A two temperature, two PO2 method of estimating the determinants of tcPO2.

We have prepared an algorithm describing the relationship of tcPO2 to PaO2 and used this with measured values of both tcPO2 and PaO2 under four conditions (two PO2 levels, two temperatures) to generate four equation sets that yielded unique solutions for the four unknown parameters. In adults under a 44 degree C electrode, capillary temperature averaged about 43 degrees C, O2 consumption about 0.0042 ml/gm/min, blood flow about 0.64 ml/gm/min, and diffusion gradient, D, about 32 mm Hg. We have not attempted to define these values in premature or normal newborn infants, because the method requires about one hour of exposure to 100% O2.