Anaesthesia for elective neurosurgery

Passive mapping of hand motor cortex across altered states of consciousness

OBJECTIVE

To evaluate the ability of median nerve stimulation (MNS)-induced high gamma band (HGB) activity in mapping the hand motor cortex at different states of consciousness.

METHODS

Five patients undergoing awake craniotomy were recruited. MNS-induced electrocorticographic signals were recorded from awake to anesthetic states, with the loss of consciousness (LOC) session divided into three stages (LOC1, LOC2, and LOC3) based on conscious level. HGB signals were analyzed to localize hand motor cortex. Linear models were applied to analyze HGB dynamics during LOC.

RESULTS

The sensitivity of hand motor cortex mapping based on HGB average envelope at short-latency period was 100%, 96.67%±3.33%, 83.47%±8.19%, and 82.22%±11.44% for the awake, LOC1, LOC2 and LOC3 stages. The sensitivity for HGB average envelope at long-latency period was 92.67%±4.52%, 90.85%±4.13%, 72.27%±17.07%, and 40.53%±12.82% across the same stages. The sensitivity based on HGB average power at short-latency period decreased from 100% in awake stage to 72.83%±12.95%, 48.11%±15.95%, and 21.12%±5.70% across LOC stages. The sensitivity for HGB average power at long-latency period dropped from 92.67%±4.52% in awake stage to 70.94%±10.79%, 58.37%±17.49%, and 25.71%±14.95% in the subsequent LOC stages. The slope coefficient of the simple linear model for long-latency average envelope was significantly smaller than that for short-latency. In the linear mixed effects model, the Condition × Sliding Window estimate coefficient was -0.794.

CONCLUSION

In awake state, HGB average envelope and average power both effectively localized hand motor cortex. With declining consciousness, the mapping ability of average power significantly deteriorated, while the mapping ability of short-latency average envelope remained relatively stable.

The effect of spaced learning on the learning outcome and retention of nurse anesthesia students: a randomized-controlled study

BACKGROUND

Poor learning and retention are common problems of students, which may be alleviated by optimization of widely used educational methods such as lectures. This study aimed to investigate the effect of spaced learning on the learning outcome and retention of nurse anesthesia students.

METHODS

This was a randomized controlled study with a pre-and post-test design on 64 nurse anesthesia students who were divided into two groups of spaced lecture (n = 32) and conventional lecture (n = 32). The spaced lectures included three 30-minute training sessions with 10-minute intervals while the conventional sessions including 90 min of continuous training. Students' knowledge was measured using one valid and reliable questionnaire developed by the research team. All students in both groups took a pre-test, and their level of knowledge acquisition was evaluated immediately after the training. Their level of knowledge retention was tested two and four weeks after the lecture.

RESULTS

There was no significant difference between the two groups regarding demographic characteristics (p > 0.05). In the pre-test, the mean score of knowledge in the intervention group was lower than that in the control group, there was no significant difference (p = 0.177). But after the intervention, the mean scores of learning outcome and retention in the intervention group were significantly higher than those in the control group (p < 0.001, eta = 0.576). Also, the results showed that learning outcome and retention across the three academic semesters in the two groups are significantly different, and students with a higher academic semester obtained a significantly higher mean score of knowledge and retention (p < 0.001, eta = 0.604).

CONCLUSION

Spaced learning improves nurse anesthesia students' knowledge and retention more than conventional method. Future studies focusing on spaced learning should specifically examine the impact of duration and number of intervals, as well as the time gap between training and measurement of learning retention.

Comparison of Opioid-Based Versus Opioid-Sparing Anesthesia in Patients Undergoing Glioma Surgery

Background In the neurosurgical population, opioids may cause respiratory depression, leading to hypercapnia, increased cerebral blood flow (CBF), and ultimately increased intracranial pressure (ICP), which can mask early signs of intracranial complications and delayed emergence. This study was designed to compare perioperative hemodynamic stability, analgesia, and recovery parameters in opioid-based (fentanyl) general anesthesia versus opioid-sparing (dexmedetomidine) general anesthesia in patients undergoing glioma surgeries. Methodology This prospective observational comparative study compared 52 patients in two groups. Twenty-six (50%) patients in group F received Inj. fentanyl IV (intravenous; bolus 2 mcg/kg 10 minutes before induction and then infusion 1 mcg/kg/hour till 30 minutes before skin closure), whereas 26 (50%) patients in group D received Inj. dexmedetomidine IV (0.5 mcg/kg infusion 10 minutes before induction and then maintenance with a 0.5 mcg/kg/hour infusion till 30 minutes before skin closure). Perioperative heart rate (HR), mean arterial pressure (MAP), Numerical Rating Scale for Pain (NRS) assessment and postoperative emergence time, modified Aldrete score, patient satisfaction, and surgeon satisfaction score were estimated and compared in both groups. Results The mean HR was less in group D compared to group F at following time points - 10 minutes after infusion (P = 0.006), laryngoscopy and intubation (P = 0.003), pinning of the skull (P < 0.001), one hour after dura opening (P = 0.007), two hours after dura opening (P = 0.006), five minutes after extubation (P < 0.001), and 30 minutes after extubation (P = 0.011). MAP was lower in group D compared to group F at the following time intervals: 10 minutes after infusion (P = 0.008), five minutes after extubation (P = 0.007), 30 minutes after extubation (P < 0.001), and one hour after extubation (P = 0.023). A significant decrease in emergence time in group D compared to group F (P < 0.001) was noted. NRS was lower in group D at eight hours (P = 0.005) and 12 hours (P < 0.001) post-extubation. Conclusions Dexmedetomidine can be used as an alternative to fentanyl in terms of perioperative hemodynamic stability, perioperative analgesia, smooth early recovery from anesthesia, patient satisfaction, and surgeon satisfaction.

Stereoelectroencephalography: a review of complications and outcomes in a new Australian centre

BACKGROUND

Surgical management of refractory focal epilepsy requires preoperative localisation of the epileptogenic zone (EZ). To augment noninvasive studies, stereoelectroencephalography (SEEG) is being increasingly adopted as a form of intracranial monitoring.

AIMS

This study aimed to determine the rate of complications for patients undergoing SEEG and to report the success of SEEG with regard to EZ detection and seizure outcome following definitive surgery.

