In this episode, I’ll discuss the balance between the risk of cerebral edema from severe hyponatremia vs osmotic demyelination from overly rapid sodium correction.
The risk of irreversible neurologic damage from osmotic demyelination after overly rapid correction of severe hyponatremia is significant. Over the years the maximum recommended increase in sodium in the first 24 hours of hyponatremia correction has been lowered to less than 8 mEq. However, there is also a risk of significant neurologic damage and even death from cerebral edema that can result from inadequately corrected severe hyponatremia.
A group of researchers published in Academic Emergency Medicine a retrospective study to determine the true risk of cerebral edema and osmotic demyelination syndrome in a cohort of ED patients with a plasma sodium of 125 mEq/L or less. Data from 852 patients were analyzed, about a third of which had severe symptoms of hyponatremia. Four patients had cerebral edema and eleven patients had osmotic demyelination syndrome. When the analysis was restricted only to those patients who had sodium results available in the timeframe between 18 and 30 hours, overly rapid sodium correction was the most important risk factor for osmotic demyelination syndrome.
The authors concluded:
Patients presenting to the ED with severe hyponatremia with and without severe symptoms most frequently do not have life-threatening global cerebral edema and do not necessarily require immediate treatment. The risk of development of ODS seems to outmatch the risk of edema. Overly rapid sodium correction cannot be ruled out as a risk factor for ODS and, thus, recommended treatment limits should be maintained until more evidence is available.
The authors argue that withholding immediate therapy in a severely hyponatremic patient allows for more time to make an accurate diagnosis of whether the patient has acute hyponatremia or chronic hyponatremia, the later of which may indicate the patient is at less risk from cerebral edema because their brain volume will have compensated from the chronic state of hyponatremia. In their cohort of patients, the vast majority were chronically hyponatremic.
The article in this episode is a selection from my Hospital Pharmacy Academy’s weekly literature digest. Have you ever felt like your physician colleagues are one step ahead of you with new literature developments? Every week, Academy members are provided a summary curated and explained by me of the top hospital pharmacy-related articles published that week from over 20 major journals and sources to save you time and keep you up to date with the literature. To get immediate access, go to pharmacyjoe.com/academy.
If you like this post, check out my book – A Pharmacist’s Guide to Inpatient Medical Emergencies: How to respond to code blue, rapid response calls, and other medical emergencies.
Leave a Reply