Skin-fold thickness, body mass, and obesity indexes and the arterial to skin-surface PO2 gradient

Trends in transcutaneous oxygen tension (tcPO2) correlate closely with Pao2 in the absence of circulatory insufficiency. Individual variation, however, in the arterial to skin-surface Po2 gradient (Pao2-tcPo2 gradient) have limited the usefulness of tcPo2 measurements as precise indicators of Pao2. This individual variability in the Pao2-tcPo2 gradient has been speculated as being caused by "skin factors." This study was performed to examine the relationship between skin-fold thickness (triceps and infraclavicular), body mass index, body surface area, and ponderal index and the Pao2-tcPo2 gradient with a view to delineating correction factors that might be useful in increasing the accuracy of tcPo2 as an estimate of the absolute value of the corresponding Pao2. Skin-fold thickness measurements, body mass index, body surface area, and ponderal index were unrelated to the Po2 gradient. This was thought to be primarily due to an inherent inaccuracy of these measurements as indicators of stratum corneum thickness and dermal capillary depth, the major involved variables.