Hypertonic saline: first-line therapy for cerebral edema?

Efficacy and Renal Safety of Protocol-based 11.7% Hypertonic Saline Infusion Compared with 20% Mannitol in Patients with Elevated Intracranial Pressure: A Study Protocol for a Randomized Clinical Trial

Background

Elevated intracranial pressure (ICP) is a potentially life-threatening condition requiring prompt intervention. While both mannitol and hypertonic saline (HTS) are commonly used hyperosmotic agents for treating elevated ICP, there is insufficient evidence comparing their renal safety profiles and overall effectiveness. This study protocol outlines a pragmatic randomized trial to compare protocol-based 11.7% HTS with 20% mannitol in patients with elevated ICP, focusing particularly on renal outcomes and treatment efficacy.

Methods

This single-center, pragmatic randomized trial will enroll 116 intensive care unit patients with elevated ICP. Participants will be randomly assigned to receive either 11.7% HTS or 20% mannitol following a schedule-based randomization approach, with HTS administration during odd-numbered months and mannitol during even-numbered months. The study will regularly monitor serum electrolytes, osmolarity, and renal function, with brain CT evaluations conducted on days 3 and 7. Comprehensive clinical assessments, including neurological evaluations and laboratory tests, will be performed at specified intervals throughout the study period.

Measured Outcomes

Primary outcomes include the incidence of acute kidney injury within 7 days according to KDIGO guidelines, requirement for mechanical ventilation, development of pulmonary edema, and significant fluid retention. Secondary outcomes encompass ICU and hospital length of stay, 30- and 90-day mortality rates, and neurological outcomes assessed by Glasgow Coma Scale scores at days 7 and 30. The study hypothesizes that protocol-based HTS administration will demonstrate a lower incidence of acute kidney injury and related complications while maintaining comparable efficacy in managing elevated ICP.

Conclusion

This study aims to provide definitive evidence regarding the relative efficacy and safety profiles of HTS compared to mannitol in managing elevated ICP. The findings will help establish clearer clinical guidelines for selecting appropriate hyperosmotic agents, potentially improving patient care outcomes and reducing treatment-related complications. This research will address a significant gap in current clinical knowledge and practice by focusing on treatment efficacy and renal safety considerations in patients with elevated ICP.

Effect of continuous hypertonic saline infusion on clinical outcomes in patients with traumatic brain injury

Osmotic therapy has been recognized as an important treatment option for patients with traumatic brain injury (TBI). Nevertheless, the effect of hypertonic saline (HTS) remains unknown, as findings are primarily based on a large database. This study aimed to elucidate the effect of HTS on the clinical outcomes of patients with TBI admitted to the intensive care unit (ICU). We retrospectively identified patients with moderate-to-severe TBI from two public databases: Medical Information Mart for Intensive Care (MIMIC)-IV and eICU Collaborative Research Database (eICU-CRD). A marginal structural Cox model (MSCM) was used, with time-dependent variates designed to reflect exposure over time during ICU stay. Trajectory modeling based on the intracranial pressure evolution pattern allowed for the identification of subgroups. Overall, 130 (6.65%) of 1955 eligible patients underwent HTS. MSCM indicated that the HTS significantly associated with higher infection complications (e.g., urinary tract infection (HR 1.88, 95% CI 1.26-2.81, p = 0.002)) and increased ICU LOS (HR 2.02, 95% CI 1.71-2.40, p < 0.001). A protective effect of HTS on GCS was found in subgroups with medium and low intracranial pressure. Our study revealed no significant difference in mortality between patients who underwent HTS and those who did not. Increased occurrence rates of infection and electrolyte imbalance are inevitable outcomes of continuous HTS infusion. Although the study suggests slight beneficial effects, including better neurological outcomes, these results warrant further validation.

Use of a Novel Buffered Hypertonic Saline Solution for Fluid Replacement and Resuscitation During Spinal Surgery in Adolescents

Background

During major orthopedic procedures, such as posterior spinal fusion (PSF), isotonic fluids, colloids, starches, or gelatins are commonly used to replace the preoperative fluid deficit and provide ongoing fluid resuscitation. Given recent concerns regarding the potential adverse physiologic effects of albumin solutions, we have modified our intraoperative practice to include the use of a novel 2% buffered hypertonic saline solution during major orthopedic procedures. We present our preliminary clinical experience with this novel fluid for intraoperative resuscitation and its impact on limiting the use of 5% albumin.

Methods

A retrospective review was performed to identify patients who received 2% buffered hypertonic saline during PSF. The intraoperative course of these patients was compared to case-matched control patients who received standard care with isotonic fluids plus 5% albumin as an adjunct for intravascular resuscitation.

Results

The study cohort included 23 patients who received 2% buffered hypertonic saline and 25 in the case-matched control group. There was no difference in the volume of intraoperative isotonic crystalloid fluids, estimated blood loss, and urine output between the two groups. In the control cohort, 19 of 25 patients (76%) received 5% albumin compared to only six of 23 patients (26%, P = 0.0005) in the 2% buffered hypertonic saline group. The final pH was higher in the patients that received 2% buffered hypertonic saline than in the control group (7.40 ± 0.03 versus 7.36 ± 0.06, P = 0.0131). Additionally, the starting and final serum sodium values were higher in the patients that received 2% buffered hypertonic saline, although no difference was noted in the mean change from the starting value (average increase of 2 mEq/L in both groups).

Conclusion

Use of a novel 2% buffered hypertonic saline solution for intraoperative resuscitation during major orthopedic procedures decreases the need for 5% albumin while avoiding the development of hyperchloremic metabolic acidosis which may occur with standard sodium chloride solutions.

A systematic review and meta-analysis on the efficacy of glibenclamide in animal models of intracerebral hemorrhage

Intracerebral hemorrhage (ICH) is a devastating stroke with many mechanisms of injury. Edema worsens outcome and can lead to mortality after ICH. Glibenclamide (GLC), a sulfonylurea 1- transient receptor potential melastatin 4 (Sur1-Trpm4) channel blocker, has been shown to attenuate edema in ischemic stroke models, raising the possibility of benefit in ICH. This meta-analysis synthesizes current pre-clinical (rodent) literature regarding the efficacy of post-ICH GLC administration (vs. vehicle controls) on behaviour (i.e., neurological deficit, motor, and memory outcomes), edema, hematoma volume, and injury volume. Six studies (5 in rats and 1 in mice) were included in our meta-analysis (PROSPERO registration = CRD42021283614). GLC significantly improved behaviour (standardized mean difference (SMD) = -0.63, [-1.16, -0.09], n = 70-74) and reduced edema (SMD = -0.91, [-1.64, -0.18], n = 70), but did not affect hematoma volume (SMD = 0.0788, [-0.5631, 0.7207], n = 18-20), or injury volume (SMD = 0.2892, [-0.4950, 1.0734], n = 24). However, these results should be interpreted cautiously. Findings were conflicted with 2 negative and 4 positive reports, and Egger regressions indicated missing negative edema data (p = 0.0001), and possible missing negative behavioural data (p = 0.0766). Experimental quality assessed via the SYRCLE and CAMARADES checklists was concerning, as most studies demonstrated high risks of bias. Studies were generally low-powered (e.g., average n = 14.4 for behaviour), and future studies should employ sample sizes of 41 to detect our observed effect size in behaviour and 33 to detect our observed effect in edema. Overall, missing negative studies, low study quality, high risk of bias, and incomplete attention to key recommendations (e.g., investigating female, aged, and co-morbid animals) suggest that further high-powered confirmatory studies are needed before conclusive statements about GLC's efficacy in ICH can be made, and before further clinical trials are performed.

