The 50 most-cited articles in Anesthesiology, 2018

Chronic pain is maintained in part by central sensitization, a phenomenon of synaptic plasticity, and increased neuronal responsiveness in central pain pathways after painful insults. Accumulating evidence suggests that central sensitization is also driven by neuroinflammation in the peripheral and central nervous system. A characteristic feature of neuroinflammation is the activation of glial cells, such as microglia and astrocytes, in the spinal cord and brain, leading to the release of proinflammatory cytokines and chemokines. Recent studies suggest that central cytokines and chemokines are powerful neuromodulators and play a sufficient role in inducing hyperalgesia and allodynia after central nervous system administration. Sustained increase of cytokines and chemokines in the central nervous system also promotes chronic widespread pain that affects multiple body sites. Thus, neuroinflammation drives widespread chronic pain via central sensitization. We also discuss sex-dependent glial/immune signaling in chronic pain and new therapeutic approaches that control neuroinflammation…

Cognitive change affecting patients after anaesthesia and surgery has been recognised for more than 100 yr. Research into cognitive change after anaesthesia and surgery accelerated in the 1980s when multiple studies utilised detailed neuropsychological testing for assessment of cognitive change after cardiac surgery. This body of work consistently documented decline in cognitive function in elderly patients after anaesthesia and surgery, and cognitive changes have been identified up to 7.5 yr afterwards. Importantly, other studies have identified that the incidence of cognitive change is similar after non-cardiac surgery. Other than the inclusion of non-surgical control groups to calculate postoperative cognitive dysfunction, research into these cognitive changes in the perioperative period has been undertaken in isolation from cognitive studies in the general population. The aim of this work is to develop similar terminology to that used in cognitive classifications of the general population for use in investigations of cognitive changes after anaesthesia and surgery. A…

WHAT WE ALREADY KNOW ABOUT THIS TOPIC: WHAT THIS ARTICLE TELLS US THAT IS NEW: BACKGROUND:: With appropriate algorithms, computers can learn to detect patterns and associations in large data sets. The authors' goal was to apply machine learning to arterial pressure waveforms and create an algorithm to predict hypotension. The algorithm detects early alteration in waveforms that can herald the weakening of cardiovascular compensatory mechanisms affecting preload, afterload, and contractility. METHODS: The algorithm was developed with two different data sources: (1) a retrospective cohort, used for training, consisting of 1,334 patients' records with 545,959 min of arterial waveform recording and 25,461 episodes of hypotension; and (2) a prospective, local hospital cohort used for external validation, consisting of 204 patients' records with 33,236 min of arterial waveform recording and 1,923 episodes of hypotension. The algorithm relates a large set of features calculated from the high-fidelity arterial pressure waveform to the prediction of an upcoming hypotensive event (mean…

BACKGROUND: Few studies of how exposure of children to anesthesia may affect neurodevelopment employ comprehensive neuropsychological assessments. This study tested the hypothesis that exposure to multiple, but not single, procedures requiring anesthesia before age 3 yr is associated with adverse neurodevelopmental outcomes. METHODS: Unexposed, singly exposed, and multiply exposed children born in Olmsted County, Minnesota, from 1994 to 2007 were sampled using a propensity-guided approach and underwent neuropsychological testing at ages 8 to 12 or 15 to 20 yr. The primary outcome was the Full-Scale intelligence quotient standard score of the Wechsler Abbreviated Scale of Intelligence. Secondary outcomes included individual domains from a comprehensive neuropsychological assessment and parent reports. RESULTS: In total, 997 children completed testing (411, 380, and 206 unexposed, singly exposed, and multiply exposed, respectively). The primary outcome of intelligence quotient did not differ significantly according to exposure status; multiply exposed and singly exposed children…

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The development of chronic pain is considered a major complication after surgery. Basic science research in animal models helps us understand the transition from acute to chronic pain by identifying the numerous molecular and cellular changes that occur in the peripheral and central nervous systems. It is now well recognized that inflammation and nerve injury lead to long-term synaptic plasticity that amplifies and also maintains pain signaling, a phenomenon referred to as pain sensitization. In the context of surgery in humans, pain sensitization is both responsible for an increase in postoperative pain via the expression of wound hyperalgesia and considered a critical factor for the development of persistent postsurgical pain. Using specific drugs that block the processes of pain sensitization reduces postoperative pain and prevents the development of persistent postoperative pain. This narrative review of the literature describes clinical investigations evaluating different preventative pharmacologic strategies that are routinely used by anesthesiologists in their daily clinical…

WHAT WE ALREADY KNOW ABOUT THIS TOPIC: WHAT THIS ARTICLE TELLS US THAT IS NEW: BACKGROUND:: Complications in pediatric regional anesthesia are rare, so a large sample size is necessary to quantify risk. The Pediatric Regional Anesthesia Network contains data on more than 100,000 blocks administered at more than 20 children's hospitals. This study analyzed the risk of major complications associated with regional anesthesia in children. METHODS: This is a prospective, observational study of routine clinical practice. Data were collected on every regional block placed by an anesthesiologist at participating institutions and were uploaded to a secure database. The data were audited at multiple points for accuracy. RESULTS: There were no permanent neurologic deficits reported (95% CI, 0 to 0.4:10,000). The risk of transient neurologic deficit was 2.4:10,000 (95% CI, 1.6 to 3.6:10,000) and was not different between peripheral and neuraxial blocks. The risk of severe local anesthetic systemic toxicity was 0.76:10,000 (95% CI, 0.3 to 1.6:10,000); the majority of cases occurred in infants.…

