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Trial Lecture – time and place
See Trial Lecture.
Adjudication committee
- First opponent: Professor Anders Jeppsson, University of Gothenburg, Sweden
- Second opponent: Consultant Hege Kristin Brekke, Haukeland University Hospital, Norway
- Third member and chair of the evaluation committee: Professor Peder Langeland Myhre, University of Oslo
Chair of the Defence
Professor Are Martin Holm, University of Oslo
Principal Supervisor
Associate Professor Johannes Lagethon Bjørnstad, University of Oslo
Summary
Intraoperative hemoadsorption may be a solution for reducing perioperative bleeding and mortality in apixaban-treated patients undergoing emergency surgery for acute type A aortic dissection (ATAAD).
The aim of this thesis was to investigate the effectiveness of a hemoadsorptive device in lowering plasma concentrations of the oral anticoagulant apixaban. Paper I demonstrated a >90% reduction in apixaban concentrations after 30 minutes in an in vitro circuit including a hemoadsorptive device. Analyses of global coagulation parameters indicated that the reduction of apixaban contributed to the normalization of coagulation. Paper II included eight apixaban-treated ATAAD patients requiring emergency aortic surgery. There was a mean apixaban concentration decline of 59% after 30 minutes of surgery with intraoperative hemoadsorption. However, there was a slight increase in apixaban concentrations postoperatively. Postoperative bleeding, measured by 24-hours chest tube drainage, was at an acceptable 621 (±136) mL. There were no reoperations due to bleeding.
The apixaban concentration decline was less pronounced in vivo than in vitro. Subsequently, hemolysis was investigated as a possible interfering factor. Hemolysis was induced in blood samples from 20 apixaban-treated patients. Apixaban concentrations were measured using both anti-Xa activity assay and liquid chromatography mass spectrometry. Hemolysis did not significantly affect apixaban concentrations, and the two methods for quantification showed excellent concordance in the presence of hemolysis. Other factors such as fluid shift and drug redistribution may contribute to the subtle apixaban concentration decline seen in vivo. Larger clinical studies are warranted to assess whether intraoperative hemoadsorption can significantly improve clinical and financial outcomes.
Additional information
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