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Anesthetic agents cause unique electroencephalogram (EEG) activity resulting from actions on their diverse molecular targets. Typically to produce balanced anesthesia in the clinical setting, several anesthetic and adjuvant agents are combined. This creates challenges for the clinical use of intraoperative EEG monitoring, because computational approaches are mostly limited to spectral analyses and different agents and combinations produce different EEG responses. Thus, testing of many combinations of agents is needed to generate accurate, protocol independent analyses. Additionally, most studies to develop new computational approaches take place in young, healthy adults and electrophysiological responses to anesthetics vary widely at the extremes of age, due to physiological brain differences. Below, we discuss the challenges associated with EEG biomarker identification for anesthetic depth based on the diversity of molecular targets. We suggest that by focusing on the generalized effects of anesthetic agents on network activity, we can create paths for improved universal analyses.

Objective: Previous studies have reported that propofol has antitumor, anti-inflammatory, and antioxidant effects in addition to its anesthetic properties. To confirm this, a retrospective investigation was conducted to determine whether different anesthetic agents, particularly propofol and inhalation anesthetics, have an effect on the recurrence of hepatocellular carcinoma (HCC) in patients who were diagnosed with primary HCC and underwent laparoscopic hepatectomy., Subjects and Methods: Patients with Barcelona Clinic Liver Cancer stages 0, A, and B HCC, who underwent laparoscopic hepatic resection, were enrolled in this study. Post-operative HCC recurrence, which was determined from postoperative liver CT, was evaluated 24 months postoperatively with respect to the main anesthetic agents. The characteristics of HCC and other patient-related or surgery-related variables were evaluated together., Results and Conclusion: During the 24-month period after hepatic resection, less HCC patients in the propofol group than in the inhalation group recurred (p = 0.046). The mean time to recurrence was 20.8 months (95% CI, 19.7-22.0) and 19.1 months (95% CI, 17.8-20.4) in the propofol group and the inhalation group, respectively. In addition, multivariable Cox proportional regression analysis revealed that the propofol group showed significantly decreased recurrence versus the inhalation group (hazard ratio, 0.57; 95% CI, 0.47-0.69; p = 0.029). When propofol was used as the main general anesthetic agent for laparoscopic hepatic resection, the postoperative 2-year recurrence rate decreased in early- and intermediate-stage HCC., (© 2020 The Author(s) Published by S. Karger AG, Basel.)

The prevalence of obesity is increasing globally. Rational perioperative anesthetic drug selection and administration require knowledge of how obesity interacts with those drugs. In this review, we summarize different aspects of the anesthetic agents, including pharmacokinetics (PK), pharmacodynamics (PD) and clinical application of the most commonly used medications with particular focus on the enhanced recovery of the obese patient., (Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.net.)

Opioid-free anesthesia is revolutionizing anesthetic practices for its potential benefits in selected patients. Opioid-free anesthesia represents a step forward in anesthetic practice as it has been suggested to provide potential clinical benefits for selected patients. Opioid-free anesthesia spares the use of opioids and involves the administration of multiple adjuvant anesthetics, which may have an impact on cancer progression. All this have added to the growing interest in the immune response to anesthetics, making opioid-free anesthesia a promising avenue for future research. Assessing the role of anesthetics in immunomodulation in the surgical setting is challenging, and results are often contradictory. Indeed, there is a scarcity of data of studies on humans, which hinder the interpretation of results. However, promising evidence has been published that cancer progression can be delayed by the administration of specific anesthetic agents., (Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.net.)

