Showing papers in "Anesthesiology in 2013"

practice Guidelines for Management of the Difficult airway An Updated Report by the American Society of Anesthesiologists Task Force on Management of the Difficult Airway

Abstract: RACTICE Guidelines are systematically developed recommendations that assist the practitioner and patient in making decisions about health care. These recommendations may be adopted, modified, or rejected according to clinical needs and constraints and are not intended to replace local institutional policies. In addition, Practice Guidelines developed by the American Society of Anesthesiologists (ASA) are not intended as standards or absolute requirements, and their use cannot guarantee any specific outcome. Practice Guidelines are subject to revision as warranted by the evolution of medical knowledge, technology, and practice. They provide basic recommendations that are supported by a synthesis and analysis of the current literature, expert and practitioner opinion, open-forum commentary, and clinical feasibility data. This document updates the “Practice Guidelines for Management of the Difficult Airway: An Updated Report by

Pain intensity on the first day after surgery: a prospective cohort study comparing 179 surgical procedures.

Abstract: Background Severe pain after surgery remains a major problem, occurring in 20-40% of patients. Despite numerous published studies, the degree of pain following many types of surgery in everyday clinical practice is unknown. To improve postoperative pain therapy and develop procedure-specific, optimized pain-treatment protocols, types of surgery that may result in severe postoperative pain in everyday practice must first be identified. Methods This study considered 115,775 patients from 578 surgical wards in 105 German hospitals. A total of 70,764 patients met the inclusion criteria. On the first postoperative day, patients were asked to rate their worst pain intensity since surgery (numeric rating scale, 0-10). All surgical procedures were assigned to 529 well-defined groups. When a group contained fewer than 20 patients, the data were excluded from analysis. Finally, 50,523 patients from 179 surgical groups were compared. Results The 40 procedures with the highest pain scores (median numeric rating scale, 6-7) included 22 orthopedic/trauma procedures on the extremities. Patients reported high pain scores after many "minor" surgical procedures, including appendectomy, cholecystectomy, hemorrhoidectomy, and tonsillectomy, which ranked among the 25 procedures with highest pain intensities. A number of "major" abdominal surgeries resulted in comparatively low pain scores, often because of sufficient epidural analgesia. Conclusions Several common minor- to medium-level surgical procedures, including some with laparoscopic approaches, resulted in unexpectedly high levels of postoperative pain. To reduce the number of patients suffering from severe pain, patients undergoing so-called minor surgery should be monitored more closely, and postsurgical pain treatment needs to comply with existing procedure-specific pain-treatment recommendations.

Relationship between intraoperative mean arterial pressure and clinical outcomes after noncardiac surgery: toward an empirical definition of hypotension.

Abstract: Background:Intraoperative hypotension may contribute to postoperative acute kidney injury (AKI) and myocardial injury, but what blood pressures are unsafe is unclear. The authors evaluated the association between the intraoperative mean arterial pressure (MAP) and the risk of AKI and myocardial inju

Development and psychometric evaluation of a postoperative quality of recovery score: the QoR-15.

Abstract: BACKGROUND Quality of recovery (QoR) after anesthesia is an important measure of the early postoperative health status of patients The aim was to develop a short-form postoperative QoR score, and test its validity, reliability, responsiveness, and clinical acceptability and feasibility METHODS Based on extensive clinical and research experience with the 40-item QoR-40, the strongest psychometrically performing items from each of the five dimensions of the QoR-40 were selected to create a short-form version, the QoR-15 This was then evaluated in 127 adult patients after general anesthesia and surgery RESULTS There was good convergent validity between the QoR-15 and a global QoR visual analog scale (r = 068, P < 00005) Construct validity was supported by a negative correlation with duration of surgery (r = -049, P < 00005), time spent in the postanesthesia care unit (r = -041, P < 00005), and duration of hospital stay (r = -053, P < 00005) There was also excellent internal consistency (085), split-half reliability (078), and test-retest reliability (ri = 099), all P < 00005 Responsiveness was excellent with an effect size of 135 and a standardized response mean of 104 The mean ± SD time to complete the QoR-15 was 24 ± 08 min CONCLUSIONS The QoR-15 provides a valid, extensive, and yet efficient evaluation of postoperative QoR

Perioperative comparative effectiveness of anesthetic technique in orthopedic patients.