Hyperosmolar therapies for neurological deterioration in mild and moderate traumatic brain injury: A scoping review

OBJECTIVE

To explore the available evidence on hyperosmolar therapies(HT) in mild and moderate traumatic brain injury(TBI) and to evaluate the effects on outcomes.A scoping review was conducted according to the Joanna Briggs Institute methodology. Inclusion criteria: (a)randomized controlled trials(RCTs), prospective and retrospective cohort studies and case-control studies; (b)all-ages mild and moderate TBIs; (c)HT administration; (d)functional outcomes recorded; (e)comparator group.

RESULTS

From 4424 records, only 3 respected the inclusion criteria. In a retrospective cohort study of adult moderate TBIs, the Glasgow Coma Scale(GCS) remained the same at 48 hours in those treated with hypertonic saline(HTS) while it worsened in the non-treated. A trend toward increased pulmonary infections and length of stay was found. In an RCT of adult severe and moderate TBIs, moderate TBIs treated with HTS showed a trend toward better secondary outcomes than standard care alone, with similar odds of adverse effects. An RCT enrolling children with mild TBI found a significant improvement in concussive pain immediately after HTS administration and after 2-3 days. No adverse events occurred.

CONCLUSIONS

A gap in the literature about HTs' role in mild and moderate TBI was found. Some benefits may exist with limited side effects and further studies are desirable.

Computational modelling of cerebral oedema and osmotherapy following ischaemic stroke

In ischaemic stroke, a large reduction in blood supply can lead to the breakdown of the blood brain barrier and to cerebral oedema after reperfusion therapy. Cerebral oedema is marked by elevated intracranial pressure (ICP), tissue herniation and reduced cerebral perfusion pressure. In clinical settings, osmotherapy has been a common practice to decrease ICP. However, there are no guidelines on the choice of administration protocol parameters such as injection doses, infusion time and retention time. Most importantly, the effects of osmotherapy have been proven controversial since the infusion of osmotic agents can lead to a range of side effects. Here, a new Finite Element model of brain oedema and osmotherapy is thus proposed to predict treatment outcome. The model consists of three components that simulate blood perfusion, oedema, and osmotherapy, respectively. In the perfusion model (comprising arteriolar, venous, and capillary blood compartments), an anatomically accurate brain geometry is used to identify regions with a perfusion reduction and potential oedema occurrence in stroke. The oedema model is then used to predict ICP using a porous circulation model with four fluid compartments (arteriolar blood, venular blood, capillary blood, and interstitial fluid). In the osmotherapy model, the osmotic pressure is varied and the changes in ICP during different osmotherapy episodes are quantified. The simulation results of the model show excellent agreement with available clinical data and the model is employed to study osmotherapy under various parameters. Consequently, it is demonstrated how therapeutic strategies can be proposed for patients with different pathological parameters based on simulations.

Hypertonic saline for traumatic brain injury: a systematic review and meta-analysis

BACKGROUND

Traumatic brain injury (TBI) causes mortality and long-term disability among young adults and imposes a notable cost on the healthcare system. In addition to the first physical hit, secondary injury, which is associated with increased intracranial pressure (ICP), is defined as biochemical, cellular, and physiological changes after the physical injury. Mannitol and Hypertonic saline (HTS) are the treatment bases for elevated ICP in TBI. This systematic review and meta-analysis evaluates the effectiveness of HTS in the management of patients with TBI.

METHODS

This study was conducted following the Joanna Briggs Institute (JBI) methods and PRISMA statement. A systematic search was performed through six databases in February 2022, to find studies that evaluated the effects of HTS, on increased ICP. Meta-analysis was performed using comprehensive meta-analysis (CMA).

RESULTS

Out of 1321 results, 8 studies were included in the systematic review, and 3 of them were included in the quantitative synthesis. The results of the meta-analysis reached a 35.9% (95% CI 15.0-56.9) reduction in ICP in TBI patients receiving HTS, with no significant risk of publication bias (t-value = 0.38, df = 2, p-value = 0.73). The most common source of bias in our included studies was the transparency of blinding methods for both patients and outcome assessors.

CONCLUSION

HTS can significantly reduce the ICP, which may prevent secondary injury. Also, based on the available evidence, HTS has relatively similar efficacy to Mannitol, which is considered the gold standard therapy for TBI, in boosting patients' neurological condition and reducing mortality rates.

Equiosmolar hypertonic saline and mannitol for brain relaxation in patients undergoing supratentorial tumor surgery: A systematic review and meta-analysis

Background:

Hypertonic saline (HS) and mannitol are hyperosmolar agents that are usually used to reduce intracranial pressure (ICP) and provide a satisfactory brain relaxation. The aim of the study was to perform a systematic review and meta-analysis to compare the efficacy of HS and mannitol on brain relaxation intraoperatively in patient undergoing craniotomies for supra-tentorial brain tumors.

Methods:

A systematic review and meta-analysis of randomized control trials. We included randomized control trials that compared equiosmolar HS and mannitol in supratentorial tumors craniotomies and reported at least one of the following outcomes: degree of brain relaxation, ICP, central venous pressure, mean arterial pressure, perioperative fluid input, urine output, Na+ levels, and K+ levels. We searched Medline, Cochrane Central Register of Controlled Trials, and Embase using MESH terms and keywords. The bibliographic references of included studies and trial registries were also searched.

Results:

Seven articles were included. The degree brain of relaxation was comparable across the two groups with slight tendency toward HS (RR = 1.13, 95% CI 0.99–1.29; P = 0.08). Mannitol was associated with significantly higher urine output (standardized mean difference [SMD] = −1.33, 95% CI −1.56–−1.10; P < 0.001). Na⁺ levels were higher in HS group (SMD = 1.47, 95% CI 0.86–2.09; P < 0.001). Mannitol was associated with non-significant decrease in CVP and increase fluid input (SMD = 0.42, 95% CI 0.00–0.85 and SMD = −0.18, 95% CI −0.37–0.02, respectively).

Conclusion:

Both HS and mannitol are associated with satisfactory brain relaxation with a non-statistically significant tendency for HS to achieve better relaxation scores with mannitol resulting in higher urine output while HS with higher Na⁺ levels.

Elevated intraspinal pressure in traumatic spinal cord injury is a promising therapeutic target

The currently recommended management for acute traumatic spinal cord injury aims to reduce the incidence of secondary injury and promote functional recovery. Elevated intraspinal pressure (ISP) likely plays an important role in the processes involved in secondary spinal cord injury, and should not be overlooked. However, the factors and detailed time course contributing to elevated ISP and its impact on pathophysiology after traumatic spinal cord injury have not been reviewed in the literature. Here, we review the etiology and progression of elevated ISP, as well as potential therapeutic measures that target elevated ISP. Elevated ISP is a time-dependent process that is mainly caused by hemorrhage, edema, and blood-spinal cord barrier destruction and peaks at 3 days after traumatic spinal cord injury. Duraplasty and hypertonic saline may be promising treatments for reducing ISP within this time window. Other potential treatments such as decompression, spinal cord incision, hemostasis, and methylprednisolone treatment require further validation.

Management of Acute Ischemic Stroke

Objectives:

Concise “synthetic” review of the state of the art of management of acute ischemic stroke.

Data Sources:

Available literature on PubMed.

Study Selection:

We selected landmark studies, recent clinical trials, observational studies, and professional guidelines on the management of stroke including the last 10 years.

Data Extraction:

Eligible studies were identified and results leading to guideline recommendations were summarized.

Data Synthesis:

Stroke mortality has been declining over the past 6 decades, and as a result, stroke has fallen from the second to the fifth leading cause of death in the United States. This trend may follow recent advances in the management of stroke, which highlight the importance of early recognition and early revascularization. Recent studies have shown that early recognition, emergency interventional treatment of acute ischemic stroke, and treatment in dedicated stroke centers can significantly reduce stroke-related morbidity and mortality. However, stroke remains the second leading cause of death worldwide and the number one cause for acquired long-term disability, resulting in a global annual economic burden.

