A Comparison of Two Doses of Mannitol on Brain Relaxation During Supratentorial Brain Tumor Craniotomy: A Randomized Trial

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.

Brain relaxation using desflurane anesthesia and total intravenous anesthesia in patients undergoing craniotomy for supratentorial tumors: a randomized controlled study

BACKGROUND

Satisfactory brain relaxation is essential in neurosurgery. Desflurane anesthesia and propofol-based total intravenous anesthesia (TIVA) have different effects on cerebral hemodynamics, potentially contributing to discrepant brain relaxation. The purpose of this study was to compare the effects of desflurane and TIVA on brain relaxation in patients undergoing craniotomy for supratentorial tumors.

METHODS

In this randomized, controlled study, we enrolled patients aged 18-60 years, with ASA I-III, who were scheduled to undergo elective craniotomy for supratentorial tumors. Patients were randomly assigned in a 1:1 ratio to receive desflurane anesthesia or TIVA. The primary outcome was the proportion of satisfactory brain relaxation. Secondary outcomes included emergence and extubation times, recovery of cognitive function and postoperative complications.

RESULTS

Of 369 patients who were assessed for eligibility, 111 were randomized and 110 were included in the modified intention-to-treat analysis (55 in the desflurane group and 55 in the TIVA group). The proportion of satisfactory brain relaxation was similar between the two groups: 69% in the desflurane group and 73% in the TIVA group (RR: 0.950, 95% CI: 0.748-1.207; P = 0.675). Patients assigned to the desflurane group had shorter emergence (10 [8-13] min vs. 13 [10-20] min, P < 0.001) and extubation times (13 [10-18] min vs. 17 [13-23] min, P < 0.001), and better recovery of cognitive function at 15 min after extubation (16 [0-24] vs. 0 [0-20], P = 0.003), but experienced increased postoperative nausea and vomiting (PONV) (16 [29%] vs. 6 [11%] P = 0.017) and tachycardia (22 [40%] vs. 9 [16%], P = 0.006) during recovery.

CONCLUSIONS

Desflurane anesthesia and TIVA provide similar brain relaxation in patients without intracranial hypertension undergoing elective craniotomy. Desflurane accelerates the recovery from anesthesia but is associated with increased PONV and tachycardia during the recovery period.

TRIAL REGISTRATION

Clinicaltrial.gov (NCT04691128). Date of registration: December 31, 2020.

Multiple Meningioma Resection by Bilateral Extended Rostrotentorial Craniotomy with a 3D-Print Guide in a Cat

Simple Summary

Meningioma is the most common intracranial neoplasia in cats. Treatments for meningiomas—including complete surgical resection, debulking, irradiation, or palliative therapy—have been reported in veterinary medicine. However, multiple meningiomas (two or more meningiomas in the same patient, separated by anatomical location) have been reported to affect the complication rate and prognosis. Moreover, the characteristics of neurosurgery—such as accurate localization and awareness of the anatomical structures of the lesions—make the surgery especially difficult for inexperienced surgeons. Surgical navigation systems have been developed, but recently, patient-specific three-dimensional(3D)-printed models and guides have also been used in orthopedics and neurosurgeries for treating many disorders with good results. A 13-year-old castrated male domestic shorthair cat was referred with multiple meningiomas located within the right frontal and occipital lobes. The cat suffered from generalized tonic–clonic seizures and mild proprioceptive ataxia. After removing both of the tumors, the cat showed a favorable clinical outcome and no neurological abnormalities throughout long-term follow-up. With a patient-specific 3D guide technology, a craniotomy for multiple meningiomas can be performed safely and accurately.

Abstract

A 13-year-old castrated male domestic shorthair cat was referred for the surgical removal of multiple meningiomas. The cat experienced generalized tonic–clonic seizures, altered mentation, mild proprioceptive ataxia, and circling. Magnetic resonance imaging (MRI) revealed two round, solitary, well-delineated, space-occupying lesions suggestive of multiple meningiomas in the right frontal and occipital lobes. Before surgery, patient-specific three-dimensional (3D) printed models and guides were produced using a 3D program based on MRI and computed tomography (CT), and a rehearsal surgery was performed. With a 3D guide to find the location of the craniotomy lines, bilateral extended rostrotentorial craniotomy allowed en bloc resection of multiple meningiomas. The bone fragment was replaced and secured to the skull with a craniofacial plate and screws with an artificial dura. All of the surgical steps were performed without complications. The preoperative presenting signs were resolved by the time of follow-up examinations 2 weeks after surgery. Twelve months after the removal of the multiple meningiomas, the cat survived without further neurological progression. For the resection of multiple meningiomas, surgery can result in large bone defects and risk of massive hemorrhage. For this challenging surgery, patient-specific 3D models and guides can be effective for accurate and safe craniotomies.

