Mannitol and hypertonic saline are the most commonly used medications to ward off the catastrophic complications of malignant increased intracranial pressure. Hypertonic saline, in my experience, has typically been 3%, but there are multiple different concentrations in use.
These authors perform a systematic review and meta-analysis of 23.4% saline. After all, the theory goes, a more osmotically powerful concentrated solution will exert greater physiologic effects. They identified 11 articles, six of which they included in a meta-analysis to identify an effect size for intracranial pressure reduction. Using the pooled data, the measured effect was a 55.6% (CI 44%-67%) decrease in ICP within 60 minutes. Their systematic review uncovered few adverse effects of 23.4% – transient hypotension and rare hemolytic anemia – and even reported acute reversal of herniation syndromes with good neurologic outcomes.
There is a ton of heterogeneity between studies – both in dosing of 23.4% saline, co-administration of mannitol, and underlying pathophysiology of ICP. Most studies are also tiny, ranging between 8 and 68, and either retrospective reviews or prospective non-random selection. Many studies did not report patient-oriented outcomes, so it’s hard to truly compare this practice to the current standard of care.
That being said, it seems interesting for potential use as “rescue” therapy when the alternative is permanent cerebral asphyxiation – and further study is needed to describe the appropriate (if any) population for use.
For reference: the salinity of seawater is about 3.5%, the Great Salt Lake varies between 5-27%, and the Dead Sea is approximately 33.7%. Definitely not appropriate for a peripheral intravenous line!
“High-Osmolarity Saline in Neurocritical Care: Systematic Review and Meta-Analysis”