CARD31: Novel Tubing Connectors Reduce ECMO Circuit Thrombosis

Abstract

Background: Extracorporeal Membrane Oxygenator (ECMO) circuit thrombosis is a common complication that plagues the clinical management of patients receiving mechanical circulatory support. High doses of anticoagulation required to reduce circuit thrombus burden can increase hemorrhagic complication risk, yet concomitantly persistent circuit clots result in frequent circuit replacement. Prior studies have identified the tubing-connector junction as contributing over 80% of circuit clots. Analysis and alteration of this junction can optimize mechanical flow properties to reduce the overall clot burden. We have designed a novel connector to reduce or eliminate the primary source of ECMO circuit clots. Methods: Our study utilized a combination of ex vivo and in vivo evaluation of our novel tubing connectors in comparison to current connectors. Our novel connectors were designed for use with 3/8” tubing and created using injection molding (Fig 1). For ex vivo simulation, we created a flow loop with 3/8” tubing and alternated current and novel connectors. Heparinized porcine blood was perfused for 96 hours. For in vivo assessment, we cannulated four goats with arterial and venous large-bore catheters and created an ECMO circuit with an oxygenator per standard clinical practice. These circuits were run for varying time periods, ranging from 12h to 48h. After completion of blood perfusion in both experimental setups, connectors were excised from the circuits and inspected. Clots were quantified for presence and radial protrusion into the connector lumen, and compared across connector type. Results: In both ex vivo and in vivo configurations, the current connectors formed large clots. In contrast, novel connectors formed almost no clots (p<0.01). Ex vivo flow loops showed more than one clot per current connector (upstream and downstream), while novel connectors contained only a single clot amongst 9 connectors with no luminal protrusion (Fig 2). In vivo connectors (Fig 3) were analyzed using a grading system involving clot presence and luminal protrusion. Current connectors had a significantly higher clot presence score (p<0.01) and lumen protrusion score (p<0.01) than novel connectors. Summary: Novel ECMO tubing connectors significantly reduce clot burden and can be easily integrated into current clinical practice, suggesting they may make significant impact in clinical ECMO circuits. Substantial reduction in thrombogenicity has the potential to reduce the need for anticoagulation, thereby also reducing adverse hemorrhagic events.