Mark Wefers Bettink

Chapter 8 148 show the dynamics of mitoPO 2 under unstable hemodynamic conditions during acute blood loss and hypovolemia. Methods Trial design, setting, participants The study was approved by the Institutional Review Board (IRB) at the Erasmus Medical Center CCMO-register ‘Non-invasive monitoring of mitochondrial oxygen consumption and oxygenation (COMET): observational clinical study’, (NL51937.078.15). The additional cases also come from an IRB-approved study running in the Erasmus Medical Center ‘ Noninvasive measurement of mitochondrial oxygen tension (mitoPO 2 ) compared to continuous hemoglobin-monitoring during major surgery.’ (NL63158.078.17). All study procedures were performed in accordance with the relevant guidelines and regulations. Written informed consent was obtained from all patients prior to study participation. This single center observational study was performed at the Erasmus Medical Center, a tertiary care center in the Netherlands. Inclusion ran from April 2016 up until March 2020. Patients aged between 18-70 years old and scheduled for neurosurgery were considered eligible for participation. Exclusion criteria included surgeries without need for invasive intra-arterial blood pressure monitoring, presence of mitochondrial diseases and pregnancy or lactation. The goal of the study was to measure mitoPO 2 in the operation room under stable conditions. Therefore, patients were excluded if hemodynamic unstable situations during surgery occurred: 1) if blood transfusion was required, 2) if the mean arterial pressure (MAP) decreased more than 25% from baseline or 3) if high doses of vasopressors were needed (noradrenaline ≥ 0,10 mcg/kg/min or the equivalent dose of phenylephrine.) The raise in blood pressure during the hemostasis, induced by increasing the rate of infusion noradrenaline or phenylephrine is according to standard procedure and is not taken into account for the analysis of the results Patient screening was performed by the research team, based on data collected at the standard care perioperative consult. Written informed consent was obtained from all patients prior to study participation. Principle of mitoPO2 measurements The background and principles of the PpIX-TSLT are described in detail elsewhere 2,5,9 . In short, PpIX is the final precursor of heme in the heme biosynthetic pathway. PpIX