Zero balance ultrafiltration (Z-BUF) in blood-primed CRRT circuits achieves electrolyte and acid-base homeostasis prior to patient connection

Abstract

Infants requiring CRRT present a unique challenge due to the large circuit volume to blood volume ratio. Blood priming is often used, but some patients can become unstable during the initiation of CRRT due to electrolyte and acid-base imbalance. We postulated that using Z-BUF we could normalize electrolytes and improve the acid base status of the prime prior to patient connection. To test this we set up a circuit using the Baxter BM-25 CRRT pump, a polysulfone or AN-69 membrane, and a three-way stopcock. The circuit was primed with a 60/40 mix of expired autologous donor pRBCs and 5% albumin. The modalities of CVVH, CVVHD, and CVVHDF were compared for relative efficacy. Electrolytes, lactate, pH, cytokines (TNF-alpha, IL-1beta, bradykinin, and IL-6) were measured. Plasma hemoglobin levels were also measured before and after the Z-BUF procedure. Bradykinin production and elimination in AN-69 membrane circuits were assessed. All lab values equilibrated by 35 minutes. All CRRT modalities were equally efficacious for Z-BUF. Cytokine production or significant hemolysis was not found. In addition, no bradykinin accumulation occurred in AN-69 membrane-containing circuits. We conclude that Z-BUF is a simple and effective way to normalize electrolyte and acid-base status in the CRRT circuit when blood priming is required.

Innovative Techniques to Decrease Blood Exposure and Minimize Interruptions in Pediatric Continuous Renal Replacement Therapy

“…Manipulation of the bloodprimed circuit before connection to the patient is often necessary. Either the zero-balance ultrafiltration technique, which results in buffered blood priming, 30 or the circuit bypass method, which avoids initial contact of the acidotic donated red blood cells with the AN-69 membrane can be used. 28 Compared with traditional blood priming methods, the circuit-to-circuit exchange technique takes place over 3 to 5 minutes, thereby reducing the risk of fluid accumulation and reduced solute clearance associated with prolonged interruptions of CRRT.…”

Recent innovations in perfusion and cardiopulmonary bypass for neonatal and infant cardiac surgery

“…While centrifugal cell washing as of 2004 was used in 60% of congenital heart surgery centers (16) and has been shown to be effective in correcting pH and lowering potassium, lactate and glucose (17)(18)(19), several studies have reported that the process increases cell wall fragility and leads to increased hemolysis (20)(21)(22). Blood prime ultrafiltration has also been reported to make the prime physiologic, but without the attendant hemolysis or additional disposables cost (23)(24)(25)(26).…”

Complications During Continuous Renal Replacement Therapy in Critically Ill Neonates

“…However, packed RBCs have frequently abnormal electrolyte and acid-base balance, which are used for blood priming [12]. Therefore, the mixed fluid, which primed the circuit, should be purified before connecting to neonates, and the carrying out of blood priming takes up to 30 min more [6,12]. In addition, the frequent use of packed RBCs would increase the risk of transfusion-associated complications, such as various infections [24,25].…”

“…However, packed RBCs have frequently abnormal electrolyte and acid-base balance, which are used for blood priming [12]. Therefore, the mixed fluid, which primed the circuit, should be purified before connecting to neonates, and the carrying out of blood priming takes up to 30 min more [6,12].…”

“…Therefore, all cases needed priming of the circuit with packed red blood cells (RBCs) mixed with 5% albumin (ratio of 6-4) before starting CRRT [6]. Thereafter, the priming blood was purified until the high level of potassium, low level of calcium, low pH, and acidemia were corrected; water was removed until the hematocrit was corrected before connecting to the patients [12]. All CRRT sessions used nafamostat mesilate for anticoagulation.…”