In this episode, I’ll discuss using sodium bicarbonate instead of hypertonic saline to treat severe hyponatremia.
Severe hyponatremia requires prompt treatment with a bolus of 100mL 3% hypertonic saline to raise serum sodium by 4-6 mEq/L to prevent morbidity and mortality. The main problem with this treatment is that 3% saline does not come in a ready-to-use 100 mL bolus; rather it must either be compounded by the pharmacy (which delays treatment) or prepared from a larger 500 mL infusion bag at the bedside (which increases the risk of error).
However, a 50 mL prefilled syringe of 8.4% sodium bicarbonate provides a similar sodium load and is readily available in critical care areas for immediate administration. Therefore, a group of authors published in Academic Emergency Medicine a retrospective cohort study comparing 3% sodium chloride with 8.4% sodium bicarbonate for the initial management of severe hyponatremia.
There were 21 patients in each group. The primary goal of the study was to determine the number of patients whose serum sodium concentrations increased by ≥ 4 mEq/L following administration of either medication.
The number of patients whose post-intervention serum sodium concentration increased by ≥ 4 mEq/L in the sodium bicarb and sodium chloride groups was 10 (48%) and 2 (10%), respectively. This difference was statistically significant. The sodium bicarb group also had a statistically significantly higher median change in serum sodium concentration compared with sodium chloride.
There were no significant differences between the groups in the change in serum bicarbonate concentrations, chloride concentrations, and anion gap levels following study drug administration, and no patient experienced osmotic demyelination syndrome.
The authors concluded:
This study found that a single 50 mL dose of HTB more often resulted in obtainment of guideline-recommended post-intervention serum sodium goal concentrations than a 100 mL HTS dose. Additional studies are needed to confirm these findings and provide a more comprehensive assessment of safety and efficacy outcomes.
This is a simple and practical solution to the problem of quickly and precisely giving an adequate dose of sodium to a patient with severe hyponatremia. While I agree with the author’s call for a larger study for additional assessment of safety and efficacy, this may be a useful trick up the sleeve of a pharmacist that could be used in a unique scenario where the manifestation of hyponatremia is especially severe, and they know a long delay in obtaining 3% sodium chloride is likely.
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