Concordance analysis between dosed serum bicarbonate and that calculated by gas analysis in chronic renal patients

Abstract

Introduction: The control of metabolic acidosis in dialysis patients focuses on the supply of bicarbonate during the dialysis session, and it is not standard in all hemodialysis to assess serum bicarbonate concentrations. Bicarbonate expressed in blood gas analysis is the most sensitive standard of analysis and it is measured indirectly, using the Henderson-Hasselbalch equation. There are no studies in this population evaluating the concordance between the calculated bicarbonate with the direct method of biochemical analysis. The aim of this study was to analyze the concordance between the measured and calculated serum bicarbonate levels using blood gas analysis. Methods: We analyzed blood samples from chronic kidney patients undergoing hemodialysis, using the same sample of bicarbonate analysis by biochemistry and gasometry. The concordance was assessed using the Bland-Altman method. Results: 51 samples were analyzed. The analysis revealed a high correlation (r = 0.73) and a mean difference (bias) of 1.15 ± 3 mmol/L. The median time between collection and examination was 241 minutes. Discussion: We can conclude that the biochemical bicarbonate analysis compared to that calculated from blood gas analysis in chronic renal patients was consistent. For greater concordance between the data, it is important that the time between the collection of the samples and the referral to the laboratory for carrying out the dosages does not exceed four hours. The serum bicarbonate dosage can result in cost savings when compared to that of bicarbonate in blood gas analysis.

Valores de la gasometría arterial y lactato sérico transoperatorio en pacientes con hemorragia obstétrica que ingresaron a una unidad de terapia intensiva

“…6 El bicarbonato reportado en la gasometría no es el resultado de una medida directa, sino el cálculo mediante la fórmula de Hasselbalch, en la cual se tiene en cuenta el pH y la PCO 2 . 7 Éste es el amortiguador por excelencia del equilibrio ácido-base por acción de los riñones, con valores normales entre 22 a 26 mmol/L. 8 El déficit de base o exceso de base en sangre arterial es un parámetro para valorar en el estado ácido-base, que se usa comúnmente en el proceso de reanimación en estados de choque que se evidencia con acidosis metabólica como resultado de la hipoperfusión tisular por diversas etiologías, este valor se calcula a partir de los valores de pH y de PaCO 2 .…”