Modified Ultrafiltration After Congenital Heart Surgery: A Veno–Venous Method Using a Dual-Lumen Hemodialysis Catheter

Abstract

Perfusion practice surveys on modified ultrafiltration show most clinicians reporting the use of arterial to venous cannulation. With an arterial–venous (A–V) approach, the patient’s blood is accessed in a retrograde direction from the cardiopulmonary bypass aortic cannula, and the hemoconcentrated blood is returned to a catheter placed at a systemic venous return site. To avoid possible hazards of these arterial–venous techniques, we developed a veno–venous (V–V) modified ultrafiltration circuit and method that: (1) uses an 11.5 F dual-lumen hemodialysis catheter placed at a right atrial cannulation site for concomitant pickup and return of the patient’s blood; (2) places the ultrafiltration circuit within the cardioplegia delivery system, enabling the use of the heat exchanger/bubble trap features and also allowing hemoconcentration during cardiopulmonary bypass; and (3) uses an elevated, collapsible transfusion bag within the circuit as a holding reservoir for crystalloid-chased blood from the CPB circuit. The product literature and our lab testing of the hemodialysis catheter indicates adequate hemodynamics for modified ultrafiltration in children, and our clinical experience shows routine completion of the process in about 10–15 min (12.67 ± 1.73 mins; mean ± 1 SD, N = 9). Advantages of this V–V approach compared to A–V access include: (1) no potential aortic air entrainment at the aortic cannula purse-string suture; (2) modified ultrafiltration in patients regardless of aortic size or anatomy; and (3) avoidance of significant arterial to venous shunts during the performance of modified ultrafiltration. The elevated reservoir within the modified ultrafiltration circuit allows: (1) efficient pre- and/or postultrafiltration fluid chasing of blood from the main cardiopulmonary bypass circuit, thereby keeping it safely primed and allowing for the concentration of all circuit contents before and/or following the ultrafiltration method; (2) maintenance of desired patient filling pressures, temperature, and blood oxygen saturation within the ultrafiltration circuit by intermittent addition of warmed, oxygenated blood to the V–V modified ultrafiltration circuit.