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Burst-suppression is an electroencephalographic pattern that results from a diverse array of pathophysiological causes and/or metabolic neuronal suppression secondary to the administration of anesthetic medications. The purpose of this review is to provide an overview of the physiological mechanisms that underlie the burst-suppression pattern and to present in a comprehensive way the available evidence both supporting and in opposition to the clinical use of this electroencephalographic pattern as a therapeutic measure in various perioperative settings.

Defining optimal hemodynamic targets for brain-injured patients is a challenging undertaking. The physiological interference observed in various intracranial pathologies can have varying effects on cerebral physiology at different time points. This narrative review provides an overview of cerebral autoregulatory physiology and common misconceptions, and examines the physiological considerations and clinical evidence for determining optimal hemodynamic parameters in acutely brain-injured patients with relevance to modern neuroanesthesia and neurocritical care practice.

Background The COVID-19 pandemic is an international crisis placing tremendous strain on medical systems around the world. Like other specialties, neuroanesthesiology has been adversely affected and training programs have had to quickly adapt to the constantly changing environment. Methods An email-based survey was used to evaluate the effects of the pandemic on clinical workflow, clinical training, education, and trainee well-being. The impact of the International Council on Perioperative Neuroscience Training (ICPNT) accreditation was also assessed. Results Responses were received from 14 program directors (88% response rate) in 10 countries and from 36 fellows in these programs. Clinical training was adversely affected because of the cancellation of elective neurosurgery and other changes in case workflow, the introduction of modified airway and other protocols, and redeployment of trainees to other sites. To address educational demands, most programs utilized online platforms to organize clinical discussions, journal clubs, and provide safety training modules. Several initiatives were introduced to support trainee well-being during the pandemic. Feelings of isolation and despair among trainees varied from 2 to 8 (on a scale of 1 to 10). Fellows all reported concerns that their clinical training had been adversely affected by the coronavirus disease 2019 (COVID-19) pandemic because of decreased exposure to elective subspecialty cases and limited opportunities to complete workplace-based assessments and training portfolio requirements. Cancellation of examination preparation courses and delayed examinations were cited as common sources of stress. Programs accredited by the ICPNT reported that international networking and collaboration was beneficial to reduce feelings of isolation during the pandemic. Conclusion Neuroanesthesia fellowship training program directors introduced innovative ways to maintain clinical training, educational activity and trainee well-being during the COVID-19 pandemic.

Administration of rocuronium to facilitate intubation has traditionally been regarded as acceptable for intraoperative motor evoked potential (MEP) monitoring because of sufficiently rapid spontaneous neuromuscular blockade recovery. We hypothesized that residual neuromuscular blockade, in an amount that could hinder optimal neuromonitoring in patients undergoing intracranial aneurysm clipping, was still present at dural opening. We sought to identify how often this was occurring and to identify factors which may contribute to prolonged blockade. Records of 97 patients were retrospectively analyzed. Rocuronium was administered to facilitate intubation with no additional neuromuscular blockade given. Prolonged spontaneous recovery time to a train-of-four (TOF) ratio of 0.75 after rocuronium administration was defined as 120 min, which was approximately when dural opening and the setting of baseline MEPs were occurring. Logistic regression analysis was used to identify factors related to prolonged spontaneous recovery time. Prolonged spontaneous recovery time to a TOF ratio of 0.75 was observed in 44.3% of patients. Multivariable analysis showed that only the dosage of rocuronium based on ideal body weight had a positive correlation with prolonged spontaneous recovery time (P = 0.01). There was no significant association between dosage of rocuronium based on total body weight, age, sex, or body temperature and prolonged recovery time. This study demonstrates that the duration of relaxation for MEP monitoring purposes is well-beyond the routinely recognized clinical duration of rocuronium. Residual neuromuscular blockade could result in lower amplitude MEP signals and/or lead to higher required MEP stimulus intensities which can both compromise monitoring sensitivity.

The α2-adrenergic receptor agonist dexmedetomidine has sedative, anxiolytic, analgesic, and sympatholytic effects. The potential advantages of neuroprotection, minimal impact on neuronal function, stable hemodynamics, opioid and anesthesia sparing effects, and minimal respiratory depression during awake procedures render it an effective anesthetic adjuvant in various neurosurgical settings. However, both the benefits and drawbacks of the use dexmedetomidine in neuroanesthesia should be considered. This narrative review will summarize the applications of dexmedetomidine in various neurosurgical settings, highlighting evidence regarding both its common and controversial uses.

Intraoperative neurophysiologic monitoring (IONM) includes various neurophysiologic tests which assess the functional integrity of the central and peripheral nervous systems during surgical procedures which place these structures at risk for iatrogenic injury. The rational for using IONM is to provide timely feedback of changes in neural function to enable the reversal of such insult before the development of irreversible neural injury. There are various causes of intraoperative loss of neuromonitoring signals and it is important to systematically rule out all possible causes quickly and thoroughly in order to target the cause of signal loss, correct it and take measures to prevent the same in the future. One such rare cause, is targeted and pressurized cold (room temperature) irrigation of the surgical site, which may induce irritation and vasospasm leading to ischemia of the affected portion of the spinal cord, hence leading to signal changes. We present this case to stress the importance of having knowledgeable members of the team who are well acquainted with all aspects of monitoring in close proximity to the operating room, so as to minimize troubleshooting time. Furthermore, we suggest the use of warm (body temperature) saline during irrigation to the surgical site, especially when using pressurized irrigation systems.

