The Time Course of Clinical Oxygenator Failure Due to Clot Formation

BackgroundLong-term use of extracorporeal membrane oxygenation (ECMO) remains limited because of poor biocompatibility, which often leads to clot formation and device failure. Despite this common pathway to failure, there are no published studies on the rate of clot formation and resulting performance deficits in current oxygenators. MethodsECMO cases with either Maquets CardioHelp (CH, n=28) or Quadrox (Qx, n=14) oxygenators were evaluated over a three-month period. Data was collected prospectively and included patient characteristics and hematological data. The inlet-outlet oxygen content difference ({Delta}CO2) and blood flow resistance were calculated as measures of device function, and device failure due to clot formation was defined as a resistance increase greater than 1 mmHg/(L/min)/day for more than one day. ResultsThere were no statistically significant differences in patient age, total days on ECMO, platelet count (PLT) prior to ECMO, activated partial thromboplastin time during ECMO, initial resistance, and device blood flow rate. During ECMO, the Qx group had a significantly greater change in PLT (Qx: - 34{+/-}10%; CH: 7{+/-}15%), rapidity to failure due to clot formation, and a greater decline in {Delta}CO2 (all p<0.05). Clot burden was focused at the center of the CH oxygenator, farthest from all inlets, whereas Qx devices developed a more diffuse clot pattern. ConclusionsQx oxygenators clot earlier than CH oxygenators with a correlated drop in {Delta}CO2 and greater PLT reduction. These differences are likely due to the distributed, four-inlet CH design vs. the single inlet Qx design and differences in pump-induced platelet activation.