Effects of phenylephrine on systemic and cerebral circulations in humans: a systematic review with mechanistic explanations

We conducted a systematic review of the literature reporting phenylephrine-induced changes in blood pressure, cardiac output, cerebral blood flow and cerebral tissue oxygen saturation as measured by near-infrared spectroscopy in humans. We used the proportion change of the group mean values reported by the original studies in our analysis. Phenylephrine elevates blood pressure whilst concurrently inducing a reduction in cardiac output. Furthermore, despite increasing cerebral blood flow, it decreases cerebral tissue oxygen saturation. The extent of phenylephrine's influence on cardiac output (r = -0.54 and p = 0.09 in awake humans; r = -0.55 and p = 0.007 in anaesthetised humans), cerebral blood flow (r = 0.65 and p = 0.002 in awake humans; r = 0.80 and p = 0.003 in anaesthetised humans) and cerebral tissue oxygen saturation (r = -0.72 and p = 0.03 in awake humans; r = -0.24 and p = 0.48 in anaesthetised humans) appears closely linked to the magnitude of phenylephrine-induced blood pressure changes. When comparing the effects of phenylephrine in awake and anaesthetised humans, we found no evidence of a significant difference in cardiac output, cerebral blood flow or cerebral tissue oxygen saturation. There was also no evidence of a significant difference in effect on systemic and cerebral circulations whether phenylephrine was given by bolus or infusion. We explore the underlying mechanisms driving the phenylephrine-induced cardiac output reduction, cerebral blood flow increase and cerebral tissue oxygen saturation decrease. Individualised treatment approaches, close monitoring and consideration of potential risks and benefits remain vital to the safe and effective use of phenylephrine in acute care.

A prospective randomized study examining the impact of intravenous versus inhalational anesthesia on postoperative cognitive decline and delirium

The present prospective randomized study was designed to investigate whether the development of Post Operative Cognitive Decline (POCD) is related to anesthesia type in older adults. All patients were screened for delirium and mental status, received baseline neuropsychological assessment, and evaluation of activities of daily living (ADLs). Follow-up assessments were performed at 3-6 months and 12-18 months. Patients were randomized to receive either inhalation anesthesia (ISO) with isoflurane or total intravenous anesthesia (TIVA) with propofol for maintenance anesthesia. ISO (n = 99) and TIVA (n = 100) groups were similar in demographics, preoperative cognition, and incidence of post-operative delirium. Groups did not differ in terms of mean change in memory or executive function from baseline to follow-up. Pre-surgical cognitive function is the only variable predictive of the development of POCD. Anesthetic type was not predictive of POCD. However, ADLs were predictive of post-operative delirium development. Overall, this pilot study represents a prospective, randomized study demonstrating that when examining ISO versus TIVA for maintenance of general anesthesia, there is no significant difference in cognition between anesthetic types. There is also no difference in the occurrence of postoperative delirium. Postoperative cognitive decline was best predicted by lower baseline cognition and functional status.

The effects of aneurysmal subarachnoid hemorrhage on cerebral vessel diameter and flow velocity

BACKGROUND

Transcranial Doppler flow velocity is used to monitor for cerebral vasospasm following aneurysmal subarachnoid hemorrhage. Generally, blood flow velocities appear inversely related to the square of vessel diameter representing local fluid dynamics. However, studies of flow velocity-diameter relationships are few, and may identify vessels for which diameter changes are better correlated with Doppler velocity. We therefore studied a large retrospective cohort with concurrent transcranial Doppler velocities and angiographic vessel diameters.

METHODS

This is a single-site, retrospective, cohort study of adult patients with aneurysmal subarachnoid hemorrhage, approved by the UT Southwestern Medical Center Institutional Review Board. Study inclusion required transcranial Doppler measurements within </= 24 hours of vessel imaging. Vessels assessed were: bilateral anterior, middle, posterior cerebral arteries; internal carotid siphons; vertebral arteries; and basilar artery. Flow velocity-diameter relationships were constructed and fitted with a simple inverse power function. A greater influence of local fluid dynamics is suggested as power factors approach two.

RESULTS

98 patients were included. Velocity-diameter relationships are curvilinear, and well fit by a simple inverse power function. Middle cerebral arteries showed the highest power factors (>1.1, R²>0.9). Furthermore, velocity and diameter changed (P<0.033) consistent with the signature time course of cerebral vasospasm.

CONCLUSIONS

These results suggest that middle cerebral artery velocity-diameter relationships are most influenced by local fluid dynamics, which supports these vessels as preferred endpoints in Doppler detection of cerebral vasospasm. Other vessels showed less influence of local fluid dynamics, pointing to greater role of factors outside the local vessel segment in determining flow velocity.

Comparison of Bispectral Index Monitor Data Between Standard Frontal-Temporal Position and Alternative Nasal Dorsum Position in the Intensive Care Unit: A Pilot Study

ABSTRACT

BACKGROUND: The Bispectral (BIS) monitor is a validated, noninvasive monitor placed over the forehead to titrate sedation in patients under general anesthesia in the operating room. In the neurocritical care unit, there is limited room on the forehead because of incisions, injuries, and other monitoring devices. This is a pilot study to determine whether a BIS nasal montage correlates to the standard frontal-temporal data in this patient population. METHODS: This prospective nonandomized pilot study enrolled 10 critically ill, intubated, and sedated adult patients admitted to the neurocritical care unit. Each patient had a BIS monitor placed over the standard frontal-temporal location and over the alternative nasal dorsum with simultaneous data collected for 24 hours. RESULTS: In the frontal-temporal location, the mean (SD) BIS score was 50.9 (15.0), average minimum BIS score was 47.0 (15.0), and average maximum BIS score was 58.4 (16.7). In the nasal dorsum location, the mean BIS score was 54.8 (21.6), average minimum BIS score was 52.8 (20.9), and average maximum BIS score was 58.0 (22.2). Baseline nonparametric tests showed nonsignificant P values for all variables except for Signal Quality Index. Generalized linear model analysis demonstrated significant differences between the 2 monitor locations (P < .0001). CONCLUSION: The results of this pilot study do not support using a BIS nasal montage as an alternative for patients in the neurocritical care unit.

Comparison of the effect of epidural versus intravenous patient controlled analgesia on inpatient and outpatient functional outcomes after adult degenerative scoliosis surgery: a comparative study

BACKGROUND

Perioperative pain can negatively impact patient recovery after spine surgery and be a contributing factor to increased hospital length of stay and cost. Most data currently available is extrapolated from adolescent idiopathic cases and may not apply to adult and geriatric populations with thoracolumbar spine degeneration.

PURPOSE

Study the impact of epidural analgesia on pain control and outcomes after adult degenerative scoliosis surgery in a large single-institution series of adult patients undergoing thoraco-lumbar-pelvic fusion.

STUDY DESIGN/SETTING

Retrospective single-center review of prospectively collected data.

PATIENT SAMPLE

Patients undergoing thoracolumbar fusion with pelvic fixation.

OUTCOME MEASURES

Self-reported measures: Visual analog scale for pain. Physiologic Measures: Oral pain control requirements converted into daily morphine equivalents. Functional Measures: Ambulation perimeter after surgery, urinary retention and constipation rates.

