Ca2+ measurement with ion selective electrodes. The French coordinated evaluation of seven analyzers, for a better clinical relevance and acceptance.

The measurement of ionized calcium has evolved in the last decade, and can now be easily performed by clinical laboratories using direct potentiometric analyzers available from a number of manufacturers. An original protocol for a comparison of the analyzers was used through a parallel multicenter evaluation in France. Using newly developed aqueous buffered solutions, this study focused not only on the analytical performance and operational handling of analyzers, but also on possible interferences in biological samples and the clinical relevance of the measurement with respect to the techniques of sample collection. All the instruments exhibited good precision and linearity, and were easy to handle and robust for daily use. However, not all the models gave identical results on the same patient's specimen. The utility of some Ca2+ analyzers has been further enhanced by the ability to "correct" the results to pH 7.40, although care must be taken in the interpretation of these results. While there are a number of clear-cut situations in which Ca2+ measurement is more relevant than total calcium, it seems that chemical activity of Ca2+ in blood may sometimes be considered with great caution under pathological conditions. The role of Ca2+ measurement in routine will be discussed in relation to the potential benefits of the instruments in laboratories.

[Extrarenal purification in severe salicylate poisoning in adults]. / L'épuration extra-rénale dans les intoxications salicylées graves de l'adulte.

About a new case of severe salicylate intoxication, the authors wanted to confirm the advantages of extrarenal epuration in some circumstances. Besides of usual treatments, it decreases the severity of this intoxication and the delay in its treatment by reducing quickly blood salicylate level to a moderate or benign rate whose prognosis is really better. Of course, the choice among the most common treatments (hemodialysis, hemoperfusion, peritoneal dialysis) depends with technical disposals, but hemodialysis seems the most efficient with minor risks than the intoxication itself.

[Comparison of 3 high-permeability dialysers]. / Comparaison de 3 dialyseurs à haute perméabilité.

Three capillary dialyzers, with highly permeable membranes, have been compared for their capacity of epuration of blood urea nitrogen, creatinine, phosphorus, uric acid and beta 2 microglobulin, and for their respective protein losses. There were very little differences between the dialyzers for epuration of small uremic molecules, with no benefit due to high permeability membranes in comparison with conventional dialyzers. Protein losses may be important and have to be known. About beta 2 microglobulin, filtered quantities are not correlated to changes in serum levels, suggesting the presence of other mechanisms (adsorption on the membrane and generation during hemodialysis) which influence, together with epuration, perdialytic changes of serum beta 2 microglobulin concentrations.