Using Zero Balance Ultrafiltration with Dialysate as a Replacement Fluid for Hyperkalemia during Cardiopulmonary Bypass

Abstract

Avoiding or managing hyperkalemia during cardiac surgery, especially in a patient with chronic renal insufficiency, can be challenging. Hyperkalemic cardioplegia solution is usually administered to achieve and maintain an electrical arrest of the heart. This solution eventually mixes in with the systemic circulation, contributing to elevated systemic potassium levels. Administration of packed red blood cells, hemolysis, tissue damage, and acidosis are also common causes of hyperkalemia. Current strategies to avoid or manage hyperkalemia include minimizing the volume of cardioplegia administered, shifting potassium from the extracellular into the intracellular space (by the administration of sodium bicarbonate when the pH is low and/or dextrose–insulin when effects relatively independent of serum pH are desired), using zero-balanced ultrafiltration (Z-BUF) with normal saline as the replacement fluid (to remove potassium from the body rather than simply shift the electrolyte across cellular membranes), and, occasionally, hemodialysis (1). We report the application of Z-BUF using an electrolyte-balanced, low potassium dialysate solution rather than isotonic saline to avoid a high chloride load and the potential for hyperchloremic acidosis to successfully treat hyperkalemia while on cardiopulmonary bypass.

Kidney Replacement Therapy for Patients Requiring Cardiopulmonary Bypass Support during Cardiac Surgery

“…Although early descriptions of intraoperative management of KRT-dependent patients on cardiopulmonary bypass relied exclusively on medical management, we feel that the risks of the aforementioned potential intraoperative complications necessitate KRT support while on cardiopulmonary bypass. Given the physical space constraints of the operating room for patients with complex cardiac surgical cases, the unpredictable timing of cardiopulmonary bypass support in relation to the operating room case time, and the large intraoperative multidisciplinary teams already caring for these patients, we prefer a strategy relying on hemofiltration on the cardiopulmonary bypass circuit over HD or CKRT (5,7). Utilizing hemofiltration performed by the perfusion team streamlines the coordination of timing between KRT and cardiopulmonary bypass support and minimizes the need for additional personnel and equipment in the operating room.…”

“…The cardiopulmonary bypass circuit is depicted in Figure 1A. The hemofiltration procedure utilizes a high-flux polyethersulfone membrane hemoconcentrator (effective surface area of 0.68 m 2 ) (8), which is connected in parallel to the cardiopulmonary bypass circuit (Figure 1A) (5,7). The estimated BP postoxygenator is approximately 200-300 mm Hg, with variable blood flows ranging from 300 to 500 ml/min.…”

Hemofiltration Improves Blood Perfusate Conditions Leading to Improved Ex Situ Heart Perfusion

“…The hemofiltrator has previously been used in cardiopulmonary bypass (CPB) research as zero-balance ultrafiltration, where saline fluid is given back to the patient’s circulation in a 1:1 ratio with the removed ultrafiltrate to achieve fluid balance. 11,12 Zero-balance ultrafiltration has been used to optimize potassium levels during CPB 12 and has been shown to improve cardiac function in acute porcine studies, possibly by removing potential deleterious substances 13,14 and several inflammatory mediators, such as Interleukin (IL)-6, IL-8, Tumor Necrosis Factor (TNF), and activated complement factors. 11,15 Recently, hemofiltration (HF) showed reduced mortality in dialysis patients compared with hemodialysis.…”