EVALUATION OF BLOOD-GAS QUALITY-CONTROL AND PROFICIENCY TESTING MATERIALS BY TONOMETRY

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Abstract
Because of previous consistent differences, P[partial pressure]O2 and PCO2 concentrations of fresh blood, plasma and several commercial quality control materials were systematically tonometered, sampled and measured in 3 models of semiautomated blood gas machines. No significant differences between materials or machines were found for PCO2 between 25-72 mm Hg. For tonometered PO2 of .apprx. 25-100 mm Hg, the measured PO2 concentrations were accurate for blood, high for materials with Hb fluorocarbon (high O2 capacity), and very high for other materials (low O2 capacity). A low O2 capacity material tonometered to a PO2 of 0 mm Hg gave very high values in semiautomated machines and gave correct values only when injected repeatedly without interrupting rinse cycles into a manual machine. These findings indicate significant contamination of blood gas machines with fluids other than the sample so that low O2 capacity quality control materials are inadequate for proficiency testing at degrees of PO2 < 100 mm Hg.