METHODS

We retrospectively reviewed patient data for the years 2016 and 2017 before the use of patient controlled epidural analgesia (PCEA), and then 2018 and 2019 after its implementation, for all thoracolumbar degenerative procedures, and compared their postoperative outcomes measures.

RESULTS

There were 46 patients in the PCEA group and 37 patients in the intravenous PCA (IVPCA) groups. All patients underwent long segment posterolateral thoracolumbar spinal fusion with pelvic fixation. Patients in the PCEA group had lower pain scores and ambulated greater distances compared with those in the IVPCA group. PCEA patients also had lower urinary retention and constipation rates, but no increased intraoperative or postoperative complications related to catheter placement.

CONCLUSIONS

PCEA can provide optimal pain control after adult degenerative scoliosis spine surgery, and may promote greater early ambulation, while decreasing postoperative constipation and urinary retention rates.

Enhanced Recovery After Surgery Reduces Postoperative Opioid Use and 90-Day Readmission Rates After Open Thoracolumbar Fusion for Adult Degenerative Deformity

BACKGROUND

The role of enhanced recovery after surgery (ERAS) pathways implementation has not been previously explored in adult deformity patients.

OBJECTIVE

To determine the impact of ERAS pathways implementation in adult patients undergoing open thoraco-lumbar-pelvic fusion for degenerative scoliosis on postoperative outcome, opioid consumption, and unplanned readmission rates.

METHODS

In this retrospective single-center study, we included 124 consecutive patients who underwent open thoraco-lumbar-pelvic fusion from October 2016 to February 2019 for degenerative scoliosis. Primary outcomes consisted of postoperative supplementary opioid consumption in morphine equivalent dose (MED), postoperative complications, and readmission rates within the postoperative 90-d window.

RESULTS

There were 67 patients in the ERAS group, and 57 patients served as pre-ERAS controls. Average patient age was 69 yr. The groups had comparable demographic and intraoperative variables. ERAS patients had a significantly lower rate of postoperative supplemental opioid consumption (248.05 vs 314.05 MED, P = .04), a lower rate of urinary retention requiring catheterization (5.97% vs 19.3%, P = .024) and of severe constipation (1.49% vs 31.57%, P < .0001), and fewer readmissions after their surgery (2.98% vs 28.07%, P = .0001).

CONCLUSION

A comprehensive multidisciplinary approach to complex spine surgery can reduce opioid intake, postoperative urinary retention and severe constipation, and unplanned 90-d readmissions in the elderly adult population.

Calcium Channel Blockers in Acute Care: The Links and Missing Links Between Hemodynamic Effects and Outcome Evidence

Calcium channel blockers (CCBs) exert profound hemodynamic effects via blockage of calcium flux through voltage-gated calcium channels. CCBs are widely used in acute care to treat concerning, debilitating, or life-threatening hemodynamic changes in many patients. The overall literature suggests that, for systemic hemodynamics, although CCBs decrease blood pressure, they normally increase cardiac output; for regional hemodynamics, although they impair pressure autoregulation, they normally increase organ blood flow and tissue oxygenation. In acute care, CCBs exert therapeutic efficacy or improve outcomes in patients with aneurysmal subarachnoid hemorrhage, acute myocardial infarction and unstable angina, hypertensive crisis, perioperative hypertension, and atrial tachyarrhythmia. However, despite the clear links, there are missing links between the known hemodynamic effects and the reported outcome evidence, suggesting that further studies are needed for clarification. In this narrative review, we aim to discuss the hemodynamic effects and outcome evidence for CCBs, the links and missing links between these two domains, and the directions that merit future investigations.

American Society for Enhanced Recovery and Perioperative Quality Initiative Joint Consensus Statement on Postoperative Delirium Prevention

Postoperative delirium is a geriatric syndrome that manifests as changes in cognition, attention, and levels of consciousness after surgery. It occurs in up to 50% of patients after major surgery and is associated with adverse outcomes, including increased hospital length of stay, higher cost of care, higher rates of institutionalization after discharge, and higher rates of readmission. Furthermore, it is associated with functional decline and cognitive impairments after surgery. As the age and medical complexity of our surgical population increases, practitioners need the skills to identify and prevent delirium in this high-risk population. Because delirium is a common and consequential postoperative complication, there has been an abundance of recent research focused on delirium, conducted by clinicians from a variety of specialties. There have also been several reviews and recommendation statements; however, these have not been based on robust evidence. The Sixth Perioperative Quality Initiative (POQI-6) consensus conference brought together a team of multidisciplinary experts to formally survey and evaluate the literature on postoperative delirium prevention and provide evidence-based recommendations using an iterative Delphi process and Grading of Recommendations Assessment, Development and Evaluation (GRADE) Criteria for evaluating biomedical literature.

A Novel Approach to Maintaining Normothermia in Major Spinal Deformity Surgery with an Esophageal Warming Device

Maintenance of normothermia is a priority during major spinal deformity surgery. However, this is difficult due to the large body surface area exposed to ambient temperatures. We report the novel use of an esophageal warming device, added to standard care, to maintain normothermia in three patients. We conclude that esophageal warming is feasible in major spine surgery with no apparent complications. Safety and efficacy, as compared to standard warming devices, will need to be determined in future prospective trials.

Intravenous vs oral acetaminophen in sinus surgery: A randomized clinical trial

BACKGROUND

Multimodal perioperative analgesia including acetaminophen is recommended by current guidelines. The comparative efficacy of intravenous vs oral acetaminophen in sinus surgery is unknown. We aimed to determine whether intravenous or oral acetaminophen results in superior postoperative analgesia following sinus surgery.

METHODS

This was a prospective randomized trial with blinded endpoint assessments conducted at a single large academic medical center. Subjects undergoing functional endoscopic sinus surgery were randomized to intravenous vs oral acetaminophen in addition to standard anesthetic and surgical care. The primary outcome was visual analogue scale pain score at 1 hour postoperatively.

RESULTS

One hundred and ten adult patients were randomized; 9 were excluded from the data analysis. Fifty patients were assigned to intravenous acetaminophen and 51 to oral acetaminophen. Postoperative pain scores at 1 hour (primary endpoint) were not significantly different between the intravenous and oral acetaminophen groups. Similarly, there was no significant difference in pain scores at 24 hours postoperatively. Finally, there was no significant difference in postoperative opioid usage in the postanesthesia care unit or over the first 24 hours postoperatively.

CONCLUSIONS

This is the first comparative efficacy trial of oral vs intravenous acetaminophen in sinus surgery. There was no significant difference in pain scores at 1 or 24 hours postoperatively, and no difference in postoperative opioid use. Intravenous acetaminophen offers no apparent advantage over oral acetaminophen in patients undergoing sinus surgery.

LEVEL OF EVIDENCE

1b.

Associations between Features of External Ventricular Drain Management, Disposition, and Shunt Dependence

Background In the United States, nearly 25,000 patients annually undergo percutaneous ventriculostomy for the management of increased intracranial pressure with little consensus on extraventricular drain management. To characterize relationships between external ventricular drain management, permanent ventriculoperitoneal shunt placement, and hospital disposition, we hypothesized that patients requiring extended drainage would have greater association with ventriculoperitoneal shunt placement and unfavorable disposition.