Conclusions:

Appropriate treatment of ischemic stroke is essential in the reduction of mortality and morbidity. Management of stroke involves a multidisciplinary approach that starts and extends beyond hospital admission.

Hyperosmolar therapy: A century of treating cerebral edema

Hyperosmolar therapy is a cornerstone for the management of elevated intracranial pressure in patients with devastating neurological injuries. Its discovery and use in various pathologies has become a valuable therapy in modern neurological critical care across the globe. Although hyperosmolar therapy is used routinely, the history of its origin is still elusive to many physicians. Understanding the basis of discovery and use of different hyperosmolar agents lends insight into the complex management of elevated intracranial pressure. There are very few practices in medicine which has stood the test of time. The discovery of hyperosmolar therapy has not only provided us a wealth of data for the management of intracranial hypertension but has also allowed us to develop new treatment strategies by improving our understanding of the molecular mechanisms of cerebral inflammation, blood-brain permeability, and cerebral edema in all modes of neuronal injury.

Effect of hypertonic saline in the management of elevated intracranial pressure in children with cerebral edema: A systematic review and meta-analysis

Objective:

To determine the hypertonic saline efficacy in children with cerebral edema and raised intracranial pressure.

Method:

Studies assessing the efficacy and safety of hypertonic saline in children with cerebral edema and elevated intracranial pressure were identified using Medline, Web of Science, Scopus, and Google Scholar databases. Two reviewers independently assessed papers for inclusion. The primary outcome was a reduction of elevated intracranial pressure by the administration of hypertonic saline.

Results:

We initially evaluated 1595 potentially relevant articles, and only 7 studies met the eligibility criteria for the final analysis. Out of the seven studies, three of them were randomized controlled trials. Three of the studies found that hypertonic saline significantly reduced elevated intracranial pressure compared to control. One study reported a resolution of the comatose state as a measure of reduced intracranial pressure. It also found a significantly higher resolution of coma in the hypertonic saline group rather than the control. Three studies reported that the reduction of intracranial pressure was comparable between the groups. The random-effects model using pooled estimates from four studies showed no difference in hypertonic saline and conventional therapy mortality outcomes. Hypertonic saline was administered as bolus-only therapy at a rate of 1–10 mL/kg/dose over 5 min to 2 h and or bolus followed by infusion therapy (0.5–2 mL/kg/h). One study reported a twofold faster resolution of high intracranial pressure following hypertonic saline administration compared to controls. The re-dosing schedule varied greatly in all included studies. However, three studies reported adverse events but not methodically, and there were no reports on neurological sequelae.

Conclusion:

Hypertonic saline appears to reduce intracranial pressure in children with cerebral edema. However, we cannot draw a firm conclusion regarding the safest dose regimens of hypertonic saline, including the safe and effective therapeutic hypernatremia threshold in the management of raised intracranial pressure with cerebral edema. Future clinical trials should focus on the appropriate concentration, dose, duration, mode of administration, and adverse effects of hypertonic saline to standardize the treatment.

Randomized Clinical Trial of 20% Mannitol Versus 3% Hypertonic Saline in Children With Raised Intracranial Pressure Due to Acute CNS Infections

OBJECTIVES

Mannitol is a commonly used osmotherapy agent in raised intracranial pressure. However, the side effects of mannitol are significant. In traumatic brain injury (adult and pediatric), hypertonic saline (3%) shows varied results in comparison with 20% mannitol. We compared the effect of 3% hypertonic saline versus 20% mannitol (using common dosing strategies) on raised intracranial pressure in pediatric acute CNS infections.

DESIGN

Open-label randomized controlled trial.

SETTING

PICU of a quaternary care academic institute.

PATIENTS

Children 1-12 years old, with raised intracranial pressure and modified-Glasgow Coma Scale scores less than or equal to 8, were enrolled.

INTERVENTIONS

Patients were randomly assigned to 20%-mannitol (n = 28), 0.5 gram/kg/dose versus 3%-hypertonic saline (n = 29), 10 mL/kg loading followed by 0.5-1 mL/kg/hr infusion. An intraparenchymal catheter was used to monitor the intracranial pressure. The primary outcome was the proportion of patients achieved target average intracranial pressure less than 20 mm Hg during 72 hours. Secondary outcomes were interventions, morbidity, and mortality.

MEASUREMENTS AND MAIN RESULTS

The proportion of patients with target average intracranial pressure (< 20 mm Hg) was higher in hypertonic saline-group as compared to mannitol-group (79.3% vs 53.6%; adjusted hazard ratio 2.63; 95% CI: 1.23-5.61). Mean (± SE) reduction of intracranial pressure (-14.3 ± 1.7 vs -5.4 ± 1.7 mm Hg; p ≤ 0.001) and elevation of cerebral perfusion pressure (15.4 ± 2.4 vs 6 ± 2.4 mm Hg; p = 0.007) from baseline were significant in hypertonic saline-group. Mean (± SE) intracranial pressure over 72 hours was lower (14 ± 2 vs 22 ± 2 mm Hg; p = 0.009), and cerebral perfusion pressure was higher (65 ± 2.2 vs 58 ± 2.2; p = 0.032) in hypertonic saline-group. Hypertonic saline-group had higher modified-Glasgow Coma Scale score at 72 hours (median, interquartile range 10; 7-11 vs 7; 3-9; p = 0.003), lower mortality (20.7% vs 35.7%; p = 0.21), shorter duration of mechanical ventilation (5 vs 15 d; p = 0.002), and PICU stay (11 vs 19 d; p = 0.016) and less severe neurodisability at discharge (31% vs 61%; p = 0.049).

CONCLUSIONS

In pediatric acute CNS infections, 3%-hypertonic saline was associated with a greater reduction of intracranial pressure as compared to 20% mannitol.

Drug development in targeting ion channels for brain edema

Cerebral edema is a pathological hallmark of various central nervous system (CNS) insults, including traumatic brain injury (TBI) and excitotoxic injury such as stroke. Due to the rigidity of the skull, edema-induced increase of intracranial fluid significantly complicates severe CNS injuries by raising intracranial pressure and compromising perfusion. Mortality due to cerebral edema is high. With mortality rates up to 80% in severe cases of stroke, it is the leading cause of death within the first week. Similarly, cerebral edema is devastating for patients of TBI, accounting for up to 50% mortality. Currently, the available treatments for cerebral edema include hypothermia, osmotherapy, and surgery. However, these treatments only address the symptoms and often elicit adverse side effects, potentially in part due to non-specificity. There is an urgent need to identify effective pharmacological treatments for cerebral edema. Currently, ion channels represent the third-largest target class for drug development, but their roles in cerebral edema remain ill-defined. The present review aims to provide an overview of the proposed roles of ion channels and transporters (including aquaporins, SUR1-TRPM4, chloride channels, glucose transporters, and proton-sensitive channels) in mediating cerebral edema in acute ischemic stroke and TBI. We also focus on the pharmacological inhibitors for each target and potential therapeutic strategies that may be further pursued for the treatment of cerebral edema.

