Effects of four different methods of sampling arterial blood and storage time on gas tensions and shunt calculation in the 100% oxygen test.
Plastic syringes of 5 and 20 ml capacity of various composition were filled with either 8% CO2 in nitrogen or with 50% O2 in nitrogen. The syringes were closed with plastic stopcocks, stored on benches in a laboratory, and the gas concentrations within the syringes was measured at intervals up to 33 hours. Changes in oxygen and carbon dioxide tensions in the first three hours were negligible. Over the longer time span carbon dioxide diffusion was 18-65 times faster than that of oxygen.