Transcutaneous PO2 measurement.

Transcutaneous PO2 sensors have been developed over the past ten years from the same basic electrodes used in conventional blood gas machines. The skin is heated to enable the skin surface sensors to respond quickly to the gas tensions beneath them. PtcO2 is a variable which reflects the PO2 in the peripheral tissue. PtcO2 has its own range of normal values and it responds to cardiopulmonary changes which affect tissue oxygenation. In the majority of patients, those without decreased cardiac output, PtcO2 follows the trend of the arterial gas tension, and the PtcO2 value decreases relative to PaO2 with increasing patient age (Table II). When there is severely reduced cardiac output and peripheral perfusion, the PtcO2 values will deviate from their relationship with the arterial tensions and become blood flow dependent, thus providing quantitative information regarding blood flow. It is likely that the technique of transcutaneous PO2 monitoring will gain wider acceptance because it is a noninvasive and continuous monitor which provides useful information regarding tissue oxygenation.