Hyperosmolar Treatment for Patients at Risk for Increased Intracranial Pressure: A Single-Center Cohort Study

Treatment with osmoactive agents such as mannitol or hypertonic saline (HTS) solutions is widely used to manage or prevent the increase of intracranial pressure (ICP) in central nervous system (CNS) disorders. We sought to evaluate the variability and mean plasma concentrations of the water and electrolyte balance parameters in critically ill patients treated with osmotic therapy and their influence on mortality. This cohort study covered patients hospitalized in an intensive care unit (ICU) from January 2017 to June 2019 with presumed increased ICP or considered to be at risk of it, treated with 15% mannitol (G1, n = 27), a combination of 15% mannitol and 10% hypertonic saline (HTS) (G2, n = 33) or 10% HTS only (G3, n = 13). Coefficients of variation (Cv) and arithmetic means (mean) were calculated for the parameters reflecting the water and electrolyte balance, i.e., sodium (NaCv/NaMean), chloride (ClCv/ClMean) and osmolality (mOsmCv/mOsmMean). In-hospital mortality was also analyzed. The study group comprised 73 individuals (36 men, 49%). Mortality was 67% (n = 49). Median NaCv (G1: p = 0.002, G3: p = 0.03), ClCv (G1: p = 0.02, G3: p = 0.04) and mOsmCv (G1: p = 0.001, G3: p = 0.02) were higher in deceased patients. NaMean (p = 0.004), ClMean (p = 0.04), mOsmMean (p = 0.003) were higher in deceased patients in G3. In G1: NaCv (AUC = 0.929, p < 0.0001), ClCv (AUC = 0.817, p = 0.0005), mOsmCv (AUC = 0.937, p < 0.0001) and in G3: NaMean (AUC = 0.976, p < 0.001), mOsmCv (AUC = 0.881, p = 0.002), mOsmMean (AUC = 1.00, p < 0.001) were the best predictors of mortality. The overall mortality prediction for combined G1+G2+G3 was very good, with AUC = 0.886 (p = 0.0002). The mortality of critically ill patients treated with osmotic agents is high. Electrolyte disequilibrium is the independent predictor of mortality regardless of the treatment method used. Variations of plasma sodium, chloride and osmolality are the most deleterious factors regardless of the absolute values of these parameters.

Hypertonic saline versus other intracranial pressure-lowering agents for people with acute traumatic brain injury

BACKGROUND

Increased intracranial pressure has been shown to be strongly associated with poor neurological outcomes and mortality for patients with acute traumatic brain injury. Currently, most efforts to treat these injuries focus on controlling the intracranial pressure. Hypertonic saline is a hyperosmolar therapy that is used in traumatic brain injury to reduce intracranial pressure. The effectiveness of hypertonic saline compared with other intracranial pressure-lowering agents in the management of acute traumatic brain injury is still debated, both in the short and the long term.

OBJECTIVES

To assess the comparative efficacy and safety of hypertonic saline versus other intracranial pressure-lowering agents in the management of acute traumatic brain injury.

SEARCH METHODS

We searched Cochrane Injuries' Specialised Register, CENTRAL, PubMed, Embase Classic+Embase, ISI Web of Science: Science Citation Index and Conference Proceedings Citation Index-Science, as well as trials registers, on 11 December 2019. We supplemented these searches with searches of four major Chinese databases on 19 September 2018. We also checked bibliographies, and contacted trial authors to identify additional trials.

SELECTION CRITERIA

We sought to identify all randomised controlled trials (RCTs) of hypertonic saline versus other intracranial pressure-lowering agents for people with acute traumatic brain injury of any severity. We excluded cross-over trials as incompatible with assessing long-term outcomes.

DATA COLLECTION AND ANALYSIS

Two review authors independently screened search results to identify potentially eligible trials and extracted data using a standard data extraction form. Outcome measures included: mortality at end of follow-up (all-cause); death or disability (as measured by the Glasgow Outcome Scale (GOS)); uncontrolled intracranial pressure (defined as failure to decrease the intracranial pressure to target and/or requiring additional intervention); and adverse events e.g. rebound phenomena; pulmonary oedema; acute renal failure during treatment).

MAIN RESULTS

Six trials, involving data from 287 people, met the inclusion criteria. The majority of participants (91%) had a diagnosis of severe traumatic brain injury. We had concerns about particular domains of risk of bias in each trial, as physicians were not reliably blinded to allocation, two trials contained participants with conditions other than traumatic brain injury and in one trial, we had concerns about missing data for important outcomes. The original protocol was available for only one trial and other trials (where registered) were registered retrospectively. Meta-analysis for both the primary outcome (mortality at final follow-up) and for 'poor outcome' as per conventionally dichotomised GOS criteria, was only possible for two trials. Synthesis of long-term outcomes was inhibited by the fact that two trials ceased data collection within two hours of a single bolus dose of an intracranial pressure-lowering agent and one at discharge from the intensive care unit (ICU). Only three trials collected data after participants were released from hospital, one of which did not report mortality and reported a 'poor outcome' by GOS criteria in an unconventional way. Substantial missing data in a key trial meant that in meta-analysis we report 'best-case' and 'worst-case' estimates alongside available case analysis. In no scenario did we discern a clear difference between treatments for either mortality or poor neurological outcome. Due to variation in modes of drug administration (including whether it followed or did not follow cerebrospinal fluid (CSF) drainage, as well as different follow-up times and ways of reporting changes in intracranial pressure, as well as no uniform definition of 'uncontrolled intracranial pressure', we did not perform meta-analysis for this outcome and report results narratively, by individual trial. Trials tended to report both treatments to be effective in reducing elevated intracranial pressure but that hypertonic saline had increased benefits, usually adding that pretreatment factors need to be considered (e.g. serum sodium and both system and brain haemodynamics). No trial provided data for our other outcomes of interest. We consider evidence quality for all outcomes to be very low, as assessed by GRADE; we downgraded all conclusions due to imprecision (small sample size), indirectness (due to choice of measurement and/or selection of participants without traumatic brain injury), and in some cases, risk of bias and inconsistency. Only one of the included trials reported data on adverse effects; a rebound phenomenon, which was present only in the comparator group (mannitol). None of the trials reported data on pulmonary oedema or acute renal failure during treatment. On the whole, trial authors do not seem to have rigorously sought to collect data on adverse events.

AUTHORS' CONCLUSIONS

This review set out to find trials comparing hypertonic saline to a potential range of other intracranial pressure-lowering agents, but only identified trials comparing it with mannitol or mannitol in combination with glycerol. Based on limited data, there is weak evidence to suggest that hypertonic saline is no better than mannitol in efficacy and safety in the long-term management of acute traumatic brain injury. Future research should be comprised of large, multi-site trials, prospectively registered, reported in accordance with current best practice. Trials should investigate issues such as the type of traumatic brain injury suffered by participants and concentration of infusion and length of time over which the infusion is given.

Hypertonic saline versus other intracranial pressure-lowering agents for people with acute traumatic brain injury

BACKGROUND

Increased intracranial pressure (ICP) has been shown to be strongly associated with poor neurological outcomes and mortality for patients with acute traumatic brain injury (TBI). Currently, most efforts to treat these injuries focus on controlling the ICP. Hypertonic saline (HTS) is a hyperosmolar therapy that is used in traumatic brain injury to reduce intracranial pressure. The effectiveness of HTS compared with other ICP-lowering agents in the management of acute TBI is still debated, both in the short and the long term.

OBJECTIVES

To assess the comparative efficacy and safety of hypertonic saline versus other ICP-lowering agents in the management of acute TBI.

SEARCH METHODS

We searched the Cochrane Injuries Group's Specialised Register, The Cochrane Library, PubMed, Embase Classic+Embase (OvidSP), ISI Web of Science: Science Citation Index and Conference Proceedings Citation Index-Science, as well as trials registers, on 11 December 2019. We supplemented these searches using four major Chinese databases on 19 September 2018. We also checked bibliographies, and contacted study authors to identify additional studies.

SELECTION CRITERIA

We sought to identify all randomised controlled trials (RCTs) of HTS versus other intracranial pressure-lowering agents for people with acute TBI of any severity. We excluded cross-over trials as incompatible with assessing long term outcomes.