Abstract: Background The impact of anesthetic technique on perioperative outcomes remains controversial. We studied a large national sample of primary joint arthroplasty recipients and hypothesized that neuraxial anesthesia favorably influences perioperative outcomes.

Protective Mechanical Ventilation during General Anesthesia for Open Abdominal Surgery Improves Postoperative Pulmonary Function

Abstract: The impact of intraoperative ventilation on postoperative pulmonary complications is not defined. The authors aimed at determining the effectiveness of protective mechanical ventilation during open abdominal surgery on a modified Clinical Pulmonary Infection Score as primary outcome and postoperative pulmonary function. Prospective randomized, open-label, clinical trial performed in 56 patients scheduled to undergo elective open abdominal surgery lasting more than 2 h. Patients were assigned by envelopes to mechanical ventilation with tidal volume of 9 ml/kg ideal body weight and zero-positive end-expiratory pressure (standard ventilation strategy) or tidal volumes of 7 ml/kg ideal body weight, 10 cm H2O positive end-expiratory pressure, and recruitment maneuvers (protective ventilation strategy). Modified Clinical Pulmonary Infection Score, gas exchange, and pulmonary functional tests were measured preoperatively, as well as at days 1, 3, and 5 after surgery. Patients ventilated protectively showed better pulmonary functional tests up to day 5, fewer alterations on chest x-ray up to day 3 and higher arterial oxygenation in air at days 1, 3, and 5 (mmHg; mean ± SD): 77.1 ± 13.0 versus 64.9 ± 11.3 (P = 0.0006), 80.5 ± 10.1 versus 69.7 ± 9.3 (P = 0.0002), and 82.1 ± 10.7 versus 78.5 ± 21.7 (P = 0.44) respectively. The modified Clinical Pulmonary Infection Score was lower in the protective ventilation strategy at days 1 and 3. The percentage of patients in hospital at day 28 after surgery was not different between groups (7 vs. 15% respectively, P = 0.42). A protective ventilation strategy during abdominal surgery lasting more than 2 h improved respiratory function and reduced the modified Clinical Pulmonary Infection Score without affecting length of hospital stay

Disruption of frontal-parietal communication by ketamine, propofol, and sevoflurane.

Abstract: INTRODUCTION Directional connectivity from anterior to posterior brain regions (or "feedback" connectivity) has been shown to be inhibited by propofol and sevoflurane. In this study the authors tested the hypothesis that ketamine would also inhibit cortical feedback connectivity in frontoparietal networks. METHODS Surgical patients (n = 30) were recruited for induction of anesthesia with intravenous ketamine (2 mg/kg); electroencephalography of the frontal and parietal regions was acquired. The authors used normalized symbolic transfer entropy, a computational method based on information theory, to measure directional connectivity across frontal and parietal regions. Statistical analysis of transfer entropy measures was performed with the permutation test and the time-shift test to exclude false-positive connectivity. For comparison, the authors used normalized symbolic transfer entropy to reanalyze electroencephalographic data gathered from surgical patients receiving either propofol (n = 9) or sevoflurane (n = 9) for anesthetic induction. RESULTS Ketamine reduced alpha power and increased gamma power, in contrast to both propofol and sevoflurane. During administration of ketamine, feedback connectivity gradually diminished and was significantly inhibited after loss of consciousness (mean ± SD of baseline and anesthesia: 0.0074 ± 0.003 and 0.0055 ± 0.0027; F(5, 179) = 7.785, P < 0.0001). By contrast, feedforward connectivity was preserved during exposure to ketamine (mean ± SD of baseline and anesthesia: 0.0041 ± 0.0015 and 0.0046 ± 0.0018; F(5, 179) = 2.07; P = 0.072). Like ketamine, propofol and sevoflurane selectively inhibited feedback connectivity after anesthetic induction. CONCLUSIONS Diverse anesthetics disrupt frontal-parietal communication, despite molecular and neurophysiologic differences. Analysis of directional connectivity in frontal-parietal networks could provide a common metric of general anesthesia and insight into the cognitive neuroscience of anesthetic-induced unconsciousness.