METHODS

A retrospective cohort design investigated all cases of SEEG at our institution. Surgical, anaesthetic and medical complications with subsequent epilepsy surgery and seizure outcome data were extracted from medical records. Multivariate logistic regression was used to investigate the relationship between both the number of electrodes per patient and the duration of SEEG recording with the rate of complications.

RESULTS

Sixty-four patients with 66 implantations were included. Headache was the most common complication (n = 54, 82%). There were no major surgical or medical complications. Two anaesthetic complications occurred. EZ localisation was successful in 63 cases (95%). Curative intent surgery was performed in 39 patients (59%) and 23 patients achieved an Engel class I outcome (59% of those undergoing surgery). The number of electrodes and duration of recording were not associated with complications.

CONCLUSIONS

No patients in our series experienced major surgical or medical complications and we have highlighted the challenges associated with neuroanaesthesia in SEEG. Our complication rates and seizure outcomes are equivalent to published literature indicating that this technique can be successfully established in newer centres using careful case selection. Standardised reporting of SEEG complications should be adopted.

Dopaminergic Cell Replacement for Parkinson's Disease: Addressing the Intracranial Delivery Hurdle

Parkinson's disease (PD) is an increasingly prevalent neurological disorder, affecting more than 8.5 million individuals worldwide. α-Synucleinopathy in PD is considered to cause dopaminergic neuronal loss in the substantia nigra, resulting in characteristic motor dysfunction that is the target for current medical and surgical therapies. Standard treatment for PD has remained unchanged for several decades and does not alter disease progression. Furthermore, symptomatic therapies for PD are limited by issues surrounding long-term efficacy and side effects. Cell replacement therapy (CRT) presents an alternative approach that has the potential to restore striatal dopaminergic input and ameliorate debilitating motor symptoms in PD. Despite promising pre-clinical data, CRT has demonstrated mixed success clinically. Recent advances in graft biology have renewed interest in the field, resulting in several worldwide ongoing clinical trials. However, factors surrounding the effective neurosurgical delivery of cell grafts have remained under-studied, despite their significant potential to influence therapeutic outcomes. Here, we focus on the key neurosurgical factors to consider for the clinical translation of CRT. We review the instruments that have been used for cell graft delivery, highlighting current features and limitations, while discussing how future devices could address these challenges. Finally, we review other novel developments that may enhance graft accessibility, delivery, and efficacy. Challenges surrounding neurosurgical delivery may critically contribute to the success of CRT, so it is crucial that we address these issues to ensure that CRT does not falter at the final hurdle.

Effect of Different Surgical Positions on the Changes in Cerebral Venous Drainage in Patients Undergoing Neurosurgery: A Prospective Observational Study

BACKGROUND

Some patient positions employed to facilitate neurosurgery can compromise cerebral venous drainage and lead to increased intracranial pressure, intraoperative bleeding, and brain bulge. This study evaluated the impact of different surgical positions on internal jugular vein (IJV) flow as a measure of cerebral venous drainage and on optic nerve sheath diameter (ONSD) as an indirect assessment of intracranial pressure.

METHODS

Ninety patients scheduled for elective primary brain tumor resection surgery were included in 3 groups of 30 each according to the surgical position: supine, prone, or lateral. Bilateral IJV flow was recorded at 3-time points: before the induction of anesthesia in the supine position (T0), 10 minutes after the induction of anesthesia in the supine position (T1), and 10 minutes after final positioning (T2). The ONSD was measured at T1 and T2.

RESULTS

Mean IJV flow decreased from baseline by 36%, 10% and 38% in the supine, prone and lateral position groups, respectively. Mean IJV flow was 1005.9±463 mL/min versus 634.7±245 mL/min ( P =0.036) in Group S, 752.5±384.8 mL/min versus 672.3±391.0 mL/min ( P =0.002) in group P, and 831.8±337.4 mL/min versus 514.4±305.3 mL/min ( P <0.001) in group L at T0 and T2, respectively. Mean ONSD did not change between T1 and T2 in Groups S and P but increased in group L ( P <0.05).

CONCLUSIONS

Mean IJV flow decreased from baseline following the final neurosurgical positioning. Ultrasound-guided assessment of IJV flow could be a useful tool to quantify position-related changes in IJV drainage.

Opioid-Free Anesthesia for Awake Neurosurgery in a Patient With Asthma and Von Willebrand Disease: A Case Report

Anesthesia for awake neurosurgery requires meticulous planning. We report the case of a 44-year-old female with glioblastoma undergoing an awake craniotomy. Due to her asthma and von Willebrand disease, an opioid-free approach was chosen. Conscious sedation was attained using propofol and dexmedetomidine. The operation was successful after nine hours with patient comfort maintained. The patient was discharged from the intensive care unit in two days without sequelae. However, the use of desmopressin caused hyponatremia and cerebral edema. The scalp block was effective for pain management. This case highlights the importance of individualized anesthetic strategies in awake neurosurgeries.

Pulse Pressure Variance (PPV)-Guided Fluid Management in Adult Patients Undergoing Supratentorial Tumor Surgeries: A Randomized Controlled Trial

Objective  Appropriate fluid management in neurosurgery is critical due to the risk of secondary brain injury. Determination of volume status is challenging with static variables being unreliable. Goal-directed fluid therapy with dynamic variables allows reliable determination of fluid responsiveness and promises better outcomes. We aimed to compare the intraoperative fluid requirement between conventional central venous pressure (CVP)-guided and pulse pressure variance (PPV)-guided fluid management in supratentorial tumor surgeries. Materials and Methods  This prospective, randomized, double-blind, single-center trial was conducted with 72 adults undergoing supratentorial tumor surgery in a supine position. Patients were divided into two groups of 36 patients each receiving CVP- and PPV-guided fluid therapy. The CVP-guided group received boluses to target CVP greater than 8 mm Hg along with hourly replacement of intraoperative losses and maintenance fluids. The PPV-guided group received boluses to target PPV less than 13% in addition to maintenance fluids. Total intraoperative fluids administered and the incidence of hypotension was recorded along with the brain relaxation score. Postoperatively, serum lactate levels, periorbital and conjunctival edema, as well as postoperative nausea and vomiting were assessed. Statistical Analyses  All statistical analyses were performed with Statistical Package for Social Sciences, version-20 (SPSS-20, IBM, Chicago, Illinois, United States). To compare the means between the two groups (CVP vs. PPV), independent samples t -test was used for normal distribution data and Mann-Whitney U test for nonnormal distribution data. The chi-square test or Fischer's exact test was used for categorical variables. Results  The CVP group received significantly more intraoperative fluids than the PPV group (4,340 ± 1,010 vs. 3,540 ± 740 mL, p  < 0.01). Incidence of hypotension was lower in the PPV group (4 [11.1%] vs. 0 [0%], p  = 0.04). Brain relaxation scores, serum lactate levels, periorbital and conjunctival edema, and incidence of postoperative nausea and vomiting were comparable between the groups. Conclusion  The requirement for intraoperative fluids was less in PPV-guided fluid management with better hemodynamic stability, adequate brain conditions, and no compromise of perfusion.

