Mini-circuit cardiopulmonary bypass with vacuum assisted venous drainage: feasibility of an asanguineous prime in the neonate

Conventional cardiopulmonary bypass (CPB) in neonates results in increased transfusion requirements and hemodilution. There has been little advancemen t in CPB for the neonatal population. There is evidence that increased prim ing volumes and blood product transfusion enhances inflammatory response to CPB and increases myocardial and pulmonary dysfunction. We have devised a miniaturized CPB circuit that utilizes vacuum-assisted venous drainage (VAV D) in an effort to decrease priming volume and avoid transfusion requiremen ts. The purpose of this study was to evaluate the safety and efficacy of th is miniaturized CPB system and determine the feasibility of an asanguineous prime. Ten 1-week-old piglets were randomized to five mini- and five conve ntional CPB pump circuits. Subjects were supported with CPB at 100 ml/kg/mi n, cooled to 28 degrees C, exposed to 10 min aortic crossclamp with cardiop legic arrest, rewarmed to 37 degrees C, weaned from bypass, and subjected t o modified-ultrafiltration (MUF) for approximately 10 min. This method was chosen to simulate a situation with all the elements of clinical CPB. Blood transfusion trigger was a hematocrit <15 on CPB. Serum samples were obtain ed pre-CPB, at 15 min of CPB onset, immediately post-CPB completion, and im mediately post-MUF. indices of hemolysis (SGOT, LDH), production of inflamm atory mediators (interleukin (IL)-8, tumor necrosis factor-alpha (TNF alpha )), and physiologic parameters of inflammation were measured. The overall b lood requirement was significantly less in the mini-circuit compared to con ventional CPB (47.0 +/- 5.8 ml vs 314.2 +/- 31.6 ml. p < 0.0001). The only significant blood requirement in the mini-circuit was to replace the volume removed for samples. During the study, mean arterial pressure (MAP) (p = 0 .004), static pulmonary compliance(p = 0.04). platelets (p = 0.0003), and w hite blood cells (p = 0.003) significantly decreased across the groups. Lun g water content (p = 0.02), TNF alpha levels (p = 0.05). and SGOT (p = 0.00 9) increased significantly during the study, across the groups. Among all p arameters tested, except for blood requirement and hematocrit post-CPB, the re were no significant differences between the two circuits. VAVD makes asa nguineous prime in neonates feasible. When used in this study to miniaturiz e a conventional-CPB circuit, VAVD with a reconfigured neonatal CPB console and circuit resulted in no detrimental effects, and allowed for markedly d ecreased priming volumes and blood transfusion requirements.