Comparison of equiosmolar hypertonic saline and mannitol for brain relaxation during craniotomies: A meta-analysis of randomized controlled trials

Comparing equiosmolar hypertonic saline and mannitol for achieving brain relaxation in elective craniotomy patients: A systematic review and meta-analysis

Background

This study strives to provide a current and thorough assessment of the comparative efficacy and safety between equiosmolar quantities of hypertonic saline (HS) and mannitol in facilitating brain relaxation for patients undergoing elective craniotomies.

Methods

This systematic review and meta-analysis, following preferred reporting items for systematic reviews and meta-analyses guidelines, compared the efficacy and safety of equiosmolar concentrations of mannitol and HS in elective craniotomies. PubMed, Scopus, Cochrane Library, ScienceDirect, and Proquest databases were searched using keywords related to mannitol, HS, and craniotomy. Results were analyzed through a random-effects model using Mantel-Haenszel risk ratio and standard mean difference. P < 0.05 was considered significant.

Results

Thirteen randomized controlled trials encompassing 965 patients (516 in the HS group and 448 in the mannitol group) were analyzed. The quality of studies was moderate-to-high, and no significant publication bias was observed. The primary outcome, brain relaxation, favored HS over mannitol without significant heterogeneity. Mannitol was associated with increased urine output compared to HS, irrespective of dose, with high heterogeneity. HS was linked to significantly reduced fluid input, confirmed by subgroup analysis with lower heterogeneity. No significant difference was found in serum osmolality between the two agents. Serum sodium (Na+) levels favored HS, whereas arterial blood Na+ levels also favored HS despite considerable heterogeneity. Maximum mean arterial pressure was higher with HS, but it displayed significant heterogeneity. Maximum central venous pressure showed no significant difference between the two agents, with moderate heterogeneity.

Conclusion

HS appears more effective than mannitol in achieving brain relaxation, and it may offer advantages in fluid management and Na+ balance. Clinicians should consider these findings when selecting hyperosmotic agents for neurosurgical procedures. Further research is needed to address heterogeneity in certain outcomes and guide clinical practice.

Comparison of 20% mannitol and 3% hypertonic saline for intraoperative brain relaxation during supratentorial brain tumour craniotomy in patients with a midline shift

PURPOSE OF THE STUDY

A prospective, randomized, double-blind study was designed to assess differences in brain relaxation between 20% mannitol and 3% hypertonic saline (HS) during elective supratentorial brain tumour surgery in patients with midline shift.

MATERIAL AND METHODS

Sixty patients undergoing supratentorial craniotomy for tumour resection were enrolled to receive either 5mL/kg of 20% mannitol (n=30) or 3% HS (n=30) administered at skin incision. PCO2 in arterial blood was maintained within 35-40mmHg and arterial blood pressure was controlled within baseline values ±20%. The primary outcome was the proportion of satisfactory brain relaxation. The surgeon assessed brain relaxation on a four-point scale (1=excellent with no swelling, 2=minimal swelling, 3=serious swelling not requiring treatment, 4=severe swelling requiring treatment). Postsurgical intracranial changes determined by imaging techniques, postoperative complications, PACU and hospital stay, and mortality at 30 days were also recorded. Appropriate statistical tests were used for comparison; P<0.05 was considered as significant. This trial was registered in Eudract.ema.europa.eu (#2021-006290-40).

RESULTS

There was no difference in brain relaxation: 2.00 [1.00-2.00] and 2.00 [1.75-3.00] for patients in mannitol and HS groups, respectively (P=0.804). Tumour size (OR: 0.99, 95% CI: 0.99-1.01; P=0.371), peritumoral oedema classification (OR: 0.57, 95% CI: 0.11-2.84; P=0.493), mass effect (OR: 0.86, 95% CI: 0.16-4.87; P=0.864), anaesthesia (OR: 4.88, 95% CI: 0.82-28.96; P=0.081) and midline shift (OR: 5.00, 95% CI: 0.84-29.70; P=0.077) did not have a significant influence on brain swelling in patients treated with either mannitol or HS. No significant differences in perioperative outcomes, mortality and length of PACU and hospital stay were observed.