Case Series in the Utility of Invasive Blood Pressure Monitoring in Microvascular Decompression

BACKGROUND

The utility of arterial lines in microvascular decompression (MVD) is not well described.

OBJECTIVE

To examine the safety and costs of arterial lines compared with noninvasive blood pressure (NIBP) monitoring in MVDs.

METHODS

We retrospectively reviewed patients undergoing MVD from 2012 to 2020. Patients were grouped by procedure date from 2012 to 2014 and 2015 to 2020, reflecting our institution's decreasing trend in arterial line placement around 2014 to 2015. Patient features, intraoperative characteristics, and postoperative complications were collected for all cases. Statistical differences were evaluated using chi-squared analyses and t-tests.

RESULTS

Eight hundred fifty-eight patients underwent MVDs, with 204 between 2012 and 2014 and 654 between 2015 and 2020. Over time, the frequency of arterial line placement decreased from 64.2% to 30.1%, P < .001. Arterial lines involved 11 additional minutes of preincision time, P < .001. Patients with arterial lines required both increased doses and costs of vasoactive medications intraoperatively. Patients receiving arterial lines demonstrated no significant differences in complications compared with patients with NIBP monitoring. On average, patients with arterial lines incurred $802 increased costs per case compared with NIBP monitoring.

CONCLUSION

NIBP monitoring in MVDs provides neurologically and hemodynamically safe outcomes compared with invasive blood pressure monitoring. For patients without significant cardiopulmonary risk factors, NIBP monitoring may be a cost-effective alternative in MVDs.

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.

Twenty years on - has patient-centered care been equally well integrated among medical specialties?

OBJECTIVE

The concept of 'patient-centered care' was touted as a pillar of good clinical practice and endorsed by the US Institute of Medicine in a seminal 2001 publication. We explore the extent to which differing medical specialties have engaged with the concept over the last 20 years and how and why this attention has varied among a sample of medical specialties since 2001.

METHODS

Reference to patient-centered care in the medical literature for selected specialties was used as a proxy for clinical application of patient-centered care in those disciplines. We undertook a statistical analysis and historical review of the medical literature that references the concept of patient-centered care in pediatrics, obstetrics and gynecology (OB-GYN), orthopedics, radiology, dermatology, and neurosurgery. We analyzed the extent to which the literature referencing patient-centered care has changed for the six disciplines since first mentioned in the Institute of Medicine 2001 publication. We measured changes over time in reference to patient-centered care in the medical literature for the six diverse medical specialties.

RESULTS

The six disciplines differed significantly in reference to patient-centered care when comparing publications between the disciplines (p < 0.001). Pediatrics showed the most extensive reference to the concept followed by OB-GYN. In contrast, patient-centered care was hardly mentioned in dermatology and neurosurgery, nor orthopedics or radiology. When correcting for the number of papers published in the different fields, reference to patient-centered care is ~18X more common in pediatrics than in neurosurgery.

CONCLUSION

Uptake, attention, and applicability of the principles of patient-centered care have varied over the last 20 years. Differences among specialties appear to reflect true differences in patient centricities in the disciplines, with higher uptake in specialties that are person-oriented rather than technique-oriented. Greater engagement with patient-centered care correlates strongly with the number of female physicians in each field.

Predictors for time to awake in patients undergoing awake craniotomies

OBJECTIVE

Awake craniotomies are often characterized by alternating asleep-awake-asleep periods. Preceding the awake phase, patients are weaned from anesthesia and mechanical ventilation. Although clinicians aim to minimize the time to awake for patient safety and operating room efficiency, in some patients, the time to awake exceeds 20 minutes. The goal of this study was to determine the average time to awake and the factors associated with prolonged time to awake (> 20 minutes) in patients undergoing awake craniotomy.

METHODS

Records of patients who underwent awake craniotomy between 2003 and 2020 were evaluated. Time to awake was defined as the time between discontinuation of propofol and remifentanil infusion and the time of extubation. Patient and perioperative characteristics were explored as predictors for time to awake using logistic regression analyses.

RESULTS

Data of 307 patients were analyzed. The median (IQR) time to awake was 13 (10-20) minutes and exceeded 20 minutes in 17% (95% CI 13%-21%) of the patients. In both univariate and multivariable analyses, increased age, nonsmoker status, and American Society of Anesthesiologists (ASA) class III versus II were associated with a time to awake exceeding 20 minutes. BMI, as well as the use of alcohol, drugs, dexamethasone, or antiepileptic agents, was not significantly associated with the time to awake.

CONCLUSIONS

While most patients undergoing awake craniotomy are awake within a reasonable time frame after discontinuation of propofol and remifentanil infusion, time to awake exceeded 20 minutes in 17% of the patients. Increasing age, nonsmoker status, and higher ASA classification were found to be associated with a prolonged time to awake.