WHAT WE ALREADY KNOW ABOUT THIS TOPIC: WHAT THIS ARTICLE TELLS US THAT IS NEW: BACKGROUND:: Intraoperative lung-protective ventilation has been recommended to reduce postoperative pulmonary complications after abdominal surgery. Although the protective role of a more physiologic tidal volume has been established, the added protection afforded by positive end-expiratory pressure (PEEP) remains uncertain. The authors hypothesized that a low fixed PEEP might not fit all patients and that an individually titrated PEEP during anesthesia might improve lung function during and after surgery. METHODS: Forty patients were studied in the operating room (20 laparoscopic and 20 open-abdominal). They underwent elective abdominal surgery and were randomized to institutional PEEP (4 cm H2O) or electrical impedance tomography-guided PEEP (applied after recruitment maneuvers and targeted at minimizing lung collapse and hyperdistension, simultaneously). Patients were extubated without changing selected PEEP or fractional inspired oxygen tension while under anesthesia and submitted to chest computed…

For half a century, it has been known that some patients experience neurocognitive dysfunction after cardiac surgery; however, defining its incidence, course, and causes remains challenging and controversial. Various terms have been used to describe neurocognitive dysfunction at different times after cardiac surgery, ranging from "postoperative delirium" to "postoperative cognitive dysfunction or decline." Delirium is a clinical diagnosis included in the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5). Postoperative cognitive dysfunction is not included in the DSM-5 and has been heterogeneously defined, though a recent international nomenclature effort has proposed standardized definitions for it. Here, the authors discuss pathophysiologic mechanisms that may underlie these complications, review the literature on methods to prevent them, and discuss novel approaches to understand their etiology that may lead to novel treatment strategies. Future studies should measure both delirium and postoperative cognitive dysfunction to help clarify the relationship…

WHAT WE ALREADY KNOW ABOUT THIS TOPIC: WHAT THIS ARTICLE TELLS US THAT IS NEW: BACKGROUND:: Hypotension is a risk factor for adverse perioperative outcomes. Machine-learning methods allow large amounts of data for development of robust predictive analytics. The authors hypothesized that machine-learning methods can provide prediction for the risk of postinduction hypotension. METHODS: Data was extracted from the electronic health record of a single quaternary care center from November 2015 to May 2016 for patients over age 12 that underwent general anesthesia, without procedure exclusions. Multiple supervised machine-learning classification techniques were attempted, with postinduction hypotension (mean arterial pressure less than 55 mmHg within 10 min of induction by any measurement) as primary outcome, and preoperative medications, medical comorbidities, induction medications, and intraoperative vital signs as features. Discrimination was assessed using cross-validated area under the receiver operating characteristic curve. The best performing model was tuned and final performance…

Obstetric anesthesia has evolved over the course of its history to encompass comprehensive aspects of maternal care, ranging from cesarean delivery anesthesia and labor analgesia to maternal resuscitation and patient safety. Anesthesiologists are concerned with maternal and neonatal outcomes, and with preventing and managing complications that may present during childbirth. The current review will focus on recent advances in obstetric anesthesia, including labor anesthesia and analgesia, cesarean delivery anesthesia and analgesia, the effects of maternal anesthesia on breastfeeding and fever, and maternal safety. The impact of these advances on maternal and neonatal outcomes is discussed. Past and future progress in this field will continue to have significant implications on the health of women and children.

BACKGROUND: Multimodal analgesia is increasingly considered routine practice in joint arthroplasties, but supportive large-scale data are scarce. The authors aimed to determine how the number and type of analgesic modes is associated with reduced opioid prescription, complications, and resource utilization. METHODS: Total hip/knee arthroplasties (N = 512,393 and N = 1,028,069, respectively) from the Premier Perspective database (2006 to 2016) were included. Analgesic modes considered were opioids, peripheral nerve blocks, acetaminophen, steroids, gabapentin/pregabalin, nonsteroidal antiinflammatory drugs, cyclooxygenase-2 inhibitors, or ketamine. Groups were categorized into "opioids only" and 1, 2, or more than 2 additional modes. Multilevel models measured associations between multimodal analgesia and opioid prescription, cost/length of hospitalization, and opioid-related adverse effects. Odds ratios or percent change and 95% CIs are reported. RESULTS: Overall, 85.6% (N = 1,318,165) of patients received multimodal analgesia. In multivariable models, additions of analgesic modes…

WHAT WE ALREADY KNOW ABOUT THIS TOPIC: WHAT THIS ARTICLE TELLS US THAT IS NEW: BACKGROUND:: Stroke is a leading cause of morbidity, mortality, and disability in patients undergoing cardiac surgery. Identifying modifiable perioperative stroke risk factors may lead to improved patient outcomes. The association between the severity and duration of intraoperative hypotension and postoperative stroke in patients undergoing cardiac surgery was evaluated. METHODS: A retrospective cohort study was conducted of adult patients who underwent cardiac surgery requiring cardiopulmonary bypass at a tertiary center between November 1, 2009, and March 31, 2015. The primary outcome was postoperative ischemic stroke. Intraoperative hypotension was defined as the number of minutes spent within mean arterial pressure bands of less than 55, 55 to 64, and 65 to 74 mmHg before, during, and after cardiopulmonary bypass. The association between stroke and hypotension was examined by using logistic regression with propensity score adjustment. RESULTS: Among the 7,457 patients included in this analysis, 111…

