[Preservative effects of nitrous oxide on stored red cells]

While various additive solutions, containers and temperature have been shown to improve qualities of stored red cells, there are no reports on gas environment during blood storage. Nitrous oxide (N2O) showed a very high permeability through polyvinyl chloride membrane and high blood solubility. The whole blood with CPD was stored in N2 O (N2O-group) and compared with the control which was stored in air (Air-group). After storage (21 days at 5 degrees C and 35 days at 1 degree C), N2O-group showed significantly lower decreases of pH as well as significantly lower increases of Pco2 than Air-group. At both temperatures, glucose concentrations and ATP levels showed no differences between the two groups, but concentrations of lactate and 2, 3-DPG in N2O-group are significantly higher than those in Air-group. It is concluded that nitrous oxide gas environment can prevent decrease of pH by the suppression of increasing Pco2 in the stored blood due to high permeability and solubility into the cooled blood from ambient and can maintain functions of stored red cells, while neither oxidation toxicity nor antioxidation effects of N2O were demonstrated.