Tissue Plasminogen Activator for Suspected Oxygenator Thrombosis of Venovenous Extracorporeal Membrane Oxygenation for Severe COVID-19 Hypoxemic Respiratory Failure: A Case Series

ABSTRACT

Background: Although commonly seen as a respiratory causing disease, COVID-19 is associated with increased coagulopathy and thrombus formation. Venovenous extracorporeal membrane oxygenation (VV-ECMO), a rescue therapy for severe acute respiratory distress syndrome (ARDS) usually requires anticoagulation. We present three patients with suspected oxygenator thrombosis that were successfully treated with a protocolized tissue plasminogen activator (Alteplase). Case Presentation All three cases were male patients, with a median age of 42, that tested positive for SARS-CoV-2 requiring mechanical ventilation and subsequently VV-ECMO (Maquet Cardiohelp HLS HIT 7.0, Getinge, Sweden) for severe ARDS. In all patients, heparin infusion was the anticoagulation of choice. During the first 24-48 hours of starting ECMO, transmembrane pressure (delta-P) elevation started and was sustained in the range 70-100 mmHg. This was associated with a drop in blood flow rate, elevated fibrinogen, fibrinogen degradation products, and hypercoagulable state on rotational thromboelastometry (ROTEM, TEM Ltd, Germany), raising the possibility of oxygenator thrombosis. After determining low risk of bleeding, Alteplase was administered following the K-ECLS protocol, mitigating the need to change the ECMO circuit. Two patients were successfully decannulated and discharged home in good condition. Whilst, one of the patients remains on ECMO. Conclusions: Protocolized t-PA for ECMO oxygenators with suspected thrombosis is feasible and cost-effective in mitigating circuit change for patients on VV-ECMO for ARDS due to COVID-19. Such protocol might be generalizable to all ECMO patients who have low risk of bleeding. To our knowledge, this is the first case series of such therapy and protocol.