Neuroimaging research has demonstrated definitive involvement of the central nervous system in the development, maintenance, and experience of chronic pain. Structural and functional neuroimaging has helped elucidate central nervous system contributors to chronic pain in humans. Neuroimaging of pain has provided a tool for increasing our understanding of how pharmacologic and psychologic therapies improve chronic pain. To date, findings from neuroimaging pain research have benefitted clinical practice by providing clinicians with an educational framework to discuss the biopsychosocial nature of pain with patients. Future advances in neuroimaging-based therapeutics (e.g., transcranial magnetic stimulation, real-time functional magnetic resonance imaging neurofeedback) may provide additional benefits for clinical practice. In the future, with standardization and validation, brain imaging could provide objective biomarkers of chronic pain, and guide treatment for personalized pain management. Similarly, brain-based biomarkers may provide an additional predictor of perioperative…

WHAT WE ALREADY KNOW ABOUT THIS TOPIC: Cardiac surgery is associated with cognitive decline and postoperative delirium. The relationship between postoperative delirium and cognitive decline after cardiac surgery is unclear WHAT THIS ARTICLE TELLS US THAT IS NEW: The development of postoperative delirium is associated with a greater degree of cognitive decline 1 month after cardiac surgery. The development of postoperative delirium is not a predictor of cognitive decline 1 yr after cardiac surgery. BACKGROUND: Delirium is common after cardiac surgery and has been associated with morbidity, mortality, and cognitive decline. However, there are conflicting reports on the magnitude, trajectory, and domains of cognitive change that might be affected. The authors hypothesized that patients with delirium would experience greater cognitive decline at 1 month and 1 yr after cardiac surgery compared to those without delirium. METHODS: Patients who underwent coronary artery bypass and/or valve surgery with cardiopulmonary bypass were eligible for this cohort study. Delirium was assessed with…

WHAT WE ALREADY KNOW ABOUT THIS TOPIC: WHAT THIS ARTICLE TELLS US THAT IS NEW: BACKGROUND:: The authors tested the hypothesis that deep neural networks trained on intraoperative features can predict postoperative in-hospital mortality. METHODS: The data used to train and validate the algorithm consists of 59,985 patients with 87 features extracted at the end of surgery. Feed-forward networks with a logistic output were trained using stochastic gradient descent with momentum. The deep neural networks were trained on 80% of the data, with 20% reserved for testing. The authors assessed improvement of the deep neural network by adding American Society of Anesthesiologists (ASA) Physical Status Classification and robustness of the deep neural network to a reduced feature set. The networks were then compared to ASA Physical Status, logistic regression, and other published clinical scores including the Surgical Apgar, Preoperative Score to Predict Postoperative Mortality, Risk Quantification Index, and the Risk Stratification Index. RESULTS: In-hospital mortality in the training and test…

WHAT WE ALREADY KNOW ABOUT THIS TOPIC: WHAT THIS ARTICLE TELLS US THAT IS NEW: BACKGROUND:: Previous research has shown different effects of anesthetics on cancer cell growth. Here, the authors investigated the association between type of anesthetic and patient survival after elective colon cancer surgery. METHODS: A retrospective cohort study included patients who received elective colon cancer surgery between January 2005 and December 2014. Patients were grouped according to anesthesia received: propofol or desflurane. After exclusion of those who received combined propofol anesthesia with inhalation anesthesia or epidural anesthesia, survival curves were constructed from the date of surgery to death. After propensity matching, univariable and multivariable Cox regression models were used to compare hazard ratios for death. Subgroup analyses were performed for tumor-node-metastasis staging and postoperative metastasis. RESULTS: A total of 706 patients (307 deaths, 43.5%) with desflurane anesthesia and 657 (88 deaths, 13.4%) with propofol anesthesia were eligible for analysis.…

Abstract EDITOR’S PERSPECTIVE What We Already Know about This Topic Positive end-expiratory pressure protects against ventilation-induced lung injury by improving homogeneity of ventilation, but positive end-expiratory pressure contributes to the mechanical power required to ventilate the lung What This Article Tells Us That Is New This in vivo study (36 pigs mechanically ventilated in the prone position) suggests that low levels of positive end-expiratory pressure reduce injury associated with atelectasis, and above a threshold level of power, positive end-expiratory pressure causes lung injury and adverse hemodynamics Background Positive end-expiratory pressure is usually considered protective against ventilation-induced lung injury by reducing atelectrauma and improving lung homogeneity. However, positive end-expiratory pressure, together with tidal volume, gas flow, and respiratory rate, contributes to the mechanical power required to ventilate the lung. This study aimed at investigating the effects of increasing mechanical power by selectively modifying its positive…

Abstract EDITOR’S PERSPECTIVE What We Know about This Topic IV anesthesia may impair anticancer immunity less than volatile anesthesia and therefore reduce recurrence risk What This Article Tells Us That Is New In a large propensity-matched retrospective cohort analysis, the authors compared total IV and volatile anesthesia for breast cancer surgery Recurrence hazard was similar with each approach Selection of IV or volatile anesthesia should be based on factors other than cancer recurrence Background The association between type of anesthesia used and recurrence of cancer remains controversial. This retrospective cohort study compared the influence of total IV anesthesia and inhalation anesthesia on the primary outcome of recurrence-free survival after breast cancer surgery. Methods The authors reviewed the electronic medical records of patients who had breast cancer surgery at a tertiary care teaching hospital between January 2005 and December 2013. The patients were grouped according to whether IV or inhalation anesthesia was used for surgery. Propensity score matching was used…