DATA COLLECTION AND ANALYSIS

Two review authors independently screened search results to identify potentially eligible trials and extracted data using a standard data extraction form. Outcome measures included: mortality at end of follow-up (all-cause); death or disability (as measured by the Glasgow Outcome Scale (GOS)); uncontrolled ICP (defined as failure to decrease the ICP to target and/or requiring additional intervention); and adverse events (AEs) (e.g. rebound phenomena; pulmonary oedema; acute renal failure during treatment).

MAIN RESULTS

Six trials, involving data from 295 people, met the inclusion criteria. The majority of participants (89%) had a diagnosis of severe TBI. We had concerns about particular domains of risk of bias in each trial, as physicians were not reliably blinded to allocation, two trials contained participants with conditions other than TBI and in one trial, there were concerns about missing data for important outcomes. The original protocol was available for only one study and other trials (where registered) were registered retrospectively. Meta-analysis for both the primary outcome (mortality at final follow up) and for 'poor outcome' as per conventionally dichotomised GOS criteria, was only possible for two studies. Synthesis of long-term outcomes was inhibited by the fact that two ceased data collection within two hours of a single bolus dose of an ICP-lowering agent and one at discharge from ICU. Only three studies collected data after release from hospital. Due to variation in modes of drug administration, follow-up times, and ways of reporting changes in ICP, as well as no uniform definition of 'uncontrolled ICP', we did not perform meta-analysis for this outcome and report results narratively, by individual trial. Trials tended to report both treatments to be effective in reducing elevated ICP but that HTS had increased benefits, usually adding that pretreatment factors need to be considered (e.g. serum sodium and both system and brain hemodynamics). No trial provided data for our other outcomes of interest. Evidence for all outcomes is considered very low, as assessed by GRADE. All conclusions were downgraded due to imprecision (small sample size), indirectness (due to choice of measurement and/or selection of patients without TBI), and in some cases, risk of bias and inconsistency. Only one of the included trials reported data on adverse effects (AEs) - a rebound phenomenon, which was present only in the comparator group (mannitol). No data were reported on pulmonary oedema or acute renal failure during treatment. On the whole, investigators do not seem to have rigorously sought to collect data on AEs.

AUTHORS' CONCLUSIONS

This review set out to find trials comparing HTS to a potential range of other ICP-lowering agents, but only identified trials comparing it with mannitol or mannitol in combination with glycerol. Based on limited data, there is weak evidence to suggest that HTS is no better than mannitol in efficacy and safety in the long-term management of acute TBI. Future research should be comprised of large, multi-site trials, prospectively registered, reported in accordance with current best practice. Issues such as the type of TBI suffered by participants and concentration of infusion and length of time over which the infusion is given should be investigated.

Comparison of equiosmolar dose of hyperosmolar agents in reducing intracranial pressure-a randomized control study in pediatric traumatic brain injury

INTRODUCTION

There are no comparative studies available for hyperosmolar therapy in children. The present study is a prospective open label randomized control trial to compare the effect of equiosmolar doses of mannitol and hypertonic saline in reducing intracranial pressure in children who sustained severe traumatic brain injury.

METHODS

This is a prospective open-label randomized controlled trial. Thirty children aged less than or equal to 16 years with severe traumatic brain injury and raised intracranial pressure as measured by ventricular catheter insertion were enrolled. Sixteen children received 20% mannitol, and 14 children received 3% saline as 2.5 ml/kg bolus for episodes of intracranial pressure above cutoff value for age. The mean reduction in intracranial pressure and Glasgow outcome scale at 6 months after injury was measured.

RESULTS

The mean reduction in intracranial pressure in mannitol group was 7.13 mmHg and in hypertonic saline group was 5.67 mmHg, and the difference was not statistically significant, p = 0.33. The incidence of death or survival in vegetative state was 23.07% in mannitol group and 16.66% in hypertonic saline group, and the difference was not statistically significant, p = 0.69.

CONCLUSION

Both mannitol and hypertonic saline were equally effective for treatment of raised intracranial pressure in children with severe traumatic brain injury.

Hypertonic Solutions in Traumatic Brain Injury: A Systematic Review and Meta-Analysis

This study aims to evaluate the efficacy of hypertonic saline versus crystalloids (normal Saline/lactated Ringers) in improving clinical outcome in patients with traumatic brain injury (TBI). Electronic databases and grey literature (unpublished articles) were searched under different MeSH terms from 1990 to present. Randomized control trials, case–control studies and prospective cohort studies on decompressive craniectomy in TBI (>18-year-old). Clinical outcome measures included Glasgow Coma Outcome Scale (GCOS), Extended GCOS, and mortality. Data were extracted to Review Manager Software. A total of 115 articles that met the inclusion criteria were retrieved and analyzed. Ultimately, five studies were included in our meta-analysis, which revealed that patients with TBI who had hypertonic saline had no statistically significant likelihood of having a good outcome at discharge or 6 months than those who had crystalloid (odds ratio [OR]: 0.01; 95% confidence interval (CI): 0.03–0.05; P = 0.65). The relative risk (RR) of mortality in hypertonic saline versus the crystalloid at discharge or 6-month is RR: 0.80; 95% CI: 0.64–0.99; P = 0.04. The subgroup analysis showed that the group who had hypertonic solution significantly decreases the number of interventions versus the crystalloid group OR: 0.53; 95% CI: 0.48–0.59; P < 0.00001 and also reduces the length of intensive care unit stay (OR: 0.46; 95% CI: 0.21–1.01; P = 0.05). Hypertonic saline decreases the financial burden, but neither impacts the clinical outcome nor reduces the mortality. However, further clinical trials are required to prove if hypertonic saline has any role in improving the clinical and neurological status of patients with TBI versus the normal saline/lactated Ringers.

Hypertonic Saline Alleviates Brain Edema After Traumatic Brain Injury via Downregulation of Aquaporin 4 in Rats

Background

Hypertonic saline (HS) has been successfully used for treatment of various forms of brain edema. Decreased expression of aquaporin (AQP)4 and pro-inflammatory cytokines such as tumor necrosis factor (TNF)-α and interleukin (IL)-1β have been linked to edema pathogenesis. This study examined the effect of 3% HS on brain edema in a rat model of traumatic brain injury (TBI).

Material/Methods

Sprague-Dawley rats were subjected to TBI induced by a controlled cortical impactor. The HS group was injected with 3% NaCl until the end of the study period. AQP4, TNF-α, IL-1β, and caspase-3 levels were measured by Western blotting, immunohistochemistry, enzyme-linked immunosorbent assay, and quantitative real-time PCR. Brain water content was also measured. Apoptotic cells in brain tissue were detected with terminal deoxynucleotidyl transferase dUTP nick-end labeling. Brain water content decreased following treatment with 3% HS relative to the TBI group.

Results

This was accompanied by decreases in AQP4, TNF-α, and IL-1β mRNA and protein levels. TBI resulted in increases in caspase-3 mRNA expression and the number of apoptotic cells; treatment with 3% HS suppressed apoptosis as compared to the TBI group.

Conclusions

Treatment with 3% HS ameliorated TBI-induced brain edema, possibly by suppressing brain edema, pro-inflammatory cytokine expression, and apoptosis.