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.

Efficacy and safety of sevoflurane vs propofol in combination with remifentanil for anesthesia maintenance during craniotomy: A meta-analysis

BACKGROUND

The purpose of this study was to evaluate the efficacy and safety of sevoflurane-remifentanil (SR) vs propofol-remifentanil (PR) as inhalation anesthesia or total intravenous anesthesia in patients undergoing craniotomy, respectively.

METHODS

Electronic databases included PubMed, ScienceDirect, Embase, Cochrane library, CNKI, and Wanfang data were searched using suitable search items. Randomized clinical controlled trials comparing the combination of SR and PR as anesthetics for neurosurgery were included. The outcomes included wake-up time, spontaneous respiration time, extubation time, and safety.

RESULTS

Seventeen studies were included in this meta-analysis. There were no statistically significant differences in wake-up time (P = .25, standardized mean difference (SMD) = 0.29, 95% CI -0.20 to 0.77), extubation time (P = .1, SMD = 0.52, 95% CI -0.11 to 1.14) and spontaneous respiration time (P = .58, SMD = 0.43, 95% CI -1.07 to 1.93) when patients with SF and PF for anesthesia maintenance. Moreover, the changes of hemodynamic parameters are similar between the 2 groups. During anesthesia maintenance, SF could significantly increase the incidence of hypotension and brain edema than PF (P = .02, SMD = 1.68, 95% CI 1.07 to 2.62; P < .0001, SMD = 3.37, 95% CI 1.86 to 6.12), PF markedly promoted the incidence of hypertension (P = .001, SMD = 0.55, 95% CI 0.39 to 0.79). The postoperative adverse reactions were similar between the 2 groups (P > .05), but the incidence of postoperative nausea and vomiting proved to be higher in SF group (P < .0001, SMD = 2.12, 95% CI 1.47 to 3.07).

CONCLUSIONS

SR and PR as anesthetics in patients underwent craniotomy had similar effects, but PR was superior to SR in terms of safety of intraoperation and postoperation.

Comparison of 1.0 g/kg of 20% mannitol initiated at different time points and effects on brain relaxation in patients with midline shift undergoing supratentorial tumor resection: a randomized controlled trial

OBJECTIVE

Previous studies have suggested the use of 1.0 g/kg of 20% mannitol at the time of skin incision during neurosurgery in order to improve brain relaxation. However, the incidence of brain swelling upon dural opening is still high with this dose. In the present study, the authors sought to determine a better timing for mannitol infusion.

METHODS

One hundred patients with midline shift who were undergoing elective supratentorial tumor resection were randomly assigned to receive early (immediately after anesthesia induction) or routine (at the time of skin incision) administration of 1.0 g/kg body weight of 20% mannitol. The primary outcome was the 4-point brain relaxation score (BRS) immediately after dural opening (1, perfectly relaxed; 2, satisfactorily relaxed; 3, firm brain; and 4, bulging brain). The secondary outcomes included subdural intracranial pressure (ICP) measured immediately before dural opening; serum osmolality and osmole gap (OG) measured immediately before mannitol infusion (T0) and at the time of dural opening (TD); changes in serum electrolytes, lactate, and hemodynamic parameters at T0 and 30, 60, 90, and 120 minutes thereafter; and fluid balance at TD.

RESULTS

The time from the start of mannitol administration to dural opening was significantly longer in the early administration group than in the routine administration group (median 66 [IQR 55-75] vs 40 [IQR 38-45] minutes, p < 0.001). The BRS (score 1/2/3/4, n = 14/26/9/1 vs 3/25/18/4, p = 0.001) was better and the subdural ICP (median 5 [IQR 3-6] vs 7 [IQR 5-10] mm Hg, p < 0.001) was significantly lower in the early administration group than in the routine administration group. Serum osmolality and OG increased significantly at TD compared to levels at T0 in both groups (all p < 0.001). Intergroup comparison showed that serum osmolality and OG at TD were significantly higher in the routine administration group (p < 0.001 and = 0.002, respectively). Patients who had received early administration of mannitol had more urine output (p = 0.001) and less positive fluid balance (p < 0.001) at TD. Hemodynamic parameters, serum lactate concentrations, and incidences of electrolyte disturbances were comparable between the two groups.

