Optimization of inhaled anesthesia for Octodon degus using electroencephalography

Anaesthetic management of a known or suspected malignant hyperthermia susceptible patient

Objective: to provide a rationale for a need to introduce the new constant — the minimum alveolar concentration for respiratory depression (MACrespiratory depression) and to determine its value. Subjects and methods. Forty-three patients aged 20— 45 years, who had normal weight and ASA physical status I—II, were examined. All the patients underwent induction of sevorane anesthesia without narcotic analgesics, nitrous oxide, and myorelaxants. A laryngeal mask was installed after MAClm was achieved. Sevorane concentrations were increased on a vaporizer, by changing Etanesth at a rate of 0.2 vol% per min until Etanesthresp;ratory depression was achieved. Results. A rationale was provided for a need to introduce the new inhalation anesthesia constant MACrespiratory depression that is, in accordance with the MAC conception, regarded as the inhalation anesthetic concentration that necessitates assisted ventilation in 50% of the patients. MACrespiratory depression was 1.8 MAC. This is essentially more than both MAC and 1.3 MAC, the anesthetic concentration at which any operation can be performed in 90% of patients. At the same time, the derived value of 3.7 vol% is somewhat below MACbarr (4.07 vol%), which means that anesthesia with sevorane only under spontaneous respiration will be inadequate in few patients or its performance will be associated with the risk of hypoxia. Conclusion. The authors’ successively developed concept of anesthesia with preserved spontaneous respiration necessitates the introduction of the new inhalation anesthesia constant MACrespiratory depression. Its value is 3.7% vol% for sevoflurane. Key words: induction of anesthesia, minimum alveolar concentration, spontaneous respiration, inhalation anesthesia.

Anesthesia, which constitutes a state in which noxious events such as surgical procedures are imperceptible, may or may not be accompanied by loss of consciousness. A complete or general anesthetic given by the inhalation or intravenous routes produces hypnosis (profound sleep), analgesia, muscle relaxation, and protection against the increase in blood pressure and heart rate resulting from surgical stress (maintains homeostasis). An anesthetic which blocks the neural transmission of painful stimuli through afferent nerves and does not affect the level of consciousness can be classified as a local anesthetic. Induction of general anesthesia produces a progressive deepening of the anesthetic state and represents a descending desensitization of the central nervous system (CNS). A progression of clinical signs useful for estimating the depth of anesthesia. Four stages can be defined: first, a state of altered consciousness and analgesia begin; second, loss of consciousness, accompanied by irregular respiration and motor movement from depression of higher motor inhibitory centers with release of lower motor mechanisms, occurs; third, surgical anesthesia is reached, in which spinal cord and spinal reflexes are abolished, providing relaxation of skeletal musculature, and loss of corneal, conjunctival, pharyngeal, and laryngeal reflexes occurs progressively; fourth, onset of respiratory paralysis resulting from significant depression of the medullary respiratory center occurs, and subsequent cardiovascular collapse ensues. Monitoring via an electroencephalogram (EEG) and hemodynamic and blood gas monitoring help assess the depth of anesthesia. The potency of inhaled agents is expressed as the minimum alveolar concentration (MAC) that is required to prevent spontaneous movement in response to a surgical or equivalent stimulus in 50% of patients. The onset of action is fast (within 60 s) for the intravenous anesthetic agents and somewhat slower for inhalation and local anesthetics. Although the modern practice of anesthesia is exceedingly sophisticated, identification of the basic molecular mechanism underlying it is still lacking. Inhalational anesthetics are very diverse chemically and extrapolation from the effect of a particular agent to the physiological state of anesthesia is problematic. Anesthesia theories may be divided into two categories: lipid theories and protein theories. Lipid theory postulates that inhalational anesthetics exert their primary effects by dissolving in the lipid portions of nerves, altering the conductivity. In protein theories, the direct interaction of inhalation anesthetics and proteins has been proposed as the cause of anesthesia. All inhalation anesthetics agents introduced after 1950, except ethyl vinyl ether, contain fluorine. Agents such as ether, chloroform, trichloroethylene (Trilene), cyclopropane, and fluoroxene (Fluoromar), which were once used, have been displaced by the newer fluorinated anesthetics. The intravenous (iv) anesthetic agents are of two types: those which are used to induce, but not maintain, anesthesia, and those useful for induction and also maintenance. The need is for an anesthetic agent having an extremely fast rate of onset and limited side effects. Fast onset minimizes the stress and agitation. Among the various classes of compounds that have been used are barbiturates, opioids, steroids, benzodiazepines, and hindered phenols. Balanced anesthesia, a potent opioid combined with an inhalation agent, is often used. The inhalational agents probably exert their biological activity through physical effects, while function through a biological receptor‐mediated pathway. At the end of a surgery, the primary concern is to eliminate respiratory depressant effects. This reversal can also diminish analgesic effects. There are two types of reversal agents: pure antagonists and mixed agonist–antagonists. The antagonists naloxone and naltrexone are the most commonly used. Local anesthetics act by inhibiting the channel opening allowing influx of sodium ions. The degree of blockage depends not only on the amount of drug, but also on the rate of nerve stimulation. In the clinically useful agents the polar group is an ester or an amide, although activity may be maintained when the polar function is an ether, thioether, ketone, or thioester. The ideal agent should have a short onset of nesthesia and be useful for multiple indications.