Sevoflurane and Desflurane Exposures Following Aneurysmal Subarachnoid Hemorrhage Confer Multifaceted Protection against Delayed Cerebral Ischemia

Numerous studies have demonstrated the ability of isoflurane conditioning to provide multifaceted protection against aneurysmal subarachnoid hemorrhage (SAH)-associated delayed cerebral ischemia (DCI); however, preclinical studies have not yet examined whether other commonly used inhalational anesthetics in neurological patients such as sevoflurane or desflurane are also protective against SAH-induced neurovascular deficits. We therefore sought to identify the potential for sevoflurane and desflurane conditioning to protect against DCI in an endovascular perforation mouse model of SAH. Neurological function was assessed daily via neuroscore. Large artery vasospasm and microvessel thrombosis were assessed three days after SAH or sham surgery. Four groups were examined: Sham, SAH + room air, SAH + 2% Sevoflurane, and SAH + 6% Desflurane. For the SAH groups, one hour after surgery, mice received 2% sevoflurane, 6% desflurane, or room air for one hour. We found that conditioning with sevoflurane or desflurane attenuated large artery vasospasm, reduced microvessel thrombosis, and improved neurologic function. Given their frequent clinical use and strong safety profile in patients (including those with SAH), these data strongly support further studies to validate these findings in preclinical and clinical studies and to elucidate the mechanisms by which these agents might be acting.

Inhaled anesthesia in neurosurgery: Still a role?

In patients undergoing craniotomy, general anesthesia should be addressed to warrant good hypnosis, immobility, and analgesia, to ensure systemic and cerebral physiological status and provide the best possible surgical field. Regarding craniotomies, it is unclear if there are substantial differences in providing general anesthesia using total intravenous anesthesia (TIVA) or balanced anesthesia (BA) accomplished using the third generation halogenates. New evidence highlighted that the last generation of halogenated agents has possible advantages compared with intravenous drugs: rapid induction, minimal absorption and metabolization, reproducible pharmacokinetic, faster recovery, cardioprotective effect, and opioid spare analgesia. This review aims to report evidence related to the use of the latest halogenated agents in patients undergoing craniotomy and to present available clinical evidence on their effects: cerebral and systemic hemodynamic, neurophysiological monitoring, and timing and quality of recovery after anesthesia.

Regional Anesthesia in Neuroanesthesia Practice

Regional anesthesia has been an undervalued entity in neuroanesthetic practice. However, in the past few years, owing to the development of more advanced techniques, drugs and the prolific use of ultrasound guidance, the unrecognised potential of these modalities have been highlighted. These techniques confer the advantages of reduced requirements for local anesthetics, improved hemodynamic stability in the intraoperative period, better pain score postoperatively and reduced analgesic requirements in the postoperative period. Reduced analgesic requirement translates into lesser side effects associated with analgesic use. Furthermore, the transition from the traditional blind landmark-based techniques to the ultrasound guidance has increased the reliability and the safety profile. In this review, we highlight the commonly practised blocks in the neuroanesthesiologist's armamentarium and describe their characteristics, along with their individual particularities.

Comparison of the Effects of Propofol and Sevoflurane Induced Burst Suppression on Cerebral Blood Flow and Oxygenation: A Prospective, Randomised, Double-Blinded Study

OBJECTIVE

Pharmacologically induced electroencephalogram (EEG) silence increases tolerance of ischemic period by reducing cerebral metabolism. We hypothesized that sevoflurane, a cerebral vasodilator, will maintain cerebral blood flow (CBF) and cerebral metabolic rate of oxygen (CMRO₂) better than propofol, a cerebral vasoconstrictor, during EEG silence. To validate this, we compared the effect of sevoflurane and propofol on CBF and CMRO₂ during surgical plane of anasthesia (SP) and burst suppression on EEG (BS).

METHODS

We conducted a prospective, double-blinded trial where patients undergoing neurosurgery were randomized to receive propofol or sevoflurane. Mean velocity (MV) and pulsatility index (PI) of bilateral middle cerebral arteries (MCA) were measured as surrogate of CBF. Jugular venous oxygen saturation (SjvO₂) and arteriovenous oxygen difference (AjvDO₂) were obtained to assess CMRO₂. The values were compared between groups using Student t test and within the group with analysis of variance at SP and BS.

RESULTS

BS decreased MV and increased PI in propofol group (P < 0.001 and P < 0.02 on normal side, P < 0.004 and P < 0.001 on tumor side). There was no significant change in sevoflurane group. BS with sevoflurane increased SjvO₂ (P < 0.001) and decreased AjvDO₂ (P < 0.001). Change in SjvO₂ and AjvDO₂ with propofol at SP and BS was variable.

CONCLUSIONS

In our study, sevoflurane had a safer profile on cerebral oxygenation during BS while not altering the CBF, suggesting increased availability of oxygen. Propofol, on the other hand, produced cerebral vasoconstriction with BS. The effect of propofol on oxygenation was unpredictable, with low SjvO₂ and high AjvDO₂ even at surgical plane of anesthesia.

Multimodal analgesia in pain management after spine surgery

Multimodal analgesia (MMA) is the simultaneous use of multiple analgesic medications that work in a synergistic manner to provide pain control. In recent years, spine surgery has seen the growth of multimodal perioperative protocols for managing pain. Postoperative pain following spinal procedures is a common complaint, with persistent pain even after the immediate convalescent period leading to negative impacts on health. A multidisciplinary approach is essential in reducing postoperative morbidity and complication rates. This review demonstrates the efficacy in the combined use of opioid-alternative medications such as NSAIDs, gabapentinoids, local anesthetics, acetaminophen, and other neuromodulatory pharmacologic agents. Continued research will be essential in the optimization of the MMA protocol for treating patients who undergo spine procedures.