CONCLUSIONS

5mL/kg of 20% mannitol or 3% HS result in similar brain relaxation scores in patients undergoing craniotomy for supratentorial brain tumour with midline shift.

A Brief Explanation on Surgical Approaches for Treatment of Different Brain Tumors

The main goal of brain tumor surgery is to achieve gross total tumor resection without postoperative complications and permanent new deficits. However, when the lesion is located close or within eloquent brain areas, cranial nerves, and/or major brain vessels, it is imperative to balance the extent of resection with the risk of harming the patient, by following a so-called maximal safe resection philosophy. This view implies a shift from an approach-guided attitude, in which few standard surgical approaches are used to treat almost all intracranial tumors, to a pathology-guided one, with surgical approaches actually tailored to the specific tumor that has to be treated with specific dedicated pre- and intraoperative tools and techniques. In this chapter, the basic principles of the most commonly used neurosurgical approaches in brain tumors surgery are presented and discussed along with an overview on all available modern tools able to improve intraoperative visualization, extent of resection, and postoperative clinical outcome.

Comparison of Equiosmolar Doses of 7.5% Hypertonic Saline and 20% Mannitol on Cerebral Oxygenation Status and Release of Brain Injury Markers During Supratentorial Craniotomy: A Randomized Controlled Trial

BACKGROUND

Hyperosmolar therapy is the mainstay of treatment to reduce brain bulk and optimize surgical exposure during craniotomy. This study investigated the effect of equiosmolar doses of 7.5% hypertonic saline (HTS) and 20% mannitol on intraoperative cerebral oxygenation and metabolic status, systemic hemodynamics, brain relaxation, markers of cerebral injury, and perioperative craniotomy outcomes.

METHODS

A total of 51 patients undergoing elective supratentorial craniotomy were randomly assigned to receive 7.5% HTS (2 mL/kg) or 20% mannitol (4.6 mL/kg) at scalp incision. Intraoperative arterial and jugular bulb blood samples were collected at predefined time intervals for assessment of various indices of cerebral oxygenation; multiple hemodynamic variables were concomitantly recorded. S100B protein and neuron-specific enolase levels were determined at baseline, and at 6 and 12 hours after surgery for assessment of neuronal injury. Brain relaxation and perioperative outcomes were also assessed.

RESULTS

Demographic and intraoperative data, brain relaxation score, and perioperative outcomes were comparable between groups. Jugular bulb oxygen saturation and partial pressure of oxygen, arterial-jugular oxygen and carbon dioxide differences, and brain oxygen extraction ratio were favorably affected by 7.5% HTS up to 240 minutes postinfusion ( P <0.05), whereas mannitol was associated with only a short-lived (up to 15 min) improvement of these indices ( P <0.05). The changes in cerebral oxygenation corresponded to transient expansion of intravascular volume and improvements of cardiovascular performance. Increases in S100B and neuron-specific enolase levels at 6 and 12 hours after surgery ( P <0.0001) were comparable between groups.

CONCLUSIONS

The conclusion is that 7.5% HTS has a more beneficial effect on cerebral oxygenation than an equiosmolar dose of 20% mannitol during supratentorial craniotomy, yet no clear-cut clinical superiority of either solution could be demonstrated.

Equiosmolar doses of hypertonic saline versus mannitol for brain relaxation in patients undergoing elective craniotomies: an updated systematic review and meta-analysis

Background

Hypertonic saline and mannitol are hyperosmolar agents frequently used to lower ICP and relax the brain during surgeries. Several methods have been used to achieve a good and relaxed brain, such as hyperventilation, cerebrospinal fluid drainage, head position correction, and administration of hyperosmolar agents. Comparing equiosmolar doses between hypertonic saline and mannitol in patients undergoing elective craniotomies is important to further notice the differences in several outcomes. This study aims to compare the outcome of hypertonic saline versus mannitol on brain relaxation in patients undergoing elective craniotomy.

