Determination of concordance between the results measured in the COBASR b221 gasometry equipment, compared to those obtained in the COBASR c111 autoanalyzer, for glucose and lactate.

Abstract

By its nature, the emergency laboratory must respond to the demand of results in a very short time. There are times when the chemical analyzers break down simultaneously; in that moment a gasometry equipment can be vital to supply the analyzer conventional. However, for the result to be reliable, the method or analyzer must be validated. In our service, the most requested determinations in the critical patient are glycemia and lactate, that is why our work has the purpose of validating the Cobas^R b221 gas equipment as a glucose and lactate analyzer. 210 blood samples were processed in order to study the concordance of the results of these analytes, in whole blood and in plasma. In order to evaluate the agreement between the analytical methodologies for the analyzed analytes, tests were performed by comparing paired means. The Lin concordance coefficient and its confidence interval were determined, and the Bland-Altman chart was also constructed. In the case of lactate determination, to determine the clinical importance of the difference between the results obtained in both equipment, the percentage of concordance between both methods used was calculated, based on three clinically relevant lactate concentration ranges. COBAS^R b221 tends to overestimate both parameters, this leads us to conclude that the different results provided by this equipment have clinical relevance and we must be careful when assessing both glucose and lactate.