Literature ReviewHypertonic Saline for Increased Intracranial Pressure After Aneurysmal Subarachnoid Hemorrhage: A Systematic Review
Introduction
The use of hyperosmolar agents, such as mannitol or hypertonic saline (HTS), for intracranial patients with traumatic brain injury (TBI) has been well documented.1, 2 HTS has gained popularity among physicians treating patients for intracranial hypertension from any cause.3 Increased intracranial pressure (ICP) is common in acute aneurysmal subarachnoid hemorrhage (aSAH), particularity in patients with poor grade aSAH.4 The underlying pathophysiology between TBI and aSAH-induced increased ICP is likely different, and hyperosmolar agents and doses used in TBI cannot necessarily be used in patients with aSAH.5 Marginal literature on the use of HTS in aSAH-induced increased ICP exist.6 The indication to use HTS versus mannitol, HTS concentration, and bolus infusion rate is even more undefined.
The primary goal of this study was to conduct a systematic review on the use of HTS to lower increased ICP in patients with aSAH and examine the current evidence of HTS effects on aSAH outcomes. Second, we sought to clarify HTS concentration, infusion rates, volume, frequency of redosing, and serum sodium/osmolality restrictions in aSAH.
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Search Strategy and Study Eligibility
Peer-reviewed articles were collected through MEDLINE, Embase, Scopus, and Cochrane Central Register of Controlled Trials searches according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA)7 guidelines. The key words used in combination included “hypertonic saline,” “intracranial pressure,” and “subarachnoid hemorrhage.” There were no restrictions on publications' language, or dates. One reviewer conducted the search (C.R.P.) and then the search was verified by
Search Results
The number of articles retained at each stage of data acquisition is illustrated in a PRISMA flow chart (Figure 1). A total of 438 nonduplicate articles were initially found. Most (390) articles were found using the key words “hypertonic saline and intracranial pressure” as the TBI literature with respect to increased ICP is extensive. After removing all duplicate articles and those pertaining only to TBI, central nervous system tumors, or the perioperative use of hyperosmolar agents, 15
Discussion
Increased ICP (≥20 mm Hg) is very common after poor-grade aSAH and is a well-known predictor of morbidity and mortality.4, 24, 25 After instituting measures, such as elevating the head of the bed, maintaining arterial carbon dioxide tension between 35 and 40 mm Hg, sedation, ventriculostomy for hydrocephalus, and evacuation of any surgical hematoma, the use of hyperosmolar agents is very common.5 There are no specific guidelines on which hyperosmolar agent should be first-line. Most ICP
Conclusion
The current literature suggests that HTS is effective at reducing refractory increased ICP in patients with aSAH and may improve functional outcomes. There are not enough data to recommend the optimal and safest concentration, volume, and infusion rate of HTS. Repeat boluses have been documented with safety providing serum sodium <155–160 mEq and serum osmolality <320 mEq. Further studies should be undertaken to determine the optimal dose concentration and volume of HTS administered.
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Conflict of interest statement: Dr. Macdonald receives grant support from the Brain Aneurysm Foundation, Canadian Institutes for Health Research and the Heart and Stroke Foundation of Canada; and is an employee and Chief Scientific Officer of Edge Therapeutics, Inc. The other authors declare that they have no competing interests.