STRESS is associated with an increase in the activity of the hypothalamic-pituitary-adrenal (HPA) axis. It has been shown that some anaesthetics may stimulate a stress response (Gonzalez Gil and others...

Correlation between bispectral index and age-adjusted minimal alveolar concentration

Breast cancer is one of the most common cancers in women. General anesthesia is a commonly used anesthesia method for breast cancer surgery, and studies have confirmed that general anesthesia can induce immunosuppression in breast cancer patients and increase the metastasis rate of tumors. However, the difference between the effects of intravenous general anesthesia and inhalation anesthesia on the function of T-lymphocytes is still controversial, and it is necessary to explore reasonable anesthesia methods to reduce immunosuppression caused by surgery and anesthesia. Databases (Embase, PubMed, Cochrane Library, CBM, CNKI, and Wanfang) were searched (up to October 2022) for randomized controlled trials (RCTs) comparing intraoperative inhalation anesthesia and propofol intravenous anesthesia in breast cancer patients, with the outcome of T-lymphocyte subsets. The meta-analysis was performed by STATA 14.0. Six RCTs with 352 patients were included in the study. Compared with inhalation anesthesia, there was no difference in T-lymphocyte subsets between the two groups immediately after surgery, but the activities of CD4+ T cells in patients with propofol anesthesia were higher (standard mean difference [SMD] = 0.234, 95% confidence interval [CI]: 0.003-0.466, P = 0.047, I2 = 44.1%) than those under inhalation anesthesia 1 day after surgery, and CD4+/CD8+ activities in patients with propofol anesthesia were higher (SMD = 304, 95% CI: 0.072-0.537, P = 0.010, I2 = 48.0%) than those under inhalation anesthesia 1 day after surgery. There were no differences in the effects of propofol and inhalation anesthetics on T-lymphocytes immediately after surgery, but the inhibitory effects of inhalation anesthetics on CD4+ and CD4+/CD8+ cells were stronger 1 day after surgery.