Acquisition of sensorimotor fMRI under general anaesthesia: Assessment of feasibility, the BOLD response and clinical utility

We evaluated whether task-related fMRI (functional magnetic resonance imaging) BOLD (blood oxygenation level dependent) activation could be acquired under conventional anaesthesia at a depth enabling neurosurgery in five patients with supratentorial gliomas. Within a 1.5 T MRI operating room immediately prior to neurosurgery, a passive finger flexion sensorimotor paradigm was performed on each hand with the patients awake, and then immediately after the induction and maintenance of combined sevoflurane and propofol general anaesthesia. The depth of surgical anaesthesia was measured and confirmed with an EEG-derived technique, the Bispectral Index (BIS). The magnitude of the task-related BOLD response and BOLD sensitivity under anaesthesia were determined. The fMRI data were assessed by three fMRI expert observers who rated each activation map for somatotopy and usefulness for radiological neurosurgical guidance. The mean magnitudes of the task-related BOLD response under a BIS measured depth of surgical general anaesthesia were 25% (tumour affected hemisphere) and 22% (tumour free hemisphere) of the respective awake values. BOLD sensitivity under anaesthesia ranged from 7% to 83% compared to the awake state. Despite these reductions, somatotopic BOLD activation was observed in the sensorimotor cortex in all ten data acquisitions surpassing statistical thresholds of at least p < 0.001_uncorr. All ten fMRI activation datasets were scored to be useful for radiological neurosurgical guidance. Passive task-related sensorimotor fMRI acquired in neurosurgical patients under multi-pharmacological general anaesthesia is reproducible and yields clinically useful activation maps. These results demonstrate the feasibility of the technique and its potential value if applied intra-operatively. Additionally these methods may enable fMRI investigations in patients unable to perform or lie still for awake paradigms, such as young children, claustrophobic patients and those with movement disorders.

Pre-administration of remifentanil in target-controlled propofol and remifentanil anesthesia prolongs anesthesia induction in neurosurgical patients: A double-blind randomized controlled trial

BACKGROUND

Pre- and co-administration of remifentanil in target-controlled propofol and remifentanil anesthesia are the most common methods in clinical practice. However, anesthesia induction time by timing remifentanil administration was not identified. Therefore, we investigated the induction time of anesthesia based on type of remifentanil administration in target-controlled anesthesia.

METHODS

A total of 60 patients were randomly assigned to 1 of 2 groups: Pre-administered with remifentanil before propofol infusion (Group R, n = 30) and co-administered with remifentanil with propofol (Group N, n = 30). The primary outcome was total induction time based on the order of remifentanil administration. Secondary outcomes were from start of the propofol infusion time to loss of consciousness (LOC), rocuronium onset time, time to Bispectral index (BIS) 60, and hemodynamic variables.

RESULTS

The mean ± SD of total induction time was 180.5 ± 49.0 s in Group N and 246.3 ± 64.7 s in Group R (mean difference: 65.8 seconds; 95% CI: 35.0-96.5 s, P < .01). Time to BIS 60 and rocuronium onset time were longer in the Group R (P < .01 and P < .01, respectively). The Δheart rate and Δcardiac output values were lower in the Group R (P = .02 and P = .04, respectively). Injection pain was reported by 11 of 28 (39%) in the Group N and in 2 of 28 (7%) in the Group R (difference in proportion: 32%, 95% CI: 10-51%, P = .01).

CONCLUSION

Pre-administration of remifentanil in target-controlled propofol and remifentanil anesthesia prolongs total induction time about 35% compared to co-administration of remifentanil and propofol by decreased CO.

The effect of anesthetic agents on cerebral vasospasms after subarachnoid hemorrhage: A retrospective study

Cerebral vasospasm is the most important cause of morbidity after an aneurysm clipping in the early postoperative period. The aim of this retrospective study was to evaluate whether the incidence of vasospasms differs when using propofol or desflurane for an emergent aneurysm clipping.The data from 102 patients (50 in the propofol group, 52 in the desflurane group) were analyzed. The occurrence of vasospasm based on daily transcranial Doppler, angiography, and cerebral infarction during 14 days after surgery were compared by anesthetic agents. Postoperative data including Glasgow Coma Scale (GCS) score on day 14 after surgery, and the Glasgow Outcome Scale (GOS) score at 3 months were documented.Patients that intraoperatively received propofol for anesthesia maintenance, had higher incidence of transcranial Doppler (TCD)-evident vasospasm than those that received desflurane (54% vs 30.8%, P = .027). The occurrence of TCD-evident vasospasm was still higher (odds ratio: 2.84; 95% confidence interval: 1.12-7.20) in the propofol group than in the desflurane group after adjusting for confounding factors. However, the incidence of angiographic vasospasm, cerebral infarction, and interventions to treat cerebral vasospasms were similar between both groups. GCS score on day 14 after surgery and the GOS score at 3 months were similar between groups.No effect of anesthetic agents on angiographic vasospasm, cerebral infarction, or clinical outcome was observed, whereas desflurane anesthesia was associated with a lower incidence of TCD-evident vasospasms compared to propofol anesthesia. Our study provides a basis for further randomized controlled studies in a larger patient population to clarify the effects of anesthetic agents on the occurrence of cerebral vasospasms.

The use of desflurane for neurosurgical procedures in rhesus macaque ( Macaca mulatta)

Volatile agents are widely used to anaesthetise laboratory non-human primates as they allow a rapid induction and recovery as well as an easy adjustment of the anaesthesia plan. Desflurane is currently the volatile agent with the lowest solubility in blood, and hence enables the most rapid onset of anaesthesia and most rapid recovery. This study aimed to investigate the suitability of desflurane for maintenance of general anaesthesia in rhesus macaques undergoing elective experimental neurosurgery. Fourteen primates (five males and nine females) were sedated with ketamine (10 mg kg^-1) and anaesthesia was induced with propofol (usually 8 mg kg^-1 IV). Anaesthesia was maintained with desflurane (5.9 ± 0.8 %) and alfentanil (0.2-0.5 µg kg^-1 min^-1 IV). Animals were mechanically ventilated. Meloxicam (0.3 mg kg^-1) and methylprednisolone infusion (5.4 mg kg^-1 h^-1) were also administered. All the primates were successfully anaesthetised and no severe complications related to the procedure or the anaesthesia regimen occurred. No major differences in physiological parameters and recovery times between the male and female groups were found. Emergence from anaesthesia was rapid (male 5.2 ± 2.4 min; female 4.1 ± 1.7 min) but its quality was assessed as equivalent to two other volatile anaesthetics, isoflurane and sevoflurane. These had previously been assessed for neuroanaesthesia in rhesus macaques. In conclusion, this study demonstrated that desflurane was suitable for maintenance of general anaesthesia for elective experimental neurosurgical procedures in rhesus macaque. However the vasodilatory action of the desflurane may limit its use in cases of severe intracranial hypertension or systemic hypotension.