Methods Adult patients admitted to the Duke University Hospital Neuroscience Intensive Care Unit between 2008 and 2010 with extraventricular drains were analyzed. A total of 115 patient encounters were assessed to determine relative impact of age, sex, days of extraventricular placement, weaning attempts, cerebrospinal fluid drainage volumes, Glasgow Coma Scale, and physician’s experience on disposition at discharge and ventriculoperitoneal shunt placement. Univariate logistic regression was first used to test the effect of each variable on the outcome, followed by backward selection to determine a final multivariable logistic regression. Variables in the final model meeting p < 0.05 were declared as significant factors for the outcome.

Results Increased extraventricular drain duration (odds ratio [OR] = 1.17, confidence interval [CI] = 1.05–1.30, p = 0.0049) was associated with ventriculoperitoneal shunt placement, while older age (OR = 1.05, CI = 1.02–1.08, p = 0.0027) and less physician extraventricular drain management experience (OR = 4.04, CI = 1.67–9.79, p = 0.0020) were associated with unfavorable disposition.

Conclusion In a small cohort, exploratory analyses demonstrate potentially modifiable factors are associated with important clinical outcomes. These findings warrant further study to refine how such factors affect patient outcomes.

Temporary Transvenous Diaphragmatic Neurostimulation in Prolonged Mechanically Ventilated Patients: A Feasibility Trial (RESCUE 1)

Prolonged mechanical ventilation promotes diaphragmatic atrophy and weaning difficulty. The study uses a novel device containing a transvenous phrenic nerve stimulating catheter (Lungpacer IntraVenous Electrode Catheter) to stimulate the diaphragm in ventilated patients. We set out to determine the feasibility of temporary transvenous diaphragmatic neurostimulation using this device.

DESIGN

Multicenter, prospective open-label single group feasibility study.

SETTING

ICUs of tertiary care hospitals.

PATIENTS

Adults on mechanical ventilation for greater than or equal to 7 days that had failed two weaning trials.

INTERVENTIONS

Stimulation catheter insertion and transvenous diaphragmatic neurostimulation therapy up to tid, along with standard of care.

MEASUREMENTS AND MAIN RESULTS

Primary outcomes were successful insertion and removal of the catheter and safe application of transvenous diaphragmatic neurostimulation. Change in maximal inspiratory pressure and rapid shallow breathing index were also evaluated. Eleven patients met all entry criteria with a mean mechanical ventilation duration of 19.7 days; nine underwent successful catheter insertion. All nine had successful mapping of one or both phrenic nerves, demonstrated diaphragmatic contractions during therapy, and underwent successful catheter removal. Seven of nine met successful weaning criteria. Mean maximal inspiratory pressure increased by 105% in those successfully weaned (mean change 19.7 ± 17.9 cm H2O; p = 0.03), while mean rapid shallow breathing index improved by 44% (mean change -63.5 ± 64.4; p = 0.04).

CONCLUSIONS

The transvenous diaphragmatic neurostimulation system is a feasible and safe therapy to stimulate the phrenic nerves and induce diaphragmatic contractions. Randomized clinical trials are underway to compare it to standard-of-care therapy for mechanical ventilation weaning.

The effectiveness of tranexamic acid on operative and perioperative blood loss in long-segment spinal fusions: a consecutive series of 119 primary procedures

OBJECTIVE

The aim of this study was to determine if the use of tranexamic acid (TXA) in long-segment spinal fusion surgery can help reduce perioperative blood loss, transfusion requirements, and morbidity.

METHODS

In this retrospective single-center study, the authors included 119 consecutive patients who underwent thoracolumbar fusion spanning at least 4 spinal levels from October 2016 to February 2019. Blood loss, transfusion requirements, perioperative morbidity, and adverse thrombotic events were compared between a cohort receiving intravenous TXA and a control group that did not.

RESULTS

There was no significant difference in any measure of intraoperative blood loss (1514.3 vs 1209.1 mL, p = 0.29) or transfusion requirement volume between the TXA and control groups despite a higher number of pelvic fusion procedures in the TXA group (85.9% vs 62.5%, p = 0.003). Postoperative transfusion volume was significantly lower in TXA patients (954 vs 572 mL, p = 0.01). There was no difference in the incidence of thrombotic complications between the groups.

CONCLUSIONS

TXA appears to provide a protective effect against blood loss in long-segment spine fusion surgery specifically when pelvic dissection and fixation is performed. TXA also seems to decrease postoperative transfusion requirements without increasing the risk of adverse thrombotic events.

Education Research: Variation in priorities for neurocritical care education expressed across role groups

OBJECTIVE

To define expectations for neurocritical care (NCC) core competencies vs competencies considered within the domain of other subspecialists.

METHODS

An electronic survey was disseminated nationally to NCC nurses, physicians, fellows, and neurology residents through Accreditation Council for Graduate Medical Education neurology residency program directors, United Council for Neurologic Subspecialties neurocritical care fellowship program directors, and members of the Neurocritical Care Society.

RESULTS

A total of 268 neurocritical care providers and neurology residents from 30 institutions responded. Overall, >90% supported NCC graduates independently interpreting and managing systemic and cerebral hemodynamic data, or performing brain death determination, neurovascular ultrasound, vascular access, and airway management. Over 75% endorsed that NCC graduates should independently interpret EEG and perform bronchoscopies. Fewer but substantial respondents supported graduates being independent performing intracranial bolt (45.8%), ventriculostomy (39.0%), tracheostomy (39.8%), or gastrostomy (19.1%) procedures. Trainees differed from physicians and program directors, respectively, by advocating independence in EEG interpretation (92.8%, 61.8%, and 65.3%) and PEG placement (29.3%, 9.1%, and 8.5%).

CONCLUSIONS

Broad support exists across NCC role groups for wide-ranging NCC competencies including skills often performed by other neurology and non-neurology subspecialties. Variations highlight natural divergences in expectations among trainee, physician, and nurse role groups. These results establish expectations for core competencies within NCC and initiate dialogue across subspecialties about best practice standards for the spectrum of critically ill patients requiring neurologic care.

The Effect of Propofol vs. Isoflurane Anesthesia on Postoperative Changes in Cerebrospinal Fluid Cytokine Levels: Results from a Randomized Trial

Introduction

Aside from direct effects on neurotransmission, inhaled and intravenous anesthetics have immunomodulatory properties. In vitro and mouse model studies suggest that propofol inhibits, while isoflurane increases, neuroinflammation. If these findings translate to humans, they could be clinically important since neuroinflammation has detrimental effects on neurocognitive function in numerous disease states.

Materials and methods

To examine whether propofol and isoflurane differentially modulate neuroinflammation in humans, cytokines were measured in a secondary analysis of cerebrospinal fluid (CSF) samples from patients prospectively randomized to receive anesthetic maintenance with propofol vs. isoflurane (registered with http://www.clinicaltrials.gov, identifier NCT01640275). We measured CSF levels of EGF, eotaxin, G-CSF, GM-CSF, IFN-α2, IL-1RA, IL-6, IL-7, IL-8, IL-10, IP-10, MCP-1, MIP-1α, MIP-1β, and TNF-α before and 24 h after intracranial surgery in these study patients.

