Case Report: Navigating the bleeding-thrombosis paradox: regional nafamostat anticoagulation in a post-intracerebral hemorrhage patient on VV-ECMO.

Extracorporeal membrane oxygenation (ECMO) in patients following intracerebral hemorrhage (ICH) poses a critical dilemma between circuit thrombosis and catastrophic rebleeding. While nafamostat mesylate (NM) has been increasingly explored for ECMO anticoagulation in patients with ICH, it is conventionally administered as a systemic anticoagulant with high activated partial thromboplastin time (aPTT) targets, which still carries significant bleeding risks. Moreover, whether NM can achieve effective regional anticoagulation in venovenous (VV) ECMO remains highly controversial. Here, we present a post-ICH patient with severe ARDS who required VV-ECMO. Due to suspected rebleeding, anticoagulation was transitioned from heparin to an anticoagulant-free strategy, which subsequently led to significant oxygenator thrombosis. To navigate this crisis, NM was initiated with an ultra-low systemic target, but it initially failed to establish a regional anticoagulant effect when infused at the conventional pre-membrane, post-pump site. Crucially, relocating the NM infusion to the pre-pump position successfully established a significant circuit-to-systemic aPTT gradient. This technical optimization enabled effective circuit anticoagulation while minimizing systemic bleeding risk, allowing for successful ECMO weaning without bleeding complications. This dynamic intra-patient observation highlights the potential impact of infusion site on coagulation outcomes. We hypothesize that harnessing the centrifugal pump's high-shear turbulence for homogenous drug mixing might serve as a crucial prerequisite for achieving regional anticoagulation in VV-ECMO. These findings bridge the gap between theoretical pharmacology and practical circuit engineering, offering a practical preliminary reference for the future anticoagulant management of similar high-bleeding-risk patients on ECMO.