<p>Mitochondria are the primary consumers of oxygen and therefore an important location for oxygen availability and consumption measurement. A technique has been developed for mitochondrial oxygen tension (mitoPO<sub>2</sub>) measurement, incorporated in the COMET. In contrast to most textbooks, relatively high average mitoPO<sub>2</sub> values have been reported. The first aim of this study was to verify the validity of the COMET calibration for mitoPO<sub>2</sub> measurements in human skin. The second aim was to compare the dynamics of mitoPO<sub>2</sub> to several other techniques assessing tissue oxygenation. Firstly, we performed a two-point calibration. Mitochondrial oxygen depletion was achieved with vascular occlusion. A high mitoPO<sub>2</sub> was reached by local application of cyanide. MitoPO<sub>2</sub> was compared to the arterial oxygen partial pressure (PaO<sub>2</sub>). Secondly, for deoxygenation kinetics we compared COMET variables with the LEA O2C, SenTec OxiVenT™ and Medtronic INVOS™ parameters during a vascular occlusion test. 20 healthy volunteers were recruited and resulted in 18 datasets (2 times 9 subjects). The lowest measured mitoPO<sub>2</sub> value per subject had a median [IQR] of 3.0 [1.0–4.0] mmHg, n = 9. After cyanide application the mitoPO<sub>2</sub> was 94.1 mmHg [87.2–110.9] and did not differ significantly (n = 9, p = 0.5) from the PaO<sub>2</sub> of 101.0 [98.0–106.0] mmHg. In contrast to O2C, OxiVenT™ and INVOS parameters, mitoPO<sub>2</sub> declined within seconds with pressure on the probe. The kinetics from this decline are used to mitochondrial oxygen consumption (mitoVO<sub>2</sub>). This study validates the calibration of the COMET device in humans. For mitoVO<sub>2</sub> measurements not only blood flow cessation but application of local pressure is of great importance to clear the measurement site of oxygen-carrying erythrocytes.</p>

doi.org/10.1007/s10877-020-00602-y, hdl.handle.net/1765/136825
Journal of Clinical Monitoring and Computing
Erasmus MC: University Medical Center Rotterdam

R. (Rinse) Ubbink, M.A. (Mark) Wefers Bettink, W (Willem) van Weteringen, & E.G. (Bert) Mik. (2021). Mitochondrial oxygen monitoring with COMET. Journal of Clinical Monitoring and Computing, 35(6), 1357–1366. doi:10.1007/s10877-020-00602-y