BACKGROUND:External cephalic version (ECV) is a frequently performed obstetric procedure for fetal breech presentation to avoid cesarean delivery. Neuraxial, intravenous, and inhalational anesthetic techniques have been studied to reduce maternal discomfort caused by the forceful manipulation. This study compares the effects of these anesthetic techniques on ECV and incidence of cesarean delivery.METHODS:We conducted a comprehensive literature search for published randomized controlled trials (RCTs) or well-conducted quasi-randomized trials of ECV performed either without anesthesia or under neuraxial, intravenous, or inhalational anesthesia. Pairwise random-effects meta-analyses and network meta-analyses were performed to compare and rank the perinatal outcomes of the 3 anesthetic interventions and no anesthesia control, including the rate of successful version, cesarean delivery, maternal hypotension, nonreassuring fetal response, and adequacy of maternal pain control/satisfaction.RESULTS:Eighteen RCTs and 1 quasi-randomized trial involving a total of 2296 term parturients with a noncephalic presenting singleton fetus were included. ECV under neuraxial anesthesia had significantly higher odds of successful fetal version compared to control (odds ratio [OR] = 2.59; 95% confidence interval [CI], 1.88–3.57), compared to intravenous anesthesia (OR = 2.08; 95% CI, 1.36–3.16), and compared to inhalational anesthesia (OR = 2.30; 95% CI, 1.33–4.00). No association was found between anesthesia interventions and rate of cesarean delivery. Neuraxial anesthesia was associated with higher odds of maternal hypotension (OR = 9.33; 95% CI, 3.14–27.68). Intravenous anesthesia was associated with significantly lower odds of nonreassuring fetal response compared to control (OR = 0.36; 95% CI, 0.16–0.82). Patients received neuraxial anesthesia reported significantly lower visual analog scale (VAS) of procedure-related pain (standardized mean difference [SMD] = −1.61; 95% CI, −1.92 to −1.31). The VAS scores of pain were also significantly lower with intravenous (SMD = −1.61; 95% CI, −1.92 to −1.31) and inhalational (SMD = −1.19; 95% CI, −1.58 to −0.8) anesthesia. The VAS of patient satisfaction was significantly higher with intravenous anesthesia (SMD = 1.53; 95% CI, 0.64–2.43).CONCLUSIONS:Compared to control, ECV with neuraxial anesthesia had a significantly higher successful rate; however, the odds of maternal hypotension increased significantly. All anesthesia interventions provided significant reduction of procedure-related pain. Intravenous anesthesia had significantly higher score in patient satisfaction and lower odds of nonreassuring fetal response. No evidence indicated that anesthesia interventions were associated with significant decrease in the incidence of cesarean delivery compared to control.

Department of Anesthesiology, University of Utah School of Medicine, Salt Lake City, Utah. talmage.egan@hsc.utah.edu.The Pharmacology of Inhaled Anesthetics. By Edmond I Eger, II, M.D., James B. Eisenkraft, M.D., Richard B. Weiskopf, M.D., Baxter Healthcare Corporation, New Providence, New Jersey, 2003. ISBN: TXV1-035635. Pages: 327 and 2 DVDs. Price: Complimentary.Authored by a group of distinguished clinician scientists who are internationally recognized for their contributions to the topic, The Pharmacology of Inhaled Anesthetics is an effectively organized, copiously illustrated, well-written review of both the basic and clinical pharmacology of inhalation anesthetics. From a clinical perspective, perhaps the primary aim of the authors was to compare and contrast the newer inhaled anesthetics, sevoflurane and desflurane, with the older, more soluble