A 25 year old female with an unknown past medical history arrives via EMS for altered mental status. The only history obtained from roommates was that she was found unresponsive on the floor and she was normal yesterday. She was intubated in the field for poor mental status and inability to protect airway. Physical exam shows no evidence of trauma. GCS is E1 V1T M4. Vitals are within normal limits. Head CT shows no evidence of acute intracranial abnormality. Basic metabolic panel results a sodium level of 116. Urine drug screen and urine electrolyte studies are in process. Which of the following is the recommended initial management of her electrolyte derangement at this time?
A: 0.9% normal saline at maintenance rate
B: 1 liter of 0.9% normal saline bolus
C: 150 mL of 3% hypertonic saline over 20 minutes
D: 2 mcg of IV desmopressin
Answer: C. 150 mL of 3% hypertonic saline over 20 minutes
This patient is presenting with acute hyponatremia. The etiology is broad, but in the acute setting, it is most commonly due to excessive water intoxication, psychiatric illness, or substance use. The recommended initial treatment for adult hyponatremic patients with severe neurologic symptoms such as seizures or coma is 100-150 mL of 3% hypertonic saline IV over 15-20 minutes. This may be repeated up to 3 times for an improvement in neurologic status or increase in sodium concentration up to 5 mEq/L. In general, hyponatremic patients should be fluid restricted until differentiating the underlying cause. Thus, 1 liter of normal saline bolus or at maintenance rate is incorrect. A bolus of 1 liter of normal saline may also correct the sodium too quickly, resulting in osmotic demyelination syndrome. Desmopressin is frequently used when hyponatremia is corrected too rapidly in addition to its use in the treatment of diabetes insipidus.
References:
Petrino R, & Marino R (2020). Fluids and electrolytes. Tintinalli J.E., & Ma O, & Yealy D.M., & Meckler G.D., & Stapczynski J, & Cline D.M., & Thomas S.H.(Eds.), Tintinalli’s Emergency Medicine: A Comprehensive Study Guide, 9e. McGraw Hill.