Comparison of emergence times and quality between isoflurane and sevoflurane in rhesus macaque (Macaca mulatta) undergoing neurosurgical procedure

Volatile agents for anaesthesia are widely used for anaesthetizing laboratory primates, and isoflurane is one of the most frequently used agents. Sevoflurane has been shown to offer a more rapid recovery than isoflurane in a number of species, but no comparisons have been made in non-human primates. This study compared the recovery characteristics of isoflurane and sevoflurane in rhesus macaques undergoing experimental neurosurgery. Twelve primates (7 males and 5 females) were randomly allocated to the treatment groups. They were sedated with ketamine (10 mg/kg) and anaesthesia was induced with propofol (usually 8 mg/kg intravenously [IV]). Anaesthesia was maintained with either sevoflurane (SEVO) (2.2 ± 0.4%) or isoflurane (ISO) (1.2 ± 0.2%) and alfentanil (0.2–0.5 µg/kg/min IV) for 332–592 min. Animals were mechanically ventilated. Meloxicam (0.3 mg/kg) and methylprednisolone infusion (5.4 mg/kg/h) were also administered. Time to extubation after cessation of anaesthesia was significantly shorter with sevoflurane (ISO: 7.0 ± 1.8 min; SEVO: 3.6 ± 1.5; *P = 0.005) as was the time to the animal sitting unaided (ISO: 15.7 ± 8.2 min; SEVO: 7.1 ± 1.7 min; *P = 0.004) . No significant difference in the quality of recovery following isoflurane or sevoflurane anaesthesia was found. In conclusion, isoflurane and sevoflurane are both suitable volatile agents for the maintenance of general anaesthesia in rhesus macaques undergoing experimental neurosurgical procedures. The two volatile agents presented a similar emergence quality profile, however sevoflurane anaesthesia was associated with a faster recovery, offering the possibility of conducting earlier post-operative neurological assessment.

Comparison of propofol pharmacokinetic and pharmacodynamic models for awake craniotomy: A prospective observational study

BACKGROUND

Anaesthesia for awake craniotomy aims for an unconscious patient at the beginning and end of surgery but a rapidly awakening and responsive patient during the awake period. Therefore, an accurate pharmacokinetic/pharmacodynamic (PK/PD) model for propofol is required to tailor depth of anaesthesia.

OBJECTIVE

To compare the predictive performances of the Marsh and the Schnider PK/PD models during awake craniotomy.

DESIGN

A prospective observational study.

SETTING

Single university hospital from February 2009 to May 2010.

PATIENTS

Twelve patients undergoing elective awake craniotomy for resection of brain tumour or epileptogenic areas.

INTERVENTION

Arterial blood samples were drawn at intervals and the propofol plasma concentration was determined.

MAIN OUTCOME MEASURES

The prediction error, bias [median prediction error (MDPE)] and inaccuracy [median absolute prediction error (MDAPE)] of the Marsh and the Schnider models were calculated. The secondary endpoint was the prediction probability PK, by which changes in the propofol effect-site concentration (as derived from simultaneous PK/PD modelling) predicted changes in anaesthetic depth (measured by the bispectral index).

RESULTS

The Marsh model was associated with a significantly (P = 0.05) higher inaccuracy (MDAPE 28.9 ± 12.0%) than the Schnider model (MDAPE 21.5 ± 7.7%) and tended to reach a higher bias (MDPE Marsh -11.7 ± 14.3%, MDPE Schnider -5.4 ± 20.7%, P = 0.09). MDAPE was outside of accepted limits in six (Marsh model) and two (Schnider model) of 12 patients. The prediction probability was comparable between the Marsh (PK 0.798 ± 0.056) and the Schnider model (PK 0.787 ± 0.055), but after adjusting the models to each individual patient, the Schnider model achieved significantly higher prediction probabilities (PK 0.807 ± 0.056, P = 0.05).

CONCLUSION

When using the 'asleep-awake-asleep' anaesthetic technique during awake craniotomy, we advocate using the PK/PD model proposed by Schnider. Due to considerable interindividual variation, additional monitoring of anaesthetic depth is recommended.

TRIAL REGISTRATION

ClinicalTrials.gov identifier: NCT 01128465.

Principles of Neuro-anesthesia in Neurosurgery for Intensive Care Unit Nurses

As neurosurgical interventions and procedures are advancing, so is the specialty of neuro-anesthesia. The neurosurgeon and the neuro-anesthetist are focused on providing each patient with the best possible outcome. Throughout the surgery, the main priorities of the neuro-anesthetist are patient safety, patient well-being, surgical field exposure, and patient positioning. Potential postoperative complications include nausea and vomiting. Postoperative visual loss is a complication of neurosurgery, most specifically spine surgery, whose origins are unknown. Postoperative considerations for the intensive care unit nurse should include receiving a thorough clinical handoff from the anesthesia provider to ensure care continuity and patient safety.

Effects of Anesthetic Management on Early Postoperative Recovery, Hemodynamics and Pain After Supratentorial Craniotomy

Various clinical trials have assessed how intraoperative anesthetics can affect early recovery, hemodynamics and nociception after supratentorial craniotomy. Whether or not the difference in recovery pattern differs in a meaningful way with anesthetic choice is controversial. This review examines and compares different anesthetics with respect to wake-up time, hemodynamics, respiration, cognitive recovery, pain, nausea and vomiting, and shivering. When comparing inhalational anesthetics to intravenous anesthetics, either regimen produces similar recovery results. Newer shorter acting agents accelerate the process of emergence and extubation. A balanced inhalational/intravenous anesthetic could be desirable for patients with normal intracranial pressure, while total intravenous anesthesia could be beneficial for patients with elevated intracranial pressure. Comparison of inhalational anesthetics shows all appropriate for rapid emergence, decreasing time to extubation, and cognitive recovery. Comparison of opioids demonstrates similar awakening and extubation time if the infusion of longer acting opioids was ended at the appropriate time. Administration of local anesthetics into the skin, and addition of corticosteroids, NSAIDs, COX-2 inhibitors, and PCA therapy postoperatively provided superior analgesia. It is also important to emphasize the possibility of long-term effects of anesthetics on cognitive function. More research is warranted to develop best practices strategies for the future that are evidence-based.