2016 Background: The blood-brain barrier (BBB) is a major impediment to pharmacological treatment of gliomas, a diffuse tumor infiltrating the peri-tumoral normal brain. Low-intensity pulsed ultrasound directed at the brain with concomitant administration of intravenous microbubbles (LIPU/MB), temporarily opens the BBB. This technique was previously shown with a first generation of the device in combination with carboplatin chemotherapy (Idbaih et al. 2019). Here we investigate the pharmacokinetics and safety of this approach in the context of repeated delivery of albumin-bound paclitaxel (ABX) to the peri-tumoral brain. To perform LIPU/MB-based BBB opening prior to ABX infusions, we used a novel 6 x 6 cm device with 9 ultrasound emitters (SC9) that is implanted in a skull window after tumor resection. Methods: A Phase 1 dose-escalation trial using Bayesian adaptive design was initiated at our institution (NCT04528680). Patients with recurrent operable glioblastoma, a WHO PS ≤ 2 and normal bone marrow and organ function were eligible. After tumor resection and implantation of SC9, repeated cycles of BBB opening by LIPU/MB immediately followed by ABX, was performed every 3 weeks. Intraoperative LIPU/MB and low dose ABX was given prior to tumor resection for investigation of pharmacokinetics. Results: Seventeen patients have been enrolled and six dose levels of ABX were used (40-260 mg/m2). Severe, reversible taxane-associated encephalopathy was observed in one patient at the max. planned dose level (260 mg/m2). The patient continued treatment at a lower dose in subsequent cycles. One patient developed grade 2 cumulative peripheral neuropathy. Other mild to moderate and reversible toxicities for ABX including myelosuppression, fatigue, alopecia were observed as expected. Intraoperative sonication and pharmacokinetic studies showed that ABX tissue concentrations in non-enhancing peri-tumoral brain were increased several-fold after LIPU/MB. On electron microscopy, sonicated tissue showed ultra-structural alterations in brain capillary endothelial cells. Molecular studies showed transcriptional dysregulation of membrane transporters, pathways related to trans-cytosis, cell permeability as well as cell-cell and cell-matrix adhesion. Updated results will be presented. Conclusions: The LIPU/MB using skull-implantable ultrasound enhances the penetration of large chemotherapeutic drugs such as ABX in large regions of the brain, a procedure that can be performed repeatedly and safely. LIPU-based BBB opening leads to ultrastructural and transcriptional alterations in brain endothelial cells. A Phase 2 clinical trial is planned to investigate efficacy of this approach. Funding: NIH/NCI 1R01CA245969-01A1, Carthera (SC9 devices), Celgene/BMS, Malnati Brain Tumor Institute, Moceri Family Foundation. Clinical trial information: NCT04528680.

Neurological complications of cardiac surgery have a large impact on patient morbidity and mortality. Clinicians have relied on several modes of monitoring of the central nervous system as a means for reducing the risk of these complications including the electroencephalogram. While electroencephalogram changes are specific for cerebral ischemia, the reliability is tempered by many confounding factors. The effectiveness of the processed electroencephalogram for ensuring amnesia during surgery is controversial but it may have value for minimizing anesthetic dose as a strategy to reduce the frequency of postoperative delirium. Somatosensory and motor evoked potential provide critical information about the continuity of the central nervous system particularly of value for surgery where spinal cord blood supply is compromised. Transcranial Doppler (TCD) can be used for confirming cerebral blood flow during aortic arch surgery and in detecting cerebral emboli. Measuring the sufficiency of cerebral oxygen supply versus metabolic demand can be monitored with jugular bulb venous oxygen saturation or near infrared spectroscopy (NIRS) monitoring. The latter is achieved using sensors placed on the forehead and, is thus, technically easier than the former. There is growing evidence for the use of cerebral autoregulation monitoring to individualize blood pressure during and after surgery. This can be performed using TCD but this method is technically challenging. The results of laboratory and clinical studies suggests that NIRS measured regional cerebral oxygen saturation can provide an acceptable surrogate of cerebral blood flow for autoregulation monitoring. A growing body of evidence using NIRS-based autoregulation monitoring supports its further development and clinical implementation as an approach for ensuring organ perfusion during cardiac surgery.

Defining optimal hemodynamic targets for brain-injured patients is a challenging undertaking. The physiological interference observed in various intracranial pathologies can have varying effects on cerebral physiology at different time points. This narrative review provides an overview of cerebral autoregulatory physiology and common misconceptions, and examines the physiological considerations and clinical evidence for determining optimal hemodynamic parameters in acutely brain-injured patients with relevance to modern neuroanesthesia and neurocritical care practice.