Results

10 articles from 2007 to 2021 were included. Hypertonic saline is associated with better brain relaxation (OR  = 1.84, 95% CI 1.31–2.59; P = 0.001) but significantly increase blood natrium level, both serum and arterial (MD = 3.03, 95% CI 1.70–4.36; P =  < 0.001 and MD = 7.14, 95% CI 0.04–14.24; P =  < 0.001, respectively). Mannitol was associated with increased fluid input and urine output (SMD = − 0.56, 95% CI − 0.98 to − 0.15; P =  < 0.001 and SMD = − 0.96, 95% CI − 1.42 to − 0.50; P =  < 0.001, respectively). Serum osmolality and hemodynamic parameters difference was insignificant.

Conclusions

Hypertonic saline is associated with significantly better brain relaxation score and increased blood sodium level without increase in urine. This may prove to be clinically significant in patients with electrolyte imbalance.

Risk Factors Associated With Inadequate Brain Relaxation in Craniotomy for Surgery of Supratentorial Tumors

Introduction: Cerebral swelling often occurs during craniotomy for cerebral tumors. Poor brain relaxation can increase the risk of cerebral ischemia, possibly worsening the outcome. The surgical team should identify any risk factors that could cause perioperative brain swelling and decide which therapies are indicated for improving it. The present investigation aimed to elucidate the risk factors associated with brain swelling during elective craniotomy for supratentorial brain tumors.

Methods: This prospective, nonrandomized, observational study included 52 patients scheduled for elective supratentorial tumor surgery. The degree of brain relaxation was classified upon the opening of the dura according to a four-point scale (brain relaxation score: 1, perfectly relaxed; 2, satisfactorily relaxed; 3, firm brain; and 4, bulging brain). Moreover, hemodynamic and respiratory parameters, arterial blood gas, and plasma osmolality were recorded after the removal of the bone flap.

Results: This study showed that the use of preoperative dexamethasone was associated with a brain relaxation score of ≤2 (p = 0.005). The median midline shift of 6 (3-0) mm and median hemoglobin level of >13 g/dL were associated with a brain relaxation score of ≥3 (p = 0.02 and p = 0.01, respectively). The dosage of mannitol (0.25 g/kg versus 0.5 g/kg), physical status, intraoperative position, tumor diameter and volume, peritumoral edema and mass effect, World Health Organization (WHO) grading, mean arterial pressure, PaCO₂, osmolality, and core temperature were not identified as risk factors associated with poor relaxation.

Conclusion: The use of preoperative dexamethasone was associated with improved brain relaxation, whereas the presence of a preoperative midline shift and a higher level of hemoglobin were associated with poor brain relaxation.

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.

Evaluation of equiosmolar 20% mannitol, 3% hypertonic saline and 8.4% sodium bicarbonate on intraoperative brain relaxation and hemodynamic parameters in patients undergoing craniotomy for supratentorial tumors: a prospective randomized study

BACKGROUND

Research comparing 20% mannitol, 3% hypertonic saline and 8.4% sodium bicarbonate for intraoperative hyperosmolar therapy during supratentorial tumor excision is sparse. With the hypothesis that equiosmolar concentration of these agents will produce equivalent effects, this study was conducted to compare the effects on intraoperative brain relaxation and hemodynamics.

METHODS

The prospective study was conducted over a period of one year. Ninety patients, aged 18-60 years, American Society of Anesthesiologists class Ι and ΙΙ with supratentorial tumor and scheduled for surgery were randomized into three groups to receive equiosmolar 20% mannitol (group 1), 3% hypertonic saline (group 2) and 8.4% sodium bicarbonate (group 3). Primary outcome assessed was the effect on intraoperative brain relaxation score while hemodynamic parameters, changes in arterial blood gas parameters, serum electrolytes, serum osmolarity, urine output, fluid intake, post-operative course, hospital stay were the secondary outcomes.

RESULTS

Demographic characteristics, surgical and anesthetic variables, were comparable between the three groups. Brain relaxation scores were significantly better in group 3 compared to group 2 and group 1 respectively. Patients in group 1 had lower mean blood pressure and central venous pressure values, higher urine output, fluid intake compared to other groups. Patients of group 3 had significantly higher pH, bicarbonate, partial pressure of carbon dioxide, serum sodium and serum osmolarity values compared to groups 1 and 2.