Hypertonic saline for brain relaxation and intracranial pressure in patients undergoing neurosurgical procedures: a meta-analysis of randomized controlled trials

Background

A wealth of evidence from randomized controlled trials (RCTs) has indicated that hypertonic saline (HS) is at least as effective as, if not better than, mannitol in the treatment of increased intracranial pressure(ICP). However, there is little known about the effects of HS in patients during neurosurgery. Thus, this meta-analysis was performed to compare the intraoperative effects of HS with mannitol in patients undergoing craniotomy.

Methods

According to the research strategy, we searched PUBMED, EMBASE and Cochrane Central Register of Controlled Trials. Other sources such as the internet-based clinical trial registries and conference proceedings were also searched. After literature searching, two investigators independently performed literature screening, quality assessment of the included trials and data extraction. The outcomes included intraoperative brain relaxation, intraoperative ICP, total volume of fluid required, diuresis, hemodynamic parameters, electrolyte level, mortality or dependence and adverse events.

Results

Seven RCTs with 468 participants were included. The quality of the included trials was acceptable. HS could significantly increase the odds of satisfactory intraoperative brain relaxation (OR: 2.25, 95% CI: 1.32–3.81; P = 0.003) and decrease the mean difference (MD) of maximal ICP (MD: −2.51mmHg, 95% CI: −3.39—1.93mmHg; P<0.00001) in comparison with mannitol with no significant heterogeneity among the study results. Compared with HS, mannitol had a more prominent diuretic effect. And patients treated with HS had significantly higher serum sodium than mannitol-treated patients.

Conclusions

Considering that robust outcome measures are absent because brain relaxation and ICP can be influenced by several factors except for the hyperosmotic agents, the results of present meta-analysis should be interpreted with cautions. Well-designed RCTs in the future are needed to further test the present results, identify the impact of HS on the clinically relevant outcomes and explore the potential mechanisms of HS.

Principles of neuroanesthesia in aneurysmal subarachnoid hemorrhage

Aneurysmal subarachnoid hemorrhage is associated with high mortality. Understanding of the underlying pathophysiology is important as early intervention can improve outcome. Increasing age, altered sensorium and poor Hunt and Hess grade are independent predictors of adverse outcome. Early operative interventions imposes an onus on anesthesiologists to provide brain relaxation. Coiling and clipping are the two treatment options with increasing trends toward coiling. Intraoperatively, tight control of blood pressure and adequate brain relaxation is desirable, so that accidental aneurysm rupture can be averted. Patients with poor grades tolerate higher blood pressures, but are prone to ischemia whereas patients with lower grades tolerate lower blood pressure, but are prone to aneurysm rupture if blood pressure increases. Patients with Hunt and Hess Grade I or II with uneventful intraoperative course are extubated in operation theater, whereas, higher grades are kept electively ventilated. Postoperative management includes attention toward fluid status and early management of vasospasm.

[Awake craniotomy. Considerations in special situations]

Awake craniotomy was the earliest surgical procedure known, and it has become fashionable again. In the past it was used for the surgical management of intractable epilepsy, but nowadays, its indications are increasing, and it is a widely recognized technique for the resection of mass lesions involving the eloquent cortex, and for deep brain stimulation. The procedure is safe, provides excellent results, and saves money and resources. The anesthesiologist should know the principles underlying neuroanesthesia, the technique of scalp blockade, and the sedation protocols, as well as feeling comfortable with advanced airway management. The main anesthetic aim is to keep patients cooperating when required (analgesia-based anesthesia). This review attempts to summarize the most recent evidence from the clinical literature, a long as the number of patients undergoing craniotomies in the awake state are increasing, specifically in the pediatric population.

Intermittent general anesthesia with controlled ventilation for asleep-awake-asleep brain surgery: a prospective series of 140 gliomas in eloquent areas

BACKGROUND

Awake brain tumor surgery is a unique opportunity for mapping sensorimotor and cognitive functions, allowing the operator to optimize the resection while preserving the patient's quality of life. During this type of procedure, active participation of the patient is necessary.

OBJECTIVE

To assess the efficacy and safety of a method of intermittent general anesthesia with controlled ventilation for performing invasive cerebral mapping.

METHODS

We report our prospective and observational single-center study with an asleep-awake-asleep protocol. Aspects of feasibility, airway management, timing of each phase, and occurrence of adverse events were detailed.

RESULTS

During a 35-month period, 140 patients underwent resection of a glioma in an eloquent area. During the asleep phases, controlled ventilation with a laryngeal mask was always efficient. Orotracheal intubation was performed for some patients for the second asleep period. The patients remained fully awake for a mean time of 98 minutes. Postural discomfort was reported in 17.8% of cases. There was 1 case of aspiration of gastric contents with a favorable outcome and no mortality.

CONCLUSION

Intermittent general anesthesia with controlled ventilation for this type of neurosurgical procedure remains an anesthesiological challenge. However, the results of this study suggest that it may be feasible, reproducible, and relatively safe in the context of a standardized protocol involving members of both anesthesiology and surgery teams. Such a technique has a great potential to improve the surgical results, from both oncological and functional perspectives.

An optofluidic mechanical system for elasticity measurement of thin biological tissues

As dura mater has an anisotropic fibrous structure and exists under wet and dynamic stretching conditions in the brain, its mechanical properties have not yet been properly investigated. Here we developed a fluid-assisted mechanical system integrated with a photonic sensor and a pressure sensor in order to measure the elasticity of the dura mater. Porcine dura mater sample was loaded as a stretched diaphragm into a liquid chamber to mimic the in vivo condition. Increasing the flow rate of saline solution into the chamber swelled and deformed the dura mater. The micron-scale deflection of the dura mater was optically detected by the photonic sensor. Fluid pressure and deflection values were then used to calculate the elastic modulus. The average elastic modulus of the porcine dura mater was 31.14 MPa. We further measured the elasticity of a well-known material to further validate the system. We expect that this optofluidic system developed in this study will be useful to measure the elasticity of a variety of thin biological tissues.

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.

A multicentre, randomised, open-label, controlled trial evaluating equivalence of inhalational and intravenous anaesthesia during elective craniotomy

CONTEXT

A clear preference for intravenous or inhalational anaesthesia has not been established for craniotomy in patients without signs of cerebral hypertension.

