What are the major anesthetic concerns for renal transplantation?

What are the major anesthetic concerns for renal transplantation?

Anesthetic management for patients receiving kidney transplantation is similar to that for patients with chronic renal failure. Many patients have diabetes mellitus, so there is a need to monitor blood glucose concentrations in the perioperative period. Preoperative hemodialysis optimizes uremic coagulopathies due to platelet dysfunction, improves acid–base imbalance, reduces intravascular vol-ume, and corrects serum K⁺ levels. Both general and regional anesthesia have been used successfully during renal transplantation.

When general anesthesia is chosen certain anesthetic considerations come into play. A useful approach is the administration of volatile inhalation agents combined with nitrous oxide and short-acting opioids. Patients with diabetic gastroparesis require aspiration prophylaxis and rapid sequence induction with cricoid pressure. Pretreatment with a nonparticulate antacid, such as bicitrate, and a prokinetic, such as metoclopramide, to increase lower esophageal tone and increase gastrointestinal motility are recommended. These drugs will increase gastric pH and decrease gastric volume. If serum K⁺ levels are equal to or greater than 5.5 mEq/L, succinylcholine may be contra-indicated. K⁺ levels can increase by as much as 0.5–1.0 mEq/L after a single dose of succinylcholine, predisposing to hemodynamically significant acute hyperkalemia and its complications. Choice of muscle relaxant pivots on the unpredictable nature of renal function after renal transplantation. Intermediate-acting muscle relaxants degraded by Hoffman elimination, such as cisatracurium or atracurium, are more predictable than a renally excreted nondepolarizing neuromuscular blocker, such as pan-curonium. Rocuronium and vecuronium are acceptable choices also.

Regardless of the muscle relaxant selected, doses should be carefully titrated. Patients should be closely observed for early postoperative skeletal muscle weakness. The duration of anticholinesterase drugs used to antagonize nondepo-larizing neuromuscular blockers is prolonged.

K⁺-containing intravenous fluids should be used with caution, if at all. Anephric patients require approximately 8 mL/kg per day of fluid to replace insensible water losses, which can be accomplished with hyponatremic solutions, such as dextrose in water. For other intraoperative fluid requirements, normal saline may be preferable to lactated Ringer’s solution when hyperkalemia is a concern. Tissue oxygen delivery is improved with adequate volume replace-ment. Central venous pressure (CVP) monitoring is some-times used to optimize fluid management. Poor cardiac reserves may indicate the need for pulmonary artery mon-itoring. Diuretics are administered to improve urine out-flow in the newly transplanted kidney. Mannitol, an osmotic diuretic, is used frequently. A loop diuretic, such as furosemide or ethacrynic acid, may be added to mannitol. Unlike loop diuretics, mannitol does not depend on renal tubular concentrating ability to produce a diuresis.

Regional anesthesia has been used successfully during renal transplantation. It frequently avoids the need for tracheal intubation and the associated hemodynamic changes. However, there are disadvantages to regional anesthesia. Sympathetic blockade secondary to regional anesthesia predisposes to hypotension, especially at times of intravascular volume fluxes. It may be necessary to administer more fluid to optimize blood pressure. Consequently, when sympathetic tone returns and the vascular space shrinks in size, pulmonary edema may occur. Epidural and spinal techniques are contraindicated in the presence of uremic coagulopathy secondary to platelet dysfunction. It may be necessary to supplement regional anesthetics with intravenous agents, which depress respiration and thus increase the possibility of respiratory support.