Selective Anesthesia-induced Neuroinflammation in Developing Mouse Brain and Cognitive Impairment

Abstract: BACKGROUND : Recent population studies have suggested that children with multiple exposures to anesthesia and surgery at an early age are at an increased risk of cognitive impairment. The authors therefore have established an animal model with single versus multiple exposures of anesthetic(s) in young versus adult mice, aiming to distinguish the role of different types of anesthesia in cognitive impairment. METHODS : Six- and 60-day-old mice were exposed to various anesthesia regimens. The authors then determined the effects of the anesthesia on learning and memory function, levels of proinflammatory cytokine interleukin-6 and tumor necrosis factor-α in brain tissues, and the amount of ionized calcium-binding adaptor molecule 1-positive cells, the marker of microglia activation, in the hippocampus. RESULTS : In this article, the authors show that anesthesia with 3% sevoflurane for 2 h daily for 3 days induced cognitive impairment and neuroinflammation (e.g., increased interleukin-6 levels, 151 ± 2.3% [mean ± SD] vs. 100 ± 9.0%, P = 0.035, n = 6) in young but not in adult mice. Anesthesia with 3% sevoflurane for 2 h daily for 1 day and 9% desflurane for 2 h daily for 3 days induced neither cognitive impairment nor neuroinflammation. Finally, an enriched environment and antiinflammatory treatment (ketorolac) ameliorated the sevoflurane-induced cognitive impairment. CONCLUSIONS : Anesthesia-induced cognitive impairment may depend on developmental stage, anesthetic agent, and number of exposures. These findings also suggest the cellular basis and the potential prevention and treatment strategies for anesthesia-induced cognitive impairment, which may ultimately lead to safer anesthesia care and better postoperative outcomes for children.

Incidence, predictors, and outcome of difficult mask ventilation combined with difficult laryngoscopy: a report from the multicenter perioperative outcomes group.

Abstract: Background Research regarding difficult mask ventilation (DMV) combined with difficult laryngoscopy (DL) is extremely limited even though each technique serves as a rescue for one another. Methods Four tertiary care centers participating in the Multicenter Perioperative Outcomes Group used a consistent structured patient history and airway examination and airway outcome definition. DMV was defined as grade 3 or 4 mask ventilation, and DL was defined as grade 3 or 4 laryngoscopic view or four or more intubation attempts. The primary outcome was DMV combined with DL. Patients with the primary outcome were compared to those without the primary outcome to identify predictors of DMV combined with DL using a non-parsimonious logistic regression. Results Of 492,239 cases performed at four institutions among adult patients, 176,679 included a documented face mask ventilation and laryngoscopy attempt. Six hundred ninety-eight patients experienced the primary outcome, an overall incidence of 0.40%. One patient required an emergent cricothyrotomy, 177 were intubated using direct laryngoscopy, 284 using direct laryngoscopy with bougie introducer, 163 using videolaryngoscopy, and 73 using other techniques. Independent predictors of the primary outcome included age 46 yr or more, body mass index 30 or more, male sex, Mallampati III or IV, neck mass or radiation, limited thyromental distance, sleep apnea, presence of teeth, beard, thick neck, limited cervical spine mobility, and limited jaw protrusion (c-statistic 0.84 [95% CI, 0.82-0.87]). Conclusion DMV combined with DL is an infrequent but not rare phenomenon. Most patients can be managed with the use of direct or videolaryngoscopy. An easy to use unweighted risk scale has robust discriminating capacity.

Risk stratification tools for predicting morbidity and mortality in adult patients undergoing major surgery: qualitative systematic review

Abstract: Risk stratification is essential for both clinical risk prediction and comparative audit. There are a variety of risk stratification tools available for use in major noncardiac surgery, but their discrimination and calibration have not previously been systematically reviewed in heterogeneous patient cohorts.Embase, MEDLINE, and Web of Science were searched for studies published between January 1, 1980 and August 6, 2011 in adult patients undergoing major noncardiac, nonneurological surgery. Twenty-seven studies evaluating 34 risk stratification tools were identified which met inclusion criteria. The Portsmouth-Physiology and Operative Severity Score for the enUmeration of Mortality and the Surgical Risk Scale were demonstrated to be the most consistently accurate tools that have been validated in multiple studies; however, both have limitations. Future work should focus on further evaluation of these and other parsimonious risk predictors, including validation in international cohorts. There is also a need for studies examining the impact that the use of these tools has on clinical decision making and patient outcome.

Effects of fibrinogen concentrate as first-line therapy during major aortic replacement surgery: a randomized, placebo-controlled trial.

