만성 혈액투석 환자에서의 대사성 산혈증과 음이온차의 양상 = Metabolic Acidosis and Anion Gap Patterns in Chronic Hemodialy sis Patients

다국어 초록 (Multilingual Abstract)

Objectives: The aim of the present study is to evaluate the prevalence of the various patterns of metabolic acidosis and anion gap among chronic hemodyalysis patients. Methods: Analysis of predialysis arterial blood gases and anion gap patterns was performed in 67 stable chronic outpatient hemodialysis patients(>1 year) with acetate buffer. Blood samples were drawn from the arterial line of the atreriovenous fistula for determination of blood electrolytes, chemistries, and analysis of blood gases at the beginning of hemodyalysis. Results: The degree of metabolic acidosis was mild to moderate with mean pH 7.33±0.039. 82% of a total 67 patients had pH between 7.30 and 7.39 with 18% of them between 7.20 and 7.29. Simple as mixed metabolic acidosis was shown in 49 of 67 patients(73%) and 18 of 67 patients(27%), respectively. In comparison of both groups, the group with mixed metabolic acidosis had significantly lower pH(7.29±0.04 vs 7.34±0.03, p<0.001) with higher pCO₂(38.5±3.4, p<0.005) and anion gap(19.6±4.1 vs 17.6±2.9, p<0.05). The classical high anion gap of end stage renal disease (range, 16 to 29 mEq/L) was also noted in 20 of 67 patients(30%). The linear regression analysis between anion gaps and total serum carbon dioxide contents (TCO₂) didn't show any significant correlation in all patients as well as the two subdivided groups with high and normal anion gap. Furthermore, only 13 of 67 patients(20%) were included between 80 and 120% in the ratio of delta anion gap(ΔAG) over delta TCO₂(dTCO₂). Therefore, the majority of hemodialysis patients (80%) showed the discrepancy between the degrees of d AG and ΔTCO₂. The analysis of unmeasured cations(K, Ca) and anions(albumin, phosphate) in the calculation of anion gap(Na ?Cl ?HCO₃) between two groups of high and normal anion gap of all patients as well as 49 patients of simple metabolic acidosis didn't reveal any discernible contributions to the changes of anion gap. Conclusion- This study therefore showed that the mixed acid-base balance and normal anion gap metabolic acidosis is not an exception in chronic stable hemodialysis patients. Also, the impact of hemodialysis in end stage renal disease patients seemed to lead the changes in values of unidentified anions besides fixed mineral acids and/or in those of unrecognized ionic equivalents of plasma constituents.