Scalp blocks do not affect the accuracy of neuronavigation facial recognition registration.

PURPOSE: Scalp block is a regional anesthesia technique to reduce the sympathetic response to skull pin application and postoperative pain in patients undergoing craniotomy. These blocks are often performed prior to surgical incision, however, the effect that these blocks have on neuronavigation facial tracing recognition accuracy is unclear because they may distort facial anatomy. METHODS: A series of 25 patients undergoing supratentorial craniotomy were administered scalp blocks prior to surgical incision, and their effect on neuronavigation accuracy was assessed. Statistical analysis utilized a two-tailed matched t-test. RESULTS: Bilateral supraorbital and auriculotemporal scalp blocks did not significantly affect the accuracy of facial recognition registration. CONCLUSION: Scalp block does not interfere with neuronavigation facial recognition accuracy during neurosurgical procedures.

Incidence of Anaphylaxis to Sugammadex in a Single-Center Cohort of 19,821 Patients.

BACKGROUND: Sugammadex is a modified cyclodextrin that is being increasingly used in anesthetic practice worldwide for the reversal of the aminosteroid neuromuscular blockers rocuronium and vecuronium. Its safety profile, however, is incompletely understood. One such aspect is the incidence of anaphylactic reactions that occur after its administration. While several case reports exist in the literature, there is a paucity of information on the actual incidence of anaphylactic reactions. METHODS: A single-center retrospective chart review identified patients who experienced anaphylaxis to sugammadex in the institutional electronic medical record system. These charts were then reviewed to determine whether the etiology of anaphylaxis was sugammadex administration. RESULTS: Two patients experienced anaphylaxis to sugammadex, which occurred in a single institution cohort of 19,821 patients who received 23,446 total doses. This rate is markedly lower than the 1/300 that the manufacturer's package insert states and also lower than the 1/2500 that the only other large cohort study performed has reported. CONCLUSIONS: The incidence of anaphylaxis to sugammadex in this cohort of patients was 2 of 19,821 patients, who received a total of 23,446 doses.

Effect of Head Rotation on Jugular Vein Patency Under General Anesthesia.

Head rotation causes compression and occlusion of the ipsilateral internal jugular (IJ) vein. This can result in raised intracranial pressure and increased bleeding if the patient is having or has recently had surgery. The amount of head rotation in adults resulting in occlusion of the ipsilateral IJ vein is unknown however. We measured the amount of head turn that produced occlusion of the ipsilateral IJ vein in 25 patients having surgery under general anesthesia. On average, 80% of IJ veins occlude at a mean of 55.6° on the left and 53.3° on the right.

Excipients in Anesthesia Medications.

Medications used in anesthesiology contain both pharmacologically active compounds and additional additives that are usually regarded as being pharmacologically inactive. These additives, called excipients, serve diverse functions. Despite being labeled inert, excipients are not necessarily benign substances. Anesthesiologists should have a clear understanding of their chemical properties and the potential for adverse reactions. This report catalogs the excipients found in drugs commonly used in anesthesiology, provides a brief description of their function, and documents examples from the literature regarding their adverse effects.

The use of end-tidal argon to detect venous air embolism: foiled by "fake oxygen!"

Venous air-embolism (VAE) potentially catastrophic complication surgery. Based on previous data using changes in end-tidal nitrogen as an indicator of VAE, we surmised that changes in end-tidal argon (EtAr) may be an indicator of VAE. We sought to determine if a commercial mass-spectrometer (PCT Proline Analyzer 61700-8 Class 85, Ametek, Pittsburgh, PA 15238) could be used to detect changes in EtAr in an invitro model. A Drager Apollo™ (Drager, Lubeck, Germany) anesthesia machine was used to ventilate a dummy lung (2 L bag) with a minute ventilation of 6 L/min in 100% oxygen. The quadrupole mass-spectrometer (sampling at 0.0004 atm-cc/sec) was attached to the end-tidal inlet of the machine. Room air (1-60 mL) was injected into the dummy lung to simulate VAE. A strong baseline ion-current (1.2 × 10-12 amps) of argon was noted. Due to this contamination we were unable to detect "VAE" events of injected air. Argon represents approximately 0.93% of room air, or about 9300 parts per million (ppm). We detected about 2000 ppm argon in medical-grade oxygen (or 0.2%), limiting our ability to detect changes in EtAr. This is a USP-accepted contaminant, rendering this technology is insensitive for early, rapid detection of VAE. We assumed medical grade oxygen was pure and were surprised to learn otherwise. We want to share this likely largely unknown finding with the medical community.