Abstract: BACKGROUND Fibrinogen is suggested to play an important role in managing major bleeding. However, clinical evidence regarding the effect of fibrinogen concentrate (derived from human plasma) on transfusion is limited. The authors assessed whether fibrinogen concentrate can reduce blood transfusion when given as intraoperative, targeted, first-line hemostatic therapy in bleeding patients undergoing aortic replacement surgery. METHODS In this single-center, prospective, placebo-controlled, double-blind study, patients aged 18 yr or older undergoing elective thoracic or thoracoabdominal aortic replacement surgery involving cardiopulmonary bypass were randomized to fibrinogen concentrate or placebo, administered intraoperatively. Study medication was given if patients had clinically relevant coagulopathic bleeding immediately after removal from cardiopulmonary bypass and completion of surgical hemostasis. Dosing was individualized using the fibrin-based thromboelastometry test. If bleeding continued, a standardized transfusion protocol was followed. RESULTS Twenty-nine patients in the fibrinogen concentrate group and 32 patients in the placebo group were eligible for the efficacy analysis. During the first 24 h after the administration of study medication, patients in the fibrinogen concentrate group received fewer allogeneic blood components than did patients in the placebo group (median, 2 vs. 13 U; P < 0.001; primary endpoint). Total avoidance of transfusion was achieved in 13 (45%) of 29 patients in the fibrinogen concentrate group, whereas 32 (100%) of 32 patients in the placebo group received transfusion (P < 0.001). There was no observed safety concern with using fibrinogen concentrate during aortic surgery. CONCLUSIONS Hemostatic therapy with fibrinogen concentrate in patients undergoing aortic surgery significantly reduced the transfusion of allogeneic blood products. Larger multicenter studies are necessary to confirm the role of fibrinogen concentrate in the management of perioperative bleeding in patients with life-threatening coagulopathy.

Practice guidelines for postanesthetic care: an updated report by the American Society of Anesthesiologists Task Force on Postanesthetic Care.

Abstract: RACTICE Guidelines are systematically developed recommendations that assist the practitioner and patient in making decisions about health care. These recommendations may be adopted, modified, or rejected according to clinical needs and constraints, and are not intended to replace local institutional policies. In addition, Practice Guidelines developed by the American Society of Anesthesiologists (ASA) are not intended as standards or absolute requirements, and their use cannot guarantee any specific outcome. Practice Guidelines are subject to revision as warranted by the evolution of medical knowledge, technology, and practice. They provide basic recommendations that are supported by a synthesis and analysis of the current literature, expert and practitioner opinion, open forum commentary, and clinical feasibility data. This document updates the “Practice Guidelines for Postanesthetic Care: A Report by the American Society of Anesthesiologists Task Force on Postanesthetic Care,” adopted by the ASA in 2001 and published in 2002.*

Perioperative systemic magnesium to minimize postoperative pain: a meta-analysis of randomized controlled trials.

Abstract: Background:Systemic magnesium has been used to minimize postoperative pain with conflicting results by clinical studies. It remains unknown whether the administration of perioperative systemic magnesium can minimize postoperative pain. The objective of the current investigation was to evaluate the e

Adductor canal block versus femoral nerve block and quadriceps strength: a randomized, double-blind, placebo-controlled, crossover study in healthy volunteers.

Abstract: Background:The authors hypothesized that the adductor canal block (ACB), a predominant sensory blockade, reduces quadriceps strength compared with placebo (primary endpoint, area under the curve, 0.5–6 h), but less than the femoral nerve block (FNB; secondary endpoint). Other secondary endpoints wer

Pregabalin rectifies aberrant brain chemistry, connectivity, and functional response in chronic pain patients.

Abstract: Chronic pain remains a significant challenge for modern health care as its pathologic mechanisms are largely unknown and preclinical animal models suffer from limitations in assessing this complex subjective experience. However, human brain neuroimaging techniques enable the assessment of functional and neurochemical alterations in patients experiencing chronic pain and how these factors may dynamically change with pharmacologic treatment.

Development and validation of a score for prediction of postoperative respiratory complications.

Abstract: Background:Postoperative respiratory failure is associated with increased morbidity and mortality, as well as high costs of hospital care.Methods:Using electronic anesthesia records, billing data, and chart review, the authors developed and validated a score predicting reintubation in the hospital a

Real-time two-dimensional ultrasound guidance for central venous cannulation: a meta-analysis.