Administration of rocuronium to facilitate intubation has traditionally been regarded as acceptable for intraoperative motor evoked potential (MEP) monitoring because of sufficiently rapid spontaneous neuromuscular blockade recovery. We hypothesized that residual neuromuscular blockade, in an amount that could hinder optimal neuromonitoring in patients undergoing intracranial aneurysm clipping, was still present at dural opening. We sought to identify how often this was occurring and to identify factors which may contribute to prolonged blockade. Records of 97 patients were retrospectively analyzed. Rocuronium was administered to facilitate intubation with no additional neuromuscular blockade given. Prolonged spontaneous recovery time to a train-of-four (TOF) ratio of 0.75 after rocuronium administration was defined as 120 min, which was approximately when dural opening and the setting of baseline MEPs were occurring. Logistic regression analysis was used to identify factors related to prolonged spontaneous recovery time. Prolonged spontaneous recovery time to a TOF ratio of 0.75 was observed in 44.3% of patients. Multivariable analysis showed that only the dosage of rocuronium based on ideal body weight had a positive correlation with prolonged spontaneous recovery time (P = 0.01). There was no significant association between dosage of rocuronium based on total body weight, age, sex, or body temperature and prolonged recovery time. This study demonstrates that the duration of relaxation for MEP monitoring purposes is well-beyond the routinely recognized clinical duration of rocuronium. Residual neuromuscular blockade could result in lower amplitude MEP signals and/or lead to higher required MEP stimulus intensities which can both compromise monitoring sensitivity.

Background Multilevel spine fusion surgery for adult deformity correction is associated with significant blood loss and coagulopathy. Tranexamic acid reduces blood loss in high-risk surgery, but the efficacy of a low-dose regimen is unknown. Methods Sixty-one patients undergoing multilevel complex spinal fusion with and without osteotomies were randomly assigned to receive low-dose tranexamic acid (10 mg/kg loading dose, then 1 mg·kg−1·hr−1 throughout surgery) or placebo. The primary outcome was the total volume of red blood cells transfused intraoperatively. Results Thirty-one patients received tranexamic acid, and 30 patients received placebo. Patient demographics, risk of major transfusion, preoperative hemoglobin, and surgical risk of the 2 groups were similar. There was a significant decrease in total volume of red blood cells transfused (placebo group median 1460 mL vs. tranexamic acid group 1140 mL; median difference 463 mL, 95% confidence interval 15 to 914 mL, P = 0.034), with a decrease in cell saver transfusion (placebo group median 490 mL vs. tranexamic acid group 256 mL; median difference 166 mL, 95% confidence interval 0 to 368 mL, P = 0.042). The decrease in packed red blood cell transfusion did not reach statistical significance (placebo group median 1050 mL vs. tranexamic acid group 600 mL; median difference 300 mL, 95% confidence interval 0 to 600 mL, P = 0.097). Conclusions Our results support the use of low-dose tranexamic acid during complex multilevel spine fusion surgery to decrease total red blood cell transfusion.

Human albumin has been used extensively for decades as a nonwhole blood plasma replacement fluid in the perioperative and critical care setting. Its potential advantages as a highly effective volume expander must be weighed, however, against its potential harm for patients in the context of various neurological states and for various neurosurgical interventions. This narrative review explores the physiological considerations of intravenous human albumin as a replacement fluid and examines the extant clinical evidence for and against its use within the various facets of modern neuroanesthesia and neurocritical care practice.

BackgroundPatients with intracranial tumors are more sensitive to anesthetics than the general population and are therefore more susceptible to postoperative neurologic and neurocognitive dysfunction. Sevoflurane or propofol combined with remifentanil are widely used general anesthetic regimens for craniotomy, with neither regimen shown to be superior to the other in terms of neuroprotective efficacy and anesthesia quality. There is no evidence regarding the variable effects on postoperative neurologic and neurocognitive functional outcome under these two general anesthetic regimens. This trial will compare inhalational sevoflurane or intravenous propofol combined with remifentanil anesthesia in patients with supratentorial gliomas and test the hypothesis that postoperative neurologic function is equally affected between the two regimens.MethodsThis is a prospective, single-center, randomized parallel arm equivalent clinical trial, which is approved by China Ethics Committee of Registering Clinical Trials (ChiECRCT-20,160,051). Patients with supratentorial gliomas diagnosed by magnetic resonance imaging will be eligible for the trial. Written informed consent will be obtained before randomly assigning each subject to either the sevoflurane-remifentanil or propofol-remifentanil group for anesthesia maintenance to achieve an equal-desired depth of anesthesia. Intraoperative intervention and monitoring will follow a standard anesthetic management protocol. All of the physiological parameters and other medications administered during the intervention will be recorded. The primary outcome will be neurologic function change assessed by National Institute of Health Stroke Scale (NIHSS) within 4 h after general anesthesia when observer’s assessment of alertness/sedation (OAA/S) reaches 4. Secondary outcomes will include NIHSS and modified NIHSS change 1 and 2 days after general anesthesia, hemodynamic stability, intraoperative brain relaxation, quality of anesthesia emergence, quality of anesthesia recovery, postoperative cognitive function, postoperative pain, postoperative neurologic complications, as well as perioperative medical expense.DiscussionThis randomized equivalency trial will primarily compare the impacts of sevoflurane-remifentanil and propofol-remifentanil anesthesia on short-term postoperative neurologic function in patients with supratentorial gliomas undergoing craniotomy. The exclusion criteria are strict to ensure that the groups are comparable in all aspects. Repeated and routine neurologic evaluations after operation are always important to evaluate neurosurgical patients’ recovery and any newly presenting complications. The results of this trial would help specifically to interpret anesthetic residual effects on postoperative outcomes, and perhaps would help the anesthesiologist to select the optimal anesthetic regimen to minimize its impact on neurologic function in this specific patient population.Trial registrationThe study was registered and approved by the Chinese Clinical Trial Registry (Chinese Clinical Trial Registry,ChiCTR-IOR-16009177). Principle investigator: Nan Lin (email address: linnan127@gmail.com) and Ruquan Han (email address: hanrq666@aliyun.com) Date of Registration: September 8th, 2016. Country of recruitment: China.