Numerous studies using rats in stroke models have failed to translate into successful clinical trials in humans. The Stroke Therapy Academic Industry Roundtable (STAIR) has produced guidelines on the rodent stroke model for preclinical trials in order to promote the successful translation of animal to human studies. These guidelines also underline the importance of anaesthetic and monitoring techniques. The aim of this literature review is to document whether anaesthesia protocols (i.e., choice of agents, mode of ventilation, physiological support and monitoring) have been amended since the publication of the STAIR guidelines in 2009. A number of articles describing the use of a stroke model in adult rats from the years 2005 and 2015 were randomly selected from the PubMed database and analysed for the following parameters: country where the study was performed, strain of rats used, technique of stroke induction, anaesthetic agent for induction and maintenance, mode of intubation and ventilation, monitoring techniques, control of body temperature, vascular accesses, and administration of intravenous fluids and analgesics. For each parameter (stroke, induction, maintenance, monitoring), exact chi-square tests were used to determine whether or not proportions were significantly different across year and p values were corrected for multiple comparisons. An exact p-test was used for each parameter to compare the frequency distribution of each value followed by a Bonferroni test. The level of significant set at < 0.05. Results show that there were very few differences in the anaesthetic and monitoring techniques used between 2005 and 2015. In 2015, significantly more studies were performed in China and significantly fewer studies used isoflurane and nitrous oxide. The most striking finding is that the vast majority of all the studies from both 2005 and 2015 did not report the use of ventilation; measurement of blood gases, end-tidal carbon dioxide concentration, or blood pressure; or administration of intravenous fluids or analgesics. The review of articles published in 2015 showed that the STAIR guidelines appear to have had no effect on the anaesthetic and monitoring techniques in rats undergoing experimental stroke induction, despite the publication of said guidelines in 2009., Competing Interests: The authors have declared that no competing interests exist.

Hypotension following obstetric spinal anaesthesia remains a common and important problem. While recent research advances have brought us closer to the perfect recipe for the obstetric spinal anaesthetic, these advances have not been translated into practical guidelines able to reduce the unacceptable number of fatalities that occur in environments where resources are limited. In South Africa, more than half of anaesthetic deaths are still related to spinal hypotension. A gap exists between the 'perfect recipe', developed from a clinical context rooted in resource-rich research environments, and its application and performance in real-world resource-poor environments - conditions experienced by more than 75% of the world's population. This review attempts to define this knowledge gap and proposes a research agenda to address the deficiencies.

Surgery remains the mainstay treatment in the majority of solid cancers. Anesthetics and analgesics used during the perioperative period may modulate the innate and adaptive immune system, inflammation and angiogenesis, and have a direct effect on cancer cells that could ultimately modify oncological outcomes. For instance, volatile anesthetics and opioid analgesics have shown predominantly pro-tumor effects, while propofol, non-steroid anti-inflammatory drugs have mostly anticancer effects. Researchers have been especially interested in investigating the association between the use of regional anesthesia techniques and the postoperative survival of patients with cancers. Since the results of the current retrospective studies are conflicting, several researchers are conducting prospective randomized trials., (Copyright © 2015 Sociedad Española de Anestesiología, Reanimación y Terapéutica del Dolor. Publicado por Elsevier España, S.L.U. All rights reserved.)

Study Objective: To compare parenterally administered moderate sedation and paracervical block versus general anesthesia during day-case operative hysteroscopy for polypectomy in terms of patients' postoperative pain perception, operating time, and postoperative drug administration., Design: A pilot study (Canadian Task Force classification I)., Setting: A university hospital., Patients: Women undergoing hysteroscopic polypectomy procedures (N = 56)., Interventions: Hysteroscopic polypectomy with general anesthesia or moderate parenteral sedation and paracervical block., Measurements and Main Results: The patients were divided into 2 groups: 26 underwent general anesthesia (group 1), and 30 were submitted to moderate parenteral sedation and a paracervical block (group 2). General anesthesia was induced with the laryngeal mask airway with propofol (1% 1-2.5 mg/kg) and fentanyl (1-2 μg/kg) and maintained with an infusion of propofol (2% 3-5 mg/kg/h). After the procedure, patients in the general anesthesia group received postoperative analgesic medication with paracetamol (20 mg/kg) and ketorolac (0.6 mg/kg) or tramadol (2-3 mg/kg). The group receiving moderate parenterally sedation and a paracervical block received a paracervical block with mepivacaine (1% 10 mL) and lidocaine (2% 10 mL) and received fentanyl (1 μg/kg) and propofol (1% 1-3 mg/kg/h) maintaining spontaneous breathing. A blind observer recorded the operative time and the discomfort of patients using a 4-step scale (0-3). The postoperative pain assessment was performed 3 hours after the procedure with a self-administered validated tool, the Brief Pain Inventory. We found that women receiving moderate parenteral sedation and a paracervical block perceived significantly less pain in daily activity (p < .001), walking (p < .001), daily work (p < .001), relations with others (p = .007), sleep (p < .001), and pain contrasting enjoyment of life (p < .001). The total amount of time spent in the operating room in group 2 was significantly lower than in group 1 (p < .014)., Conclusion: Moderate sedation plus a paracervical block for operative hysteroscopy is associated with reduced pain perception and a shorter operative time., (Copyright © 2015 AAGL. Published by Elsevier Inc. All rights reserved.)

