Comparing Concurrent and Countercurrent Dialysate Flow in Hemodialysis: A Pilot Study on Hyponatremic Patients.

Background: In hyponatremic patients, concurrent dialysate flow during hemodialysis may be an ideal option to mitigate complications such as osmotic demyelination syndrome (ODS).

Methods: Present randomized controlled trial enrolled dialysis-requiring chronic kidney disease (CKD) and acute kidney injury (AKI) patients with serum sodium levels < 125 mEq/L during January 2020 over 16 months. Hemodynamically unstable patients, as well as those with a history of seizures and neurological conditions, were excluded. All were randomized to concurrent and countercurrent dialysate flow groups during two-h dialysis session. Hydration status was evaluated by Body Composition Monitor BCMTM and hourly sodium was estimated to guide ultrafiltration. Comparative analysis of sodium correction rates (meq/L/h) during dialysis, neurological deterioration via Mini-Mental State Examination (MMSE) scores, and ODS during 1 week and 1 month in both groups was done. Two-way repeated measures ANOVA was used to compare sodium correction trends.

Results: A total of 44 hyponatremic patients of AKI (17.39%), CKD (56.52%) and acute on CKD (26.09%) were randomized to concurrent (n = 23) and countercurrent (n = 21) dialysate groups. Postdialysis sodium correction rate was nonsignificantly slower in the concurrent group (45.45%) vs. the countercurrent group (36.36% group, p = 0.44). Neurological deterioration, measured via MMSE scores, and ODS incidence were absent in both groups. The concurrent group exhibited a higher proportion of patients without neurological deterioration (73.91%) compared to the countercurrent group (57.14%, p = 0.241). Comparable survival between the two groups was seen at 10, 20, and 30 days. No significant risk factors for mortality were identified in either group.

Conclusion: Concurrent dialysate flow demonstrates a slower but nonsignificant rate of sodium correction, making it a safer alternative for managing severe hyponatremia during hemodialysis by reducing the risk of rapid neurological shifts.