The blood gas factor: a comparison of three different oxygen electrodes.

Most of the commercially available oxygen electrodes give a lower value of Po2 for blood than for the gas with which it has been equilibrated. This systematic error, termed "the blood gas factor", has been determined for three different makes of oxygen electrode. The range of mean blood gas factors for the Radiometer system was found to be 1.8%—5.7% and for the Electronic Instruments Limited system it was 3.6%5.0%. However, the system manufactured by Instrumentation Laboratory (UK) showed a difference of less than 1.2% between the blood and the gas readings over most of the working range. At Po2 values of 150 mm Hg and below, this difference was not statistically significant.