When you care for a patient who is undergoing a kidney transplant, what fluid do you use for maintenance? If your answer is normal saline, your fluid choice matches that of the majority of anesthesiologists in the United States. The reason for this practice, is, in part, because of the fear of causing hyperkalemia if lactated Ringer’s solution is used. The problem is that normal saline contains an excess of chloride ion, which can lead to hyperchloremic acidosis, renal vasoconstriction, and decreased glomerular filtration rate. Dr. Gregor Lindner, Department of Internal Medicine Inselspital, University Hospital Bern, Bern, Switzerland, and colleagues compared 150 patients undergoing cadaveric kidney transplantation who were randomized to receive either normal saline or chloride-reduced, acetate-buffered balanced crystalloid (Elomel Isoton®, Fresenius Kabi, Austria, GmbH). The results of their study are published in this month’s issue of Anesthesia & Analgesia in the article titled “An Acetate-Buffered Balanced Crystalloid Versus 0.9% Saline in Patients with End-Stage Renal Disease Undergoing Cadaveric Renal Transplantation: A Prospective Randomized Controlled Trial.”
All patients had both a central and peripheral line. Fluid infusion rate during surgery was set at 4 mL/kg/hour. Postoperative maintenance infusion rate was set at 2 ml/kg/hour until the patient was transferred to the ward. Both during surgery and perioperatively, the amount of fluid volume administered was no different between groups. Hyperkalemia was higher in the acetate-buffered crystalloid solution group (17% saline vs. 21% acetate-buffer) while maximum chloride was higher in the saline group (109 mmol/L vs. 107 mmol/L). Metabolic acidosis, based on base excess deficit measurement, was greater in the saline group (-4 mmol/L) than the balanced crystalloid group (-1.6 mmol/L). Catecholamine use was higher in the saline group than the balanced regimen group (30% vs. 15%). There was neither a difference between the two groups in the need for dialysis until postoperative day 7 nor was there a difference with regard to urine output, serum creatinine, or blood urea nitrogen.
The fluid tested in this study is not universally available. This article does serve to remind us, however, that normal saline is almost never the preferred intraoperative fluid, even in cases of renal failure.