CONCLUSIONS

Prolonging the time interval between the start of mannitol infusion and dural incision from approximately 40 to 66 minutes can improve brain relaxation and decrease subdural ICP in elective supratentorial tumor resection.

Drug penetration in pediatric brain tumors: Challenges and opportunities

Larger clinical trial enrollments and a greater understanding of biological heterogeneity have led to improved survival rates for children diagnosed with brain tumors in the last 50 years. However, reducing long-term morbidities and improving survival rates of high-risk tumors remain major challenges. Chemotherapy can reduce tumor burden, but effective drug penetration at the tumor site is limited by barriers in the route of drug administration and within the tumor microenvironment. Bioavailability of drugs is impeded by the blood-brain barrier, plasma protein binding, and structural components by the tumor including the matrix and vasculature contributing to increased interstitial fluid pressure, hypoxia, and acidity. Designing drug delivery systems to circumvent these barriers could lead to improved drug penetration at the tumor site and reduce adverse systemic side effects. In this review, we expand on how systemic and local barriers limit drug penetration and present potential methods to enhance drug penetration in pediatric brain tumors.

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.

Hyperlactatemia After Intracranial Tumor Surgery Does Not Affect 6-Month Survival: A Retrospective Case Series

Supplemental Digital Content is available in the text.

Patients undergoing neurosurgery frequently exhibit hyperlactatemia. The aim of this study was to identify factors associated with hyperlactatemia and assess how hyperlactatemia impacts survival and hospital length of stay after intracranial tumor surgery.

Perioperative Risk Factors Associated With Acute Kidney Injury in Patients After Brain Tumor Resection

BACKGROUND

Acute kidney injury (AKI) is a serious complication after surgery. The aim of this study is to identify risk factors for postoperative AKI in patients undergoing brain tumor surgery.

METHODS

This single-center, retrospective, matched case-control study included patients undergoing elective brain tumor surgery between January 2016 and December 2018 at Beijing Tiantan Hospital, Capital Medical University, China. Patients developing postoperative AKI were compared with controls without AKI matched by age, sex, and date of surgery in a ratio of 1:3. AKI was defined using the Kidney Disease Improving Global Outcomes criteria.

RESULTS

A total of 9933 patients were identified for review, of which 115 (1.16%) developed AKI; 345 matched patients were included in the control group. AKI occurred most commonly within the first 24 hours (41/97, 42.3%) and 48 hours (33/94, 35.1%) after surgery. Preoperative administration of mannitol (odds ratio [OR], 1.64; 95% confidence interval [CI], 1.04-2.60; P= 0.034), American Society of Anesthesiologists physical status III or higher (OR, 5.50; 95% CI, 2.23-13.59; P<0.001), preoperative blood glucose (OR, 2.53; 95% CI, 1.23-5.22; P=0.012), craniopharyngioma (OR, 8.96; 95% CI, 3.55-22.63; P<0.001), nonsteroidal anti-inflammatory drug administration (OR, 3.74; 95% CI, 1.66-8.42; P<0.001), and intraoperative hypotension (OR, 2.13; 95% CI, 1.21-3.75; P=0.009) were independent risk factors for postoperative AKI.

CONCLUSION

Multiple factors, including preoperative administration of mannitol, are independently associated with the development of postoperative AKI in patients undergoing brain tumor surgery.

[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.

Pulse Pressure Variation-Guided Fluid Therapy during Supratentorial Brain Tumour Excision: A Randomized Controlled Trial

BACKGROUND:

Goal-directed fluid therapy (GDFT) improved patient outcomes in various surgical procedures; however, its role during mass brain resection was not well investigated.

AIM:

In this study, we evaluated a simple protocol based on intermittent evaluation of pulse pressure variation for guiding fluid therapy during brain tumour resection.

METHODS:

Sixty-one adult patients scheduled for supratentorial brain mass excision were randomized into either GDFT group (received intraoperative fluids guided by pulse pressure variation) and control group (received standard care). Both groups were compared according to the following: brain relaxation scale (BRS), mean arterial pressure, heart rate, urine output, intraoperative fluid intake, postoperative serum lactate, and length of hospital stay.