Fluid management concepts for severe neurological illness: an overview.

PURPOSE OF REVIEW: The acute care of a patient with severe neurological injury is organized around one relatively straightforward goal: avoid brain ischemia. A coherent strategy for fluid management in these patients has been particularly elusive, and a well considered fluid management strategy is essential for patients with critical neurological illness. RECENT FINDINGS: In this review, several gaps in our collective knowledge are summarized, including a rigorous definition of volume status that can be practically measured; an understanding of how electrolyte derangements interact with therapy; a measurable endpoint against which we can titrate our patients' fluid balance; and agreement on the composition of fluid we should give in various clinical contexts. SUMMARY: As the possibility grows closer that we can monitor the physiological parameters with direct relevance for neurological outcomes and the various complications associated with neurocritical illness, we may finally move away from static therapy recommendations, and toward individualized, precise therapy. Although we believe therapy should ultimately be individualized rather than standardized, it is clear that the monitoring tools and analytical methods used ought to be standardized to facilitate appropriately powered, prospective clinical outcome trials.

Awake craniotomy in a developmentally delayed blind man with cognitive deficits.

PURPOSE: To describe the complex perioperative considerations and anesthetic management of a cognitively delayed blind adult male who underwent awake craniotomy to remove a left anterior temporal lobe epileptic focus. CLINICAL FEATURES: A 28-yr-old left-handed blind cognitively delayed man was scheduled for awake craniotomy to resect a left anterior temporal lobe epileptic focus due to intractable epilepsy despite multiple medications. His medical history was also significant for retinopathy of prematurity that rendered him legally blind in both eyes and an intracerebral hemorrhage shortly after birth that resulted in a chronic brain injury and developmental delay. His cognitive capacity was comparable with that of an eight year old. Since patient cooperation was the primary concern during the awake electrocorticography phase of surgery, careful assessment of the patient's ability to tolerate the procedure was undertaken. There was extensive planning between surgeons and anesthesiologists, and a patient-specific pharmacological strategy was devised to facilitate surgery. The operation proceeded without complication, the patient has remained seizure-free since the procedure, and his quality of life has improved dramatically. CONCLUSION: This case shows that careful patient assessment, effective interdisciplinary communication, and a carefully tailored anesthetic strategy can facilitate an awake craniotomy in a potentially uncooperative adult patient with diminished mental capacity and sensory deficits.

Intraoperative Seizure Under General Anesthesia Not Detected by EEG: A Case Report.

Intraoperative seizures under general anesthesia are infrequent. However, seizure activity under general anesthesia confirmed by contemporaneous EEG has been reported. We describe the case of a 39-year-old female undergoing right frontal brain tumor resection who experienced an intraoperative seizure. Intraoperative neuromonitoring was utilized and included four channels of EEG, somatosensory evoked potentials (SSEP), and transcranial motor evoked potentials (MEP). During this operation, characteristic motor manifestations of a seizure occurred. However, the EEG did not demonstrate seizure activity due to limitations in EEG lead placement. Post-operatively in the ICU, motor manifestations of seizure activity continued, and subsequent EEG recordings demonstrated classic seizure activity. Due to the previous hemicraniectomy, corkscrew EEG electrodes were not placed over the right skull defect, thereby failing to detect the intraoperative seizure. Anesthesiologists should be aware that limitations with EEG electrode placement can fail to detect intraoperative seizures, and treatment to extinguish the seizure should proceed in an emergent fashion.

Differences in Perioperative Management of Patients Undergoing Complex Spine Surgery: A Global Perspective.