Results

After Bonferroni correction for multiple comparisons, we found significant increases from before to 24 h after surgery in G-CSF, IL-10, IL-1RA, IL-6, IL-8, IP-10, MCP-1, MIP-1α, MIP-1β, and TNF-α. However, we found no difference in cytokine levels at baseline or 24 h after surgery between propofol- (n = 19) and isoflurane-treated (n = 21) patients (p > 0.05 for all comparisons). Increases in CSF IL-6, IL-8, IP-10, and MCP-1 levels directly correlated with each other and with postoperative CSF elevations in tau, a neural injury biomarker. We observed CSF cytokine increases up to 10-fold higher after intracranial surgery than previously reported after other types of surgery.

Discussion

These data clarify the magnitude of neuroinflammation after intracranial surgery, and raise the possibility that a coordinated neuroinflammatory response may play a role in neural injury after surgery.

The Effect of Propofol Versus Isoflurane Anesthesia on Human Cerebrospinal Fluid Markers of Alzheimer's Disease: Results of a Randomized Trial

BACKGROUND

Preclinical studies have found differential effects of isoflurane and propofol on the Alzheimer's disease (AD)-associated markers tau, phosphorylated tau (p-tau) and amyloid-β (Aβ).

OBJECTIVE

We asked whether isoflurane and propofol have differential effects on the tau/Aβ ratio (the primary outcome), and individual AD biomarkers. We also examined whether genetic/intraoperative factors influenced perioperative changes in AD biomarkers.

METHODS

Patients undergoing neurosurgical/otolaryngology procedures requiring lumbar cerebrospinal fluid (CSF) drain placement were prospectively randomized to receive isoflurane (n = 21) or propofol (n = 18) for anesthetic maintenance. We measured perioperative CSF sample AD markers, performed genotyping assays, and examined intraoperative data from the electronic anesthesia record. A repeated measures ANOVA was used to examine changes in AD markers by anesthetic type over time.

RESULTS

The CSF tau/Aβ ratio did not differ between isoflurane- versus propofol-treated patients (p = 1.000). CSF tau/Aβ ratio and tau levels increased 10 and 24 h after drain placement (p = 2.002×10-6 and p = 1.985×10-6, respectively), mean CSF p-tau levels decreased (p = 0.005), and Aβ levels did not change (p = 0.152). There was no interaction between anesthetic treatment and time for any of these biomarkers. None of the examined genetic polymorphisms, including ApoE4, were associated with tau increase (n = 9 polymorphisms, p > 0.05 for all associations).

CONCLUSION

Neurosurgery/otolaryngology procedures are associated with an increase in the CSF tau/Aβ ratio, and this increase was not influenced by anesthetic type. The increased CSF tau/Aβ ratio was largely driven by increases in tau levels. Future work should determine the functional/prognostic significance of these perioperative CSF tau elevations.

A Case of High-dose Adenosine Usage for Anterior Communicating Artery Aneurysm Clip Ligation: What is the Dose Limit for a Resistant Response?

Intraoperative adenosine is used to induce asystole to facilitate clip ligation of intracranial aneurysms. Typically, 5–10 mg doses are used per administration and approximately 30 mg is used for a given case. An obvious concern with using adenosine is that the patient can remain in asystole or that prolonged hypotension can result in cerebral or cardiovascular ischemia. The upper limit of adenosine administration remains unclear. We present a case of a patient with a large anterior communicating artery aneurysm requiring large doses of adenosine, far exceeding previously reported cases. The patient received a 90 mg dose of adenosine to achieve 5 s of asystole as well as 30 s of hypotension that facilitated vessel dissection and clip application. Moreover, in order to successfully clip his aneurysm, he received a total of 744 mg of adenosine. After each administration of adenosine, his heart rate and blood pressure returned to baseline without the need for chest compressions or other interventions. He tolerated the procedure and had a good neurological outcome. This case is the first report of using such a high dose of adenosine in intracranial aneurysm surgery and suggests that more aggressive administration of adenosine during aneurysm clipping is feasible. Transient hypotension, as seen in this report, can provide surgeons the crucial moments they need to safely secure an aneurysm from circulation.

Postoperative complications of spine surgery

A variety of surgical approaches are available for the treatment of spine diseases. Complications can arise intraoperatively, in the immediate postoperative period, or in a delayed fashion. These complications may lead to severe or even permanent morbidity if left unrecognized and untreated [1-4]. Here we review a range of complications in the early postoperative period from more benign complications such as postoperative nausea and vomiting (PONV) to more feared complications leading to permanent loss of neurological function or death [5]. Perioperative pain management is covered in a separate review (Chapter 8).

Intra-operative hydroxyethyl starch is not associated with post-craniotomy hemorrhage

Background

Intraoperative intravascular volume expansion with hydroxyethyl starch-based colloids is thought to be associated with an increased risk of post-craniotomy hemorrhage. Evidence for this association is limited. Associations between resuscitation with hydroxyethyl starch and risk of repeat craniotomy for hematoma evacuation were examined.

Methods

Using a retrospective cohort of neurosurgical patients at Duke University Medical Center between March 2005 and March 2012, patient characteristics were compared between those who developed post-craniotomy hemorrhage and those who did not.

Results

A total of 4,109 craniotomy procedures were analyzed with 61 patients having repeat craniotomy for post-operative hemorrhage (1.5%). The rate of reoperation in the group receiving 6% High Molecular Weight Hydroxyethyl Starch (Hextend^®) was 2.6 vs. 1.3% for patients that did not receive hetastarch (P = 0.13). The reoperation rate for those receiving 6% hydroxyethyl Starch 130/0.4 (Voluven^®) was 1.4 vs. 1.6% in patients not receiving Voluven (P = 0.85).

Conclusions

In this retrospective cohort, intra-operative hydroxyethyl starch was not associated with an increased risk of post-craniotomy hemorrhage.

Rapid ventricular pacing assisted hypotension in the management of sudden intraoperative hemorrhage during cerebral aneurysm clipping

Sudden intraoperative hemorrhage during intracranial aneurysm surgery from vascular injury or aneurysmal rupture has been known to dramatically increase the associated morbidity and mortality. We describe the first reported use of rapid ventricular pacing (RVP) assisted hypotension to control sudden intraoperative hemorrhage during intracranial aneurysm surgery where temporary arterial occlusion was not achievable.

Neurological complications of cardiac surgery

As increasing numbers of elderly people undergo cardiac surgery, neurologists are frequently called upon to assess patients with neurological complications from the procedure. Some complications mandate acute intervention, whereas others need longer term observation and management. A large amount of published literature exists about these complications and guidance on best practice is constantly changing. Similarly, despite technological advances in surgical intervention and modifications in surgical technique to make cardiac procedures safer, these advances often create new avenues for neurological injury. Accordingly, rapid and precise neurological assessment and therapeutic intervention rests on a solid understanding of the evidence base and procedural variables.