Cognitive aids and evidence-based checklists are frequently utilized in complex situations across many disciplines and sectors. The purpose of such aids is not simply to provide instruction so as to fulfill a task, but rather to ensure that all contingencies related to the emergency are considered and accounted for and that the task at hand is completed fully, despite possible distractions. Furthermore, utilization of a checklist enhances communication to all team members by allowing all stakeholders to know and understand exactly what is occurring, what has been accomplished, and what remains to be done. Here we present a set of evidence-based critical event cognitive aids for neuroanesthesia emergencies developed by the Society for Neuroscience in Anesthesiology and Critical Care (SNACC) Education Committee.

Neurological complications of cardiac surgery have a large effect on patient outcomes. In this review, the value of several modes of central nervous system monitoring for improving perioperative care is critiqued. The electroencephalogram (EEG) has been used as a means for detecting brain ischemia. Even though EEG changes are specific for ischemia, the reliability is tempered by many confounding factors. The effectiveness of the processed EEG for ensuring amnesia during surgery is controversial, but it may have value for optimizing anesthetic dose and thus reducing the risk for delirium. Transcranial Doppler may be beneficial in confirming flow to both cerebral hemispheres during antegrade cerebral perfusion such as during aortic arch surgery and in detecting cerebral emboli. Transcranial Doppler can be used for monitoring cerebral autoregulation, allowing for individualization of blood pressure targets during surgery. Measures of adequacy of cerebral oxygen balance include jugular bulb venous oxygen saturation and near-infrared spectroscopy monitoring. Both monitors have limitations that reduce the sensitivity for detecting brain ischemia. Because near-infrared spectroscopy-measured regional cerebral oxygen saturation does not distinguish arterial from venous blood, these measurements reflect the adequacy of oxygen delivery versus demand. Over short periods, filtered regional cerebral oxygen saturation data may provide a clinically feasible method of monitoring cerebral autoregulation that overcomes many limitations of transcranial Doppler. Ongoing studies have demonstrated that the latter methodology for determining perioperative blood pressure targets has large potential for reducing organ injury from cardiac surgery.

An anterior cervical discectomy and fusion (ACDF) is a routinely performed surgery whose purpose is to relieve spinal stenosis, remove intervertebral disk and bony matter which may be impinging upon neural elements, and also to mechanically stabilize the cervical spine after such material is removed. The safety of an ACDF for patients with cervical radiculopathy, with or without neurophysiologic monitoring, is extremely high, with very low rates of temporary or permanent neurologic sequelae. The most frequently used modalities of neurophysiologic monitoring in these cases are somatosensory-evoked potentials (SSEPs), spontaneous electromyography (EMG), and transcranial motor-evoked potentials (MEPs).

Background: Surgery for posterior spine instrumentation often requires major transfusion. The aim of this study was to develop and test the validity of a model for predicting intraoperative major transfusion (>4 U total red blood cells), based on preoperative patient and surgical variables, that was applicable to adult patients undergoing cervical, thoracic, and/or lumbar spine deformity surgery with and without osteotomies. Materials and Methods: The perioperative data from 548 patients who underwent ≥3 levels of posterior spinal fusion with instrumentation between January 1, 2003 and May 30, 2009, were retrospectively collected to create a model for predicting major blood transfusion. The validity of the model was retrospectively tested with a separate data set of 95 patients who underwent surgery from June 1, 2009 through September 30, 2010. Results: There was a 59.5% incidence of major transfusion in the derivation set of patients. Independent predictors of major transfusion were operation duration, number of posterior levels instrumented, surgical complexity score, and preincision hemoglobin. This model was able to predict major transfusion significantly better than a previously published model (ROCAUC=0.89; 99% confidence interval, 0.80-0.90; P Conclusions: Our model has an increased accuracy for predicting the probability of major transfusion compared with a previously published model. In addition, our model is applicable to all types of spine fusion surgery and accounts for the complexity of surgical instrumentation, the number of levels instrumented, and the predicted duration of surgery as independent variables.

When temporary arterial occlusion of the parent artery is difficult for anatomical reasons, or when inadvertent aneurysmal rupture occurs during surgical dissection, adenosine administration can be used to produce flow arrest and brief, profound systemic hypotension that can facilitate intracranial aneurysm clip ligation. There is a concern, however, that the flow arrest and profound hypotension produced by adenosine, although brief, may cause cerebral ischemia and therefore worsen neurologic outcome compared with other techniques to facilitate aneurysm clip ligation. Therefore, we performed a retrospective, case-control study to determine whether adenosine-induced flow arrest had negative effects on the neurologic outcome of our patients.We reviewed the perioperative records of all patients in our intracranial aneurysm surgery outcomes database between August 1, 2006, and June 15, 2012. The primary outcome was the presence or absence of a poor neurologic outcome 48 hours after surgery, with a modified Rankin scale score2 being defined as a poor neurologic outcome. The neurologic outcome at the time of hospital discharge was a secondary outcome. Secondary outcomes related to cardiac morbidity included atrial or ventricular arrhythmia requiring treatment and elevated cardiac biomarkers consistent with ischemia (i.e., Troponin-I).During the study period, adenosine-induced flow arrest was used in 72 of the 413 patients (17.4%) who underwent intracranial aneurysm clip ligation. The difference in the incidence of poor neurological outcome, with or without the use of adenosine, was no larger than 15.7% at 48 hours after surgery (P =0.524) or -12.7% at discharge (P = 0.741). In addition, the difference in the incidence of cardiac morbidity was no larger than -16.0% for persistent arrhythmia (P = 0.155) or -9.4% for biomarkers of myocardial ischemia (P = 0.898) in the initial 48 hours after surgery.When used to facilitate intracranial aneurysm clip ligation, adenosine-induced flow arrest was associated with no more than a 15.7% increase or a 12.7% decrease in the incidence of a poor neurologic outcome at either 48 hours or at the time of hospital discharge. In addition, adenosine use was not associated with cardiac morbidity in the perioperative period (i.e., persistent arrhythmia or biomarkers of cardiac ischemia).