WHAT WE ALREADY KNOW ABOUT THIS TOPIC: WHAT THIS ARTICLE TELLS US THAT IS NEW: BACKGROUND:: The mechanism by which anesthetics induce a loss of consciousness remains a puzzling problem. We hypothesized that a cortical signature of anesthesia could be found in an increase in similarity between the matrix of resting-state functional correlations and the anatomical connectivity matrix of the brain, resulting in an increased function-structure similarity. METHODS: We acquired resting-state functional magnetic resonance images in macaque monkeys during wakefulness (n = 3) or anesthesia with propofol (n = 3), ketamine (n = 3), or sevoflurane (n = 3). We used the k-means algorithm to cluster dynamic resting-state data into independent functional brain states. For each condition, we performed a regression analysis to quantify function-structure similarity and the repertoire of functional brain states. RESULTS: Seven functional brain states were clustered and ranked according to their similarity to structural connectivity, with higher ranks corresponding to higher function-structure…

BACKGROUND: Limited evidence suggests that children have a lower incidence of perioperative respiratory adverse events when intravenous propofol is used compared with inhalational sevoflurane for the anesthesia induction. Limiting these events can improve recovery time as well as decreasing surgery waitlists and healthcare costs. This single center open-label randomized controlled trial assessed the impact of the anesthesia induction technique on the occurrence of perioperative respiratory adverse events in children at high risk of those events. METHODS: Children (N = 300; 0 to 8 yr) with at least two clinically relevant risk factors for perioperative respiratory adverse events and deemed suitable for either technique of anesthesia induction were recruited and randomized to either intravenous propofol or inhalational sevoflurane. The primary outcome was the difference in the rate of occurrence of perioperative respiratory adverse events between children receiving intravenous induction and those receiving inhalation induction of anesthesia. RESULTS: Children receiving intravenous…

The ventilatory control system is highly vulnerable to exogenous administered opioid analgesics. Particularly respiratory depression is a potentially lethal complication that may occur when opioids are overdosed or consumed in combination with other depressants such as sleep medication or alcohol. Fatalities occur in acute and chronic pain patients on opioid therapy and individuals that abuse prescription or illicit opioids for their hedonistic pleasure. One important strategy to mitigate opioid-induced respiratory depression is cotreatment with nonopioid respiratory stimulants. Effective stimulants prevent respiratory depression without affecting the analgesic opioid response. Several pharmaceutical classes of nonopioid respiratory stimulants are currently under investigation. The majority acts at sites within the brainstem respiratory network including drugs that act at α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptors (ampakines), 5-hydroxytryptamine receptor agonists, phospodiesterase-4 inhibitors, D1-dopamine receptor agonists, the endogenous peptide…

WHAT WE ALREADY KNOW ABOUT THIS TOPIC: WHAT THIS ARTICLE TELLS US THAT IS NEW: BACKGROUND:: Postoperative delirium complicates approximately 15 to 20% of major operations in patients at least 65 yr old and is associated with adverse outcomes and increased resource utilization. Furthermore, patients with postoperative delirium might also be at risk of developing long-term postoperative cognitive dysfunction. One potentially modifiable variable is use of intraoperative processed electroencephalogram to guide anesthesia. This systematic review and meta-analysis examines the relationship between processed electroencephalogram monitoring and postoperative delirium and cognitive dysfunction. METHODS: A systematic search for randomized controlled trials was conducted using Ovid MEDLINE, PubMed, EMBASE, Cochrane Library, and Google search using the keywords processed electroencephalogram, Bispectral Index, postoperative delirium, postoperative cognitive dysfunction. Screening and data extraction were conducted by two independent reviewers, and risk of bias was assessed. Postoperative…

WHAT WE ALREADY KNOW ABOUT THIS TOPIC: WHAT THIS ARTICLE TELLS US THAT IS NEW: BACKGROUND:: With facet interventions under scrutiny, the authors' objectives were to determine the effectiveness of different lumbar facet blocks and their ability to predict radiofrequency ablation outcomes. METHODS: A total of 229 participants were randomized in a 2:2:1 ratio to receive intraarticular facet injections with bupivacaine and steroid, medial branch blocks, or saline. Those with a positive 1-month outcome (a 2-point or more reduction in average pain score) and score higher than 3 (positive satisfaction) on a 5-point satisfaction scale were followed up to 6 months. Participants in the intraarticular and medial branch block groups with a positive diagnostic block (50% or more relief) who experienced a negative outcome proceeded to the second phase and underwent radiofrequency ablation, while all saline group individuals underwent ablation. Coprimary outcome measures were average reduction in numerical rating scale pain score 1 month after the facet or saline blocks, and average numerical…

BACKGROUND: The interscalene nerve block provides analgesia for shoulder surgery, but is associated with diaphragm paralysis. One solution may be performing brachial plexus blocks more distally. This noninferiority study evaluated analgesia for blocks at the supraclavicular and anterior suprascapular levels, comparing them individually to the interscalene approach. METHODS: One hundred-eighty-nine subjects undergoing arthroscopic shoulder surgery were recruited to this double-blind trial and randomized to interscalene, supraclavicular, or anterior suprascapular block using 15 ml, 0.5% ropivacaine. The primary outcome was numeric rating scale pain scores analyzed using noninferiority testing. The predefined noninferiority margin was one point on the 11-point pain scale. Secondary outcomes included opioid consumption and pulmonary assessments. RESULTS: All subjects completed the study through the primary outcome analysis. Mean pain after surgery was: interscalene = 1.9 (95% CI, 1.3 to 2.5), supraclavicular = 2.3 (1.7 to 2.9), suprascapular = 2.0 (1.4 to 2.6). The primary outcome, mean…

