Mitochondrial Oxygen Measurement Variability in Critically Ill Patients (INOX Variability Study)

Photonics Healthcare B.V. has developed an innovative non-invasive bedside monitoring system to measure Cellular Oxygen METabolism (the COMET).The COMET's non-invasive cutaneous mitoPO2 measurements rely on the protoporphyrin IX-triple state lifetime technique (PpIX-TSLT). This technique measures oxygen by oxygen-dependent quenching of delayed fluorescence lifetime of 5-aminolevulinic acid-induced mitochondrial PpIX (protoporphyrin IX). PpIX is the final precursor of haem in the haem biosynthesis pathway and is synthetized in the mitochondria. Administration of exogenous 5-aminolevulinic acid enhances PpIX to detectable levels and enhances mitochondrial origin of the delayed fluorescence signal. Measurements are based on the detection of time of extinction of red light emitted by the tissue following excitation with green light. The technique has been tested and calibrated for use in isolated organs and in vivo.