Assessing the ABL 500 blood gas analyser

Abstract

The ABL 500 blood gas analyser from Radiometer has cordless electrodes and does not use a humidifier for calibrating gases. During the evaluation of the analytical performance of this instrument, the problem of p0₂ accuracy was approached by comparing the values obtained with two kinds of tonometry (film and bubble). An acceptable level of imprecision was demonstrated for all measured parameters. For within-run precision, with tonometry, coefficients of variation (CV) were ≆0.37% for pO₂ and ≆0.52% for pCO₂. A CV of 1.76% was found for day-to-day precision for both p0₂ and pCO₂. In the linearity study, with both tonometry methods, and in the inter-instrument comparisons (the ABL was compared with the Ciba Corning 178), pO₂ values obtained on the ABL 500 exhibited a slight overestimation above 150 mmHg (2.2-3.4% at 600 mmHg). This minor discrepancy is discussed with reference to the new design of the pO₂ electrode, the algorithm for pO₂ correction and the tonometry procedure. The results reported in this paper stress the importance of pO₂ accuracy assessment for the evaluation of blood gas analysers.

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