Evaluation of the transcutaneous oxygen method used at 37 degrees C for measurement of reactive hyperaemia in the skin.

The transcutaneous oxygen electrode used at an electrode temperature of 35-37 degrees C measures changes in PO2 at the skin surface that are mainly determined by changes in skin blood flow. Simultaneously, information about tissue PO2 in a defined skin area can be obtained by calculation. The reproducibility of this new application of the transcutaneous PO2 technique and factors influencing the recordings were analysed. Reactive hyperaemia was best recorded at 37 degrees C, where the coefficient of variation (CV) was 14% and the correlation coefficient was 0.90 between duplicate measurements within 15 min (n = 57). The day-to-day variation was greater (CV 19-28%). No significant spatial differences in reactive hyperaemia were noted when the distance between the electrodes was no more than 3 cm on the same forearm. A slightly lower reactive hyperaemia was noted when the arm with the electrode was elevated above the level of the heart, as compared with a lower position. Age and sex had significant influence, children (n = 34) exhibiting a greater postocclusive peak tcPO2 response than adults (n = 67). In adults, females (n = 30) showed significantly higher peak tcPO2 values during reactive hyperaemia than males. This method is a new application of the tcPO2 technique and can be used as a noninvasive tool for simultaneous blood flow and tissue PO2 studies in microcirculatory research.