Comparison of hollow-fiber membrane oxygenators in terms of pressure drop of the membranes during normothermic and hypothermic cardiopulmonary bypass in neonates Akif U ¨ ndar 1,2 , W Richard Owens 1 , Mary Claire McGarry 1 , Deborah L Surprise 1 , Vicki D Kilpack 1 , Maryann W Mueller 1 , E Dean McKenzie 1,2 and Charles D Fraser Jr. 1,2 1 Congenital Heart Surgery Service, Texas Children’s Hospital, Houston, USA; 2 Division of Congenital Heart Surgery, Michael E. DeBakey Department of Surgery, Baylor College of Medicine, Houston, USA The objective of this study was to investigate the effects of two hollow-fiber membrane oxygenators, the Capiox SX10 and the Lilliput 901, on pressure drop of the membranes during normothermic and hypothermic car- diopulmonary bypass (CPB) in neonates. Methods : Twenty-six congenital heart surgery patients (n  /13 in each group) with a mean weight of 3 kg were included in this study. Pressure drops of the membranes, pre- and post-oxygenator extracorporeal circuit pressures (ECC) were recorded during normothermic CPB, hypo- thermic CPB (208C) and after rewarming. There were no differences between the groups in mean arterial pressure, pump flow rate, temperature, duration of CPB, cross- clamp time or the severity of the surgical repairs. Results : Pressure drop of the Capiox SX10 oxygenator was significantly lower during normothermic (329 /10 versus 559 /16 mmHg, p B /0.001), hypothermic (389 /15 versus 729 /18 mmHg, p B /0.001) and post-rewarming (429 /13 versus 729 /21 mmHg, p B /0.001) periods com- pared to the Lilliput oxygenator. In the Capiox group, the pre-oxygenator ECC pressure was also significantly lower during normothermic CPB (1429 /27 versus 1849 /43 mmHg, p B /0.01), hypothermic CPB (1629 /30 versus 1999 /38 mmHg, p B /0.01) and after rewarming periods (1729 /32 versus 2129 /42 mmHg, p B /0.01). Post-oxygena- tor pressures in the Capiox group were also lower than in the Lilliput group, but results were not statistically significant. Conclusions : These results suggest that the Capiox SX10 hollow-fiber membrane oxygenator pro- duced significantly lower membrane pressure drops and pre- and post-oxygenator ECC during normothermic and hypothermic CPB. Thus, blood trauma with the Capiox during extracorporeal circulation may be signifi- cantly lower compared to the Lilliput. Further studies, including the level of complements, platelets, neutrophils and cytokines, with these oxygenators are warranted. Perfusion (2005) 20, 135  /138. Introduction During the past two decades, mortality rates after pediatric cardiopulmonary bypass (CPB) procedures have significantly lowered, but the morbidity to the vital organs remains a significant clinical problem. 1  5 Today, most of the research on this topic is focused on developing alternate methods for minimizing the vital organ injury in pediatric cardiac patients, particularly in neonates and in- fants. 6  14 The pressure drop (difference between the inlet and outlet pressures) of membrane oxygenators is an important factor in minimizing the adverse effects of CPB procedures in terms of less systemic inflamma- tion and hemolysis. 15  17 A membrane oxygenator with a lower pressure drop is more favourable because of lower resistance to the blood flow. 15  17 The biggest difference in perfusion protocols between the adult and pediatric CPB is the pump flow rates. In particular, the pump flow rates in neonates are three or four times higher (150  /200 versus 50 mL/kg per min) than in adults during CPB. Therefore, the pressure drop of the membrane is more important in neonatal CPB because of the Address for correspondence: Akif U ¨ ndar, Associate Professor of Pediatrics, Surgery and Bioengineering, Department of Pediatrics  / H085, Penn State College of Medicine, 500 University Drive, P.O. Box 850, Hershey, PA 17033-0850, USA. E-mail: aundar@psu.edu Perfusion 2005; 20: 135 /138 # 2005 Edward Arnold (Publishers) Ltd 10.1191/0267659105pf796oa © 2005 SAGE Publications. All rights reserved. Not for commercial use or unauthorized distribution. at PENNSYLVANIA STATE UNIV on October 2, 2007 http://prf.sagepub.com Downloaded from