A trial of the direct method for determining the tensions of O2 and CO2 in blood.

There is a demand for a quick and reliable method for determining the tensions of 02 and CO2 in arterial and venous blood in the investigation of pulmonary and cardiac function. The direct bubble equilibration method described by Riley, Proemmel, and Franke (1945) seems to answer this demand, for within about 30 minutes duplicate analyses may be performed, only 3 ml. of blood is required, and the equipment is simple and relatively inexpensive. But the reliability of the method is in question, for a number of modifications have been reported both from the authors' laboratories (Brinkman, Johns, Donoso, and Riley, 1954; Riley, Campbell, and Shepard, 1957), and from others (Lambertsen, Bunce, Drabkin, and Schmidt, 1952; Filley, Gay, and Wright, 1954; Bjork and Hilty, 1954). The purpose of this investigation was to carry out a further trial of the technique and to assess its value for routine investigation and research.