The Effects of Clinically Relevant Hypertonic Saline and Conivaptan Administration on Ischemic Stroke

Cerebral edema after stroke is associated with poor neurological outcomes. Current therapies are limited to osmotic agents, such as hypertonic saline (HS), which reduce intracranial pressure. Although studies have demonstrated edema reductions following HS, tissue survival has not been thoroughly examined. Additionally, the efficacy of promising pharmacological agents has not been evaluated for synergy with osmotic agents. Conivaptan is an FDA-approved vasopressin receptor antagonist that may exert both osmotic and anti-inflammatory effects. In this study, rats were subjected to middle cerebral artery occlusion prior to treatment with 5 % HS bolus +5 % HS maintenance (HS), conivaptan alone (Con), conivaptan +5 % HS maintenance (Con + HS), or conivaptan +5 % HS bolus +5 % maintenance (Con + HSb). Treatments were initiated at six (Early) or 24 h (Late) following stroke and rats were euthanized at 48 h to evaluate infarct volume, brain edema, and microglia/macrophage activation. Infarct volume and brain edema in the Early HS, Early Con, and Late HS groups were significantly reduced compared with controls. Interestingly, only the Early Con group demonstrated reduced microglia/macrophage activation. These data suggest an anti-inflammatory mechanism for conivaptan and provide support for a multipronged approach combining osmotic agents with compounds that inhibit the neuroinflammatory response to stroke.

Osmotherapy With Hypertonic Saline Attenuates Global Cerebral Edema Following Experimental Cardiac Arrest via Perivascular Pool of Aquaporin-4

OBJECTIVES

We tested the hypothesis that osmotherapy with hypertonic saline attenuates cerebral edema following experimental cardiac arrest and cardiopulmonary resuscitation by exerting its effect via the perivascular pool of aquaporin-4. We used mice with targeted disruption of the gene encoding α-syntrophin (α-Syn) that demonstrate diminished perivascular aquaporin-4 pool but retain the non-endfoot and ependymal pools.

DESIGN

Laboratory animal study.

SETTING

University animal research laboratory.

INTERVENTIONS

Isoflurane-anesthetized adult male wild-type C57B/6 or α-Syn mice were subjected to cardiac arrest/cardiopulmonary resuscitation and treated with either a continuous IV infusion of 0.9% saline or various concentrations of hypertonic saline. Serum osmolality, regional brain water content, blood-brain barrier disruption, and aquaporin-4 protein expression were determined at 24 hours after cardiac arrest/cardiopulmonary resuscitation.

MEASUREMENTS AND MAIN RESULTS

Hypertonic saline (7.5%) treatment significantly attenuated water content in the caudoputamen complex and cortex compared with 0.9% saline treatment in wild-type mice subjected to cardiac arrest/cardiopulmonary resuscitation. In contrast, in α-Syn mice subjected to cardiac arrest/cardiopulmonary resuscitation, 7.5% hypertonic saline treatment did not attenuate water content. Treatment with 7.5% hypertonic saline attenuated blood-brain barrier disruption at 24 hours following cardiac arrest/cardiopulmonary resuscitation in wild-type mice but not in α-Syn mice. Total aquaporin-4 protein expression was not different between 0.9% saline and hypertonic saline-treated wild-type mice.

CONCLUSIONS

Following experimental cardiac arrest/cardiopulmonary resuscitation: 1) continuous hypertonic saline therapy maintained to achieve serum osmolality of ≈ 350 mOsm/L is beneficial for the treatment of cerebral edema; 2) perivascular pool of aquaporin-4 plays a critical role in water egress from brain; and 3) hypertonic saline attenuates blood-brain barrier disruption via perivascular aquaporin-4 pool.

The Use of Mannitol and Hypertonic Saline Therapies in Patients with Elevated Intracranial Pressure: A Review of the Evidence

Patients with increased intracranial pressure generally require pharmacologic therapies and often more definitive treatments, such as surgical intervention. The overall goal of these interventions is to maintain or re-establish adequate cerebral blood flow and prevent herniation. Regardless of the cause of increased intracranial pressure, osmotherapy is considered the mainstay of medical therapy, and should be administered as soon as possible. This article reviews the history of hyperosmolar and hypertonic therapies, the Monro-Kellie hypothesis, and types of cerebral edema. Pharmacologic properties, clinical applications, complications, recommended monitoring during therapy, and risks versus benefits are also discussed.

Hypertonic saline attenuates expression of Notch signaling and proinflammatory mediators in activated microglia in experimentally induced cerebral ischemia and hypoxic BV-2 microglia

Background

Ischemic stroke is a major disease that threatens human health in ageing population. Increasing evidence has shown that neuroinflammatory mediators play crucial roles in the pathophysiology of cerebral ischemia injury. Notch signaling is recognized as the cell fate signaling but recent evidence indicates that it may be involved in the inflammatory response in activated microglia in cerebral ischemia. Previous report in our group demonstrated hypertonic saline (HS) could reduce the release of interleukin-1 beta and tumor necrosis factor-alpha in activated microglia, but the underlying molecular and cellular mechanisms have remained uncertain. This study was aimed to explore whether HS would partake in regulating production of proinflammatory mediators through Notch signaling.

Results

HS markedly attenuated the expression of Notch-1, NICD, RBP-JK and Hes-1 in activated microglia both in vivo and in vitro. Remarkably, HS also reduced the expression of iNOS in vivo, while the in vitro levels of inflammatory mediators Phos-NF-κB, iNOS and ROS were reduced by HS as well.

Conclusion

Our results suggest that HS may suppress of inflammatory mediators following ischemia/hypoxic through the Notch signaling which operates synergistically with NF-κB pathway in activated microglia. Our study has provided the morphological and biochemical evidence that HS can attenuate inflammation reaction and can be neuroprotective in cerebral ischemia, thus supporting the use of hypertonic saline by clinicians in patients with an ischemia stroke.

Electronic supplementary material

The online version of this article (doi:10.1186/s12868-017-0351-6) contains supplementary material, which is available to authorized users.

Hypertonic saline protects brain endothelial cells against hypoxia correlated to the levels of epidermal growth factor receptor and interleukin-1β

OBJECTIVE

The aim of this study was to verify the protective effect of hypertonic saline (HS) on brain endothelial cells under hypoxic conditions and the relevant underlying mechanism.

METHODS

bEnd.3 cells were treated with oxygen-glucose deprivation (OGD)-induced injury. To measure HS performance, cell viability was determined using the 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium salt assay, and cell apoptosis was assessed by flow cytometry and Terminal deoxynucleotidyl transferase UTP nick-end labeling staining. RNA-seq was performed to assess the expression profiles and screen the candidate genes that participated in OGD-induced injury and the HS protective effect. Quantitative real-time polymerase chain reaction (qPCR) and western blot analysis were used to confirm the expression of candidate genes, and enzyme-linked immunosorbent assay was used to measure the level of interleukin (IL)-1β. Overexpression analyses were performed to confirm the functions of the differentially expressed genes.

RESULTS

HS with a concentration of 40 mmol/L NaCl had an obvious protective effect on bEnd.3 cells after OGD-induced injury, resulting in increased cell viability and a smaller percentage of apoptotic cells. According to the RNA-seq results, epidermal growth factor receptor (EGFR) was chosen as the differentially expressed gene target in this study. The qPCR and western blot analyses further confirmed that the levels of EGFR/phosphorylated epidermal growth factor receptor and IL-1β were enhanced after OGD-induced injury, but attenuated after treatment with 40 mmol/L of NaCl HS. Overexpressed EGFR reversed the protective effect of HS that caused low viability and high rates of apoptosis in cells.

CONCLUSION

HS can protect endothelial cells against OGD-induced injury, but is affected by the expression of EGFR/p-EGFR and IL-1β.

Effectiveness of 7.5% hypertonic saline in children with severe traumatic brain injury

PURPOSE

Hyperosmolar therapies aim at controlling increased intracranial pressure (ICP) in patients with traumatic brain injury (TBI). The aim of this study was to evaluate the effect of 7.5% hypertonic saline (HTS) on ICP and cerebral perfusion pressure (CPP) in children with severe TBI.