Abstract: Background Use of ultrasound-guided techniques to facilitate central venous cannulation (CVC) may reduce the risk of misplacement and complications. A meta-analysis was conducted to compare real-time two-dimensional ultrasound (RTUS) guidance technique with anatomical landmark technique for CVC to determine whether RTUS has any advantages. Methods Randomized studies comparing outcomes in patients undergoing CVC with either RTUS or landmark technique were retrieved from PubMed, ISI Web of Knowledge, EMBASE, and OVID EBM Reviews from their inception to March 2012. Results Twenty-six studies involving 4,185 CVC procedures met the inclusion criteria. Compared with landmark technique, patients with RTUS had a pooled relative risk (RR) of 0.18 (95% CI: 0.10-0.32) for cannulation failure, 0.25 (95% CI: 0.15-0.42) for arterial puncture, 0.30 (95% CI: 0.19-0.46) for hematoma, 0.21 (95% CI: 0.06-0.73) for pneumothorax, and 0.10 (95% CI: 0.02-0.54) for hemothorax from random-effects models. However, RTUS did not show a reduction in the risk of cannulation failure (RR = 0.26, 95% CI: 0.03-2.55), arterial puncture (RR = 0.34, 95% CI: 0.05-2.60), hematoma (RR = 0.13, 95% CI: 0.01-2.42), pneumothorax (RR = 0.40, 95% CI: 0.02-9.61), and hemothorax (RR = 0.40, 95% CI: 0.02-9.61) in children or infants when the limited data were analyzed. Conclusions Among adults receiving CVC, RTUS was associated with decreased risks of cannulation failure, arterial puncture, hematoma, and hemothorax. Additional data of randomized studies are necessary to evaluate these outcomes in pediatric patients.

Situation Awareness in Anesthesia Concept and Research

Abstract: Accurate situation awareness (SA) of medical staff is integral for providing optimal performance during the treatment of patients. An understanding of SA and how it affects treatment of patients is therefore crucial for patient safety and an essential element for research on human factors in anesthesia. This review describes the concept of SA in the anesthesia environment, including the interaction with associated medical teams. Different approaches for its assessment in the work environment of anesthesia are provided. Factors contributing to expertise in SA are described and approaches for the training of SA in anesthesia are discussed, as are types of errors that occur during the development of SA. Finally, the authors briefly present strategies to improve SA during daily anesthesia practice through altered designs of monitor displays.

Survey criteria for fibromyalgia independently predict increased postoperative opioid consumption after lower-extremity joint arthroplasty: a prospective, observational cohort study.

Abstract: Background Variance in pain following total knee and hip arthroplasty may be due to a number of procedural and peripheral factors but also, in some individuals, to aberrant central pain processing as is described in conditions like fibromyalgia. To test this hypothesis, we conducted a prospective, observational cohort study of patients undergoing lower extremity joint arthroplasty.

Isoflurane, a commonly used volatile anesthetic, enhances renal cancer growth and malignant potential via the hypoxia-inducible factor cellular signaling pathway in vitro.

Abstract: Background: Growing evidence indicates that perioperative factors, including choice of anesthetic, affect cancer recurrence after surgery although little is known about the effect of anesthetics on cancer cells themselves. Certain anesthetics are known to affect hypoxia cell signaling mechanisms in healthy cells by up-regulating hypoxia-inducible factors (HIFs). HIFs are also heavily implicated in tumorigenesis and high levels correlate with poor prognosis. Methods: Renal cell carcinoma (RCC4) cells were exposed to isoflurane for 2 h at various concentrations (0.5–2%). HIF-1α, HIF-2α, phospho-Akt, and vascular endothelial growth factor A levels were measured by immunoblotting at various time points (0–24 h). Cell migration was measured across various components of extracellular matrix, and immunocytochemistry was used to analyze proliferation rate and cytoskeletal changes. Results: Isoflurane up-regulated levels of HIF-1α and HIF-2α and intensified expression of vascular endothelial growth factor A. Exposed cultures contained significantly more cells (1.81 ± 0.25 vs. 1.00 of control; P = 0.03) and actively proliferating cells (89.4 ± 2.80 vs. 64.74 ± 7.09% of control; P = 0.016) than controls. These effects were abrogated when cells were pretreated with the Akt inhibitor, LY294002. Exposed cells also exhibited greater migration on tissue culture–coated (F = 16.89; P = 0.0008), collagen-coated (F = 20.99; P = 0.0003), and fibronectin-coated wells (F = 8.21; P = 0.011) as along with dramatic cytoskeletal rearrangement, with changes to both filamentous actin and α-tubulin. Conclusions: These results provide evidence that a frequently used anesthetic can exert a protumorigenic effect on a human cancer cell line. This may represent an important contributory factor to high recurrence rates observed after surgery.