RESULTS:

Demographic data, cardiovascular data (mean arterial pressure and heart rate), and BRS were comparable between both groups. GDFT group received more intraoperative fluids {3155 (452) mL vs 2790 (443) mL, P = 0.002}, had higher urine output {2019 (449) mL vs 1410 (382) mL, P < 0.001}, and had lower serum lactate {0.9 (1) mmol versus 2.5 (1.1) mmol, P = 0.03} compared to control group.

CONCLUSION:

In conclusion, PPV-guided fluid therapy during supratentorial mass excision, increased intraoperative fluids, and improved peripheral perfusion without increasing brain swelling.

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.

Effects of Hypertonic Saline and Sodium Lactate on Cortical Cerebral Microcirculation and Brain Tissue Oxygenation

BACKGROUND

Hyperosmolar solutions have been used in neurosurgery to modify brain bulk. The aim of this animal study was to compare the short-term effects of equivolemic, equiosmolar solutions of hypertonic saline (HTS) and sodium lactate (HTL) on cerebral cortical microcirculation and brain tissue oxygenation in a rabbit craniotomy model.

METHODS

Rabbits (weight, 1.5 to 2.0 kg) were anesthetized, ventilated mechanically, and subjected to a craniotomy. The animals were allocated randomly to receive a 3.75 mL/kg intravenous infusion of either 3.2% HTS (group HTS, n=9), half-molar sodium lactate (group HTL, n=10), or normal saline (group C, n=9). Brain tissue partial pressure of oxygen (PbtO2) and microcirculation in the cerebral cortex using sidestream dark-field imaging were evaluated before, 20 and 40 minutes after 15 minutes of hyperosmolar solution infusion. Global hemodynamic data were recorded, and blood samples for laboratory analysis were obtained at the time of sidestream dark-field image recording.

RESULTS

No differences in the microcirculatory parameters were observed between the groups before and after the use of osmotherapy. Brain tissue oxygen deteriorated over time in groups C and HTL, this deterioration was not significant in the group HTS.

CONCLUSIONS

Our findings suggest that equivolemic, equiosmolar HTS and HTL solutions equally preserve perfusion of cortical brain microcirculation in a rabbit craniotomy model. The use of HTS was better in preventing the worsening of brain tissue oxygen tension.

A prospective randomized trial of the optimal dose of mannitol for intraoperative brain relaxation in patients undergoing craniotomy for supratentorial brain tumor resection

OBJECTIVE

Mannitol is used intraoperatively to induce brain relaxation in patients undergoing supratentorial brain tumor resection. The authors sought to determine the dose of mannitol that provides adequate brain relaxation with the fewest adverse effects.

METHODS

A total of 124 patients were randomized to receive mannitol at 0.25 g/kg (Group A), 0.5 g/kg (Group B), 1.0 g/kg (Group C), and 1.5 g/kg (Group D). The degree of brain relaxation was classified according to a 4-point scale (1, bulging; 2, firm; 3, adequate; and 4, perfectly relaxed) by neurosurgeons; Classes 3 and 4 were considered to indicate satisfactory brain relaxation. The osmolality gap (OG) and serum electrolytes were measured before and after mannitol administration.

RESULTS

The brain relaxation score showed an increasing trend in patients receiving higher doses of mannitol (p = 0.005). The incidence of satisfactory brain relaxation was higher in Groups C and D than in Group A (67.7% and 64.5% vs 32.2%, p = 0.011 and 0.022, respectively). The incidence of OG greater than 10 mOsm/kg was also higher in Groups C and D than in Group A (100.0% in both groups vs 77.4%, p = 0.011 for both). The incidence of moderate hyponatremia (125 mmol/L ≤ Na+ < 130 mmol/L) was significantly higher in Group D than in other groups (38.7% vs 0.0%, 9.7%, and 12.9% in Groups A, B, and C; p < 0.001, p = 0.008, and p = 0.020, respectively). Hyperkalemia (K+ > 5.0 mmol/L) was observed in 12.9% of patients in Group D only.

CONCLUSIONS

The higher doses of mannitol provided better brain relaxation but were associated with more adverse effects. Considering the balance between the benefits and risks of mannitol, the authors suggest the use of 1.0 g/kg of intraoperative mannitol for satisfactory brain relaxation with the fewest adverse effects.

