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

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

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.

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.

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.