Transcutaneous measurement of the oxygen partial pressure using argon to correct for the oxygen consumption of the probe.

The oxygen consumption of a transcutaneous probe creates an oxygen diffusion gradient between the skin capillaries and the probe, and this gradient causes the ratio between the oxygen partial pressure at the surface of the transcutaneous probe and the mean capillary pO2 to be less than 1. The ratio is usually increased towards unity by heating the skin to 43-45 degrees C, but this method introduces both practical and theoretical complications: the risk of skin burns and the increase in pO2 over the value in the blood at 37 degrees C. We present a new method to evaluate the ratio between the oxygen partial pressure at the surface of the transcutaneous probe and the mean capillary pO2. The method was used in measurements of the mean capillary pO2 in the skin of eight volunteers with a low-temperature probe (40 degrees C). The mean value of the ratio was 0.56 with a considerable variation from one person to another and from one skin location to another.