Oxygen demand and neuronal biomarker release during extracorporeal circulation

Abstract

Extracorporeal circulation (ECC) has revolutionized open-heart surgery, but its application has also extended beyond cardiac procedures into other medical domains, including locoregional cancer treatment, where ECC is combined with chemotherapy. The overall aim of this thesis was to explore patient physiological response and alternative approaches in extracorporeal circulation to increase understanding of procedure related side effects.

In Paper I, a randomized controlled non-inferiority trial, we investigated the possibility of replacing the current erythrocyte-based prime solution with a crystalloid-based one, while ensuring sufficient oxygen delivery for patients undergoing isolated limb perfusion (ILP). We found no significant benefits of continuing adding erythrocytes to the prime solution for ILP, a finding leading to practice and guideline changes. In Paper II the oxygen demand in an isolated extremity was measured and described for the first time. Based on the findings, recommendations for nadir oxygen delivery during ILP was provided. Patients treated with ILP can develop transient peripheral nerve damage, and in Paper III, we explored if this could be detected using novel neuronal biomarkers. We found the biomarkers measurable and significantly increased during ILP. However, in this small feasibility study, we found no correlation to clinical outcomes. In Paper IV, a randomized controlled trial, we investigated the release pattern for biomarkers associated with brain injury in patients undergoing open-heart surgery randomized to either a standard or a high ECC flow rate. We found several correlations between treatment characteristics and the levels of biomarkers, however, there was no reduction in biomarkers with the higher flow rate as we had hypothesized.

In conclusion, the use of ECC has emerged as a crucial component in modern healthcare. While originally applied in heart surgery, ECC has also been integrated into novel cancer treatments. This thesis underscores the importance of continued research in ECC methodology and physiological reactions to enhance the technique and minimize associated side effects.