Reasons for Performing Study: Multicentre Confidential Enquiries into Perioperative Equine Fatalities (CEPEF) have not been conducted since the initial CEPEF Phases 1-3, 20 years ago., Objectives: To collect data on current practice in equine anaesthesia and to recruit participants for CEPEF-4., Study Design: Online questionnaire survey., Methods: An online questionnaire was prepared and the link distributed internationally to veterinarians possibly performing equine anaesthesia, using emails, posters, flyers and an editorial. The questionnaire included 52 closed, semiclosed and open questions divided into 8 subgroups: demographic data, anaesthetist, anaesthesia management (preoperative, technical equipment, monitoring, drugs, recovery), areas of improvements and risks and motivation for participation in CEPEF-4. Descriptive statistics and Chi-squared tests for comparison of categorical variables were performed., Results: A total of 199 questionnaires were completed by veterinarians from 14 different countries. Of the respondents, 43% worked in private hospitals, 36% in private practices and 21% in university teaching hospitals. In 40 institutions (23%) there was at least one diplomate of the European or American colleges of veterinary anaesthesia and analgesia on staff. Individual respondents reported routinely employ the following anaesthesia monitoring modalities: electrocardiography (80%), invasive arterial blood pressures (70%), pulse oximetry (60%), capnography (55%), arterial blood gases (47%), composition of inspired and expired gases (45%) and body temperature (35%). Drugs administered frequently or routinely as part of a standard protocol were: acepromazine (44%), xylazine (68%), butorphanol (59%), ketamine (96%), diazepam (83%), isoflurane (76%), dobutamine (46%), and, as a nonsteroidal anti-inflammatory drug, phenylbutazone (73%) or flunixin meglumine (66%). Recovery was routinely assisted by 40%. The main factors perceived by the respondents to affect outcome of equine anaesthesia were the preoperative health status of the animal and training of the anaesthetist., Conclusions: Current practice in equine anaesthesia varies widely, and the study has highlighted important topics relevant for designing a future prospective multicentre cohort study (CEPEF-4). The Summary is available in Chinese - see Supporting information., (© 2014 EVJ Ltd.)

The anesthesia has been improved all over the years. However, it can have impact on health, in both patients and animals anesthetized, as well as professionals exposed to inhaled anesthetics. There is continuing effort to understand the possible effects of anesthetics at molecular levels. Knowing the effects of anesthetic agents on genetic material could be a valuable basic support to better understand the possible mechanisms of these agents. Thus, the purpose of this review is to provide an overview on the genotoxic potential, evaluated in animal models, of many anesthetics that have already been used and those currently used in anesthesia.

Background: Complex medical conditions are frequent among seniors, and their medical treatment represents a challenge. Older patients have a high rate of consumption of prescription drugs, greater risks of medication interactions, and a higher likelihood of side effects. Many common drugs used by the elderly also have addictive potential. Prescription patterns involving general practitioners (GPs) are not sufficiently known., Objective: Our objective was to examine the regular GP role in the prescription of addictive and non-addictive drugs to home-dwelling older people in Norway., Design: The study was designed as a panel data study., Setting: Data on all prescription drugs dispensed at pharmacies to patients 70 years and older from the Norwegian Prescription Database were merged with data on GPs and GPs' patient lists from the Regular General Practitioner Database. The dataset included 624,308 patients and 4,520 GPs in the period from 2004 to 2007., Outcome Measures: Outcome measures included quantities of addictive and non-addictive drugs prescribed and dispensed per patient by the regular GP, other GPs, non-GP specialists, and hospital doctors; the number of prescribers per patient; and time trend over the observation period., Results: On average, 319 defined daily doses of medication were prescribed per quarter to an older patient, 6 % of which were classified as possibly addictive medications. Of all drugs, 72 % were prescribed by the patients' regular GP, 77 % of addictives and 71 % of non-addictives. Drug quantities prescribed increased with multiple prescribers and did so to a greater extent for addictives than for non-addictives. Time trends show an increasing number of prescribers and increasing drug quantities over the observation period., Conclusion: The regular GP prescribes the major portion of non-addictive and, especially, addictive medications to older patients and thus holds a key role in the coordination of prescriptions to this group. Focusing on the role of the GP is important in view of the increasing time trends.