Sevoflurane anesthesia in pregnant mice induces neurotoxicity in fetal and offspring mice.

Abstract: Background: Each year, over 75,000 pregnant women in the United States undergo anesthesia care. The authors set out to assess the effects of the anesthetic sevoflurane on neurotoxicity in pregnant mice and on learning and memory in fetal and offspring mice. Methods: Pregnant mice (gestational day 14) and mouse primary neurons were treated with 2.5% sevoflurane for 2 h and 4.1% sevoflurane for 6 h, respectively. Brain tissues of both fetal and offspring mice (P31) and the primary neurons were harvested and subjected to Western blot and immunohistochemistry to assess interleukin-6, the synaptic markers postsynaptic density-95 and synaptophysin, and caspase-3 levels. Separately, learning and memory function in the offspring mice was determined in the Morris water maze. Results: Sevoflurane anesthesia in pregnant mice induced caspase-3 activation, increased interleukin-6 levels (256 ± 50.98% [mean ± SD] vs. 100 ± 54.12%, P = 0.026), and reduced postsynaptic density-95 (61 ± 13.53% vs. 100 ± 10.08%, P = 0.036) and synaptophysin levels in fetal and offspring mice. The sevoflurane anesthesia impaired learning and memory in offspring mice at P31. Moreover, interleukin-6 antibody mitigated the sevoflurane-induced reduction in postsynaptic density-95 levels in the neurons. Finally, environmental enrichment attenuated the sevoflurane-induced increases in interleukin-6 levels, reductions of synapse markers, and learning and memory impairment. Conclusions: These results suggest that sevoflurane may induce detrimental effects in fetal and offspring mice, which can be mitigated by environmental enrichment. These findings should promote more studies to determine the neurotoxicity of anesthesia in the developing brain.

Effect of waxy maize-derived hydroxyethyl starch 130/0.4 on renal function in surgical patients.

Abstract: Background:The aim of this meta-analysis was to evaluate renal safety with the active substance of the latest generation of waxy maize-derived hydroxyethyl starch in surgical patients. The authors focused on prospective, randomized, controlled studies that documented clinically relevant variables wi

Perioperative organ injury.

Abstract: Despite the fact that a surgical procedure may have been performed for the appropriate indication and in a technically perfect manner, patients are threatened by perioperative organ injury. For example, stroke, myocardial infarction, acute respiratory distress syndrome, acute kidney injury, or acute gut injury are among the most common causes for morbidity and mortality in surgical patients. In the current review, the authors discuss the pathogenesis of perioperative organ injury, and provide select examples for novel treatment concepts that have emerged over the past decade. Indeed, the authors are of the opinion that research to provide mechanistic insight into acute organ injury and identification of novel therapeutic approaches for the prevention or treatment of perioperative organ injury represent the most important opportunity to improve outcomes of anesthesia and surgery.

Simultaneous Electroencephalographic and Functional Magnetic Resonance Imaging Indicate Impaired Cortical Top–Down Processing in Association with Anesthetic-induced Unconsciousness

Abstract: BACKGROUND In imaging functional connectivity (FC) analyses of the resting brain, alterations of FC during unconsciousness have been reported. These results are in accordance with recent electroencephalographic studies observing impaired top-down processing during anesthesia. In this study, simultaneous records of functional magnetic resonance imaging (fMRI) and electroencephalogram were performed to investigate the causality of neural mechanisms during propofol-induced loss of consciousness by correlating FC in fMRI and directional connectivity (DC) in electroencephalogram. METHODS Resting-state 63-channel electroencephalogram and blood oxygen level-dependent 3-Tesla fMRI of 15 healthy subjects were simultaneously registered during consciousness and propofol-induced loss of consciousness. To indicate DC, electroencephalographic symbolic transfer entropy was applied as a nonlinear measure of mutual interdependencies between underlying physiological processes. The relationship between FC of resting-state networks of the brain (z values) and DC was analyzed by a partial correlation. RESULTS Independent component analyses of resting-state fMRI showed decreased FC in frontoparietal default networks during unconsciousness, whereas FC in primary sensory networks increased. DC indicated a decline in frontal-parietal (area under the receiver characteristic curve, 0.92; 95% CI, 0.68-1.00) and frontooccipital (0.82; 0.53-1.00) feedback DC (P<0.05 corrected). The changes of FC in the anterior default network correlated with the changes of DC in frontal-parietal (rpartial=+0.62; P=0.030) and frontal-occipital (+0.63; 0.048) electroencephalographic electrodes (P<0.05 corrected). CONCLUSION The simultaneous propofol-induced suppression of frontal feedback connectivity in the electroencephalogram and of frontoparietal FC in the fMRI indicates a fundamental role of top-down processing for consciousness.