A pilot study evaluating presurgery neuroanatomical biomarkers for postoperative cognitive decline after total knee arthroplasty in older adults

BACKGROUND

Total knee arthroplasty improves quality of life but is associated with postoperative cognitive dysfunction in older adults. This prospective longitudinal pilot study with a parallel control group tested the hypotheses that (1) nondemented adults would exhibit primary memory and executive difficulties after total knee arthroplasty, and (2) reduced preoperative hippocampus/entorhinal volume would predict postoperative memory change, whereas preoperative leukoaraiosis and lacunae volumes would predict postoperative executive dysfunction.

METHODS

Surgery (n = 40) and age-education-matched controls with osteoarthritis (n = 15) completed pre- and postoperative (3 weeks, 3 months, and 1 yr) memory and cognitive testing. Hypothesized brain regions of interest were measured in patients completing preoperative magnetic resonance scans (surgery, n = 31; control, n = 12). Analyses used reliable change methods to identify the frequency of cognitive change at each time point.

RESULTS

The incidence of postoperative memory difficulties was shown with delay test indices (i.e., story memory test: 3 weeks = 17%, 3 months = 25%, 1 yr = 9%). Postoperative executive difficulty with measures of inhibitory function (i.e., Stroop Color Word: 3 weeks = 21%, 3 months = 22%, 1 yr = 9%). Hierarchical regression analysis assessing the predictive interaction of group (surgery, control) and preoperative neuroanatomical structures on decline showed that greater preoperative volumes of leukoaraiosis/lacunae were significantly contributed to postoperative executive (inhibitory) declines.

CONCLUSIONS

This pilot study suggests that executive and memory declines occur in nondemented adults undergoing orthopedic surgery. Severity of preoperative cerebrovascular disease may be relevant for understanding executive decline, in particular.

Levetiracetam seizure prophylaxis in craniotomy patients at high risk for postoperative seizures

Background:

The risk of developing immediate postoperative seizures in patients undergoing supratentorial brain tumor surgery without anti-epileptic drug (AED) prophylaxis is 15-20%. Patients who present with pre-operative seizures and patients with supratentorial meningioma or supratentorial low grade gliomas are at significantly higher risk. There is little data on the efficacy of levetiracetam as a prophylactic AED in the immediate postoperative period (within 7 days of surgery) in these patients.

Methods:

We conducted a retrospective chart review of 165 adult patients classified as higher risk for postoperative seizures who underwent brain tumor resection at Duke University Hospital between time May 2010 and December 2011. All patients had received levetiracetam monotherapy in doses of 1000-3000 mg/day in the immediate postoperative period.

Results:

We identified 165 patients with following tumor locations: Frontal 83 (50.3%), Temporal 37 (22.4%), Parietal 30 (18.2%), Occipital 2 (1.2%) and 13 (7.8%) with single lesions involving more than one lobe. Histology revealed: Glioma 98 (59.4%), Meningioma 57 (34.5%) and Brain Metastases 6 (3.6%). Preoperatively, 88/165 (53.3%) patients had presented with seizures. 12/165 patients (7.3%) developed clinical seizures (generalized 10, partial 2) in the immediate post-operative period. Other than somnolence in 7 patients (4.2%), no major side-effects were noted.

Conclusions:

The incidence of seizures was significantly lower in patients treated with levetiracetam (7.3%) when compared with the expected (15-20%) rate without AED prophylaxis based on the previous literature. Levetiracetam appears effective and safe for seizure prevention in patients undergoing brain tumor resection and who are at significantly higher risk of developing post-operative seizures. These findings warrant confirmation in a prospective randomized trial.

A novel application for bolus remifentanil: blunting the hemodynamic response to Mayfield skull clamp placement

OBJECTIVE

Neurosurgery often requires skull immobilization with a Mayfield clamp, which often causes brief intense nociceptive stimulation, hypertension and tachycardia. Blunting this response may help prevent increased intracranial pressure, cerebral aneurysm or vascular malformation rupture, and/or myocardial stress. While various interventions have been described to blunt this response, no reports have compared administration of a propofol versus a remifentanil bolus.

METHODS

We retrospectively analyzed the hemodynamic response to Mayfield placement in over 800 patients who received a prior propofol or remifentanil bolus from 2004 to 2010.

RESULTS

Patients who received remifentanil experienced a 55% smaller increase in heart rate (p < 0.0001) and a 40% smaller increase in systolic blood pressure (p < 0.0001) after Mayfield placement than patients who received propofol. These data were retrospectively obtained from patients who were not randomized to receive remifentanil versus propofol, and hence these data could be subject to possible confounding. Nonetheless, these differences remained significant after multivariate analysis for possible confounding variables.

CONCLUSIONS

Thus, a remifentanil bolus is more effective than a propofol bolus in blunting hemodynamic responses to Mayfield placement, and possibly for other short, intense nociceptive stimuli.

Comparison of surgical and endovascular approach in management of spinal dural arteriovenous fistulas: A single center experience of 27 patients

Background:

Spinal dural arteriovenous fistula (SDAVF) is a rare spinal vascular malformation with an annual incidence of 5-10 cases per million. The data on efficacy, recurrence rates and complications of endovascular versus surgical treatment of SDAVF is limited.

Methods:

We conducted a retrospective chart review of 27 adult patients with a diagnosis of SDAVF and who underwent treatment at Duke University Hospital between January 1, 1993 and December 31, 2012. We compared the outcome measures by Aminoff–Logue score (ALS) in patients who underwent treatment with endovascular embolization versus surgical ligation of fistula. We compared complication rates, recurrence rates as well as data on long-term follow up in these patients.

Results:

Out of 27 patients in the study, 10 patients underwent endovascular embolization (Onyx was used in 5 patients and NBCA in 5 patients) as the first line therapy. Seventeen patients underwent surgical ligation as initial therapeutic modality. Patients in both groups showed significant improvement in clinical status (ALS) after treatment. One patient in endovascular group developed spinal infarction due to accidental embolization of medullary artery. Three patients in embolization group had recurrence of fistula during the course of follow up requiring surgical ligation. Two patients in surgical group developed local wound infection. None of the patients in surgical group had recurrence of fistula during the course of follow up.

Conclusions:

Endovascular embolization and surgical ligation are effective treatment strategies for SDAVF. Our observations show that surgical ligation may offer permanent cure without any recurrence. Endovascular approach is associated with higher incidence of recurrence, especially with use of onyx.

Effect of surgical clipping versus endovascular coiling on recovery from oculomotor nerve palsy in patients with posterior communicating artery aneurysms: A retrospective comparative study and meta-analysis

Background:

Oculomotor nerve palsy (OMNP) is a well-recognized complication of posterior communicating artery (PCOM) aneurysms. Only a few comparative studies have assessed the effect of clipping versus coiling on recovery from OMNP in PCOM aneurysms. A retrospective review and meta-analysis was conducted to assess the relationship between PCOM aneurysm treatment and OMNP.

Materials and Methods:

Medical records of all patients presenting between January 2000 and February 2013 with intracranial aneurysm were searched. All patients with OMNP secondary to PCOM aneurysm were included for analysis. Patients undergoing surgical clipping or endovascular coiling were compared with respect to complete resolution of OMNP after aneurysm surgery (i.e., primary outcome). A meta-analysis of published studies of OMNP associated with PCOM aneurysm was performed after a MEDLINE search.