Patients with muscle pathology are a challenge for anaesthesiologists because of possible life-threatening general anaesthesia complications. A review of the current medical literature on the issue clearly indicates that increasing awareness by anaesthesiologists in recent years has led to a reduction in the occurrence of adverse events in patients with diagnostically well-defined muscle disease. On the other hand, the current emerging aspect is that the great majority of complications concern subjects with clinically non-overt (silent to mildly symptomatic) and thus undiagnosed myopathy. With a view to improving prevention of possible critical anaesthesia complications in such patients, we present a "Safe Anaesthesia Table", listing both the anaesthetic drugs to be avoided and those considered harmless for myopathic patients, irrespective of age and type of pathology. In addition, a brief outline about the clinical aspects suggestive of a possible muscle pathology is also provided. Using "safe drugs" during routine surgical procedures in subjects with suspected undiagnosed myopathy will enable the anaesthesiologist to avoid delaying surgery, while protecting them from anaesthesia complications. By following this approach the presumed myopathy can be properly investigated after surgery.

Recent clinical studies have suggested that there is an increased risk of Alzheimer's disease (AD) in patients undergoing surgical interventions, but it is unknown whether this effect is related to anesthesia, cardiovascular complications of surgery, or associated conditions such as hypothermia. In addition, many patients, especially the elderly, present persistent post-operative cognitive deterioration after anesthesia, without clear complications during surgery. Experimental studies in animals may be helpful to dissect the pathogenic role of the different factors involved in surgery. Here, we review studies on the effects of anesthesia on neuronal function performed in tissue culture and in experimental animals. Several studies have shown that a small inhalation of anesthetics induces activation of caspases and cell toxicity on glioma and pheochromocitoma cells in culture, which is prevented by treatment with the metal chelating agent clioquinol. Exposure of old rodents to anesthesia produced memory deficits and increased levels of amyloid-β (Aβ) peptide and phosphorylated tau in brain. The effects of long term or short term repetitive exposure to small molecular weight anesthetics are more severe in transgenic AβPPswe than in wild type mice. In the former, low molecular weight increased the number of TUNEL(+) apoptotic cells and the ratio of pro-apoptotic proteins in hippocampus; reduced astroglial and increased microglial responses; increased Aβ aggregates and high molecular weight peptides; abnormal chaperone responses and reduced autophagy. In conclusion, anesthetic gases induce changes which may reproduce AD pathology in mice with mutations which produced AD. It would be interesting to know whether anesthetics are risky for subjects with special genetic risk factors.

This article introduces the 60 top pharmacologic treatments provided for chronic orofacial pain patients. It explains that the majority of "chronic" orofacial pain patients will not find a "cure" to their pain with medications but may find a way to manage their pain. The medications in this article are the most commonly utilized "pain" medications and where it exists. This article reviews some of the current evidence supporting their use on chronic orofacial pain disorders.

The ability to reduce brain injury before, during or after an ischaemic injury, irrespective of the cause, remains an exciting prospect. In this article, we will discuss some of the current research behind cerebral protection, which will include the use of anaesthetic agents, as well as therapies targeted specifically at the complex cascades following brain injury.

The use of experimental animals for magnetic resonance studies requires anaesthesia to provide immobility and acquire signals with minimal stress and maximal reproducibility. However, the conduct of anaesthesia within a magnetic resonance imaging (MRI) suite implicates many problems, because most of the anaesthetic and monitoring equipment contains ferromagnetic substances. To decrease disturbances during anaesthesia and make data interpretation more accurate, it is mandatory that investigators become familiar with methods and physiologic effects of anaesthesia under these special conditions. This article is intended to give an overview of anaesthetic medication, administration routes and practical instructions for anaesthesia in small rodents during MRI.

