Transcutaneous oximetry, tcpO2 or TCOM, is a local, non-invasive measurement reflecting the amount of O2 that has diffused from the capillaries, through the epidermis.
TcpO2 provides instant, continuous information about the body’s ability to deliver oxygen to the tissue. TcpO2 is dependent on oxygen uptake in the respiratory system, the oxygen transport/capacity of the blood and the general status of the circulatory system. Any impairment of the organism’s ability to deliver oxygen to the tissue will be revealed immediately since the skin is ranked very low in the body’s system of oxygenation priority.
Technically, the electrode heats the underlying tissue to create a local hyperaemia, which intensifies the blood perfusion, increasing the oxygen pressure. In addition, the heat will dissolve the lipid structure of the dead, keratinized cells in the epidermal layer making the skin permeable to gas diffusion. On its way the oxygen may be consumed by the cells if the metabolism is high.
Note that transcutaneous oxygen is not the same as the arterial oxygen pressure measured using standard pulse oximeters.
Transcutaneous monitoring of oxygen and carbon dioxide, originally developed for neonatal use, has become a routine measurement in several clinical areas including:
- Determination of peripheral vascular oxygenation
- Quantification of the degree of peripheral vascular disease
- Determination of the optimum level of amputation
- Evaluation of revascularization procedures
- Selecting candidates for hyperbaric oxygen therapy and predicting non-responders to treatment
TcpO2 measurements usually require at least two or three sites to provide a good picture. The more sites assessed, the better the oxygenation picture.