Perioperative gabapentinoids: choice of agent, dose, timing, and effects on chronic postsurgical pain.

Abstract: 1215 November 2013 T gabapentinoids pregabalin and gabapentin are both indicated for the treatment of postherpetic neuralgia and as adjuvant therapy for seizure disorders. Pregabalin is additionally approved for the treatment of fibromyalgia and neuropathic pain associated with diabetes mellitus or spinal cord injury. There are now more than 100 clinical trials examining the use of gabapentin perioperatively to reduce postoperative pain and a smaller but growing number of clinical trials examining the efficacy of pregabalin. As a body of work, they support the conclusion that perioperative use of gabapentinoids reduces early postoperative pain and opioid use.1–3 This article describes how this body of work may inform a surgeon’s or anesthesiologist’s optimization of perioperative use of gabapentinoids, including choice of agent, dose, timing, and duration of therapy. In addition, we described the less clear data for and against gabapentinoid efficacy in preventing the emergence of chronic postsurgical pain. Mechanisms of Action, Pharmacokinetics, and Adverse Effects Although both of the gabapentinoids are structural analogs of γ-aminobutyric acid, neither has any activity at the γ-aminobutyric acid receptors (fig. 1). Instead, they bind to the α-2δ subunit of presynaptic P/Q-type voltage-gated calcium channels, modulating the traffic and function of these channels. This in turn is thought to modulate the subsequent release of excitatory neurotransmitters from activated nociceptors.4 By modulating calcium-induced release of glutamate from activated pain-transmitting neurons, these drugs may inhibit pain transmission and central sensitization (fig. 2). Alternatively, some evidence indicates that their antinociceptive mechanism may arise through activation of noradrenergic pain-inhibiting pathways in the spinal cord and brain.5 The principal differences between these two drugs arise not from different modes of action but rather from differing bioavailability. Although both drugs are absorbed by amino acid carriers, gabapentin absorption is limited to a relatively small part of the duodenum, whereas pregabalin is absorbed throughout the small intestine. Once the active transport of gabapentin in the duodenum is saturated, progressively higher levels of gabapentin ingestion yield progressively smaller increases in blood concentrations. Conceptually, this provides an upper border not only to efficacy but also to adverse effects. In contrast, pregabalin appears to be absorbed throughout the small intestines and demonstrates linear uptake without transporter saturation at therapeutic concentrations.6,7 Therefore, at least conceptually, pregabalin might demonstrate both increased efficacy and increased side effects in situations that require high doses. Both pregabalin and gabapentin exhibit minimal protein binding and are renally excreted without significant metabolism. Pharmacokinetic interactions are minimal, though gabapentin absorption can be significantly impaired by antacids, even when given up to 2 h after dosing. This should be considered in preoperative Copyright © 2013, the American Society of Anesthesiologists, Inc. Lippincott Williams & Wilkins. Anesthesiology 2013; 119:1215–21 * Clinical Instructor of Anesthesiology, † Research Assistant, ‡ Professor of Anesthesiology and Pain Medicine, § Assistant Professor of Anesthesiology and Pain Medicine, Department of Anesthesiology, Perioperative, and Pain Medicine, Division of Pain Medicine, Stanford University, Palo Alto, California.

Conventional and Kilohertz-frequency Spinal Cord Stimulation Produces Intensity- and Frequency-dependent Inhibition of Mechanical Hypersensitivity in a Rat Model of Neuropathic Pain

Abstract: Background Spinal cord stimulation (SCS) is a useful neuromodulatory technique for treatment of certain neuropathic pain conditions. However, the optimal stimulation parameters remain unclear.

Managing new oral anticoagulants in the perioperative and intensive care unit setting.