Purpose of Review: To summarize recent in-vitro and in-vivo research on molecular mechanisms of general anesthetics' actions., Recent Findings: Classes of general anesthetics with distinct clinical profiles appear to induce amnesia, hypnosis, and immobility via different molecular targets. Propofol, etomidate, and barbiturates produce profound amnesia and hypnosis, but weak immobility, by enhancing the activity of specific gamma-aminobutyric acid typeA receptors. In contrast, nitrous oxide, xenon, and ketamine produce analgesia, but weak hypnosis and amnesia, by inhibiting glutamate and nicotinic receptors and activating potassium 'leak' channels such as TREK-1. Volatile halogenated anesthetics show little selectivity for molecular targets. They act on all the channels mentioned above, and other targets such as glycine receptors and mediators of neurotransmitter release., Summary: Several clinically distinct 'anesthetic states' are induced by different classes of drugs acting on neuronal circuits via different molecular targets. Understanding the mechanisms underlying the therapeutic and toxic actions of general anesthetics helps us reframe the 'art' of anesthesia into more of a 'science'. These studies also enhance efforts to develop new drugs with improved clinical utility.

A recent lack of availability of the anesthetic agent methohexital in the United States allowed for a naturalistic study of the efficacy and the adverse effects of alternatives. Methohexital, propofol, and thiopental were compared as anesthetic agents for electroconvulsive therapy in 95 patients treated during a 23-month period in a general public hospital. Missed seizures and arrhythmias were infrequently observed (<4% for any agent). Methohexital was found significantly related to longer seizure durations in comparison with both other agents (P < 0.01). The use of propofol was associated with increased risk of missed seizure (8.9%) compared with methohexital (3.9%) and thiopental (3.2%). Propofol was also associated with higher doses of administered energy, with a statistically significant difference (P = 0.018) observed between propofol and thiopental. Although propofol required the greatest energy delivery, it was associated with the shortest seizure durations. Methohexital resulted in the longest seizure duration, and thiopental was associated with the least amount of energy delivery with an intermediate seizure length.

General anesthesia is defined as complete anesthesia affecting the entire body with loss of consciousness, analgesia, amnesia, and muscle relaxation. There is a wide spectrum of agents able to partially or completely induce general anesthesia. Presently, there is not a single universally accepted technique for anesthetic management during cardiac surgery. Instead, the drugs and combinations of drugs used are derived from the pathophysiologic state of the patient and individual preference and experience of the anesthesiologist. According to the definition of general anesthesia, current practices consist of four main components: hypnosis, analgesia, amnesia, and muscle relaxation. Although many of the agents highlighted in this review are capable of producing more than one of these effects, it is logical that drugs producing these effects are given in combination to achieve the most beneficial effect. This review features a discussion of currently used anesthetic drugs and clinical practices of general anesthesia during cardiac surgery. The information in this particular review is derived from textbooks, current literature, and personal experience, and is designed as a general overview of anesthesia during cardiac surgery.

Almost all animal patients, including research subjects, presented for MRI/MRS studies are anesthetized. As MR moves rapidly beyond simple anatomic studies, becoming a powerful tool for defining physiologic processes, it is imperative that investigators become familiar with the physiologic effects of the anaesthetic drugs. This decreases confounding variables, making data interpretation more accurate and more applicable to future uses. This article is intended to be a basic resource for investigators wishing to increase their understanding of the anesthetic drugs. The following is a general discussion describing the mechanism of action and physiologic effects of the more common anaesthetic drugs used in laboratory animals. A dosing table of common anaesthetics and analgesics used in mice and rats is included because these two species comprise a great majority of MRI/MRS research subjects., (Copyright 2003 John Wiley & Sons, Ltd.)