Abstract EDITOR’S PERSPECTIVE What We Already Know about This Topic Hypotension after spinal anesthesia for cesarean delivery is common, usually treated with phenylephrine or ephedrine Norepinephrine was recently introduced in obstetric anesthesia but the optimal dose is unknown What This Article Tells Us That Is New This randomized, double-blinded trial compared prophylactic norepinephrine infusions of 0.025, 0.050, or 0.075 μg · kg -1 · min -1 , started after bupivacaine spinal anesthesia, in full-term parturients having elective cesarean delivery The primary outcome, maternal hypotension (systolic blood pressure less than 80% of baseline), occurred less frequently after both 0.050 and 0.075 μg · kg -1 · min -1 compared 0.025 μg · kg -1 · min -1 norepinephrine Background Norepinephrine has been recently introduced for prophylaxis against postspinal hypotension during cesarean delivery; however, no data are available regarding its optimum dose. The objective of this study is to compare three infusion rates of norepinephrine for prophylaxis against postspinal hypotension during…

BACKGROUND: It is unclear whether obesity is a risk factor for postpartum hemorrhage. The authors hypothesized that obese women are at greater risk of hemorrhage than women with a normal body mass index. METHODS: The authors conducted a cohort study of women who underwent delivery hospitalization in California between 2008 and 2012. Using multilevel regression, the authors examined the relationships between body mass index with hemorrhage (primary outcome), atonic hemorrhage, and severe hemorrhage (secondary outcomes). Stratified analyses were performed according to delivery mode. RESULTS: The absolute event rate for hemorrhage was 60,604/2,176,673 (2.8%). In this cohort, 4% of women were underweight, 49.1% of women were normal body mass index, 25.9% of women were overweight, and 12.7%, 5.2%, and 3.1% of women were in obesity class I, II, and III, respectively. Compared to normal body mass index women, the odds of hemorrhage and atonic hemorrhage were modestly increased for overweight women (hemorrhage: adjusted odds ratio [aOR], 1.06; 99% CI, 1.04 to 1.08; atonic hemorrhage: aOR,…

WHAT WE ALREADY KNOW ABOUT THIS TOPIC: WHAT THIS ARTICLE TELLS US THAT IS NEW: BACKGROUND:: Ketamine is an N-methyl-D-aspartate receptor antagonist that reduces temporal summation of pain and modulates antinociception. Ketamine infusions can produce significant relief of neuropathic pain, but the treatment is resource intensive and can be associated with adverse effects. Thus, it is crucial to select patients who might benefit from this treatment. The authors tested the hypothesis that patients with enhanced temporal summation of pain and the capacity to modulate pain via the descending antinociceptive brain pathway are predisposed to obtain pain relief from ketamine. METHODS: Patients with refractory neuropathic pain (n = 30) and healthy controls underwent quantitative sensory testing and resting-state functional magnetic resonance imaging and then completed validated questionnaires. Patients then received outpatient intravenous ketamine (0.5 to 2 mg · kg · h; mean dose 1.1 mg · kg · h) for 6 h/day for 5 consecutive days. Pain was assessed 1 month later. Treatment response was…

BACKGROUND: Prolonged catheter use is controversial because of the risk of catheter-related infection, but the extent to which the risk increases over time remains unknown. We thus assessed the time-dependence of catheter-related infection risk up to 15 days. METHODS: Our analysis was based on the German Network for Regional Anesthesia, which includes 25 centers. We considered 44,555 patients who had surgery between 2007 and 2014 and had continuous regional anesthesia as well as complete covariable details. Cox regression analysis was performed and adjusted for confounding covariables to examine the relationship between catheter duration and probability of infection-free catheter use. RESULTS: After adjustment for confounding factors, the probability of infection-free catheter use decreases with each day of peripheral and epidural catheter use. In peripheral catheters, it was 99% at day 4 of catheter duration, 96% at day 7, and 73% at day 15. In epidural catheters, it was 99% at day 4 of catheter duration, 95% at day 7, and 73% at day 15. Only 31 patients (0.07%) had severe…

Abstract EDITOR’S PERSPECTIVE What We Already Know about This Topic The parabrachial nucleus is a brainstem region involved in arousal. Brain regions involved in arousal regulate anesthetic induction and emergence. What This Article Tells Us That Is New Using chemogenetic techniques, activation of parabrachial nucleus glutamatergic neurons prolonged anesthetic induction and hastened emergence in mice. Inhibition of these neurons provided opposite effects. Modulating the activity of arousal centers may provide an approach to controlling the duration of general anesthesia. Background The parabrachial nucleus (PBN), which is a brainstem region containing glutamatergic neurons, is a key arousal nucleus. Injuries to the area often prevent patient reanimation. Some studies suggest that brain regions that control arousal and reanimation are a key part of the anesthesia recovery. Therefore, we hypothesize that the PBN may be involved in regulating emergence from anesthesia. Methods We investigated the effects of specific activation or inhibition of PBN glutamatergic neurons on sevoflurane…

WHAT WE ALREADY KNOW ABOUT THIS TOPIC: WHAT THIS ARTICLE TELLS US THAT IS NEW: BACKGROUND:: Several factors within the perioperative period may influence postoperative metastatic spread. Dexmedetomidine and midazolam are widely used general anesthetics during surgery. The authors assessed their effects on human lung carcinoma (A549) and neuroglioma (H4) cell lines in vitro and in vivo. METHODS: Cell proliferation and migration were measured after dexmedetomidine (0.001 to 10 nM) or midazolam (0.01 to 400 μM) treatment. Expression of cell cycle and apoptosis markers were assessed by immunofluorescence. Mitochondrial membrane potential and reactive oxygen species were measured by JC-1 staining and flow cytometry. Antagonists atipamezole and flumazenil were used to study anesthetic mechanisms of action. Tumor burden after anesthetic treatment was investigated with a mouse xenograft model of lung carcinoma. RESULTS: Dexmedetomidine (1 nM) promoted cell proliferation (2.9-fold in A549 and 2-fold in H4 cells vs. vehicle, P < 0.0001; n = 6), migration (2.2-fold in A549 and 1.9-fold in H4…