MATERIALS AND METHODS

Medical records of patients 14 years or younger with severe TBI, admitted in the pediatric intensive care unit of "Aghia Sophia" Children's Hospital, Athens, Greece, during 2009 to 2015, and received HTS apart from mannitol were retrospectively reviewed. The ICP and CPP pre-HTS and 30, 60, and 120 minutes post-HTS infusion were evaluated. Furthermore, the presence of adverse effects, the long-term neurological outcome, and survival were recorded.

RESULTS

Twenty-nine patients requiring in total 136 HTS infusions were analyzed. The ICP was significantly reduced and CPP elevated at 30, 60, and 120 minutes postinfusion; and furthermore, postadministration ICP and CPP were predominantly within acceptable limits. No significant adverse effects were recorded and most of the patients survived, however, one third had severe neurological impairment at 6 months postinjury.

CONCLUSIONS

In our study, 7.5% HTS infusion as a second-tier osmotic therapy was associated with significant reduction of ICP and increase of CPP in children with severe TBI.

Hypertonic saline alleviates experimentally induced cerebral oedema through suppression of vascular endothelial growth factor and its receptor VEGFR2 expression in astrocytes

BACKGROUND

Cerebral oedema is closely related to the permeability of blood-brain barrier, vascular endothelial growth factor (VEGF) and its receptor vascular endothelial growth factor receptor 2 (VEGFR2) all of which are important blood-brain barrier (BBB) permeability regulatory factors. Zonula occludens 1 (ZO-1) and claudin-5 are also the key components of BBB. Hypertonic saline is widely used to alleviate cerebral oedema. This study aimed to explore the possible mechanisms underlying hypertonic saline that ameliorates cerebral oedema effectively.

METHODS

Middle cerebral artery occlusion (MCAO) model in Sprague-Dawley (SD) rats and of oxygen-glucose deprivation model in primary astrocytes were used in this study. The brain water content (BWC) was used to assess the effect of 10 % HS on cerebral oedema. The assessment of Evans blue (EB) extravasation was performed to evaluate the protective effect of 10 % HS on blood-brain barrier. The quantification of VEGF, VEGFR2, ZO-1 and claudin-5 was used to illustrate the mechanism of 10 % HS ameliorating cerebral oedema.

RESULTS

BWC was analysed by wet-to-dry ratios in the ischemic hemisphere of SD rats; it was significantly decreased after 10 % HS treatment (P < 0.05). We also investigated the blood-brain barrier protective effect by 10 % HS which reduced EB extravasation effectively in the peri-ischemic brain tissue. In parallel to the above notably at 24 h following MCAO, mRNA and protein expression of VEGF and VEGFR2 in the peri-ischemic brain tissue was down-regulated after 10 % HS treatment (P < 0.05). Along with this, in vitro studies showed increased VEGF and VEGFR2 mRNA and protein expression in primary astrocytes under hypoxic condition (P < 0.05), but it was suppressed after HS treatment (P < 0.05). In addition, HS inhibited the down-regulation of ZO-1, claudin-5 effectively.

CONCLUSIONS

The results suggest that 10 % HS could alleviate cerebral oedema possibly through reducing the ischemia induced BBB permeability as a consequence of inhibiting VEGF-VEGFR2-mediated down-regulation of ZO-1, claudin-5.

Longitudinal enlargement of the lesion after spinal cord injury in the rat: a consequence of malignant edema?

STUDY DESIGN

Experimental animal study.

OBJECTIVES

Quantitative analysis of secondary changes in lesion size after experimental spinal cord injury (SCI) in the rat, with special emphasis to the formation of dorsal column lesions.

SETTING

Slovakia.

METHODS

After SCI in the rat, animals survived for different periods ranging from 5 min to 7 days. Their whole spinal cords were cut transversally into 1 mm thick slabs. On each slab, the lesion profile was outlined. The overall shape of the lesion was reconstructed from a series of consecutive profiles and its length was measured.

RESULTS

Immediately after injury, a spindle-shaped hemorrhagic contusive lesion was observed, with the length of ~15 mm. After a quiescent phase lasting for at least 1 h, there was a dramatic secondary enlargement of the lesion and its length increased up to 40 mm between 1 and 48 h. The fully developed lesion consisted of the spindle-shaped epicenter and long cranial and caudal protrusions located in the midline between dorsal columns.

CONCLUSION

We propose that secondary enlargement of the lesion can be explained by posttraumatic swelling. The expanding tissues are pushed out in longitudinal axis along the mechanically weakest parts of the spinal cord. Additional data that support this hypothesis are presented. Our findings indicate that malignant posttraumatic edema might have an important role in pathomechanisms of secondary injury after SCI.

Treatment of malignant brain edema and increased intracranial pressure after stroke

OPINION STATEMENT

The management of patients with large territory ischemic strokes and the subsequent development of malignant brain edema and increased intracranial pressure is a significant challenge in modern neurology and neurocritical care. These patients are at high risk of subsequent neurologic decline and are best cared for in an intensive care unit or a comprehensive stroke center with access to neurosurgical support. Risks include hemorrhagic conversion, herniation, poor functional outcome, and death. This review discusses recent advances in understanding the pathophysiology of edema formation, identifying patients at risk, current management strategies, and emerging therapies.

Hypertonic saline alleviates cerebral edema by inhibiting microglia-derived TNF-α and IL-1β-induced Na-K-Cl Cotransporter up-regulation

Background

Hypertonic saline (HS) has been successfully used clinically for treatment of various forms of cerebral edema. Up-regulated expression of Na-K-Cl Cotransporter 1 (NKCC1) and inflammatory mediators such as tumor necrosis factor alpha (TNF-α) and interleukin-1 beta (IL-1β) has been demonstrated to be closely associated with the pathogenesis of cerebral edema resulting from a variety of brain injuries. This study aimed to explore if alleviation of cerebral edema by 10% HS might be effected through down-regulation of inflammatory mediator expression in the microglia, and thus result in decreased NKCC1 expression in astrocytes in the cerebral cortex bordering the ischemic core.

Methods

The Sprague-Dawley (SD) rats that underwent right-sided middle cerebral artery occlusion (MCAO) were used for assessment of NKCC1, TNF-α and IL-1β expression using Western blotting, double immunofluorescence and real time RT-PCR, and the model also was used for evaluation of brain water content (BWC) and infarct size. SB203580 and SP600125, specific inhibitors of the p38 and JNK signaling pathways, were used to treat primary microglia cultures to determine whether the two signaling pathways were required for the inhibition of HS on microglia expressing and secreting TNF-α and IL-1β using Western blotting, double immunofluorescence and enzyme-linked immunosorbent assay (ELISA). The effect of TNF-α and IL-1β on NKCC1 expression in primary astrocyte cultures was determined. In addition, the direct inhibitory effect of HS on NKCC1 expression in primary astrocytes was also investigated by Western blotting, double immunofluorescence and real time RT-PCR.

Results

BWC and infarct size decreased significantly after 10% HS treatment. TNF-α and IL-1β immunoexpression in microglia was noticeably decreased. Concomitantly, NKCC1 expression in astrocytes was down-regulated. TNF-α and IL-1β released from the primary microglia subjected to hypoxic exposure and treatment with 100 mM HS were decreased. NKCC1 expression in primary astrocytes was concurrently and progressively down-regulated with decreasing concentration of exogenous TNF-α and IL-1β. Additionally, 100 mM HS directly inhibited NKCC1 up-regulation in astrocytes under hypoxic condition.

Conclusions

The results suggest that 10% HS alleviates cerebral edema through inhibition of the NKCC1 Cotransporter, which is mediated by attenuation of TNF-α and IL-1β stimulation on NKCC1.