Nicotinic acetylcholine receptors are members of the ligand-gated ion channel superfamily, that includes also gamma-amino-butiric-acid(A), glycine, and 5-hydroxytryptamine(3) receptors. Functional nicotinic acetylcholine receptors result from the association of five subunits each contributing to the pore lining. The major neuronal nicotinic acetylcholine receptors are heterologous pentamers of alpha4beta2 subunits (brain), or alpha3beta4 subunits (autonomic ganglia). Another class of neuronal receptors that are found both in the central and peripheral nervous system is the homomeric alpha7 receptor. The muscle receptor subtypes comprise of alphabetadeltagamma (embryonal) or alphabetadeltaepsilon (adult) subunits. Although nicotinic acetylcholine receptors are not directly involved in the hypnotic component of anesthesia, it is possible that modulation of central nicotinic transmission by volatile agents contributes to analgesia. The main effect of anesthetic agents on nicotinic acetylcholine receptors is inhibitory. Volatile anesthetics and ketamine are the most potent inhibitors both at alpha4beta2 and alpha3beta4 receptors with clinically relevant IC(50) values. Neuronal nicotinic acetylcholine receptors are more sensitive to anesthetics than their muscle counterparts, with the exception of the alpha7 receptor. Several intravenous anesthetics such as barbiturates, etomidate, and propofol exert also an inhibitory effect on the nicotinic acetylcholine receptors, but only at concentrations higher than those necessary for anesthesia. Usual clinical concentrations of curare cause competitive inhibition of muscle nicotinic acetylcholine receptors while higher concentrations may induce open channel blockade. Neuronal nAChRs like alpha4beta2 and alpha3beta4 are inhibited by atracurium, a curare derivative, but at low concentrations the alpha4beta2 receptor is activated. Inhibition of sympathetic transmission by clinically relevant concentrations of some anesthetic agents is probably one of the factors involved in arterial hypotension during anesthesia.

Investigations of intestinal secretion are often performed under anaesthesia. This study evaluates the influence of anaesthetic agents on the intestinal secretion induced by cholera toxin (CT) in the pig. CT was instilled for 4 h in ligated jejunal loops under anaesthesia with halothane, saffan, alpha-chloralose, or propofol. Cardiovascular parameters, blood gas data, plasma cortisol levels, net fluid accumulation, intraluminal mediators (serotonin (5-HT), prostaglandin E2 (PGE2)) and electrolyte concentrations in the accumulated fluid were determined. The systolic blood pressure and heart rate was highest for saffan-anaesthetized pigs (blood pressure: saffan > alpha-chloralose > propofol = halothane; heart rate: saffan > alpha-chloralose = propofol = halothane), while blood gases and cortisol levels were within the same range. CT induced a dose-dependent fluid accumulation under all four anaesthetics. The fluid accumulation was significantly higher in pigs treated with saffan, alpha-chloralose and propofol than in halothane-treated pigs (saffan = alpha-chloralose > propofol > halothane). There was no significant difference in electrolyte concentrations in the accumulated fluid or in the luminal content of 5-HT and PGE2 between anaesthetics. The results demonstrate that anaesthetic agents profoundly influence the secretory response in the small intestine and indicate the importance of the choice of anaesthetic in this type of experiment.

The surgical suite is a complex environment and the agents used for anesthesia are no less complex. All providers involved in a surgical case should be familiar with the agents a patient receives.

Barbiturates, etomidate and propofol decrease cerebral blood flow (CBF), mediated by a decrease in cerebral metabolism, thus decreasing intracranial pressure (ICP). As the reduction in CBF is secondary to a decrease in cerebral metabolism, these agents will have little effect on CBF or ICP in patients without active cerebral metabolic activity. Ketamine is usually not administered for the anaesthetic management of patients at risk of intracranial hypertension because of the reported increases in cerebral metabolism, CBF and ICP. The increase in CBF, however, may be partly mediated by a sympathetically induced increase in blood pressure and partly by a simultaneous increase in PaCO2 in spontaneously breathing patients. More recent studies report no increase in ICP or flow when ventilation is controlled or when other agents are associated. There is renewed interest in ketamine because it blocks excitatory amino acid receptors in the brain. Synthetic opioids including fentanyl, sufentanil, and alfentanil have been reported to cause an increase in ICP in patients with various intracranial lesions. When blood pressure was supported, no clinically relevant increase in ICP or flow velocity with alfentanil or sufentanil was observed. Thus, the increase in ICP reported with these agents may be related to the compensatory autoregulation-mediated vasodilation, underscoring the importance of administering these agents carefully to avoid systemic hypotension. Halothane consistently increases CBF and should not be used in patients with increased ICP. In contrast, isoflurane does not cause increase in CBF at concentrations below 1 to 1.5 MAC, although the effects on cerebral blood volume are less clear. Desflurane and sevoflurane have similar effects. CO2 reactivity is preserved with all inhaled agents. In patients with increased ICP however, it would be preferable to avoid these agents or to administer very low doses.