Results:

Seventeen patients with OMNP secondary to PCOM aneurysms met the inclusion criteria. Surgical clipping (seven of eight patients, or 87.5%) resulted in greater complete resolution of OMNP compared with endovascular coiling (four of nine patients, or 44.4%), P = 0.13. A meta-analysis of similar studies revealed that complete resolution of OMNP was more commonly associated with surgical clipping (36 of 43 patients, or 83.7%) than with endovascular coiling (29 of 55 patients, or 52.7%), yielding an adjusted odds ratio (OR) of 6.04 [confidence interval (CI) =1.88-19.45, P = 0.003]. Multivariate analysis found that the degree of pre-operative OMNP (OR = 0.07, CI = 0.02-0.28, P = 0.001) and surgical clipping (OR = 6.37, CI = 1.73-23.42, P = 0.005) were significant factors that affected the complete recovery of OMNP.

Conclusion:

Complete recovery of OMNP with PCOM aneurysms is more commonly associated with surgical clipping than with endovascular coiling. Also, the degree of pre-operative OMNP and the treatment modality are significant factors that affect the complete recovery of OMNP.

Perioperative Cardiac Complications and 30-Day Mortality in Patients Undergoing Intracranial Aneurysmal Surgery With Adenosine-Induced Flow Arrest

BACKGROUND:

Adenosine-induced flow arrest is a technique used to assist in the surgical clipping of complex aneurysms.

OBJECTIVE:

To assess the safety associated with adenosine-assisted intracranial aneurysm surgery.

METHODS:

Medical records of all patients presenting between January 1, 2009, and December 31, 2012, for intracranial aneurysm surgery were analyzed. Patients were divided into 2 groups based on the intraoperative administration of adenosine: the nonadenosine group (n = 262) and the adenosine group (n = 64). The primary outcome compared between groups included a composite of 30-day mortality and incidences of perioperative cardiac complications (perioperative myocardial infarction or perioperative cardiac arrhythmias).

RESULTS:

The study groups were statistically similar except for a difference in the size and location of cerebral aneurysms and the incidence of coronary artery disease. The primary composite outcome occurred in 4.6% and 9.4% of patients in the nonadenosine and adenosine groups, respectively (P = .13). After adjustment for differences in the incidence of coronary artery disease between the 2 groups, the odds of the primary outcome were not significantly different between the groups (adjusted odds ratio = 2.12; 95% confidence interval, 0.76-5.93; P = .15). There were also no significant differences in the durations of hospital and intensive care unit stay between the study groups.

CONCLUSION:

Our results suggest that adenosine-assisted intracranial aneurysm surgery is not associated with an increase in perioperative cardiac complications or mortality in patients with low risk of coronary artery disease and may be considered a safe technique to assist clipping of complex aneurysms.

Predictors of extraventricular drain-associated bacterial ventriculitis

PURPOSE

Bacterial ventriculitis (BV) may develop in patients requiring external ventricular drains (EVDs). The purpose of this study was to determine predictors of EVD-associated BV onset.

MATERIALS AND METHODS

A retrospective review of Duke University Hospital patients with EVD device placement between January 2005 and May 2010 was conducted. Subject data were captured for predefined variables. Outcomes included in-hospital mortality, length of stay, and neurologic status at discharge.

RESULTS

In 410 subjects with 420 EVDs, the BV rate was 10.2%. Univariate analysis indicated that age, sex, positive blood culture, duration of EVD placement, and the number of cerebrospinal fluid (CSF) samples taken were associated with BV. Of these, the number of CSF samples and sex retained significance in multivariable modeling (female: odds ratio, 0.47 [confidence interval, 0.23-0.97]; CSF samples: odds ratio, 1.08 [confidence interval 1.01-1.17]; P = .04; c index = 0.69). In this model, each CSF sample taken expanded the likelihood of BV by 8.3%. The most common pathogens were Staphylococcus or proprioniobacter (n = 26). Bacterial ventriculitis was associated with an increase in hospital length of stay (33 ± 22.9 days vs 24.6 ± 20.4 days; P = .04) but not mortality.

CONCLUSION

An association exists between CSF sampling frequency and the development of EVD-associated BV. Larger prospective studies should be aimed at identifying causal relationships between these variables.

Comparison of postoperative nausea between benign and malignant brain tumor patients undergoing awake craniotomy: a retrospective analysis

BACKGROUND

Benign and malignant brain tumors have different histopathological characteristics, including different degrees of tissue infiltration and inflammatory response. The aim of this retrospective study was to compare the incidence of postoperative nausea between the two categories of brain tumors in patients undergoing awake craniotomy.

METHODS

After IRB approval, we retrospectively extracted data from perioperative records between January 2005 and December 2010. Patients were divided based on the postoperative histopathological diagnosis into two groups, benign and malignant. The incidence of nausea, rescue anti-emetics, pain scores and postoperative analgesic requirements were compared between the two groups up to 12 hours postoperatively. Intraoperative anti-emetic, anesthetic, and analgesic regimens were also assessed. Limitations of this study include the retrospective design, the arbitrary dichotomization of tumors as benign or malignant, and the inability to gather accurate data regarding vomiting from the medical record.

RESULTS

Data from 415 patients were available for analysis, with 115 patients in the benign group and 300 patients in the malignant tumor group. A higher postoperative mean pain score was found in the benign brain tumor group compared to the malignant brain tumor group (P < 0.05). However, there was no difference in the incidence of nausea between the two groups.

CONCLUSION

The different histopathological characteristics of brain tumors have no association with postoperative nausea in patients undergoing awake craniotomy. Patients with benign brain tumors experience more pain than patients with malignant brain tumors. This difference in postoperative pain may be due to the younger age of the patients in the benign group.

Does midline shift predict postoperative nausea in brain tumor patients undergoing awake craniotomy? A retrospective analysis

BACKGROUND

The presence of midline shift on neuroradiologic studies in brain tumor patients represents mass effect from the tumor and surrounding edema. We hypothesized that baseline cerebral edema as measured by midline shift would increase postoperative nausea (PON). We studied the incidence of PON in brain tumor patients, with and without midline shift on preoperative magnetic resonance (MRI) or computed tomographic (CT) imaging, undergoing awake craniotomy.

METHODS

After IRB approval, we retrospectively extracted data from perioperative records between January 2005 and December 2010. Post-craniotomy nausea and pain scores were collected. Intraoperative anti-emetic, anesthetic, and analgesic regimens were assessed. Both the rescue anti-emetic and cumulative postoperative analgesic requirements were collected up to 12 hours postoperatively. The amount of midline shift on preoperative neuroimaging was gathered from radiology reports. Univariate comparisons between groups (no midline shift vs. midline shift) were made with t-tests for continuous variables, and chi-square tests for categorical variables. A multivariable analysis was performed to identify predictors of postoperative nausea. Limitations of this study include the retrospective design and the inability to gather accurate data regarding vomiting from the medical record.

