Evaluation of Capiox FX05 Oxygenator With an Integrated Arterial Filter on Trapping Gaseous Microemboli and Pressure Drop With Open and Closed Purge Line

Gaseous microemboli (GME) remain a challenge for cardiopulmonary bypass (CPB) because there is a positive correlation between microemboli exposure during CPB and postoperative neurological injury. Thus, minimizing the number of GME delivered to pediatric patients undergoing CPB procedures would lead to better clinical outcomes. In this study, we used a simulated CPB model to evaluate the effectiveness of capturing GME and the degree of membrane pressure drop for a new membrane oxygenator, Capiox Baby FX05 (Terumo Corporation, Tokyo, Japan), which has an integrated arterial filter with open and closed purge line. We used identical components in this study as our clinical CPB circuit. Three emboli detection and classification quantifier transducers were placed at prepump, preoxygenator, and postoxygenator sites in the circuit. Two flow probes as well as three pressure transducers were placed upstream and downstream of the oxygenator. The system was primed with human blood titrated to 30% hematocrit with Lactated Ringer's solution. A bolus of air (1 mL) was injected in the prepump site under nonpulsatile perfusion mode at three flow rates (500, 750, and 1000 mL/min) and with the purge line either open or closed. Six trials were performed for each unique set-up for a total of 36 trials. All trials were conducted at 35 degrees C. The circuit pressure was kept constant at 100 mm Hg. Both the size and quantity of microemboli detected at postoxygenator site were recorded for 5 min postair injection. It was found that total counts of GME were significantly reduced with the purge line open when compared to keeping the purge line closed (P < 0.0001 at 1000 mL/min). At all flow rates, most of the GME were under 20 microns in size. In terms of microemboli greater than 40 microns, the counts were significantly higher with the purge line closed compared to keeping the purge line open at flow rates of 750 mL/min and 1000 mL/min (P < 0.01). At all flow rates, there is a tiny difference of less than 1 mm Hg in membrane pressure drop between keeping the purge line open and closed, which is due to the small arteriovenous (A-V) shunt (P < 0.001). These results suggest that the integrated arterial filter of the Capiox FX05 oxygenator significantly improves the capturing of GME but has little impact on membrane pressure drop.