Calidad en el laboratorio de urgencias: determinación del estado ácido-base

measurement of blood gas, as another sample, involves three phases: preanalytical, analytical and postanalytical. the aim of this study is to evaluate the preanalytical phase comparing samples obtained from different syringes and the effect of storage time; to study the analytical performance; to compare the agreement between two instruments, and to analyse if the results were satisfactory taking into account clia specifications. two microanalyzers were used, in which ph, pco2 and po2 were tested. within-day imprecisions (cvi) and between-day imprecisions (cve) were obtained with control materials. two hundred and thirty-nine patient-samples were used; 20 were used for the comparison between samples obtained with heparinized syringes (sodium liquid heparin) and dry lithium heparin); 110 were processed to evaluate the effect of storage time, and 109 for the comparison between the analyzers. cvi and cve were acceptable for the three parameters. the difference between the different syringes did not exceed the acceptable limits. no significant difference was noticed until 120 min of storage. the correlation coefficients for processed samples in both instruments were 0.931 for ph, 0.985 for pco2 and 0.950 for po2. the bias was acceptable as the clinical equivalence for the three parameters. evaluating the results between identical instruments and introducing a systematic quality program has an important role in obtaining a progressive decrease of the total error between them, and using one or the other without distinction.