be avoided in any patient expected to have delayed graft function such as donors after cardiac death (DCD), elderly donors, and those with prolonged cold ischemia times. This tendency for hyperkalemia is not seen with usage of β-1 selective agents such as metoprolol since the β-2 receptors remain intact. Most would favor the use of perioperative beta blockers and continuation of statins because both have been associated with reduced perioperative mortality in a variety of settings. In addition, these patients will receive antibody preparations intraoperatively as part of immunosuppressive induction protocol. This could worsen further hypotension especially in the background of recent, large volume-ultrafiltration.

All medications should be reviewed closely before surgery, and agents likely to cause posttransplant complications should be stopped. In particular, angiotensin inhibitors are held by many programs because they may predispose to hyperkalemia, anemia, and elevated creatinine. Given the long-term advantages, many would restart these agents once patients are stable weeks to months later.

It is a common recommendation to avoid or minimize blood transfusions preoperatively in transplant candidates to reduce risk for sensitization. If transfusion becomes necessary during the perioperative period, leukocyte-reduced packed cells are used.