BACKGROUND Mannitol is often used during intracranial surgery to improve surgical exposure. Furosemide is often added to mannitol to augment this effect. The concern exists, however, that the augmented diuresis caused by the addition of furosemide to mannitol may cause hypovolemia and hypoperfusion, hypokalemia, and hyponatremia. We examined the intraoperative safety of low-dose furosemide (0.3 mg/kg) combined with mannitol (1 g/kg). METHODS We observed 23 patients in a double-blind, block randomized, placebo-controlled study to examine the effects of furosemide (0.3 mg/kg) when combined with mannitol (1 g/kg) on surgical brain relaxation for tumor surgery. Mannitol and the study drug (furosemide or placebo) were administered, and arterial blood gases with electrolytes (sodium, potassium, and lactic acid) and urine output volume were recorded every 30 minutes for 3 hours. Plasma sodium, potassium, and lactic acid concentrations, and interval urine outputs, were compared across time and between furosemide-placebo assignment groupings, with a P

Residual neuromuscular blockade after general anesthesia using nondepolarizing neuromuscular blocking agents has pathophysiological, clinical, and economic consequences. A significant number of patients under muscle relaxation sustain residual curarization.Observational, prospective, multicenter study of a cohort of patients (Residual Curarization in Spain Study, ReCuSS). Residual blockade was defined as TOFr0.9. Patients18 years-old under general anesthesia, including at least one dose of non-depolarizing neuromuscular blocking agents, and transferred extubated and spontaneously ventilating to the postanesthesia care unit were included. Pre- and intraoperative data were recorded, including, patient characteristics, ASA physical status, experience of the anesthesiologist, type of surgery, temperature monitoring, surgery duration, neuromuscular blockade-related parameters, type of anesthesia (halogenated-balanced, intravenous propofol-based, other), and use of neuromuscular monitoring.A total of 763 patients from 26 hospitals were included, 190 patients (26.7%) showing residual paralysis. Female patients were more prone to residual neuromuscular blockade. Length of surgery, type of relaxant used (benzylisoquinolines), halogenated anesthesia, absence of intraoperative specific monitoring, avoidance of drug reversal, and neostigmine reversal (vs. sugammadex), were significantly related to residual blockade. In the postanesthesia care unit, patients with residual neuromuscular blockade had an increased incidence of respiratory events and tracheal reintubation.The incidence of residual blockade in Spain is similar to that published in other settings and countries. Female gender, longer duration of surgery, and halogenated drugs for anesthesia maintenance were related to residual paralysis, as were NMBA specific items, such as the use of benzylisoquinoline drugs, and the absence of reversal or reversal with neostigmine.

The purpose of this study was to identify risk factors associated with intraoperative blood transfusions in patients presenting for intracranial aneurysm surgery in the current era of more restrictive transfusion guidelines.Retrospective observational cohort study with stepwise, multivariate binary logistic regression analysis.Tertiary care university teaching hospital.Four hundred seventy-one consecutive patients undergoing intracranial aneurysm surgery at Northwestern Memorial Hospital (Chicago, IL) from 2006 to 2012.Red blood cell transfusion (retrospective observational).Demographic data, medical comorbidities, hemoglobin levels, Hunt-Hess grades, intracranial aneurysm characteristics, presenting intracranial bleeding states, estimated blood losses, transfused red blood cells, and blood products.Forty-six patients (9.5%) received intraoperative red blood cell transfusions. Preoperative risk factors associated with transfusions were highly related to aneurysm rupture, including such parameters as older age (P.001), lower presenting hemoglobin level (P.001), preoperative rupture (P.001), and higher Hunt-Hess grade (P.001). Intraoperative risk factors included larger aneurysm size (10 mm; P = .03), intraventricular hemorrhage (P.001), and intracerebral hematoma evacuation (P = .02). Binary logistic regression modeling identified age (P.001), presenting hemoglobin level (P.001), larger aneurysm size (10 mm; P = .003), elevated Hunt-Hess grade (P = .021), and intraoperative rupture (P = .013) as independent predictors of intraoperative red blood cell transfusion.The incidence of intraoperative red blood cell transfusion in intracranial aneurysm surgery in our patient cohort was 9.5%, and the most significant factors associated with transfusion were presenting hemoglobin level less than 11.7 g/dL and age greater than 52 years. It would seem advisable that these patients undergo routine type and cross-matching of red blood cells before intracranial aneurysm surgery.

