Assessing the ABL 500 blood gas analyser

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 p0(2) 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 pO(2) and ≆0.52% for pCO(2). A CV of 1.76% was found for day-to-day precision for both p0(2) and pCO(2). In the linearity study, with both tonometry methods, and in the inter-instrument comparisons (the ABL was compared with the Ciba Corning 178), pO(2) 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 pO(2) electrode, the algorithm for pO(2) correction and the tonometry procedure. The results reported in this paper stress the importance of pO(2) accuracy assessment for the evaluation of blood gas analysers.