Our organ’s cells die without oxygen.

Do they have enough oxygen? Are interventions necessary? How effective are they? In many situations physicians can only answer these questions with confidence when it is too late.

Now there finally is a way to answer these questions before organs fail: measuring oxygen inside active cells. This is quite different from current measurements in blood. Only in the cells themselves can it be determined if there is enough oxygen or if cells are hypoxic – and also if cells can’t use the oxygen they receive.

COMET measurement system

The CE-marked COMET measurement system determines oxygen availability as partial pressure of oxygen [in mmHg]. It non-invasively measures oxygen in human skin cells with a high concentration of protoporphyrin IX – in real time at the bedside and only in the mitochondria of active cells.
The COMET and its technology has been used in patients and volunteers in 16 clinical trials at seven institutes in two countries. Measurements were performed perioperatively in various surgeries and in the intensive care. More clinical trials are expected to start enrolling soon.

Skin is regarded as an early warning sensor, so should give physicians time to act before damage occurs. We expect that the measurement of oxygen in the cells will enable doctors to guide interventions to prevent organ failure.  This should prove vital in acute care to direct therapy for resuscitation, to warn of complications, to assess the effects of and necessity for interventions. It should also facilitate decisions before and during peripheral interventions. It could also be useful to detect alterations of cellular metabolism and to help develop treatments for metabolic dysfunction. Measurements are possible in other organs and have been performed e.g., in the gut. A CE marked sensor, however, is only available for the skin.

Use the COMET measurement system as a low-burden adjunct to your studies and improve patient safety. Contact us for a quote (Europe only).

The science of cellular monitoring

Anesthesiologist Dr. Egbert Mik, building on his invention with Dr. Michiel Sinaasappel, developed the protoporphyrin IX-triplet state lifetime technique (PpIX-TSLT). It is the first practical way to clinically measure oxygen availability and consumption where oxygen is needed: in the tissue cells rather than in the blood. It uses the oxygen dependent duration of the ‘glow-in-the-dark’ of the precursor to heme. This protoporphyrin IX is metabolized in epidermal mitochondria after local priming with aminolevulinic acid used in photodynamic therapy or diagnosis. The signal therefore originates only in active mitochondria and reflects the balance between oxygen supply and demand. The COMET’s skin sensor collects a signal from several square millimeters of epidermis, providing an average value for the different cells. In a preclinical trial the oxygenation of cells in the gut has been measured with an endoscopic sensor. Ultimately, interstitial probes, even imaging, should be feasible with this technology. Oxygen should be measured where it is needed so doctors can treat what matters.

Editors of Anesthesiology summarized a publication of research results with a prototype of the COMET and wrote that directly measuring tissue oxygenation “would be a major advance for perioperative medicine.” O’Brien and Schmidt wrote in a separate editorial for Anesthesiology (July 2016):A reliable measure of oxygen tension at the level of the mitochondria might significantly refine transfusion practice…  Indeed, any clinical scenario where cellular oxygenation might be compromised could potentially benefit… If mitochondrial PO2 can be measured reliably in humans, the potential value of this technique is hard to overestimate.

A range of cellular oxygen availability is expected for different cells depending on their positions along capillaries and their distances from them (the Krogh model and its refinements  e.g., here or here, provide theoretical explanations). Intense perfusion can result in average epidermal mitoPO2 values only slightly below the arterial oxygen tension.  Temporary local pressure stops microvascular blood flow in the measurement region. Repeated measurements during and after pressure allow determination of cellular oxygen utilization and analysis of re-perfusion.

The technology and its application has been published in or presented at:

Eurostars supported the development and testing of the COMET measurement system (project E!7294). Photonics Healthcare collaborates with AMC, Erasmus Medical Center, Leiden University, Sanquin Blood Supply and Unitron.

Further information is found in press releases of Erasmus Medical Center in Rotterdam,  Medgadget, Leiden University Medical Center.