Transcutaneous oximetry, tcpO2 or TCOM, is a local, noninvasive measurement reflecting the amount of oxygen 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. It is dependent on the 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 warms the underlying tissue to create a local hyperemia, which intensifies blood perfusion, thereby increasing 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. If metabolism is high, the oxygen may be consumed by the cells.
Note that tcpO2 is not the same as the arterial oxygen pressure measured using standard pulse oximeters.
Transcutaneous oxygen and carbon dioxide monitoring, 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 amputation level
- Evaluation of revascularization procedures
- Candidate selection for hyperbaric oxygen therapy and prediction of non-responders to treatment
tcpO2 measurements usually require at least two or three measurement sites to provide a good image. The more sites assessed, the better the oxygenation image.
Diagnosis using tcpO2
tcpO2 is particularly useful in the prediction of wound healing, determination of amputation level and criteria for hyperbaric oxygen therapy.