RESULTS

Data from 386 patients were available for analysis. Patients were divided into two groups: no midline shift (n = 283) and midline shift (n = 103). The mean midline shift distance was 5.96 mm (95% CI [5.32, 6.59]). There was no difference in the incidence of nausea or pain scores between the two groups. More malignant brain tumor patients were in the midline shift group, as determined by the postoperative histopathological diagnosis (P < 0.05). Patients in the midline shift group also had longer anesthesia and surgical times (P < 0.05).

CONCLUSION

In patients undergoing a standardized anesthetic for awake craniotomy for tumor resection, the presence of preoperative midline shift did not correlate with postoperative nausea.

Arterial hyperoxia during cardiopulmonary bypass and postoperative cognitive dysfunction

OBJECTIVE

To determine the effect of arterial normobaric hyperoxia during cardiopulmonary bypass (CPB) on postoperative neurocognitive function. The authors hypothesized that arterial hyperoxia during CPB is associated with neurocognitive decline at 6 weeks after cardiac surgery.

DESIGN

Retrospective study of patients undergoing cardiac surgery with CPB.

SETTING

A university hospital.

PARTICIPANTS

One thousand eighteen patients undergoing coronary artery bypass graft (CABG) or CABG + valve surgery with CPB who previously had been enrolled in prospective cognitive trials.

INTERVENTIONS

A battery of neurocognitive measures was administered at baseline and 6 weeks after surgery. Anesthetic and surgical care was managed as clinically indicated.

MEASUREMENTS AND MAIN RESULTS

Arterial hyperoxia was assessed primarily as the area under the curve (AUC) for the duration that PaO2 exceeded 200 mmHg during CPB and secondarily as the mean PaO2 during bypass, as a PaO2 = 300 mmHg at any point and as AUC>150 mmHg. Cognitive change was assessed both as a continuous change score and a dichotomous deficit rate. Multivariate regression accounting for age, years of education, baseline cognition, date of surgery, baseline postintubation PaO2, duration of CPB, and percent change in hematocrit level from baseline to lowest level during CPB revealed no significant association between hyperoxia during CPB and postoperative neurocognitive function.

CONCLUSIONS

Arterial hyperoxia during CPB was not associated with neurocognitive decline after 6 weeks in cardiac surgical patients.

Effect of 6% hydroxyethyl starch 130/0.4 in 0.9% sodium chloride (Voluven®) on complications after subarachnoid hemorrhage: a retrospective analysis

Background

6% Hydroxyethyl Starch 130/0.4 in 0.9% Sodium Chloride (Voluven®; 6% HES 130/0.4) is a colloid often used for fluid resuscitation in patients with subarachnoid hemorrhage (SAH), despite a lack of safety data for this use. The purpose of our study was to evaluate the effect of 6% HES 130/0.4 on major complications associated with SAH.

Methods

Medical records of all patients presenting between May 2010 and September 2012 with aneurysmal SAH were analyzed. Patients were divided in two groups based on the administration of 6% HES 130/0.4; HES group (n=57) and Non-HES group (n=72). The primary outcome included a composite of three major complications associated with SAH: Delayed Cerebral Ischemia (DCI), Hydrocephalus (HCP) requiring cerebrospinal fluid (CSF) shunting, and Rebleeding.

Results

The study groups were similar with respect to most characteristics except the incidences of hypertension, ischemic heart disease, Fisher grade and lowest hemoglobin during stay. The odds of developing the primary composite outcome was higher in the HES group [OR= 3.1(1.30-7.36), p=0.01]. The patients in the HES group had a significantly longer median duration of hospital (19 vs 14 days) and Neurointensive Care Unit stay (14 vs 10 days) compared to the Non HES group.

Conclusion

We observed increased complications after SAH with 6% HES 130/0.4 (Voluven®) administration. An adequately powered prospective randomized controlled trial into the safety of 6% HES 130/0.4 in this patient population is warranted.

Electronic supplementary material

The online version of this article (doi:10.1186/2193-1801-2-314) contains supplementary material, which is available to authorized users.

Changes in cerebral tissue oxygen saturation during anaesthetic-induced hypotension: an interpretation based on neurovascular coupling and cerebral autoregulation

There is currently no consensus regarding how to intervene in anaesthetic-induced hypotension. Whether or not the balance between cerebral oxygen supply and demand is maintained lacks adequate elucidation. It is thus intriguing to explore how cerebral tissue oxygen saturation is affected by anaesthetic-induced hypotension. Thirty-three patients scheduled for elective non-neurosurgical procedures were included in this study. Physiological measurements were performed immediately before induction with propofol and fentanyl and after tracheal intubation. Mean (SD) Bispectral index decreased from 84.3 (9.3) to 24.4 (8.0) (p<0.001). Mean arterial pressure decreased from 84.4 (10.6) mmHg to 53.6 (11.4) mmHg (p<0.001). However, cerebral tissue oxygen saturation remained stable (67.0 (9.4) % vs 67.5 (7.8) %, p=0.6). These results imply that the fine balance between cerebral oxygen supply and demand is not disrupted by anaesthetic-induced hypotension. An interpretation based on neurovascular coupling and cerebral autoregulation is proposed.

Tongue swelling and necrosis after brain tumor surgery

We present a case of tongue necrosis due to intraoperative pressure injury. A laryngeal mask airway with adhesive electrodes was inserted into the oropharynx, over an endotracheal tube, to facilitate glossopharyngeal nerve monitoring during craniotomy for a cerebellopontine angle tumor. The case, mechanisms of injury, and modifications to our current practice are discussed.

Anesthesia for endovascular treatment of acute ischemic stroke

The initial treatment of patients with acute ischemic stroke (AIS) focuses on rapid recanalization, which often includes the use of endovascular therapies. Endovascular treatment depends upon micronavigation of catheters and devices into the cerebral vasculature, which is easier and safer with a motionless patient. Unfortunately, many stroke patients are unable to communicate and sufficiently cooperate with the procedure. Thus, general anesthesia (GA) with endotracheal intubation provides an attractive means of keeping the patient comfortable and motionless during a procedure that could otherwise be lengthy and uncomfortable. However, several recent retrospective studies have shown an association between GA and poorer outcomes in comparison with conscious sedation for endovascular treatment of AIS, though prospective studies are lacking. The underlying reasons why GA might produce a worse outcome are unknown but may include hemodynamic instability and hypotension, delays in treatment, prolonged intubation with or without neuromuscular blockade, or even neurotoxicity of the anesthetic agent itself. Currently, the choice between GA and conscious sedation should be tailored to the individual patient, on the basis of neurologic deficits, airway and hemodynamic status, and treatment plan. The use of institutional treatment protocols may best support efficient and effective care for AIS patients undergoing endovascular therapy. Important components of such protocols would include parameters to choose anesthetic modality, timeliness of induction, blood pressure goals, minimization of neuromuscular blockade, and planned extubation at the end of the procedure.

Life-saving hemicraniectomy for fulminant acute disseminated encephalomyelitis

Fulminant acute disseminated encephalomyelitis (ADEM) is a rare demyelinating disorder, which most often occurs after an infection or vaccination. It frequently presents with focal neurologic signs and an altered sensorium. Patients often require critical care for airway management but are typically treated with medical therapy alone, including intravenous steroids and other immunotherapies. We present a case of dominant hemisphere fulminant ADEM in a patient who required neurosurgical intervention and a life-saving hemicraniectomy despite maximum medical therapy.