WHAT WE ALREADY KNOW ABOUT THIS TOPIC: WHAT THIS ARTICLE TELLS US THAT IS NEW: BACKGROUND:: Ambulatory hip arthroscopy is associated with postoperative pain routinely requiring opioid analgesia. The potential role of peripheral nerve blocks for pain control after hip arthroscopy is controversial. This trial investigated whether a preoperative fascia iliaca block improves postoperative analgesia. METHODS: In a prospective, double-blinded trial, 80 patients scheduled for hip arthroscopy were randomized to receive a preoperative fascia iliaca block with 40 ml ropivacaine 0.2% or saline. Patients also received an intraarticular injection of 10-ml ropivacaine 0.2% at procedure end. Primary study endpoint was highest pain score reported in the recovery room; other study endpoints were pain scores and opioid use 24 h after surgery. Additionally, quadriceps strength was measured to identify leg weakness. RESULTS: The analysis included 78 patients. Highest pain scores in the recovery room were similar in the block group (6 ± 2) versus placebo group (7 ± 2), difference: -0.2 (95% CI, -1.1 to…

Teamwork is now recognized as important for safe, high-quality perioperative care. The relationship in each surgeon-anesthesiologist dyad is perhaps the most critical element of overall team performance. A well-functioning relationship is conducive to safe, effective care. A dysfunctional relationship can promote unsafe conditions and contribute to an adverse outcome. Yet, there is little research about this relationship, about what works well or not well, what can be done to optimize it. This article explores functional and dysfunctional aspects of the relationship, identifies some negative stereotypes each profession has of the other and calls for research to better characterize and understand how to improve working relationships. Suggestions are given for what an ideal relationship might be and actions that surgeons and anesthesiologists can take to improve how they work together. The goal is safer care for patients, and more joy and meaning in work for surgeons and anesthesiologists.

WHAT WE ALREADY KNOW ABOUT THIS TOPIC: WHAT THIS ARTICLE TELLS US THAT IS NEW: BACKGROUND:: Tracheal intubation is a common intervention in the operating room and in the intensive care unit. The authors hypothesized that tracheal intubation using direct laryngoscopy would be associated with worse intubation conditions and more complications in the intensive care unit compared with the operating room. METHODS: The authors prospectively evaluated during 33 months patients who were tracheally intubated with direct laryngoscopy in the operating room, and subsequently in the intensive care unit (within a 1-month time frame). The primary outcome was to compare the difference in glottic visualization using the modified Cormack-Lehane grade between intubations performed on the same patient in an intensive care unit and previously in an operating room. Secondary outcomes were to compare first-time success rate, technical difficulty (number of attempts, operator-reported difficulty, need for adjuncts), and the incidence of complications. RESULTS: A total of 208 patients met inclusion…

The heterogeneity of molecular mechanisms, target neural circuits, and neurophysiologic effects of general anesthetics makes it difficult to develop a reliable and drug-invariant index of general anesthesia. No single brain region or mechanism has been identified as the neural correlate of consciousness, suggesting that consciousness might emerge through complex interactions of spatially and temporally distributed brain functions. The goal of this review article is to introduce the basic concepts of networks and explain why the application of network science to general anesthesia could be a pathway to discover a fundamental mechanism of anesthetic-induced unconsciousness. This article reviews data suggesting that reduced network efficiency, constrained network repertoires, and changes in cortical dynamics create inhospitable conditions for information processing and transfer, which lead to unconsciousness. This review proposes that network science is not just a useful tool but a necessary theoretical framework and method to uncover common principles of anesthetic-induced…

BACKGROUND: Polypharmacy is increasingly prevalent in older patients and is associated with adverse events among medical patients. The impact of polypharmacy on outcomes after elective surgery is poorly described. The authors' objective was to measure the association of polypharmacy with survival, complications, and resource use among older patients undergoing elective surgery. METHODS: After registration (NCT03133182), the authors identified all individuals older than 65 yr old having their first elective noncardiac surgery in Ontario, Canada, between 2002 and 2014. Using linked administrative data, the authors identified all prescriptions dispensed in the 90 days before surgery and classified people receiving five or more unique medications with polypharmacy. The associations of polypharmacy with 90-day survival (primary outcome), complications, length of stay, costs, discharge location, and readmissions were estimated after multilevel, multivariable adjustment for demographics, comorbidities, previous healthcare use, and surgical factors. Prespecified and post hoc sensitivity…

WHAT WE ALREADY KNOW ABOUT THIS TOPIC: WHAT THIS ARTICLE TELLS US THAT IS NEW: BACKGROUND:: Respiratory muscle weakness in critically ill patients is associated with difficulty in weaning from mechanical ventilation. Previous studies have mainly focused on inspiratory muscle activity during weaning; expiratory muscle activity is less well understood. The current study describes expiratory muscle activity during weaning, including tonic diaphragm activity. The authors hypothesized that expiratory muscle effort is greater in patients who fail to wean compared to those who wean successfully. METHODS: Twenty adult patients receiving mechanical ventilation (more than 72 h) performed a spontaneous breathing trial. Tidal volume, transdiaphragmatic pressure, diaphragm electrical activity, and diaphragm neuromechanical efficiency were calculated on a breath-by-breath basis. Inspiratory (and expiratory) muscle efforts were calculated as the inspiratory esophageal (and expiratory gastric) pressure-time products, respectively. RESULTS: Nine patients failed weaning. The contribution of the…