ones. In the broader context of how this work fits within the collection of existing textbooks on inhaled anesthesia, it can be viewed as an up-to-date review, integrating recent discoveries with well-established knowledge.The structure of the book conforms to the traditional areas of investigation for inhaled anesthetics. The initial chapters are focused on basic issues including a history of inhaled anesthetics, physiochemistry, the concept of minimum alveolar concentration, mechanisms of drug action, and pharmacokinetics. Several chapters addressing pharmacodynamics are organized by organ system (e.g. , circulatory effects and pulmonary effects). Next are chapters devoted to metabolism and liver-kidney toxicity. The book finishes with very practically oriented chapters discussing inhaled anesthetic delivery systems and clinical applications, offering “how to do it” recipes.The textbook is accompanied by a number of educational enhancements that clearly increase the overall appeal of the entire package, particularly for residents in training. Each chapter has a list of specific learning objectives. At the end of the book there is a list of study questions intended for students preparing for certification examinations. The answers to these questions can be submitted for scoring and continuing medical education credit. The book is also complete with a DVD-based supplement that complements the text. The DVD is essentially a video seminar focused on the topic; it is organized with the same chapter headings as the book. Filmed in the setting of a small classroom with a group of trainees and author, Edmond I. Eger II, M.D., the DVD seminar is a comprehensive lecture series with standard computer-generated slides. A unique feature of the DVD seminar is the inclusion of “in operating room” video clips created to illustrate the scientific foundation of inhaled anesthesia at the point of clinical care.The greatest strength of the book is its authoritative authorship. As major contributors to this area of anesthesia clinical pharmacology, these authors have organized their thinking on the topic over decades and are experienced in conveying this knowledge. The book therefore represents an up-to-date review of the entire area. In part because it brings together detailed information that was previously only available in separate monographs focused on the individual agents, and also because it includes the latest discoveries in the field (e.g. , new information about locus and mechanism of action, among many others), the book can be considered a “one-stop shopping” source of information on inhalation anesthesia.A unique aspect of the book that probably deserves mention is the nontraditional publishing pathway. Inspection of the title page does not mention a publishing house or a Library of Congress catalogue number. The title cannot be found through a search of popular online booksellers that feature current books in print. Because the book and the accompanying DVD recently appeared in the mail boxes of all our residents in training, I have surmised that the book was probably produced as a collaborative educational effort between an industry sponsor and Dr. Eger and colleagues, although it is impossible to be sure by examining the book. A clear statement of support would easily address this confusion and would be appropriate in the spirit of conflict of interest disclosure. In any case, this reviewer believes that the authors have provided a balanced appraisal of the topic.All in all, I couldn’t be much more enthusiastic about this book, particularly for the resident in training audience. It’s well done. It’s authoritative. And, as best I can tell, it’s free.

