The Capability of Trapping Gaseous Microemboli of Two Pediatric Arterial Filters With Pulsatile and NonPulsatile Flow in a Simulated Infant CPB Model SHIGANG WANG,* KHIN N. WIN,* ALLEN R. KUNSELMAN,† KARL WOITAS,‡ JOHN L. MYERS,*‡ AND AKIF ¨ UNDAR*‡§ The study objective was to test the capability of Medtronic Affinity and Terumo Capiox pediatric arterial filters to trap gaseous microemboli in a simulated infant cardiopulmonary bypass (CPB) model. The filters were used in parallel pattern. The circuit was primed with lactated ringer’s solution (700 ml) and postfilter pressure was maintained at 100 mm Hg using a Hoffman clamp. Trials were conducted at flow rates ranging from 500 to 1,250 ml/min. After introducing 20 ml air into the venous line via an 18-G needle, 2-minute segments of data were recorded. This entire process was repeated 6 times for each unique combination of arterial filter, flow rate and perfusion mode, yielding a total of 96 experiments. More than 80% of gaseous microemboli were trapped by the two pedi- atric arterial filters. With increased flow rates and pulsatile mode, more gaseous microemboli passed through the arterial filters. There were no differences in terms of the percentage of gaseous microemboli trapped and pressure drops between Medtronic Affinity and Terumo Capiox pediatric arterial fil- ters. Results demonstrated that Medtronic Affinity and Terumo Capiox pediatric arterial filters could trap the major- ity of gaseous microemboli in this particular setting of an open arterial filter purge line in a simulated infant CPB circuit with pulsatile and nonpulsatile flow. ASAIO Journal 2008; 54: 519 –522. A rterial filters have been used in extracorporeal circuits for several decades, and it is generally accepted that arterial filters could alleviate postoperative neurological complications in patients undergoing cardiopulmonary bypass (CPB). 1,2 This is why the majority of heart centers utilize arterial filters in CPB circuits. The screen arterial filter is popularly used in clinics, and its different defined pore size (20 – 40 m) and geometric design influence the capability of trapping gaseous microem- boli. In addition, an open purge line of the arterial filter could augment the removal of gaseous microemboli in the circuit. Different products of the arterial filter possess different hemo- dynamic characteristics and effectiveness. 3 Our previous studies 4–6 have proven that the Emboli Detec- tion and Classification (EDAC) Quantifier is a useful tool for real-time monitoring and characterization of gaseous micro- emboli as small as 10 m in a CPB circuit. The high sensitivity facilitates the detection of gaseous microemboli and their clas- sification by size under any experimental conditions. With the aid of this device, it is possible to test the capability of the arterial filters and membrane oxygenators to trap gas- eous microemboli. 3–6 The Medtronic Affinity pediatric arterial filter was recently introduced into clinical CPB procedure, whereas the Terumo Capiox pediatric arterial filter has been used in clinic for many years. The objective of this study was to test the capability of Terumo Capiox and Medtronic Affinity pediatric arterial filters to trap gaseous microemboli in a simulated infant CPB model, thus providing information for clinical use. Materials and Methods Experimental Infant CPB Circuit Design The experimental circuit was designed to simulate an infant patient undergoing CPB (see Figure 1) and was described in our previous study. 6 The experimental circuit included a Capiox pediatric arterial filter (Terumo Corporation, Tokyo, Japan), and a special arterial filter purge line which was directly connected to the arterial filter and the venous line via a luer at the inlet of the venous reservoir. Every component of this circuit is identical to the circuit used in our institution’s pediatric cardiac surgery op- erating room. An affinity pediatric arterial filter (Medtronic Inc., Minneapolis, MN) was inserted into the circuit at both sides of a Capiox pediatric arterial filter in parallel pattern. The purge line of the Affinity arterial filter was combined with the purge line of the Capiox arterial filter using a “Y” connector. The specifications of the two arterial filters are presented in Table 1. The circuit was primed with 700 ml of lactated ringer’s solution, and de-aired according to clinical priming proce- dure. The pseudo patient and the venous reservoir level were maintained at 200 ml. A Hoffman clamp was placed at the end of the arterial line to maintain a given arterial line pressure during all flow rates. A second Hoffman clamp was placed on the proximal venous line to balance the difference between the arterial flow rate and the venous drainage. From the *Department of Pediatrics, Pediatric Cardiac Research Laboratories, Penn State Children’s Hospital; †Health Evaluation Sci- ences, Penn State College Medicine; Departments of ‡Surgery, Penn State Milton S. Hershey Medical Center; and §Bioengineering, Penn State College Medicine, Hershey, Pennsylvania. Submitted for consideration May 2008; accepted for publication in revised form May 2008. Presented at the fourth International Conference on Pediatric Me- chanical Circulatory Support Systems and Pediatric Cardiopulmonary Perfusion, May 22–24, 2008, Portland, Oregon. Reprint Requests: Akif U ¨ ndar, PhD, Department of Pediatrics, Penn State College of Medicine, H085, 500 University Drive, P. O. Box 850, Hershey, PA 17033-0850. Email: aundar@psu.edu. DOI: 10.1097/MAT.0b013e318184a9ab ASAIO Journal 2008 519