CONCLUSIONS

Eight point four percent sodium bicarbonate solution infusion is associated with superior intraoperative brain relaxation scores and improved haemodynamic stability compared to equiosmolar 3% hypertonic saline solution and 20% mannitol.

Brain-Relaxing Effect of Different Diuretic Regimens in Supratentorial Tumor Surgery: A Comparative Study Guided by Optic Nerve Sheath Diameter

Background:

Hyperosmolar therapy is a well-established method to approach brain relaxation during craniotomy. Mannitol is used with a wide range of dosing regimens, combination with loop diuretics exerts a synergistic effect resulting in both reduction of the dose and its complications. Ultrasound measurement of optic nerve sheath diameter (ONSD) gives reliable information about intracranial pressure (ICP) and avoids overdosing and complications of osmotherapy.

Aims and Objectives:

In this study, we compare the ordinary dose of mannitol with the low dose combined with furosemide and detect the effect on ICP by ONSD.

Setting and Design:

This is a prospective, randomized, double-blind study involving 60 patients undergoing supratentorial brain tumor surgery.

Materials and Methods:

Sixty patients were enrolled in this study, divided into two equal groups: Group M received mannitol 1 g.kg⁻¹: while Group F received mannitol 0.25 g.kg⁻¹ and furosemide 0.5 mg.kg⁻¹. Reduction in ONSD measurement was the primary objective, while brain-relaxation score (BRS), hemodynamic changes, urine output, serum lactate, and changes in serum electrolyte were the secondary objectives.

Statistical Analysis:

Data collected were analyzed using SPSS software, IBM, USA, version 22. P value was considered significant if <0.05.

Results:

ONSD and BRS showed no statistically significant difference between the studied groups. After diuresis, Group M showed significant reduction in heart rate and mean arterial blood pressure, serum sodium, potassium, and lactate (P = 0.02, P = 0.02, P = 0.001, P = 0.001, P = 0.001, P = 0.001 respectively), with increased urine output (UOP) and fluids replacement (P = 0.00, P = 0.01, respectively).

Conclusion:

Compared to high dose, adding loop diuretics to low-dose mannitol during supratentorial brain tumor surgeries resulted in comparable BRSs with a lower incidence of hemodynamic and metabolic disturbances.

Anesthetic Management of Asleep and Awake Craniotomy for Supratentorial Tumor Resection

Understanding how anesthetics impact cerebral physiology, cerebral blood flow, brain metabolism, brain relaxation, and neurologic recovery is crucial for optimizing anesthesia during supratentorial craniotomies. Intraoperative goals for supratentorial tumor resection include maintaining cerebral perfusion pressure and cerebral autoregulation, optimizing surgical access and neuromonitoring, and facilitating rapid, cooperative emergence. Evidence-based studies increasingly expand the impact of anesthetic care beyond immediate perioperative care into both preoperative optimization and minimizing postoperative consequences. New evidence is needed for neuroanesthesia's role in neurooncology, in preventing conversion from acute to chronic pain, and in decreasing risk of intraoperative ischemia and postoperative delirium.

Comparison of equiosmolar doses of 10% hypertonic saline and 20% mannitol for controlling intracranial hypertention in patients with large hemispheric infarction

OBJECTIVE

We conducted this prospective self-crossover controlled trial to compare the efficacy and safety of 10 % hypertonic saline (HS) and 20 % mannitol in doses of similar osmotic burden for the treatment of increased intracranial pressure (ICP) in patients with large hemispheric infarction (LHI).

PATIENTS AND METHODS

Patients with LHI were enrolled from January 2017 to January 2018. We used an alternating treatment protocol to compare the effects of HS with mannitol given for episodes of increased ICP in patients with LHI. Indicators such as ICP, mean arterial pressure (MAP) and cerebral perfusion pressure (CPP) were continuously monitored at regular intervals for 240 min after initiation of infusion. Electrolytes, plasma osmolality and renal functions were measured before and 240 min after initiation of infusion to compare the efficacy and safety of the two drugs.