The use of new inhalation anesthetics in patients with acute abdominal pathology has several advantages. However, the use of inhalation anesthetics, in particular sevoflurane, does not exclude perioperative disorders of energy-structural interactions in the body of patients, manifested by changes in higher cortical functions. The aim of our study is to improve treatment outcomes for patients with acute pathology of the abdominal organs, by giving an energy-protective orientation to the inhalation anesthesia with sevoflurane. Materials, methods and results. The work was performed on the results of perioperative audit of energy-structural interactions in the mass of body cells, reserves, properties and efficiency of autoregulation in 91 patients with acute pathology of the abdominal cavity organs. According to the initial level of energy-structural interactions in the mass of body cells, patients were divided into two groups: with dysfunction and damage. Each group consisted of treatment and control groups. The patients of the control group underwent inhalation anesthesia based on sevoflurane in accordance with the standard protocol. In the treatment group, inhalation anesthesia was supplemented with energy-protective techniques for perioperative management of patients. Analysis of the clinical study showed a close relationship between early manifestations of structural microdamage of brain cells with energy-structural changes in the mass of body cells. Conclusions. The use of energy-protective techniques significantly increases the effectiveness of inhalation anesthesia in patients with dysfunction and damage of energy-structural interactions.

Postoperative nausea and vomiting (PONV) are among the most unfavourable anaesthetic outcomes attributed to the administration of inhaled anaesthetics. Accordingly, inhaled anaesthetics are frequently substituted by propofol when patients are at risk of PONV. As, on some occasions, inhalational anaesthesia may be favourable, the relative impact of propofol anaesthesia needs to be established based on robust data. To compare the effectiveness of a single-drug pharmacological prophylaxis with total intravenous anaesthesia (TIVA) for prevention of PONV. Systematic review of randomised controlled trials with meta-analyses. All available studies until 29 April 2015 were retrieved from MEDLINE, CENTRAL and EMBASE. Randomised controlled trials on adult patients undergoing general anaesthesia with at least one group receiving propofol-based intravenous anaesthesia without further antiemetic prophylaxis, and one group receiving inhalational anaesthesia with single-drug antiemetic prophylaxis. Fourteen studies involving 2051 patients were included. Compared with TIVA, after inhalational anaesthesia and single-drug antiemetic prophylaxis, there was no difference in the overall risk of PONV [relative risk (RR) 1.06, 95% confidence interval (CI) 0.85; 1.32, GRADE rating moderate], nor was there any difference in the risk of postoperative vomiting (RR 1.17, 95% CI 0.78; 1.76), need for rescue medication (RR 1.16, 95% CI 0.68; 1.99) or early PONV (RR 1.06, 95% CI 0.88; 1.27). However, TIVA was associated with an increased risk of late PONV (RR 1.41, 95% CI 1.10; 1.79, P = 0.006). Six studies investigated other side-effects associated with anaesthesia and found no differences between the two groups. Finally, there was evidence of a publication bias that included smaller studies favouring TIVA. This meta-analysis confirms the results from indirect comparisons in individual studies: instead of substituting inhalational anaesthesia with propofol-based TIVA, a similar antiemetic effect can be achieved by adding single-drug pharmacological prophylaxis to the inhalational anaesthetic. This systematic review with meta-analysis was registered at PROSPERO (www.crd.york.ac.uk/PROSPERO), study number CRD42015019571.

Sevoflurane — A new era in inhalation anaesthesia

Objective To compare the BIS values in patients under anesthesia with minimum alveolar concentration (MAC) of sevoflurane and median effective concentration (EC50) of propofol at loss of consciousness.Methods Sixty ASA Ⅰ or Ⅱ patients,aged 18-60 yr,undergoing elective surgery under general anesthesia,were equally and randomly divided into 2 groups:inhalational anesthesia with sevoflurane group (group Sev) and intravenous anesthesia with propofol ( group Pro).The end-tidal concentration of sevoflurane was monitored using Aestiva anesthesia machine (Datex Ohmeda) in group Sev.Anesthesia was induced with intravenous injection of etomidate 0.3 mg/kg,rocuronium 1 mg/kg,and remifentanil 0.2 μg/kg.The patients were mechanically ventilated after tracheal intubafion.Sevoflurane inhalation was started 12.5 min after intubation in group Sev.Propofol was given by target-controlled infusion with the target plasma concentration set at 3.8 μg/ml 12.5 min after intubation in group Pro.When the effect-site concentrations of propofol reached EC50 of propofol at loss of consciousness (2.2 μg/ml),1.3 EC50(2.86 μg/ml) and 1.5 EC50 (3.3μg/ml) and when the end-tidal concentrations of sevoflurane reached 1.0,1.3 and 1.5 MAC,BIS value,MAP and HR were recorded.Results HR was significantly higher at 1.3 MAC or 1.3 EC50,and at 1.5 MAC or 1.5 EC50 in group Pro than in group Sev ( P ＜0.05).BIS value was significantly decreased at 1.3 MAC or 1.3 EC50,and at 1.5 MAC or 1.5 EC50 compared with that at 1.0 MAC or EC50(P ＜0.05).There was no significant difference in MAP and BIS value at each time point between the two groups ( P ＞ 0.05).Conclusion No significant change in BIS values is found in patients under anesthesia with 1.0,1.3 and 1.5 MAC of sevoflurane and with 1.0,1.3 and 1.5 EC50 of propofol. Key words: Anesthetics, inhalation; Propofol; Electroencephalography; Unconsciousness; Doseresponse relationship, drug

