EFFECT OF HYPEROXIA AT 1-ATA AND 2-ATA ON HYPOXIA AND HYPERCAPNIA IN HUMAN SKIN DURING EXPERIMENTAL INFLAMMATION

Transcutaneous Po-2 and Pco(2) measurements and estimates of skin resp iration were monitored at different levels of inspired Po-2 in 20 heal thy adults during the first 4 days of the tuberculin reaction, a conve nient model of acute inflammation. Hyperoxia at 1 and 2 ATA significan tly increased transcutaneous Po-2 levels in undisturbed and in inflame d skin but did not fully correct the relative hypoxia at the site of i nflammation. Hypercapnia was reduced with O-2 breathing at 2 ATA. The apparent rate of O-2 consumption at the reaction site was raised durin g hyperoxia, most prominently at 2 ATA. The most intense reactions sho wed a central relative slowing of laser-Doppler blood flow indicative of microcirculatory impairment. The extent of the relative hypoxia and hypercapnia was greatest in these strongest reactions. The density of lymphocytes and monocytes in biopsies of 48-h reactions was loosely r elated to the corresponding transcutaneous Po-2 measurements. The pres ent study provides evidence that diffusion barriers, in addition to in creased local respiration, can contribute to the apparent hypoxia and hypercapnia of this inflammatory model.