Underestimation of arterial oxygen tension by transcutaneous electrode with increasing age in infants.

To investigate the effect of increasing gestational and postnatal age on the relation between transcutaneous oxygen tension (tcPO2) and arterial oxygen tension (PaO2) 160 simultaneous measurements of tcPO2 and PaO2 tensions were made on 42 infants born at 24-41 weeks' gestation and aged 0-32 weeks from birth. Irrespective of gestational age a progressive fall in the tcPO2:PaO2 ratio with increasing postnatal age was found. At all postnatal ages tcPO2:PaO2 tended to be lower in the more mature infants.