RESUMO
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 similar, not equals0.37% for pO(2) and similar, not equals0.52% 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.
RESUMO
Potentiometric measurements are usually done with multiple determination electrodes. Disposable electrodes were first introduced on the Ektachem systems by Kodak with the concept of differential potentiometric measurement between the specimen and a reference fluid delivered on two parts of a single slide. In the Chempro 500 system a calibrating solution and the specimen are sequentially measured by the same potentiometric system with a classic reference electrode and selective electrodes present on a disposable device in various combinations. This device is connected to a compact analyzer with a microprocessor, a display and a printer. The authors evaluated the analytical performance of the Chempro 500 on whole blood, plasma and serum specimens over a two months period. Results and practicability are discussed and compared to those of reference instruments, according to requirements of decentralized analysis.
