Association of hypokalemia with cardiovascular mortality and residual diuresis in patients on thrice-weekly hemodialysis.

Abstract

Introduction: Potassium metabolism disorders are common in dialysis patients and are associated with an increased risk of arrhythmias and cardiovascular mortality. Dialysate potassium concentration, the correction of metabolic acidosis, and residual renal function influence potassium kinetics during dialysis.

Materials and methods: An observational study analyzing pre- and post-dialysis serum potassium concentrations, the presence of residual urine output, and the cause of cardiovascular death; an acid concentrate containing 2 mmol/L of potassium was used.

Results: Thirty-five patients were studied, with a predominance of males (62.9%) and individuals aged ≥65 years (60%). The primary etiology was diabetes mellitus (51.4%). Serum potassium levels decreased significantly after dialysis (from 4.84±0.86 to 3.20±0.30 mEq/L; p<0.001), and post-dialysis hypokalemia (<3.5 mEq/L) was highly prevalent (88.6%). No significant association was found with the type of cardiovascular death (p=1.000) or with residual urine output (p=0.268), although the latter was more frequent in patients without residual urine output (92.3% vs. 77.8%). Spearman analysis showed that the duration of hemodialysis was inversely correlated with pre- and post-dialysis potassium levels (ρ=-0.392 and -0.382; p<0.05), and there was a strong positive correlation between the two potassium values ​​(ρ=0.756; p<0.001). No significant correlations were found between potassium levels and the cause of death or demographic variables (p>0.05).

Conclusions: Post-dialysis hypokalemia was highly prevalent; although no significant association was found with residual urine output or cardiovascular mortality, it is necessary to individualize the potassium prescription in the dialysis fluid and monitor patients at higher risk of potassium balance disturbances.