WHAT WE ALREADY KNOW ABOUT THIS TOPIC: WHAT THIS ARTICLE TELLS US THAT IS NEW: BACKGROUND:: Success of a cricothyrotomy is dependent on accurate identification of the cricothyroid membrane. The objective of this study was to compare the accuracy of ultrasonography versus external palpation in localizing the cricothyroid membrane. METHODS: In total, 223 subjects with abnormal neck anatomy who were scheduled for neck computed-tomography scan at University Health Network hospitals in Toronto, Canada, were randomized into two groups: external palpation and ultrasound. The localization points of the cricothyroid membrane determined by ultrasonography or external palpation were compared to the reference midpoint (computed-tomography point) of the cricothyroid membrane by a radiologist who was blinded to group allocation. Primary outcome was the accuracy in identification of the cricothyroid membrane, which was measured by digital ruler in millimeters from the computed-tomography point to the ultrasound point or external-palpation point. Success was defined as the proportion of accurate…

BACKGROUND: The authors hypothesized that low tidal volume (VT) would minimize ventilator-induced lung injury regardless of the degree of mechanical power. The authors investigated the impact of power, obtained by different combinations of VT and respiratory rate (RR), on ventilator-induced lung injury in experimental mild acute respiratory distress syndrome (ARDS). METHODS: Forty Wistar rats received Escherichia coli lipopolysaccharide intratracheally. After 24 h, 32 rats were randomly assigned to be mechanically ventilated (2 h) with a combination of different VT (6 ml/kg and 11 ml/kg) and RR that resulted in low and high power. Power was calculated as energy (ΔP,L/E,L) × RR (ΔP,L = transpulmonary driving pressure; E,L = lung elastance), and was threefold higher in high than in low power groups. Eight rats were not mechanically ventilated and used for molecular biology analysis. RESULTS: Diffuse alveolar damage score, which represents the severity of edema, atelectasis, and overdistension, was increased in high VT compared to low VT, in both low (low VT: 11 [9 to 14], high VT: 18…

BACKGROUND: The authors hypothesized that a multiparameter intraoperative decision support system with real-time visualizations may improve processes of care and outcomes. METHODS: Electronic health record data were retrospectively compared over a 6-yr period across three groups: experimental cases, in which the decision support system was used for 75% or more of the case at sole discretion of the providers; parallel controls (system used 74% or less); and historical controls before system implementation. Inclusion criteria were adults under general anesthesia, advanced medical disease, case duration of 60 min or longer, and length of stay of two days or more. The process measures were avoidance of intraoperative hypotension, ventilator tidal volume greater than 10 ml/kg, and crystalloid administration (ml · kg · h). The secondary outcome measures were myocardial injury, acute kidney injury, mortality, length of hospital stay, and encounter charges. RESULTS: A total of 26,769 patients were evaluated: 7,954 experimental cases, 10,933 parallel controls, and 7,882 historical controls.…

BACKGROUND: Although opioids remain the standard therapy for the treatment of postoperative pain, the prevalence of opioid misuse is rising. The extent to which opioid abuse or dependence affects readmission rates and healthcare utilization is not fully understood. It was hypothesized that surgical patients with a history of opioid abuse or dependence would have higher readmission rates and healthcare utilization. METHODS: A retrospective cohort analysis was performed of patients undergoing major operating room procedures in 2013 and 2014 using the National Readmission Database. Patients with opioid abuse or dependence were identified using International Classification of Diseases codes. The primary outcome was 30-day hospital readmission rate. Secondary outcomes included hospital length of stay and estimated hospital costs. RESULTS: Among the 16,016,842 patients who had a major operating room procedure whose death status was known, 94,903 (0.6%) had diagnoses of opioid abuse or dependence. After adjustment for potential confounders, patients with opioid abuse or dependence had…

Practice advisories are systematically developed reports that are intended to assist decision-making in areas of patient care. Advisories provide a synthesis of scientific literature and analysis of expert opinion, clinical feasibility data, open forum commentary, and consensus surveys. Practice advisories developed by the American Society of Anesthesiologists (ASA) are not intended as standards, guidelines, or absolute requirements, and their use cannot guarantee any specific outcome. They may be adopted, modified, or rejected according to clinical needs and constraints, and they are not intended to replace local institutional policies. Practice advisories summarize the state of the literature and report opinions obtained from expert consultants and ASA members. They are not supported by scientific literature to the same degree as standards or guidelines because of the lack of sufficient numbers of adequately controlled studies. Practice advisories are subject to periodic revision as warranted by the evolution of medical knowledge, technology, and practice. This document updates…

BACKGROUND: The objective of this investigation was to determine the etiology of perioperative acute coronary syndrome with a particular emphasis on thrombosis versus demand ischemia. METHODS: In this retrospective cohort study, adult patients were identified who underwent coronary angiography for acute coronary syndrome within 30 days of noncardiac surgery at a major tertiary hospital between January 2008 and July 2015. Angiograms were independently reviewed by two interventional cardiologists who were blinded to clinical data and outcomes. Acute coronary syndrome was classified as ST-elevation myocardial infarction, non-ST-elevation myocardial infarction, or unstable angina; myocardial infarctions were adjudicated as type 1 (plaque rupture), type 2 (demand ischemia), or type 4b (stent thrombosis). RESULTS: Among 215,077 patients screened, 146 patients were identified who developed acute coronary syndrome: 117 were classified as non-ST-elevation myocardial infarction (80.1%); 21 (14.4%) were classified as ST-elevation myocardial infarction, and 8 (5.5%) were classified as unstable…

