Transcutaneous oxygen tension measurement I. Age variation and reproducibility.

In 20 patients, aged 19-80 y and without pulmonary or cardiovascular disease, transcutaneous oxygen tension (tcPO2) and arterial oxygen tension (PaO2) were measured. tcPO2 was measured with a Radiometer TCM-1 (transcutaneous oxygen monitor) at 43 C degrees. The age regression for tcPO2 was: tcPO2 = 10.4-0.035 x age (r = 0.406); the corresponding equation for PaO2 was: 13.8-0.053 x age (r = 0.687). The mean difference between tcPO2 and PaO2 was 2.6 kPa (s.d = 0.97) and the ratio tcPO2/PaO2 was 0.8. The accuracy of tcPO2 at the level 5.3-13.2 kPa based on 480 measurements was on the average +/-1.28 kPa (maximum +/-1.73 kPa) at the 95% confidence level. The accuracy of tcPO2 measurements is acceptable for clinical use, and in healthy adults tcPO2 reflects PaO2.