There has been a renewed interest in the recent literature regarding the proposed benefits of systemic steroids in the perioperative period. Among these benefits are the relief of postoperative pain, the decrease in postoperative nausea, and a higher overall multiparameter quality of recovery. Perioperative steroids, however, are not without their potential drawbacks, including decreased immune function, hyperglycemia, and impaired wound healing. The use of perioperative steroids for brain tumor treatment and resection has been a component of therapy for approximately 50 years, owing primarily to their well-described, although poorly understood, effect in minimizing vasogenic peritumoral edema, and therefore intracranial pressure. This review seeks to highlight the history, mechanisms, therapeutic efficacy, and side effects of steroid use for brain tumors in the perioperative period.

BACKGROUND Clip application for temporary occlusion is not always practical or feasible. Adenosine is an alternative that provides brief periods of flow arrest that can be used to advantage in aneurysm surgery, but little has been published on its utility for this indication. OBJECTIVE To report our 2-year consecutive experience with 40 aneurysms in 40 patients for whom we used adenosine to achieve temporary arterial occlusion during aneurysm surgery. METHODS We retrospectively reviewed our clinical database between May 2007 and December 2009. All patients who underwent microsurgical clipping of intracranial aneurysms under adenosine-induced asystole were included. Aneurysm characteristics, reasons for adenosine use, postoperative angiographic and clinical outcome, cardiac complications, and long-term neurological follow-up with the modified Rankin Scale were noted. RESULTS Adenosine was used for 40 aneurysms (10 ruptured, 30 unruptured). The most common indications for adenosine were aneurysm softening in 17 cases and paraclinoid location in 14 cases, followed by broad neck in 12 cases and intraoperative rupture in 6 cases. Troponins were elevated postoperatively in 2 patients. Echocardiography did not show acute changes in either. Clinically insignificant cardiac arrhythmias were noted in 5 patients. Thirty-six patients were available for follow-up. Mean follow-up was 12.8 months. The modified Rankin Scale score was 0 for 29 patients at the time of the last follow-up. Four patients had an modified Rankin Scale score of 1, and scores of 2 and 3 were found in 2 and 1 patients, respectively. CONCLUSION Adenosine appears to allow safe flow arrest during intracranial aneurysm surgery. This can enhance the feasibility and safety of clipping in select circumstances.

Background. The varying point at which the spinal cord terminates in the lumbar spinal canal may affect the incidence of spinal cord injuries associated with needle insertion for spinal anaesthesia, especially in patients with vertebral body or intervertebral disc disease. This is a complication which has been frequently reported when spinal needle insertion was performed at higher lumbar spinal levels. Methods. We retrospectively reviewed magnetic resonance images of the spine in 1047 Chinese patients to determine the conus medullaris terminus (CMT) in patients with and without vertebral disorders. Patients with tumours in and around the spine and those with congenital spinal anomalies were excluded from the study. Patients with mixed vertebral disorders were also excluded. Results. Our data demonstrate that patients with thoracic vertebral compression fractures had lower ending points of the CMT than those without (P,0.05), while patients with lumbar compression fractures did not demonstrate such a correlation. With regard to this difference, females were significantly at higher risk for a lower CMT than males. Conversely, lumbar disc disorders such as intervertebral disc extrusion, herniation, or bulging did not have any significant influence on the level of CMT. Moreover, patients with spondylolisthesis or scoliosis did not demonstrate an abnormal CMT location. Conclusions. When performing spinal anaesthesia, anaesthesiologists should be aware of potential differences of the CMT location, particularly in female patients with thoracic vertebral compression fractures, who may have a lower CMT than normal, extending to the level of L2. Performing spinal anaesthesia at the L2–L3 interspace would seem to be ill-advised in this patient population.

The purpose of this study was to examine the utility and feasibility of using alternative anterior reference leads when measuring left posterior tibial nerve somatosensory evoked potentials (SEPs). With IRB approval, 12 patients were monitored using both traditional (FPz and C4′) and alternative anterior (F3 and F4) reference leads during routine spine surgery with SEP monitoring. Recordings from the routine and novel electrode pairs were collected and analyzed. All of the SEP amplitudes measured were of similar magnitude except for that of F3–F4, which was significantly lower (P