Transient receptor potential vanilloid 4 mediates hypotonicity-induced enhancement of synaptic transmission in hippocampal slices

AIM AND METHODS

Changes in cerebrospinal fluid osmotic pressure modulate brain excitability. Transient receptor potential vanilloid 4 (TRPV4), which is sensitive to hypotonic stimulation, is expressed in hippocampus. The present study investigated the effect of hypotonic stimulation on hippocampal synaptic transmission and the role of TRPV4 in hypotonicity-action using electrophysiological recording and pharmacological technique.

RESULTS

Accompanied with the decrease in paired pulse facilitation, field excitatory postsynaptic potential (fEPSP) was enhanced by hypotonicity and TRPV4 agonist 4α-PDD in hippocampal slices, which was sensitive to TRPV4 antagonist HC-067047. Hypotonicity-induced increase in fEPSP was blocked by α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptor antagonist, but not N-methyl-d-aspartate receptor or N- or P/Q-type voltage-gated calcium channel antagonist. High voltage-gated calcium current (ICa ) in hippocampal CA3 pyramidal neurons was not affected by hypotonicity. AMPA-activated current (IAMPA ) in hippocampal CA1 pyramidal neurons was increased by hypotonicity and 4α-PDD, which was attenuated by HC-067047. Inhibition of protein kinase C or protein kinase A markedly attenuated hypotonicity-increased IAMPA , whereas antagonism of calcium/calmodulin-dependent protein kinase II had no such effect.

CONCLUSION

TRPV4 is involved in hypotonicity-induced enhancement of hippocampal synaptic transmission, which may be mediated through promoting presynaptic glutamate release and increasing postsynaptic AMPA receptor function.

Comparison of 7.2% hypertonic saline - 6% hydroxyethyl starch solution and 6% hydroxyethyl starch solution after the induction of anesthesia in patients undergoing elective neurosurgical procedures

OBJECTIVE

The ideal solution for fluid management during neurosurgical procedures remains controversial. The aim of this study was to compare the effects of a 7.2% hypertonic saline - 6% hydroxyethyl starch (HS-HES) solution and a 6% hydroxyethyl starch (HES) solution on clinical, hemodynamic and laboratory variables during elective neurosurgical procedures.

METHODS

Forty patients scheduled for elective neurosurgical procedures were randomly assigned to the HS-HES group orthe HES group. Afterthe induction of anesthesia, patients in the HS-HES group received 250 mL of HS-HES (500 mL/h), whereas the patients in the HES group received 1,000 mL of HES (1000 mL/h). The monitored variables included clinical, hemodynamic and laboratory parameters. Chictr.org: ChiCTR-TRC-12002357

RESULTS

The patients who received the HS-HES solution had a significant decrease in the intraoperative total fluid input (p<0.01), the volume of Ringer's solution required (p<0.05), the fluid balance (p<0.01) and their dural tension scores (p<0.05). The total urine output, blood loss, bleeding severity scores, operation duration and hemodynamic variables were similar in both groups (p>0.05). Moreover, compared with the HES group, the HS-HES group had significantly higher plasma concentrations of sodium and chloride, increasing the osmolality (p<0.01).

CONCLUSION

Our results suggest that HS-HES reduced the volume of intraoperative fluid required to maintain the patients undergoing surgery and led to a decrease in the intraoperative fluid balance. Moreover, HS-HES improved the dural tension scores and provided satisfactory brain relaxation. Our results indicate that HS-HES may represent a new avenue for volume therapy during elective neurosurgical procedures.

Hypertonic saline reduces lipopolysaccharide-induced mouse brain edema through inhibiting aquaporin 4 expression

INTRODUCTION

Three percent sodium chloride (NaCl) treatment has been shown to reduce brain edema and inhibited brain aquaporin 4 (AQP4) expression in bacterial meningitis induced by Escherichia coli. Lipopolysaccharide (LPS) is the main pathogenic component of E. coli. We aimed to explore the effect of 3% NaCl in mouse brain edema induced by LPS, as well as to elucidate the potential mechanisms of action.

METHODS

Three percent NaCl was used to treat cerebral edema induced by LPS in mice in vivo. Brain water content, IL-1β, TNFα, immunoglobulin G (IgG), AQP4 mRNA and protein were measured in brain tissues. IL-1β, 3% NaCl and calphostin C (a specific inhibitor of protein kinase C) were used to treat the primary astrocytes in vitro. AQP4 mRNA and protein were measured in astrocytes. Differences in various groups were determined by one-way analysis of variance.

RESULTS

Three percent NaCl attenuated the increase of brain water content, IL-1β, TNFα, IgG, AQP4 mRNA and protein in brain tissues induced by LPS. Three percent NaCl inhibited the increase of AQP4 mRNA and protein in astrocytes induced by IL-1β in vitro. Calphostin C blocked the decrease of AQP4 mRNA and protein in astrocytes induced by 3% NaCl in vitro.

CONCLUSIONS

Osmotherapy with 3% NaCl ameliorated LPS-induced cerebral edema in vivo. In addition to its osmotic force, 3% NaCl exerted anti-edema effects possibly through down-regulating the expression of proinflammatory cytokines (IL-1β and TNFα) and inhibiting the expression of AQP4 induced by proinflammatory cytokines. Three percent NaCl attenuated the expression of AQP4 through activation of protein kinase C in astrocytes.

Bolus injection of hypertonic solutions for cerebral edema in rats: challenge of homeostasis of healthy brain

Hypertonic solutions are mainstay of osmotherapy to cerebral edema. How hypertonic solutions affect healthy brain homeostasis, however, is not fully understood. Using rat model of cerebral edema induced by local cryoinjury, we found with immunohistochemistry that less microglial activation in healthy hemishere 24 h after hypertonic saline (HS, 3% NaCl) administration, compared to mannitol (20%, the same osmotic concentration of 3% NaCl) while dehydrating the brain tissue. To see whether blood-brain barrier (BBB) or aquaporin-4 (AQP4) contribute to this difference, HS or mannitol was intra-arterially injected to normal rats, and BBB opening, ultrastructure and AQP4 immunoreactivity were examined. Evans blue extravasation indicated that BBB was opened much lighter in HS group than mannitol group at the same time points. Electron microscopy also showed edema around the capillaries slightly lighter in HS than mannitol group 24 h after injection. Meanwhile, HS injection led to AQP4 down regulation in expression similarly as mannitol, compared with NS group. These data suggested that bolus injection of hypertonic agents may lead to microglia activation in healthy brain in different extent, due to BBB compromise, instead of water movement or AQP4 expression. Hence in clinical application, BBB of healthy brain should be considered in perspective to maintain the brain homeostasis.

Osmotherapy: use among neurointensivists

BACKGROUND

Cerebral edema and raised intracranial pressure are common problems in neurological intensive care. Osmotherapy, typically using mannitol or hypertonic saline (HTS), has become one of the first-line interventions. However, the literature on the use of these agents is heterogeneous and lacking in class I studies. The authors hypothesized that clinical practice would reflect this heterogeneity with respect to choice of agent, dosing strategy, and methods for monitoring therapy.

METHODS

An on-line survey was administered by e-mail to members of the Neurocritical Care Society. Multiple-choice questions regarding use of mannitol and HTS were employed to gain insight into clinician practices.

RESULTS

A total of 295 responses were received, 79.7% of which were from physicians. The majority (89.9%) reported using osmotherapy as needed for intracranial hypertension, though a minority reported initiating treatment prophylactically. Practitioners were fairly evenly split between those who preferred HTS (54.9%) and those who preferred mannitol (45.1%), with some respondents reserving HTS for patients with refractory intracranial hypertension. Respondents who preferred HTS were more likely to endorse prophylactic administration. Preferred dosing regimens for both agents varied considerably, as did monitoring parameters.

CONCLUSIONS

Treatment of cerebral edema using osmotically active substances varies considerably between practitioners. This variation could hamper efforts to design and implement multicenter trials in neurocritical care.