Clinical trial registration no.: NCT02168075 (clinicaltrials.gov)

Definition, evaluation, and management of brain relaxation during craniotomy

The term 'brain relaxation' is routinely used to describe the size and firmness of the brain tissue during craniotomy. The status of brain relaxation is an important aspect of neuroanaesthesia practice and is relevant to the operating conditions, retraction injury, and likely patient outcomes. Brain relaxation is determined by the relationship between the volume of the intracranial contents and the capacity of the intracranial space (i.e. a content-space relationship). It is a concept related to, but distinct from, intracranial pressure. The evaluation of brain relaxation should be standardized to facilitate clinical communication and research collaboration. Both advantageous and disadvantageous effects of the various interventions for brain relaxation should be taken into account in patient care. The outcomes that matter the most to patients should be emphasized in defining, evaluating, and managing brain relaxation. To date, brain relaxation has not been reviewed specifically, and the aim of this manuscript is to discuss the current approaches to the definition, evaluation, and management of brain relaxation, knowledge gaps, and targets for future research.

A comparison of equivolume, equiosmolar solutions of hypertonic saline and mannitol for brain relaxation in patients undergoing elective intracranial tumor surgery: a randomized clinical trial

BACKGROUND

Hyperosmolar solutions have been used in neurosurgery to modify brain bulk and prevent neurological deterioration. The purpose of the study was to compare the effects of equivolume, equiosmolar solutions of mannitol and hypertonic saline (HTS) on brain relaxation and postoperative complications in patients undergoing elective intracranial tumor surgery.

METHODS

In this prospective, randomized study, patients with American Society of Anesthesiologists physical status I to III scheduled to undergo a craniotomy for intracranial tumors were enrolled. Patients received a 3.75 mL/kg intravenous infusion of either 3.2% HTS (group HTS, n=36) or 20% mannitol (group M, n=38). The surgeon assessed the condition of the brain using a 4-point scale after opening the dura. Recorded measures included duration of surgery, blood loss, urine output, volume and type of infused fluids, hemodynamic variables, electrolytes, glucose, creatinine, predefined postoperative complications, and length of intensive care unit and hospital stays.

RESULTS

Brain relaxation conditions in group HTS (score 1/2/3/4, n=10/17/2/7) were better than those in group M (score 1/2/3/4, n=3/18/3/14, P=0.0281). Patients in group M had higher urine output, received more crystalloids during surgery, and displayed lower central venous pressure and lower natremia at the end of surgery than did patients in group HTS. No significant differences in postoperative complications or lengths of intensive care unit and hospital stays were observed between the groups.

CONCLUSIONS

Our results suggest that HTS provides better brain relaxation than mannitol during elective intracranial tumor surgery.

A comparison of equivolume, equiosmolar solutions of hypertonic saline and mannitol for brain relaxation during elective supratentorial craniotomy

BACKGROUND

Hyperosmolar solutions have been used in neurosurgery to reduce brain volume and facilitate surgical exposure. The purpose of this study was to compare the effects of equivolume, equiosmolar solutions of mannitol and hypertonic saline (HS) on brain relaxation, intensive care unit (ICU) and hospital stay, postoperative outcomes and incidence of side-effects in patients undergoing elective supratentorial craniotomy.

METHODS

In a randomised, prospective, double-blind study, 60 patients undergoing elective supratentorial craniotomy were randomised 1:1 to receive 3 ml/kg of either 20% mannitol or 3% HS. The primary outcome was the surgical condition of the brain assessed by the neurosurgeon using a 4-point scale after opening the dura (1 = relaxed, 2 = satisfactory, 3 = firm and 4 = bulging). Secondary outcomes were electrolytes, blood gases, plasma osmolality and haemodynamic variables measured at 0 min, 30 min, 2 h and 6 h after infusion. Also, predefined postoperative complications, length of ICU and hospital stay were recorded. Appropriate statistical tests were used for comparison; p < 0.05 was considered significant.

RESULTS

There was no difference in brain relaxation [mannitol, 1(1-3) versus HS, 1(1.4) points; p = 0.55]. Patients with brain midline shift showed a worse response to hyperosmolar solutions than those without midline shift: 37% versus 8%, respectively; OR = 6.6 (95% CI, 1.54-28.83); p = 0.006. Plasma osmolality increased during the study period (6 h) in both the groups (p < 0.05 compared with baseline). No significant differences in postoperative complications or length of ICU and hospital stay were observed between the groups.