Emergence hypertension after craniotomy is a well-documented phenomenon for which natural history is poorly understood. Most clinicians attribute this phenomenon to an acute and transient increase in catecholamine release, but other mechanisms such as neurogenic hypertension or activation of the renin-angiotensin-aldosterone system have also been proposed. In this open-label study, we compared the monotherapeutic antihypertensive efficacy of the 2 most titratable drugs used to treat postcraniotomy emergence hypertension: nicardipine and esmolol. We also investigated the effect of preoperative hypertension on postcraniotomy hypertension and the natural history of postcraniotomy hypertension in the early postoperative period.Fifty-two subjects were prospectively randomized to receive either nicardipine or esmolol as the sole drug for treatment of emergence hypertension at the conclusion of brain tumor resection (40 subjects finally analyzed). After a uniform anesthetic, standardized protocols of these antihypertensive medications were administered for the treatment of systolic blood pressure (SBP)130, with the goal of maintaining SBP140 throughout the first postoperative day. In the event of study medication "failure," a "rescue" antihypertensive (labetalol or hydralazine) was used. The O'Brien-Fleming Spending Function was used to calculate the appropriate α value for each interim analysis of the primary outcome; univariate analysis was performed otherwise, with a 2-sided P0.05 considered statistically significant.The incidence of nicardipine failure (5%, 95% confidence interval [CI] 0.1%-24.9%) was significantly less than that of esmolol (55%, 95% CI 31.5%-76.9%) as a sole drug in controlling SBP after brain tumor resection (difference 99% CI 13.8%-75.7%, P = 0.0012). The presence of preoperative hypertension or the approach to surgery (open craniotomy versus endonasal transsphenoidal) had no significant effect on the incidence of failure of the antihypertensive regimen used. We did not observe a difference in the need for opioid therapy for postcraniotomy pain between drug groups (99% CI difference -39.2%-30.2%). Failure of the study drug predicted the need for rescue drug therapy in the initial 12 hours after discharge from the recovery room (difference success versus failure = -41.7%, 99% CI difference -72.3% to -1.8%, P = 0.0336) but not during the period 12 to 24 hours after discharge from the recovery room (difference success versus failure = -27.4%, 99% CI difference -63.8%-9.2%, P = 0.143). However, in those patients carrying a preoperative diagnosis of hypertension, the need for rescue medication was only different during the period 12 to 24 hours after discharge from the recovery room (difference normotensive versus hypertensive = -35.4%, 99% CI difference -66.9% to -0.3%, P = 0.0254).Nicardipine is superior to esmolol for the treatment of postcraniotomy emergence hypertension. This type of hypertension is thought to be a transient phenomenon not solely related to sympathetic activation and catecholamine surge but also possibly encompassing other physiologic factors. For treating postcraniotomy emergence hypertension, nicardipine is a relatively effective sole drug, whereas if esmolol is used, rescue antihypertensive medications should be readily available.

Many factors affect the accuracy of hemoglobin concentration values. In this study, we evaluated whether the hemoglobin concentration obtained by means of arterial blood gas (ABG) co-oximetry and complete blood count (CBC) central laboratory techniques clinically correlate when using simultaneous measurements of hemoglobin concentration obtained during complex spine fusion surgery.Three hundred forty-eight patients who underwent spinal fusion of3 bony levels between September 2006 and September 2010, with concurrent ABG and CBC samples, were identified. The mean difference between pairs of measured hemoglobin values was determined using limits of agreement analysis. Error grid analysis was used to delineate correlation of samples in relation to hemoglobin values within the range considered for transfusion.The median difference (ABG-CBC) between the measured hemoglobin values was 0.4 g/dL (95% confidence interval [CI], 0.35-0.40 g/dL; P0.0001). Limits of agreement analysis correcting for repeated observations in multiple patients demonstrated that the mean difference between measured hemoglobin values (i.e., bias) was 0.4 g/dL (95% CI, 0.36-0.41 g/dL), and the 95% limits of agreement of the difference between paired measurements were -0.70 to 1.47 g/dL. The magnitude of the difference between the measured hemoglobin values was0.5 g/dL in 44.5% of patients (95% CI, 42.2%-46.8%); however, 6.8% (95% CI, 5.8%-8.1%) of paired measurements had a difference of1.0 g/dL. There was only fair-to-moderate agreement between the CBC and ABG values within the clinically significant range of hemoglobin values of 7 to 10 g/dL (Cohen κ = 0.39; 95% CI, 0.33-0.45).The hemoglobin values obtained from ABG and CBC cannot be used interchangeably when verifying accuracy of novel point-of-care hemoglobin measurement modalities or when managing a patient with critical blood loss.

Background Lumbar puncture for spinal or epidural anesthesia is commonly performed by palpating bony landmarks, but identification of the desired intervertebral level is often inaccurate. It is unclear whether such inaccuracy is related to patient factors, such as body mass index and degree of lumbar flexion. We hypothesized that overweight patients and patients with less of an ability to hyperflex their lumbar spines are prone to inaccurate lumbar spinous intervertebral level identification. Methods 52 adult volunteers were included in this study. 7 anesthesiologists with different years of experience identified and marked subjects’ levels of the iliac crests, then marked the presumed interspaces. Lumbar X-ray was then performed with metal markers, and actual radiographic findings were identified and compared to the initial markings. Results Patients with larger abdominal circumferences (mean (SD), 94.0(12.1) cm), higher body mass indices (25.9(3.9) kg/m2), and aged between 50 and 70 years old had lumbar interspaces that were higher than the presumed level; patients with smaller abdominal circumferences (82.8(13.5) cm) and lower body mass indices (21.6(4.1) kg/m2) had intervertebral levels that were lower than the presumed level. Cobb’s angle, indicating the degree of lumbar flexion, did not affect the accuracy obtained. Conclusions Patients’ abdominal circumference, body mass index, and age are factors that may impact the accuracy of lumbar level identification. Tuffier’s line, as identified by palpation, does not seem to be a reliable landmark for proper lumbar interspace identification in all cases.