Abstract EDITOR’S PERSPECTIVE What We Already Know about This Topic The incidence of major adverse cardiac events after electroconvulsive therapy is not known What This Article Tells Us That Is New Major adverse cardiac events and death after electroconvulsive therapy are infrequent and occur in about 1 of 50 patients and after about 1 of 200 to 500 electroconvulsive therapy treatments Background Cardiac events after electroconvulsive therapy have been reported sporadically, but a systematic assessment of the risk is missing. The goal of this study was to obtain a robust estimate of the incidence of major adverse cardiac events in adult patients undergoing electroconvulsive therapy. Methods Systematic review and meta-analysis of studies that investigated electroconvulsive therapy and reported major adverse cardiac events and/or mortality. Endpoints were incidence rates of major adverse cardiac events, including myocardial infarction, arrhythmia, pulmonary edema, pulmonary embolism, acute heart failure, and cardiac arrest. Additional endpoints were all-cause and cardiac mortality.…

The field of spinal cord stimulation is expanding rapidly, with new waveform paradigms asserting supraspinal sites of action. The scope of treatment applications is also broadening from chronic pain to include cerebral ischemia, dystonia, tremor, multiple sclerosis, Parkinson disease, neuropsychiatric disorders, memory, addiction, cognitive function, and other neurologic diseases. The role of neurostimulation as an alternative strategy to opioids for chronic pain treatment is under robust discussion in both scientific and public forums. An understanding of the supraspinal mechanisms underlying the beneficial effects of spinal cord stimulation will aid in the appropriate application and development of optimal stimulation strategies for modulating pain signaling pathways. In this review, the authors focus on clinical and preclinical studies that indicate the role of supraspinal mechanisms in spinal cord stimulation-induced pain inhibition, and explore directions for future investigations.

WHAT WE ALREADY KNOW ABOUT THIS TOPIC: WHAT THIS ARTICLE TELLS US THAT IS NEW: BACKGROUND:: Postoperative delirium is associated with poor long-term outcomes and increased mortality. General anesthetic drugs may contribute to delirium because they increase cell-surface expression and function of α5 subunit-containing γ-aminobutyric acid type A receptors, an effect that persists long after the drugs have been eliminated. Dexmedetomidine, an α2 adrenergic receptor agonist, prevents delirium in patients and reduces cognitive deficits in animals. Thus, it was postulated that dexmedetomidine prevents excessive function of α5 γ-aminobutyric acid type A receptors. METHODS: Injectable (etomidate) and inhaled (sevoflurane) anesthetic drugs were studied using cultured murine hippocampal neurons, cultured murine and human cortical astrocytes, and ex vivo murine hippocampal slices. γ-Aminobutyric acid type A receptor function and cell-signaling pathways were studied using electrophysiologic and biochemical methods. Memory and problem-solving behaviors were also studied. RESULTS: The…

WHAT WE ALREADY KNOW ABOUT THIS TOPIC: WHAT THIS ARTICLE TELLS US THAT IS NEW: BACKGROUND:: Although randomized trials show that patients do well when given less blood, there remains a persistent impression that orthopedic surgery patients require a higher hemoglobin transfusion threshold than other patient populations (8 g/dl vs. 7 g/dl). The authors tested the hypothesis in orthopedic patients that implementation of a patient blood management program encouraging a hemoglobin threshold less than 7 g/dl results in decreased blood use with no change in clinical outcomes. METHODS: After launching a multifaceted patient blood management program, the authors retrospectively evaluated all adult orthopedic patients, comparing transfusion practices and clinical outcomes in the pre- and post-blood management cohorts. Risk adjustment accounted for age, sex, surgical procedure, and case mix index. RESULTS: After patient blood management implementation, the mean hemoglobin threshold decreased from 7.8 ± 1.0 g/dl to 6.8 ± 1.0 g/dl (P < 0.0001). Erythrocyte use decreased by 32.5% (from 338 to…

BACKGROUND: Differentiating drug-related changes and state-related changes on the electroencephalogram during anesthetic-induced unconsciousness has remained a challenge. To distinguish these, we designed a rigorous experimental protocol with two drugs known to have distinct molecular mechanisms of action. We hypothesized that drug- and state-related changes can be separated. METHODS: Forty-seven healthy participants were randomized to receive dexmedetomidine (n = 23) or propofol (n = 24) as target-controlled infusions until loss of responsiveness. Then, an attempt was made to arouse the participant to regain responsiveness while keeping the drug infusion constant. Finally, the concentration was increased 1.5-fold to achieve presumable loss of consciousness. We conducted statistical comparisons between the drugs and different states of consciousness for spectral bandwidths, and observed how drug-induced electroencephalogram patterns reversed upon awakening. Cross-frequency coupling was also analyzed between slow-wave phase and alpha power. RESULTS: Eighteen (78%) and 10 (42%)…

Abstract EDITOR’S PERSPECTIVE What We Already Know about This Topic Intraoperative triple-low events (mean arterial pressure less than 75 mmHg, Bispectral Index less than 45, and minimum alveolar fraction of anesthetic less than 0.8) have been found to be associated with increased risk of mortality What This Article Tells Us That Is New A randomized electronic alert of triple-low events to treating clinicians did not reduce 90-day mortality The alerts minimally influenced clinician responses, assessed as vasopressor administration or reduction in end-tidal volatile anesthetic partial pressure, and there was no association between response to alerts and mortality Triple-low events predict mortality but do not appear to be causally related Background Triple-low events (mean arterial pressure less than 75 mmHg, Bispectral Index less than 45, and minimum alveolar fraction less than 0.8) are associated with mortality but may not be causal. This study tested the hypothesis that providing triple-low alerts to clinicians reduces 90-day mortality. Methods Adults having noncardiac surgery…