BACKGROUND: The aim of this survey was to understand institutional spine surgery practices and their concordance with published best practices/recommendations. METHODS: Using a global internet-based survey examining perioperative spine surgery practice, reported institutional spine pathway elements (n=139) were compared with the level of evidence published in guideline recommendations. The concordance of clinical practice with guidelines was categorized as poor (≤20%), fair (21%-40%), moderate (41%-60%), good (61%-80%), or very good (81%-100%). RESULTS: Seventy-two of 409 (17.6%) institutional contacts started the survey, of which 31 (7.6%) completed the survey. Six (19.4%) of the completed surveys were from respondents in low/middle-income countries, and 25 (80.6%) were from respondents in high-income countries. Forty-one incomplete surveys were not included in the final analysis, as most were less than 40% complete. Five of 139 (3.6%) reported elements had very good concordance for the entire cohort; hospitals with spine surgery pathways reported 18 elements with very good concordance, whereas institutions without spine surgery pathways reported only 1 element with very good concordance. Reported spine pathways included between 7 and 47 separate pathway elements. There were 87 unique elements in the reviewed pathways. Only 3 of 87 (3.4%) elements with high-quality evidence demonstrated very good practice concordance. CONCLUSIONS: This global survey-based study identified practice variation and low adoption rates of high-quality evidence in the care of patients undergoing complex spine surgery.

Perioperative Care of Patients Undergoing Major Complex Spinal Instrumentation Surgery: Clinical Practice Guidelines From the Society for Neuroscience in Anesthesiology and Critical Care.

Evidence-based standardization of the perioperative management of patients undergoing complex spine surgery can improve outcomes such as enhanced patient satisfaction, reduced intensive care and hospital length of stay, and reduced costs. The Society for Neuroscience in Anesthesiology and Critical Care (SNACC) tasked an expert group to review existing evidence and generate recommendations for the perioperative management of patients undergoing complex spine surgery, defined as surgery on 2 or more thoracic and/or lumbar spine levels. Institutional clinical management protocols can be constructed based on the elements included in these clinical practice guidelines, and the evidence presented.

Rapid Blood Transfusion: The Importance of Hemodilution and Needleless Connectors.

INTRODUCTION:  Large-bore cannulas are critical to administering IV fluids and blood products during resuscitation and treatment of hemorrhage. Although catheter flow rates for crystalloid solutions are well defined, rapid administration of blood products is poorly characterized. In this in vitro study, we examined the effects of hemodilution and needleless connectors on red blood cell (RBC) flow rates. METHODS:  To determine RBC flow rates through large-bore cannulae, a crystalloid solution (Normosol®, Hospira, Lake Forest, IL) or RBC units were warmed and delivered under pressure (360 mmHg) using a Level 1 H-1200 Fast Flow Fluid Warmer (Smiths Medical, St. Paul, MN). Flow rates for crystalloid, packed RBCs and diluted RBCs were determined using a stopwatch. Additionally, the effect of the MaxPlus® clear needleless connector (CareFusion, San Diego, CA) was measured in all three infusion groups. RESULTS:  Flow rates for undiluted RBC units were 53% slower than crystalloid solution (220 mL/min vs. 463 mL/min; p=0.0003), however, when RBC units were diluted to a hematocrit of ~30% flow rate improved to 369 mL/min (p=0.005). The addition of the MaxPlus® needleless connector reduced flow of crystalloid solution by 47% (245 mL/min; p=0.0001), undiluted RBCs by 64% (78 mL/min; p=0.01), and diluted RBCs by 51% (180 mL/min; p=0.00003). Compared to undiluted RBC units, hemodilution increased RBC delivery rate through a MaxPlus® connector by 130% (p=0.004) and by 68% (p=0.02) when the catheter was directly connected to the Level 1 tubing (MaxPlus® excluded). CONCLUSION:  In settings requiring rapid transfusion of RBC units, needleless connectors should not be used and hemodilution should be considered in order to decrease the time required to deliver an equivalent red cell mass.