RESULTS

A total of 49 episodes of increased ICP occurred in 14 patients with LHI, of which 24 were infused with 10 % HS and 25 with 20 % mannitol. Both the treatments were equally effective in reducing ICP (P < 0.01). The differences in the duration and degree of reduction were not significant between the groups (P > 0.05). Although both the osmolar agents decreased MAP, the degree was greater in the mannitol group (P < 0.05) at T120. The increase in CPP was greater in the HS group compared with the mannitol group (P < 0.05) at T120. However, HS was associated with faster heart rate (HR) and higher serum chloride levels (P < 0.05). Changes in serum sodium levels and osmolality were not significant between the groups in spite of being higher in the HS group.

CONCLUSIONS

Both the drugs can serve as first-line agents for treating intracranial hypertension caused by LHI and should be selected rationally according to the differences in efficacy and adverse effects.

Perioperative Management of Aneurysmal Subarachnoid Hemorrhage

Aneurysmal subarachnoid hemorrhage is an acute neurologic emergency. Prompt definitive treatment of the aneurysm by craniotomy and clipping or endovascular intervention with coils and/or stents is needed to prevent rebleeding. Extracranial manifestations of aneurysmal subarachnoid hemorrhage include cardiac dysfunction, neurogenic pulmonary edema, fluid and electrolyte imbalances, and hyperglycemia. Data on the impact of anesthesia on long-term neurologic outcomes of aneurysmal subarachnoid hemorrhage do not exist. Perioperative management should therefore focus on optimizing systemic physiology, facilitating timely definitive treatment, and selecting an anesthetic technique based on patient characteristics, severity of aneurysmal subarachnoid hemorrhage, and the planned intervention and monitoring. Anesthesiologists should be familiar with evoked potential monitoring, electroencephalographic burst suppression, temporary clipping, management of external ventricular drains, adenosine-induced cardiac standstill, and rapid ventricular pacing to effectively care for these patients.

[Brain tissue relaxation in craniotomy: a modern view of the perennial problem]

Intraoperative relaxation of brain tissue is one of the important factors affecting the quality and successful outcome of neurosurgical interventions. Despite many clinical studies on the problem of brain bulging, many issues remain not fully resolved. First of all, these are safety aspects of the preventive and therapeutic use of various strategies to fight this phenomenon, development of indications for introduction of hyperosmotic solutions, and use of hyperventilation or lifting of the head end of the operating table.

A dose-response relationship study of hypertonic saline on brain relaxation during supratentorial brain tumour craniotomy

Background: A prospective, randomized, double-blind study was designed to assess differences in brain relaxation between 2 doses of 3% HS during elective supratentorial brain tumour surgery.Methods: 60 patients undergoing supratentorial craniotomy for tumour resection were enrolled to receive either 3 mL/kg (group L) or 5 mL/kg (group H) of 3% HS administered at skin incision. Brain relaxation was assessed after dura opening on a scale ranging 1-4 (1 = perfectly relaxed, 2 = satisfactorily relaxed, 3 = firm brain, 4 = bulging brain). Hemodynamic variables and laboratory values (blood gases, osmolarity, haematocrit, and lactate) were collected before HS infusion and 30, 120 and 360 min after it. Presence of midline shift, postoperative complications, PCU and hospital stay, and mortality after 30 days were also recorded.Results: There was no difference in brain relaxation, with 2.0 (1.0-3.0) and 2.0 (1.0-2.3) (P = 0.535) for patients in groups L and H, respectively. If adjusted for the presence of midline shift, 50% of patients had adequate brain relaxation scores (grades 1 and 2) in group L and 61% in group H (OR 0.64, CI = 0.16-2.49, P = 0.515). No significant differences in perioperative outcome, mortality and length of PCU and hospital stay were observed.Conclusion: 3 mL/kg of 3% HS result in similar brain relaxation scores as 5 mL/kg in patients undergoing craniotomy for supratentorial brain tumour. This study reveals that both high and low doses of 3% HS may be less effective on intraoperative brain relaxation in patients with midline shift.