Abstract: Managing patients in the perioperative setting receiving novel oral anticoagulation agents for thromboprophylaxis or stroke prevention with atrial fibrillation is an important consideration for clinicians. The novel oral anticoagulation agents include direct Factor Xa inhibitors rivaroxaban and apixaban, and the direct thrombin inhibitor dabigatran. In elective surgery, discontinuing their use is important, but renal function must also be considered because elimination is highly dependent on renal elimination. If bleeding occurs in patients who have received these agents, common principles of bleeding management as with any anticoagulant (including the known principles for warfarin) should be considered. This review summarizes the available data regarding the management of bleeding with novel oral anticoagulation agents. Hemodialysis is a therapeutic option for dabigatran-related bleeding, while in vitro studies showed that prothrombin complex concentrates are reported to be useful for rivaroxaban-related bleeding. Additional clinical studies are needed to determine the best method for reversal of the novel oral anticoagulation agents when bleeding occurs.

Individually optimized hemodynamic therapy reduces complications and length of stay in the intensive care unit: a prospective, randomized controlled trial

Abstract: Background: The authors hypothesized that goal-directed hemodynamic therapy, based on the combination of functional and volumetric hemodynamic parameters, improves outcome in patients with cardiac surgery. Therefore, a therapy guided by stroke volume variation, individually optimized global end-diastolic volume index, cardiac index, and mean arterial pressure was compared with an algorithm based on mean arterial pressure and central venous pressure. Methods: This prospective, controlled, parallel-arm, open-label trial randomized 100 coronary artery bypass grafting and/or aortic valve replacement patients to a study group (SG; n = 50) or a control group (CG; n = 50). In the SG, hemodynamic therapy was guided by stroke volume variation, optimized global end-diastolic volume index, mean arterial pressure, and cardiac index. Optimized global end-diastolic volume index was defined before and after weaning from cardiopulmonary bypass and at intensive care unit (ICU) admission. Mean arterial pressure and central venous pressure served as hemodynamic goals in the CG. Therapy was started immediately after induction of anesthesia and continued until ICU discharge criteria, serving as primary outcome parameter, were fulfilled. Results: Intraoperative need for norepinephrine was decreased in the SG with a mean (SD) of 9.0 +/- 7.6 versus 14.9 +/- 11.1 mu g/kg (P = 0.002). Postoperative complications (SG, 40 vs. CG, 63; P = 0.004), time to reach ICU discharge criteria (SG, 15 +/- 6 h; CG, 24 +/- 29 h; P <0.001), and length of ICU stay (SG, 42 +/- 19 h; CG, 62 +/- 58 h; P = 0.018) were reduced in the SG. Conclusion: Early goal-directed hemodynamic therapy based on cardiac index, stroke volume variation, and optimized global end-diastolic volume index reduces complications and length of ICU stay after cardiac surgery.

Effect of Perioperative Intravenous Lidocaine Administration on Pain, Opioid Consumption, and Quality of Life after Complex Spine Surgery

Abstract: Background: The authors tested the primary hypothesis that perioperative IV lidocaine administration during spine surgery (and in the postanesthesia care unit for no more than 8 h) decreases pain and/or opioid requirements in the initial 48 postoperative hours. Secondary outcomes included major complications, postoperative nausea and vomiting, duration of hospitalization, and quality of life. Methods: One hundred sixteen adults having complex spine surgery were randomly assigned to perioperative IV lidocaine (2 mg·kg −1 ·h −1 ) or placebo during surgery and in the post anesthesia care unit. Pain was evaluated with a verbal response scale. Quality of life at 1 and 3 months was assessed using the Acute Short-form (SF) 12 health survey. The authors initially evaluated multivariable bidirectional noninferiority on both outcomes; superiority on either outcome was then evaluated only if noninferiority was established. Results: Lidocaine was significantly superior to placebo on mean verbal response scale pain scores (P < 0.001; adjusted mean [95% CI] of 4.4 [4.2-4.7] and 5.3 [5.0-5.5] points, respectively) and significantly noninferior on mean morphine equivalent dosage (P = 0.011; 55 [36-84] and 74 [49-111] mg, respectively). Postoperative nausea and vomiting and the duration of hospitalization did not differ significantly. Patients given lidocaine had slightly fewer 30-day complications than patients given placebo (odds ratio [95% CI] of 0.91 [0.84–1.00]; P = 0.049). Patients given lidocaine had significantly greater SF-12 physical composite scores than placebo at 1 (38 [31–47] vs. 33 [27–42]; P = 0.002) and 3 (39 [31–49] vs. 34 [28–44]; P = 0.04) months, postoperatively. Conclusion: IV lidocaine significantly improves postoperative pain after complex spine surgery.