Temporal changes in serum sodium during EVD wean attempts after subarachnoid hemorrhage may represent a new trigger for post-SAH dysnatremia, with the slope of serum sodium change independently associated with wean attempt outcome in multivariable analysis.
Key Findings
Results
Serum sodium on the day of wean initiation was significantly higher in the failed wean group compared to the successful wean group.
Serum sodium concentration (mEq/L, mean ± standard deviation) on the day of wean initiation was 139.3 ± 8.5 in the successful wean group versus 140.7 ± 6.6 in the failed group.
This difference was statistically significant (p < 0.001).
The cohort included 985 patients and 1,318 unique wean attempts.
Of the 1,318 wean attempts, 790 were successful and 528 were unsuccessful.
Results
Serum sodium decreased more during the first 3 days of the wean attempt in the failed group compared to the successful group.
During the first 3 days of the wean attempt, serum sodium decreased by 0.8 ± 7.8 mEq/L in the successful group compared with 1.5 ± 5.8 mEq/L in the failed group.
This difference was statistically significant (p = 0.048).
Both positive and negative sodium changes were independently associated with wean outcome when analyzed separately.
A higher rate of change in either direction was associated with increased risk of failure.
Results
In multivariable mixed effect logistic regression analysis, the slope of serum sodium change was independently associated with EVD wean attempt outcome.
The odds ratio for the slope of serum sodium change was 1.324 (95% confidence interval: 1.174–1.506).
Analysis was conducted using a multivariable mixed effect logistic regression model.
When cases with positive or negative sodium changes were analyzed separately, both were independently associated with outcome.
A higher rate of sodium change was associated with increased risk of wean failure.
Results
There was no statistically significant difference in cumulative sodium intake between successful and failed wean groups before or during the wean attempt.
Cumulative sodium intake was assessed up to 2 days before and during the wean attempt.
No statistically significant difference was found between the groups in iatrogenic sodium exposure.
This finding suggests that the observed sodium changes are not directly explained by iatrogenic exposures.
The authors conclude these findings represent a potentially new, non-iatrogenic trigger for post-SAH dysnatremia.
Results
Patients with failed EVD wean attempts had overall higher clinical and radiographic hemorrhage grades.
Patients with failed attempts had overall higher clinical and radiographic hemorrhage grades compared to those with successful attempts.
The cohort was admitted to the neuroscience ICU between 2012 and 2022 from a large volume tertiary center.
The study included patients with subarachnoid hemorrhage complicated by obstructive hydrocephalus.
Primary outcome was defined as successful wean if the EVD was removed at the end of a wean attempt, or failed if the EVD was reopened or if a ventriculoperitoneal shunt was placed.
Background
The study identified potential causes of dysnatremia following non-traumatic subarachnoid hemorrhage including induced hypernatremia and hyponatremia related to cerebral vasospasm or cerebral salt wasting syndrome.
Dysnatremia is described as a common complication following non-traumatic subarachnoid hemorrhage (SAH).
The EVD wean trial itself may represent a new, previously unrecognized trigger for post-SAH dysnatremia.
The authors characterize these as 'hypothesis-generating findings' that warrant validation in prospective trials.
The study was retrospective in design, covering admissions from 2012 to 2022.
What This Means
This research examined whether changes in blood sodium levels during a procedure called an external ventricular drain (EVD) wean trial are related to the success or failure of that procedure in patients who had a type of brain bleed called subarachnoid hemorrhage (SAH). An EVD is a tube placed in the brain to drain excess fluid, and a 'wean trial' is when doctors gradually reduce the drainage to see if the brain can manage fluid on its own. The study looked at nearly 1,000 patients and over 1,300 wean attempts over a 10-year period at a large hospital.
The researchers found that patients whose wean attempts failed had slightly higher sodium levels at the start of the trial, and their sodium levels dropped more during the first three days of the trial compared to patients who succeeded. Importantly, both rises and falls in sodium were associated with a greater chance of failure — meaning that any significant shift in sodium, in either direction, was linked to worse outcomes. These sodium changes did not appear to be caused by how much sodium patients were receiving through IV fluids or other medical treatments, suggesting the EVD weaning process itself may be triggering sodium fluctuations in the body.
This research suggests that monitoring sodium levels during EVD wean trials could provide useful information about whether a patient is likely to tolerate removal of the drain. The findings also raise the possibility that the brain's fluid regulation is disrupted during these trials in ways not previously well understood. Because this was a retrospective study — meaning it looked back at existing records rather than prospectively testing a hypothesis — the authors caution that these results need to be confirmed in future prospective clinical trials before any clinical changes are made.
Horton P, Mei Y, Ponder C, Danyluk L, Martin K, Akbik F, et al.. (2026). Changes in serum sodium during an external ventricular drain weaning in patients with subarachnoid hemorrhage.. Frontiers in neurology. https://doi.org/10.3389/fneur.2026.1843156