Transient Adenosine-Induced Asystole During the Surgical Treatment of Anterior Circulation Cerebral Aneurysms: Technical Note

BACKGROUND:

Transient adenosine-induced asystole is a reliable method for producing a short period of relative hypotension during surgical and endovascular procedures. Although the technique has been described in the endovascular treatment of brain arteriovenous malformations, aortic aneurysms, and posterior circulation cerebral aneurysms, little description of its use in anterior circulation aneurysms is available.

OBJECTIVE:

To assess the benefits of adenosine-induced transient asystole in complex anterior circulation aneurysms, to describe our experience in selected cases, and to provide the first experience of the use of adenosine in anterior circulation aneurysms.

METHODS:

The adenosine-induced cardiac arrest protocol allows us to titrate the duration of cardiac arrest on the basis of individual patient responses. The operative setup is the same as with all aneurysm clippings, with the addition of the placement of transcutaneous pacemakers as a precaution for prolonged bradycardia or asystole. Escalating doses of adenosine are given to determine the approximate dose that results in 30 seconds of asystole. When requested by the surgeon, the dose of adenosine is administered for definitive dissection and clipping. We present 6 cases in which this technique was used.

RESULTS:

The use of transient adenosine-induced asystole provided excellent circumferential visualization of the aneurysm neck and safe clip application. All patients did well neurologically and suffered no evidence of perioperative cerebral ischemia or delayed complication from the use of adenosine itself.

CONCLUSION:

Transient adenosine-induced asystole is a safe and effective technique in select circumstances that may aid in safe and effective aneurysm clipping. Along with the traditional techniques of brain relaxation, skull base approaches, and temporary clipping, adenosine-induced asystole facilitates circumferential visualization of the aneurysm neck and is another technique available to cerebrovascular surgeons.

Anesthesia and Sedation Practices Among Neurointerventionalists during Acute Ischemic Stroke Endovascular Therapy

BACKGROUND AND PURPOSE

Intra-arterial reperfusion therapies are expanding frontiers in acute ischemic stroke (AIS) management but there is considerable variability in clinical practice. The use of general anesthesia (GA) is one example. We aimed to better understand sedation practices in AIS.

METHODS

An online survey was distributed to the 68 active members of the Society of Vascular and Interventional Neurology (SVIN). Survey development was based on discussions at the SVIN Endovascular Stroke Round Table Meeting (Chicago, IL, 2008). The final survey contained 12 questions. Questions were developed as single and multiple-item responses; with an option for a free-text response.

RESULTS

There was a 72% survey response rate (N = 49/68). Respondents were interventional neurologists in practice 1-5 years (71.4%, N = 35). The mean (±SD) AIS interventions performed per year at the respondents' institutions was 42.5 ± 25, median 35.0 (IQR 20, 60). The most frequent anesthesia type used was GA (anesthesia team), then conscious sedation (nurse administered), monitored anesthesia care (anesthesia team), and finally local analgesia alone. There was a preference for GA because of eliminating movement (65.3% of respondents; N = 32/49), perceived procedural safety (59.2%, N = 29/49), and improved procedural efficacy (42.9%, N = 21/49). However, cited limitations to GA included risk of time delay (69.4%, N = 34), of propagating cerebral ischemia due to hypoperfusion or other complications (28.6%, N = 14), and lack of adequate anesthesia workforce (20.4%, N = 7).

CONCLUSIONS

The most frequent type of anesthesia used by Neurointerventionalists for AIS interventions is GA. Prior to making GA standard of care during AIS intervention, more data are needed about effects on clinical outcomes.

Perioperative hypothermia: use and therapeutic implications

Perioperative cerebral ischemic insults are common in some surgical procedures. The notion that induced hypothermia can be employed to improve outcome in surgical patients has persisted for six decades. Its principal application has been in the context of cardiothoracic and neurosurgery. Mild (32-35 degrees C) and moderate (26-31 degrees C) hypothermia have been utilized for numerous procedures involving the heart, but intensive research has found little or no benefit to outcome. This may, in part, be attributable to confounding effects associated with rewarming and lack of understanding of the mechanisms of injury. Evidence of efficacy of mild hypothermia is absent for cerebral aneurysm clipping and carotid endarterectomy. Deep hypothermia (18-25 degrees C) during circulatory arrest has been practiced in the repair of congenital heart disease, adult thoracic aortas, and giant intracranial aneurysms. There is little doubt of the protective efficacy of deep hypothermia, but continued efforts to refine its application may serve to enhance its utility. Recent evidence that mild hypothermia is efficacious in out-of-hospital cardiac arrest has implications for patients incurring anoxic or global ischemic brain insults during anesthesia and surgery, or perioperatively. Advances in preclinical models of ischemic/anoxic injury and cardiopulmonary bypass that allow definition of optimal cooling strategies and study of cellular and subcellular events during perioperative ischemia can add to our understanding of mechanisms of hypothermia efficacy and provide a rationale basis for its implementation in humans.

The effect of intravenous indigo carmine on near-infrared cerebral oximetry

The effects of IV-administered dyes on pulse oximetry have been well described. However, the effects on near-infrared cerebral oximetry have not been well documented. We report a series of four patients undergoing radical prostatectomy who were monitored with cerebral oximetry during surgery. After the administration of indigo carmine, intraoperative desaturations were observed for an extended period. Because clinical use of near-infrared cerebral oximetry is increasing, anesthesiologists should be aware of this issue.

Levetiracetam is neuroprotective in murine models of closed head injury and subarachnoid hemorrhage

OBJECTIVES

Prophylactic treatment with antiepileptic drugs is common practice following subarachnoid hemorrhage (SAH) and traumatic brain injury. However, commonly used antiepileptic drugs have multiple drug interactions, require frequent monitoring of serum levels, and are associated with adverse effects that may prompt discontinuation. In the current study, we test the hypothesis that levetiracetam, an anticonvulsant with favorable interaction and adverse event profiles, is neuroprotective in clinically relevant models of SAH and closed head injury (CHI).

METHODS

A single intravenous dose of vehicle, low-dose (18 mg/kg), or high-dose (54 mg/kg) levetiracetam was administered intravenously followed CHI. Functional assessments were performed on a daily basis, and histological assessments performed at 24 hours. In a separate series of experiments, mice were randomized to receive intravenous administration of vehicle, low-dose, or high-dose levetiracetam every 12 hours for 3 days following SAH. Functional endpoints were assessed daily, followed by measurement of MCA luminal diameter on day 3.

RESULTS

A single dose of levetiracetam improved functional and histological outcomes after CHI. This effect appeared specific for levetiracetam and was not associated with fosphenytoin treatment. Treatment with levetiracetam also improved functional outcomes and reduced vasospasm following SAH.

CONCLUSION

Levetiracetam is neuroprotective in clinically relevant animal models of SAH and CHI. Levetiracetam may be a therapeutic alternative to phenytoin following acute brain injury in the clinical setting when seizure prophylaxis is indicated.