Solubility of nitrous oxide in human blood.

The solubility of nitrous oxide in blood at body temperature was determined by Siebeck (1) with considerable accuracy as early as 1909. In his experiment, the blood was placed with a gas mixture in a tonometer of 3 liters capacity and equilibrated at 38” and atmospheric pressure. After an equilibrium had been attained, samples of both blood and gas were analyzed for nitrous oxide content. A blood cell solution was used which had been prepared from beef blood and was considered by Siebeck to be equivalent to whole blood with respect to NzO solubility. On three 100 cc. samples of this solution equilibrated at 38” with a known gas mixture, Siebeck obtained Q! values of 41.08,42.73, and 41.29, respectively, averaging 41.7 or 0.417 per cc. This a! is the Bunsen absorption coefficient described (2) as “the volume of gas (reduced to 0” and 760 mm.) taken up per unit volume of solvent when the pressure of the gas itself minus the vapor tension of the solvent is 760 mm.” In spite of the fact that the substitution of such a blood cell solution for whole blood may be open to question, the (Y value of 0.417 agrees very closely with that found by Orcutt and Seevers (a = 0.416), who have recently described a new method for determining the solubility of gases in liquids (2). This method, specifically applied to nitrous oxide in blood (3), may be considered the most accurate at the present time, and has been used in the experiments now to be reported to determine the solubility of nitrous oxide in blood at 37.5”.