CONCLUSIONS

Single doses of 3 ml/kg of 20% mannitol and 3% HS are safe and effective for intraoperative brain debulking during elective supratentorial craniotomy, but less effective in patients with pre-existing mass effect and midline shift.

Agreement of measured and calculated serum osmolality during the infusion of mannitol or hypertonic saline in patients after craniotomy: a prospective, double-blinded, randomised controlled trial

Background

Mannitol and hypertonic saline are used to ameliorate brain edema and intracranial hypertension during and after craniotomy. We hypothesized that the agreement of measured and calculated serum osmolality during the infusion of hypertonic saline would be better than mannitol. The objective was to determine the accuracy of serum osmolality estimation by different formulas during the administration of hyperosmolar agent.

Methods

A prospective, randomized, double-blinded, controlled trial was conducted in a 30-bed neurosurgical intensive care unit at a university hospital. Thirty-five adult patients requiring the use of hyperosmolar agents for prevention or treatment of brain edema after elective craniotomy were enrolled, and randomly assigned 1:1 to receive 125 mL of either 20 % mannitol (mannitol group) or 3.1 % sodium chloride solution (hypertonic saline group) in 15 min. Serum osmolality, serum sodium and potassium concentration, blood urea nitrogen and blood glucose concentration were measured during the study period. The primary outcome was the agreement of measured and estimated serum osmolality during the infusion of the two experimental agents. We used Bland and Altman’s limits of agreement analysis to clarify the accuracy of estimated serum osmolality. Bias and upper and lower limits of agreement of bias were calculated.

Results

For each formula, the bias was statistically lower in hypertonic saline group than mannitol group (p < 0.001). Within group comparison showed that the lowest bias (6.0 [limits of agreement: −18.2 to 30.2] and 0.8 [−12.9 to 14.5] mOsml/kg in mannitol group and hypertonic saline group, respectively) was derived from the formula ‘2 × ([serum sodium] + [serum potassium]) + [blood urea nitrogen] + [blood glucose]’.

Conclusions

Compared to mannitol, a better agreement between measured and estimated serum osmolality was found during the infusion of hypertonic saline. This result indicates that, if hypertonic saline is chosen to prevent or treat brain edema, calculated serum osmolality can be used as a reliable surrogate for osmolality measurement.

Trial registration

ClinicalTrials.gov identifier: NCT02037815

Effects of hypertonic saline and mannitol on cortical cerebral microcirculation in a rabbit craniotomy model

Background

Hyperosmolar solutions have been used in neurosurgery to modify brain bulk and prevent neurological deterioration. The aim of this animal study was to compare the short-term effects of equivolemic, equiosmolar solutions of mannitol and hypertonic saline (HTS) on cerebral cortical microcirculation in a rabbit craniotomy model.

Methods

Rabbits (weight, 2.0–3.0 kg) were anesthetized, ventilated mechanically, and subjected to a craniotomy. The animals were allocated randomly to receive a 3.75 ml/kg intravenous infusion of either 3.2 % HTS (group HTS, n = 8) or 20 % mannitol (group MTL, n = 8). Microcirculation in the cerebral cortex was evaluated using sidestream dark-field (SDF) imaging before and 20 min after the end of the 15-min HTS infusion. Global hemodynamic data were recorded, and blood samples for laboratory analysis were obtained at the time of SDF image recording.

Results

No differences in the microcirculatory parameters were observed between the groups before the use of osmotherapy. After osmotherapy, lower proportions of perfused small vessel density (P = 0.0474), perfused vessel density (P = 0.0457), and microvascular flow index (P = 0.0207) were observed in the MTL group compared with those in the HTS group.

Conclusions

Our findings suggest that an equivolemic, equiosmolar HTS solution better preserves perfusion of cortical brain microcirculation compared to MTL in a rabbit craniotomy model.

