Comparison of 4.54% hypertonic saline and 20% mannitol for brain relaxation during auditory brainstem implantation in pediatric patients: a single-center retrospective observational cohort study.

Background: Mannitol is frequently utilized to achieve intracranial brain relaxation during the retrosigmoid approach for auditory brainstem implantation (ABI). Hypertonic saline (HS) is an alternative for reducing intracranial pressure; however, its application during ABI surgery remains under-investigated. We aimed to compare the efficacy and safety between HS and mannitol for maintaining brain relaxation.

Methods: This single-center retrospective cohort study included pediatric patients undergoing ABI surgery from September 2020 to January 2022 who received only 4.54% HS or 20% mannitol for brain relaxation. The analysis involved initial doses, subsequent doses, and dosing intervals of the two hyperosmolar solutions, as well as the time elapsed from meningeal opening to the first ABI electrode placement attempt. Additionally, the analysis encompassed electrolyte testing, hemodynamic variables, urine output, blood transfusion, second surgeries, adverse events, intensive care unit length of stay, and 30-day mortality.

Results: We analyzed 68 consecutive pediatric patients; 26 and 42 in the HS and mannitol groups, respectively. The HS group exhibited a reduced rate of supplementary use (7.7% vs. 31%) and lower total urine volume. Perioperative outcomes, mortality, and length of intensive care unit stay did not exhibit significant between-group differences, despite transient increases in blood sodium and chloride observed within 2 h after HS infusion.

Conclusions: In pediatric ABI surgery, as an osmotherapy for cerebral relaxation, 4.54% HS demonstrated a lower likelihood of necessitating additional supplementation than 20% mannitol. Furthermore, the diuretic effect of HS was weak and the increase in electrolyte levels during surgery was temporary and slight.