OBJECTIVES

The NeuroMorfeo trial was designed to test equivalence of inhalational and intravenous anaesthesia maintenance techniques in the postoperative recovery of patients undergoing elective supratentorial surgery.

DESIGN

This trial is a multicentre, randomised, open-label, equivalence design. A balanced stratified randomisation scheme was maintained using a centralised randomisation service. Equivalence was tested using the two one-sided tests procedure.

SETTING

Fourteen Italian neuroanaesthesia centres participated in the study from December 2007 to March 2009.

PATIENTS

Adults, 18 to 75 years old, scheduled for elective supratentorial intracranial surgery under general anaesthesia were eligible for enrolment if they had a normal preoperative level of consciousness and no clinical signs of intracranial hypertension.

INTERVENTIONS

Patients were randomised to one of three anaesthesia maintenance protocols to determine if sevoflurane-remifentanil or sevoflurane-fentanyl were equivalent to propofol-remifentanil.

MAIN OUTCOME MEASURES

The primary outcome was the time to achieve an Aldrete postanaesthesia score of at least 9 after tracheal extubation. Secondary endpoints included haemodynamic parameters, quality of the surgical field, perioperative neuroendocrine stress responses and routine postoperative assessments.

RESULTS

Four hundred and eleven patients [51% men, mean age 54.8 (SD 13.3) years] were enrolled. Primary outcome data were available for 380. Median (interquartiles) times to reach an Aldrete score of at least 9 were 3.48 (2.02 to 7.56), 3.25 (1.21 to 6.45) and 3.32  min (1.40 to 8.33) for sevoflurane-fentanyl, sevoflurane-remifentanil and propofol-remifentanil anaesthesia respectively, which confirmed equivalence using the two one-sided tests approach. Between-treatment differences in haemodynamic variables were small and not clinically relevant. Urinary catecholamine and cortisol responses had significantly lower activation with propofol-remifentanil. Postoperative pain and analgesic requirements were significantly higher in the remifentanil groups.

CONCLUSION

Equivalence was shown for inhalational and intravenous maintenance anaesthesia in times to reach an Aldrete score of at least 9 after tracheal extubation. Haemodynamic variables, the quality of surgical field and postoperative assessments were also similar. Perioperative endocrine stress responses were significantly blunted with propofol-remifentanil and higher analgesic requirements were recorded in the remifentanil groups.

TRIAL REGISTRATION

Eudract 2007-005279-32.

'Anesthesia' for awake neurosurgery

PURPOSE OF REVIEW

In this review we focus on recent findings in the anesthetic management of patients undergoing craniotomy while awake, and propose a structured approach to the clinical practice of 'anesthesia' for awake neurosurgery.

RECENT FINDINGS

The increasing use of functional neurosurgery and recent evidence favoring resection of tumor involving eloquent cortex has expanded the indications for awake craniotomy, a procedure needing a fully cooperative patient and expert intraoperative anesthetic management. Despite the shorter hospital stay, the more recently published studies have highlighted perioperative anesthetic complications and have proposed ways to improve anesthesia techniques for awake procedures in adults and children.

SUMMARY

Although anesthesia for awake craniotomy is usually a well tolerated procedure it requires an extensive knowledge of the principles underlying neuroanesthesia and of specific technical strategies including local anesthesia for scalp blockade, advanced airway management, dedicated sedation protocols, and skillful management of hemodynamics.

Parkinson's disease and deep brain stimulator placement

Deep brain stimulation (DBS) has added to the comfort and quality of life for an increasing number of Parkinson's disease (PD) patients. The anesthesiologist needs to understand the pathophysiology of the disease, the surgical procedure, and its postoperative implications to most effectively manage these patients. This article examines the role of the anesthesiologist in the pre- and perioperative management of patients undergoing DBS procedures. In terms of the general anesthetic management of PD patients, it is clear that no simple anesthetic regimen exists. Anesthesiologists can provide the best care through preoperative assessment, maintenance of PD drug therapy, and avoidance of known precipitating agents.

Anaesthesiological strategies in elective craniotomy: randomized, equivalence, open trial--the NeuroMorfeo trial

BACKGROUND

Many studies have attempted to determine the "best" anaesthetic technique for neurosurgical procedures in patients without intracranial hypertension. So far, no study comparing intravenous (IA) with volatile-based neuroanaesthesia (VA) has been able to demonstrate major outcome differences nor a superiority of one of the two strategies in patients undergoing elective supratentorial neurosurgery. Therefore, current practice varies and includes the use of either volatile or intravenous anaesthetics in addition to narcotics. Actually the choice of the anaesthesiological strategy depends only on the anaesthetists' preferences or institutional policies. This trial, named NeuroMorfeo, aims to assess the equivalence between volatile and intravenous anaesthetics for neurosurgical procedures.

METHODS/DESIGN

NeuroMorfeo is a multicenter, randomized, open label, controlled trial, based on an equivalence design. Patients aged between 18 and 75 years, scheduled for elective craniotomy for supratentorial lesion without signs of intracranial hypertension, in good physical state (ASA I-III) and Glasgow Coma Scale (GCS) equal to 15, are randomly assigned to one of three anaesthesiological strategies (two VA arms, sevoflurane + fentanyl or sevoflurane + remifentanil, and one IA, propofol + remifentanil). The equivalence between intravenous and volatile-based neuroanaesthesia will be evaluated by comparing the intervals required to reach, after anaesthesia discontinuation, a modified Aldrete score > or = 9 (primary end-point). Two statistical comparisons have been planned: 1) sevoflurane + fentanyl vs. propofol + remifentanil; 2) sevoflurane + remifentanil vs. propofol + remifentanil. Secondary end-points include: an assessment of neurovegetative stress based on (a) measurement of urinary catecholamines and plasma and urinary cortisol and (b) estimate of sympathetic/parasympathetic balance by power spectrum analyses of electrocardiographic tracings recorded during anaesthesia; intraoperative adverse events; evaluation of surgical field; postoperative adverse events; patient's satisfaction and analysis of costs. 411 patients will be recruited in 14 Italian centers during an 18-month period.

DISCUSSION

We presented the development phase of this anaesthesiological on-going trial. The recruitment started December 4th, 2007 and up to 4th, December 2008, 314 patients have been enrolled.