Study design Observational cohort study. Objective To determine the accuracy of the Revised Cardiac Risk Index (RCRI) in predicting major adverse cardiac events in patients undergoing spine fusion surgery of 3 levels or more. Summary of background data Preoperative cardiac testing is extensively guided by the RCRI, which was developed and validated in thoracic, abdominal, and orthopedic surgical patients. Because multilevel spine fusion surgery is often associated with major transfusion, we hypothesize that the RCRI may not accurately characterize the risk of cardiovascular morbidity in these patients. Methods After institutional review board approval, perioperative data were collected from 547 patients who underwent 3 or more levels of spinal fusion with instrumentation. Postoperative cardiac morbidity was defined as any combination of the following: arrhythmia requiring medical treatment, myocardial infarction (either by electrocardiographic changes or troponin elevation), or the occurrence of demand ischemia. The surgical complexity was categorized as anterior surgery only, posterior cervical and/or thoracic fusion, posterior lumbar fusion, or any surgery that included transpedicular osteotomies. Logistic regression analysis was performed to determine RCRI performance. Results The RCRI performed no better than chance (area under the curve = 0.54) in identifying the 49 patients (9%) who experienced cardiac morbidity. Conclusion The RCRI did not predict cardiac morbidity in our patients undergoing major spine fusion surgery, despite being extensively validated in low-risk noncardiac surgical patients. Preoperative testing and optimization decisions, previously based on the RCRI, may need to be revised to include more frequent functional cardiac imaging and more aggressive implementation of pharmacologic modalities that may mitigate cardiac morbidity, similar to the preoperative evaluation for major vascular surgery. Level of evidence 3.

Background: Web-based delivery of educational material by scientific societies appears to have increased recently. However, the utilization of such efforts by the members of professional societies is unknown. We report the experience with delivery of educational resources on the Web site of the Society for Neuroscience in Anesthesiology and Critical Care (SNACC), and utilization of those resources by members. Methods: Three web-based educational initiatives were developed over 1 year to be disseminated through the SNACC Web site (http://www.snacc.org) for society members: (1) The SNACC Bibliography; (2) “Chat with the Author”; and (3) Clinical Case Discussions. Content experts and authors of important new research publications were invited to contribute. Member utilization data were abstracted with the help of the webmaster. Results: For the bibliography, there were 1175 page requests during the 6-month period after its launch by 122/664 (19%) distinct SNACC members. The bibliography was utilized by 107/553 (19%) of the active members and 15/91 (16.5%) of the trainee members. The “Chats with the Authors” were viewed by 56 (9%) members and the Clinical Case Discussions by 51 (8%) members. Conclusions: Educational resources can be developed in a timely manner utilizing member contributions without additional financial implications. However, the member utilization of these resources was lower than expected. These are first estimates of utilization of web-based educational resources by members of a scientific society. Further evaluation of such utilization by members of other societies as well as measures of the effectiveness and impact of such activities is needed.

BACKGROUND AND IMPORTANCE: Loeys-Dietz syndrome (LDS) is a newly described connective tissue disease associated with aortic aneurysms. A strong association between LDS and intracranial aneurysms has not yet been documented in the literature. We present the first detailed report of an intracranial aneurysm finding in an LDS patient. CLINICAL PRESENTATION: The patient is a 20-year-old female recently diagnosed with LDS and found to harbor 2 incidental intracranial aneurysms on a screening magnetic resonance angiography: a 3-mm right carotid ophthalmic aneurysm and an 8-mm partially fusiform paraclinoid carotid artery aneurysm. A standard left pterional craniotomy was performed. Intraoperative adenosine was used instead of temporary clipping because her vessels were extremely friable. After reconstruction, an intraoperative indocyanine green angiogram was obtained, confirming complete aneurysmal obliteration and internal carotid artery patency. CONCLUSION: This is the first detailed report of a clear association between intracranial aneurysms and LDS. An association between LDS and intracranial aneurysms, if substantiated in a larger study, has implications for aneurysm screening in this population. Such an association may shed light on mechanisms of aneurysm formation, growth, and rupture.

BACKGROUND: Adenosine-induced transient flow arrest has been used to facilitate clip ligation of intracranial aneurysms. However, the starting dose that is most likely to produce an adequate duration of profound hypotension remains unclear. We reviewed our experience to determine the dose-response relationship and apparent perioperative safety profile of adenosine in intracranial aneurysm patients. METHODS: This case series describes 24 aneurysm clip ligation procedures performed under an anesthetic consisting of remifentanil, low-dose volatile anesthetic, and propofol in which adenosine was used. The report focuses on the doses administered; duration of systolic blood pressure 60 mm Hg (SBP60 mm Hg); and any cardiovascular, neurologic, or pulmonary complications observed in the perioperative period. RESULTS: A median dose of 0.34 mg/kg ideal body weight (range: 0.29‐0.44 mg/kg) resulted in a SBP60 mm Hg for a median of 57 seconds (range: 26‐105 seconds). There was a linear relationship between the log-transformed dose of adenosine and the duration of a SBP60 mm Hg (R 2 0.38). Two patients developed transient, hemodynamically stable atrial fibrillation, 2 had postoperative troponin levels 0.03 ng/mL without any evidence of cardiac dysfunction, and 3 had postoperative neurologic changes. CONCLUSIONS: For intracranial aneurysms in which temporary occlusion is impractical or difficult, adenosine is capable of providing brief periods of profound systemic hypotension with low perioperative morbidity. On the basis of these data, a dose of 0.3 to 0.4 mg/kg ideal body weight may be the recommended starting dose to achieve approximately 45 seconds of profound systemic hypotension during a remifentanil/low-dose volatile anesthetic with propofol induced burst suppression. (Anesth Analg 2010;110:1406‐11)

Compartment syndrome caused by an infiltrated intravenous catheter has been previously reported, but there are no reports of compartment syndrome caused by fluids and/or medications dispensed by a properly functioning drug infusion pump. A case in which a commonly used drug infusion pump delivered propofol and remifentanil under high pressure, leading to compartment syndrome, is presented.