Determination of Blood pCO2
- 1 August 1961
- journal article
- research article
- Published by Oxford University Press (OUP) in Clinical Chemistry
- Vol. 7 (4) , 236-245
- https://doi.org/10.1093/clinchem/7.4.236
Abstract
It is demonstrated that the most accurate and precise method of determining whole blood pCO2 is with the Severinghaus modification of the pCO2 electrode. The coefficient of variation is only ± 0.33 per cent. Experiments show that the pCO2 may not be stable for more than 30 min. when whole blood is stored at O° when whole blood is diluted with saline, the pCO2 falls in exact proportion to the dilution. The pH/log pCO2 curves of separated plasma and of whole blood have the same slope when temperature is changed. The pCO2 of cold-separated plasma is lower than the pCO2 plasma separated at body temperature. The variation of pCO2 with temperature appears to follow pari passu the variation of pH with temperature. The mean pK' of 18 patient samples equilibrated at 37.5° was 6.103. The standard deviation was ± 0.012. Calculated pCO2, utilizing the Henderson-Hasselbalch equation, can have a coefficient of variation of ± 2.5 per cent if proper temperature corrections are made. If temperature corrections are not made, calculated pCO2 may have a coefficient of variation greater than ± 5 per cent.Keywords
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