Neuroanesthesiology update

We review topics pertinent to the perioperative care of patients with neurological disorders. Our review addresses topics not only in the anesthesiology literature, but also in basic neurosciences, critical care medicine, neurology, neurosurgery, radiology, and internal medicine literature. We include literature published or available online up through December 8, 2013. As our review is not able to include all manuscripts, we focus on recurring themes and unique and pivotal investigations. We address the broad topics of general neuroanesthesia, stroke, traumatic brain injury, anesthetic neurotoxicity, neuroprotection, pharmacology, physiology, and nervous system monitoring.

The effect of mannitol on intraoperative brain relaxation in patients undergoing supratentorial tumor surgery: study protocol for a randomized controlled trial

BACKGROUND

The risk of brain swelling after dural opening is high in patients with midline shift undergoing supratentorial tumor surgery. Brain swelling may result in increased intracranial pressure, impeded tumor exposure, and adverse outcomes. Mannitol is recommended as a first-line dehydration treatment to reduce brain edema and enable brain relaxation during neurosurgery. Research has indicated that mannitol enhanced brain relaxation in patients undergoing supratentorial tumor surgery; however, these results need further confirmation, and the optimal mannitol dose has not yet been established. We propose to examine whether different doses of 20% mannitol improve brain relaxation in a dose-dependent manner when administered at the time of incision. We will examine patients with preexisting mass effects and midline shift undergoing elective supratentorial brain tumor surgery.

METHODS

This is a single-center, randomized controlled, parallel group trial that will be carried out at Beijing Tiantan Hospital, Capital Medical University. Randomization will be achieved using a computer-generated table. The study will include 220 patients undergoing supratentorial tumor surgery whose preoperative computed tomography/magnetic resonance imaging results indicate a brain midline shift. Patients in group A, group B, and group C will receive dehydration treatment at incision with 20% mannitol solutions of 0.7, 1.0, and 1.4 g/kg, respectively, at a rate of 600 mL/h. The patients in the control group will not receive mannitol. The primary outcome is an improvement in intraoperative brain relaxation and dura tension after dehydration with mannitol. Secondary outcomes are postoperative outcomes and the incidence of mannitol side effects.

DISCUSSION

The aim of this study is to determine the optimal dose of 20% mannitol for intraoperative infusion. We will examine brain relaxation and outcome in patients undergoing supratentorial tumor surgery. If our results are positive, the study will indicate the optimal dose of mannitol to improve brain relaxation and avoid side effects during brain tumor surgery.

TRIAL REGISTRATION

The study is registered with the registry website http://www.chictr.org with the registration number ChiCTRTRC13003984 (17 December 2013).

Correlation of measured and calculated serum osmolality during mannitol or hypertonic saline infusion in patients after craniotomy: a study protocol and statistical analysis plan for a randomised controlled trial

INTRODUCTION

Brain oedema is a major complication after craniotomy. Hyperosmolar agents have been used as the medical treatment for this condition. Measurement and estimation of serum osmolality during hyperosmolar agent infusion is of clinical importance to evaluate clinical efficacy, adjust dosage and avoid side effects. However, several studies have shown that calculated serum osmolality may lead to a systematic bias compared with direct measurement. In the present study, mannitol or hypertonic saline (HS) will be used in patients after elective craniotomy. We aim to determine the accuracy of serum osmolality estimation during the application of hyperosmolar agent.

METHODS AND ANALYSIS

The study is a prospective, randomised, double-blinded, controlled, parallel-group design. Adult patients requiring the use of hyperosmolar agents for the prevention or treatment of postoperative brain oedema are enrolled and assigned randomly to one of the two treatment study groups, labelled as 'M group' and 'HS group'. Patients in the M and HS groups receive intravenous infusion of 125 mL of either 20% mannitol or 3.1% sodium chloride solution, respectively. Data will be collected immediately before the infusion of study agents, 15, 30, 60, 120, 240 and 360 min after the start of infusion of experimental agents, which includes serum osmolality, concentration of serum sodium, potassium, urea and glucose. Serum osmolality will be measured by means of freezing point depression. Estimated serum osmolality will also be calculated by using four formulas published previously. Osmole gap is calculated as the difference between the measured and the estimated values. The primary endpoint is the correlation of measured and estimated serum osmolality during hyperosmolar agent infusion.

ETHICS AND DISSEMINATION

The study was approved by the International Review Board (IRB) of Beijing Tiantan Hospital, Capital Medical University. Study findings will be disseminated through peer-reviewed publications and conference presentations.

TRIAL REGISTRATION NUMBER

ClinicalTrials.gov identifier: NCT02037815.