The pharmacology of disorders of the respiratory system focuses on one major parameter--bronchodilatation. Drugs are rated as effective purely on how well they reverse brochoconstriction. Patients' conditions are considered reversible if there is a 20% increase in flow rates after a bronchodilator is administered. This article evaluates many of the drugs used in the treatment of reactive airway diseases such as asthma. Particular emphasis is placed on the anesthetic drugs used during the perioperative period.

Porphyrias arise due to enzyme defects in the haem synthetic pathway. They are of concern to the anaesthetist as acute crises may be precipitated by anaesthetic drugs. Anaesthesia must be carefully managed in patients with porphyria in order to achieve a successful outcome.

Botulinum toxin, a neurotoxin responsible for botulism, is at present used to treat anomalous muscle contractions. Administration to children and relatively uncooperative patients requires general anesthesia, which should be selected taking into consideration the special characteristics of the surgical procedure and the possible interactions of anesthetic drugs and the toxin.

This paper lists and describes some of the drugs used during anesthesia in a Day Surgery Operating Room. The classification, action and implications of these drugs are addressed. The discussion is presented under the drug classes as Narcotic Analgesics/Opioids Antagonists, Opiate Antagonists, Induction Agents, Muscle Relaxants/Neuromuscular Blocking Agents, Inhalation Anesthetics, Cholinesterase Inhibitors Anticholinesterases/Parasymphathomimetics, Anticholinergics/Antimuscarinics/Parasympatholytics, and Antiemitics.

The increasing importance of intravenous anaesthesia is based on two developments, namely the synthesis of substances capable of acting selectively and over the short term, and which are rapidly eliminated (good control), and a desire on the part of the anaesthetist to have an anaesthetic whose actions can be controlled in various ways. Efforts in this area are aimed at ensuring not only a minimum of stressing of organs by the anaesthetic, but also a minimisation of risks during the intra-operative phase, and a non-problematic maximally pleasant post-operative course. There are two problems that militate against the realization of these objectives. Although the substances presented here ideally permit the realization of some of these aims, at the same time they are associated with side effects that prevent their use from ever being completely non-problematical, and which should always prompt the exercise of particular care when employing these medications. In addition, the differentiable control made possible by the use of these drugs is (partly) offset by inadequate monitoring with respect to the qualities of the anaesthetic--a fact that modifies the potential advantages of intravenous anaesthesia.

Although brain concentration of anaesthetic agents is attractive as a method of expressing anaesthetic potency, both theoretical and practical considerations limit the usefulness of this index. Therefore, the MAC concept has been utilized to develop another expression of potency: the minimum blood concentration. This takes into account the blood/gas solubility coefficient, and the fact that at equilibrium the amount of anaesthetic agent present in brain is reflected in the blood concentration, and it is applicable to both parenteral and to inhalation anaesthetic agents.

From this study an important notion emerges concerning the risk factors in accidents due to general anaesthetics and myorelaxants. Among these factors, three are clinical parameters which can be assessed by any anaesthetist: the presence of atopy, of a previous drug allergy, of previous, repeated general anaesthesia, close together in timel Two factors were the subject of an experimental study, routinely investigating an abnormal histamine reactivity of the skin, and a latent spasmophilia. No definite conclusion can be made from the results, bearing in mind certain criticisms of technical order and the small number of subjects investigated. However, these works merit being pursued. Thus, if all subjects are not equal when faced with the risks inherent to anaesthesia, a thorough study of individual risk factors will enable a preventive approach, utilising a premedication prescribed with mature consideration.

The importance of structure-activity relationships in the inhaled general anaesthetic agents may have been underestimated in the elucidation of the central and peripheral mechanisms of general anaesthesia. It is true that there is no single spatial arrangement of atoms in a molecule that is essential for anaesthetic activity; the "anesthesiophore", as it was termed, is a myth. However, the chemical structure of a compound is directly related to its physical properties which in turn are one of the major determinants in the molecular mechanisms. Second, chemical structures are the major factors in the physical, chemical and biological stability of the anaesthetics; in particular the electron distributions, bond densities and net atomic charges determine the extent and mode of biotransformation. Some of the evidence for the importance of structure in the anesthetic "side effects" on circulation, respiration and neuroelectric irritability is presented. An example of the detailed structural-molecular studies is provided by the nuclear magnetic resonance investigations of anaesthetic conformational perturbations of haemoglobin which we have used as a model system for elucidating the ground rules of anaesthetic-protein interactions.