Intraoperative Transcranial Motor-evoked Potential Stimulation Does Not Seem to Cause Seizures.

BACKGROUND: Intraoperative neurophysiological monitoring is of critical importance in evaluating the functional integrity of the central nervous system during surgery of the central or peripheral nervous system. In a large recent study, transcranial motor-evoked potentials (TcMEPs) were found to be associated with a 0.7% risk of inducing a seizure as diagnosed by clinical observation and electromyography in patients having general anesthesia with intravenous anesthetics. The gold standard for seizure diagnosis, however, is electroencephalography (EEG). The aim of this single-institution retrospective study is to ascertain the risk of intraoperative seizures detected using EEG during surgeries in adult patients undergoing intraoperative monitoring with TcMEPs. METHODS: The authors retrospectively reviewed the intraoperative EEG records of 1175 patients anesthetized with a variety of anesthetic agents, including volatile and intravenous anesthetics, to ascertain the rate of EEG-diagnosed seizures attributable to TcMEPs. RESULT: Our analysis did not reveal a single seizure event attributable to TcMEPs in 1175 patients. CONCLUSION: The intraoperative use of TcMEPs does not seem to cause seizures.

Paradoxical Critical Hyperkalemia After Acetazolamide for Cerebrovascular Reactivity Study: A Case Report.

We present the case of a 42-year-old man with moyamoya disease presenting for cerebral revascularization surgery who developed critical hyperkalemia following a single intravenous (iv) dose of 1000 mg of acetazolamide 1 day preoperatively for a cerebrovascular reactivity study. His potassium increased from 5.1 to 6.7 mmol/L. Prompt treatment of this abnormality allowed this patient to undergo surgery the next day uneventfully. A paradoxical, critical increase in potassium can result from a single 1000-mg iv dose of acetazolamide.

Intraoperative Kirschner Wire Migration during Robotic Minimally Invasive Spine Surgery.

We present the case of a 58-year-old woman who underwent a minimally invasive robotic-assisted L4-S1 instrumentation and fusion which was complicated by a Kirschner wire (K-wire) fracture and migration into the abdominal cavity necessitating emergent exploratory laparotomy. Retrieval of the K-wire proceeded without incident, and the patient had an otherwise uneventful surgery and recovery. This is the first such case description reported in the literature. As minimally invasive robotic-assisted spine procedures become more common, it is essential for the anesthesiologist to be familiar with potential complications to manage such patients in the perioperative period optimally.

Acetaminophen Does Not Reduce Postoperative Opiate Consumption in Patients Undergoing Craniotomy for Cerebral Revascularization: A Randomized Control Trial.

Background Postoperative management in patients undergoing craniotomy is unique and challenging. We utilized a population of patients who underwent bilateral extracranial-to-intracranial (EC-IC bypass) revascularization procedures for moyamoya disease and hypothesized that 1 gram (gm) of intravenous (IV) acetaminophen given immediately after intubation and again 45 minutes prior to the end of craniotomy may be more effective than saline in minimizing opiate consumption and decreasing pain scores. Methods In a double-blind, randomized, placebo-controlled crossover pilot study, 40 craniotomies in 20 patients were studied. A random number generator assigned patients to receive either 1 gram of IV acetaminophen or an equal volume of normal saline immediately after intubation and again 45 minutes prior to the end of their first operation. For the second surgery, patients received the study drug (IV acetaminophen or normal saline) that they did not receive during their first surgery. Results In the IV acetaminophen group, the average 24-hour postoperative fentanyl equivalent consumption was decreased but the difference was not statistically significant: 228 micrograms compared to 312 micrograms in the placebo group (Figure 1; p = 0.09). Pain scores did not significantly differ between the IV acetaminophen group and the placebo group in postoperative hours 0-12 (Figure 2; p = 0.44) or 24 (Figure 3; p = 0.77). Conclusion Our study demonstrates that in patients receiving bilateral craniotomies for moyamoya disease, IV acetaminophen when given immediately after intubation and again 45 minutes prior to closure does not significantly decrease 12- or 24-hour postoperative opiate consumption.