ABSTRACT
When an artificial gas pocket is formed by injection of air into a tissue space the gases equilibrate with the tissue-blood environment and assume a state of constant composition which is maintained until all the gas is eventually resorbed. In man (Rahn, 1957) and in rats (Van Liew, 1968) evidence has been presented that the O2 and CO2 tensions of gas in such pockets are virtually the same as those of the venous blood draining these tissues provided that air or gases of lower O2 concentrations are breathed (see also review by Piiper, 1965). Since the techniques required for sampling and analysis of the equilibrated gas are relatively simple, this method provides a convenient approach for the determination of gas tensions of the blood-tissue environment of unanaesthetized, unrestrained animals.
