Effect of Different Dialysate Potassium Concentrations on QTc Dispersion in Hemodialysis Patients

Background: To evaluate the impact of different dialysate potassium concentrations on the surrogate for arrhythmic risk, QTc dispersion (QTcd) during dialysis

Methods: Nineteen stable patients on maintenance hemodialysis were enrolled. Each underwent hemodialysis thrice a week, the first study week against potassium (K) dialysate with 1.0 mEq/L and the second week against K dialysate with 2.0 mEq/L. Pre- and post-midweek dialysis weights, blood pressure, electrolytes, and 12-lead surface EKG were recorded in both weeks. The QTcd were calculated before and after midweek dialysis in both weeks. QTcd data was generated from two observers and the averaged value was used for analysis. 

Results: Of the 19 patients, 10 were male. The mean age ± SD was 65.1 ± 9.1 years. There was a significant decrease in the mean weight, K, magnesium post-dialysis (compared to pre-dialysis) in both groups (p ≤ 0.002). Postdialysis concentrations of systolic or diastolic blood pressure, heart rate, hemoglobin were unchanged (compared to pre-dialysis) but pH, bicarbonate, sodium, calcium increased with both dialysate groups (p ≤ 0.001). The QTcd (pre- vs. post-dialysis) was 97.9 (79.3-127.8) vs 131.1 (105.6-179.2) ms (p = 0.02) in 1.0 mEq/L K goup and 95.8 (76.1-127.8) vs 109.6 (85.3-168.8) ms (p = 0.059) in 2.0 mEq/L K goup, respectively.

Conclusion: 1.0 but not 2.0 mEq/L K dialysate bath significantly impact QTcd in hemodynamically stable hemodialysis patients.