Optic nerve sheath diameter (ONSD) is recognized as a surrogate indicator of intracranial pressure (ICP) during surgery. Due to the requirements of surgery, the adjustment to the steep Trendelenburg position and the establishment of CO2 pneumoperitoneum can lead to an increase in ICP, resulting in an increase in the ONSD. Anesthetic agents have different impacts on cerebral blood volume and ICP. The aim of this study was to evaluate the effects of propofol and inhalational anesthetics on the ONSD based on data from randomized controlled trials (RCTs). The electronic databases of PubMed, EMBASE, Ovid MEDLINE, the Cochrane Library, and other databases were searched systematically using specified keywords from their inception to June 2021. The Chi-square test and I2 test were used to evaluate the heterogeneity across the studies. The weighted mean difference (WMD) with 95% confidence interval (CI) were adopted to analyze continuous data. A total of 379 patients from 7 studies were involved in this meta-analysis. There were borderline significant differences in the ONSD atT2 between propofol and the control group: T2 (WMD =-0.15, 95% CI: -0.31, -0.00, P=0.005). There were significant differences at T3 (WMD =-0.23,95% CI: -0.42, -0.05, P =0.013) and T4 (WMD =-0.18, 95% CI: -0.29, -0.07, P =0 .001). After statistical verification, there was no significant difference in the ONSD at T1 between the 2 groups: T1 (WMD =-0.08, 95% CI: -0.26, 0.10, P =0 .368). There were also no significant differences in mean arterial pressure (MAP) (P=0.654, 0.445, 0.698, and 0.562, respectively) and end tidal CO2 (ETCO2) (P=0.081, 0.506, 0.126, and 0.983, respectively) at T1, T2, T3 and T4 between propofol and inhalational anesthetics. The findings in the present study indicated that the ONSD during propofol anesthesia was significantly lower than that during inhalational anesthesia after adopting the Trendelenburg position and CO2 pneumoperitoneum. These analysis results suggest that propofol anesthesia may help to minimize changes in ICP compared to inhalational anesthetics.

Postoperative nausea and postoperative vomiting are frequent but often missed complications after general anesthesia in pediatric patients. Because inhaled anesthetics are known to trigger postoperative vomiting, total intravenous anesthesia is often administered in high-risk children to avoid the use of inhalational anesthesia. Since inhalational anesthesia might be advantageous in some situations, the question is raised whether administration of pharmacological prophylaxis offers equal protection from postoperative vomiting compared with total intravenous anesthesia alone. The aim of this systematic review was to compare total intravenous anesthesia with single-drug pharmacological prophylaxis for the protection of postoperative vomiting in pediatric patients. We conducted a systematic review (EMBASE, MEDLINE, and CENTRAL) with meta-analysis on randomized controlled trials including patients <18 years of age undergoing general anesthesia, with one group receiving propofol-based total intravenous anesthesia and another group receiving inhalational anesthesia with single pharmacological prophylaxis. Primary outcome was the overall incidence for postoperative vomiting. Secondary outcomes included early and late postoperative vomiting, the need for postoperative antiemetic medication, time to first oral intake, duration of stay in the postanesthesia care unit, and any adverse events defined as such by the respective authors. Risk ratios (RR) or mean differences (MD) with 95% confidence intervals (95% CI) were calculated using a random effects model with inverse variance weighting. Four randomized controlled trials including 558 children were included in the final analysis. All patients underwent strabismus surgery. Total intravenous anesthesia and single pharmacological prophylaxis were equally effective in preventing overall postoperative vomiting (RR 0.99 [95% CI 0.77; 1.27]; 4 trials), as well as vomiting in the early (1.48 [0.78; 2.83]; 4 trials) and late (0.89 [0.56;1.42]; 2 trials) postoperative period. There was no difference in the need for postoperative antiemetic medication. Although patients resumed drinking and eating significantly earlier following total intravenous anesthesia (MD -1.40 hours [-2.01; -0.80], P < .001), the duration of PACU stay did not differ between groups. The incidence of intraoperative oculocardiac reflex was the only reported adverse event, which was more likely to occur after total intravenous anesthesia (1.86 [1.01; 3.41]). Single pharmacological prophylaxis appears equally effective compared with total intravenous anesthesia in preventing postoperative vomiting in pediatric patients. However, during strabismus surgery, total intravenous anesthesia increases the risk for bradycardia due to oculocardiac reflex. Thus, when anesthesia is maintained with inhalational anesthetics, its emetogenic effects can sufficiently be compensated by the addition of a single prophylactic antiemetic medication.

Severity of airway hyperreactivity associated with laryngeal mask airway removal: correlation with volatile anesthetic choice and depth of anesthesia