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Minimum Alveolar Concentration
Minimum alveolar concentration or MAC is the concentration, often expressed as a percentage by volume, of a vapour in the alveoli of the lungs that is needed to prevent movement (motor response) in 50% of subjects in response to surgical (pain) stimulus. MAC is used to compare the strengths, or potency, of anaesthetic vapours. The concept of MAC was first introduced in 1965. MAC actually is a ''median'' value, not a minimum as term implies. The original paper proposed MAC as the ''minimal'' alveolar concentration, which was shortly thereafter revised to ''minimum'' alveolar concentration. A lower MAC value represents a more potent volatile anesthetic. Other uses of MAC include MAC-BAR (1.7–2.0 MAC), which is the concentration required to block autonomic reflexes to nociceptive stimuli, and MAC-awake (0.3–0.5 MAC), the concentration required to block voluntary reflexes and control perceptive awareness. Formal definition The MAC is the concentration of the vapour (measured ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lung
The lungs are the primary Organ (biology), organs of the respiratory system in many animals, including humans. In mammals and most other tetrapods, two lungs are located near the Vertebral column, backbone on either side of the heart. Their function in the respiratory system is to extract oxygen from the atmosphere and transfer it into the bloodstream, and to release carbon dioxide from the bloodstream into the atmosphere, in a process of gas exchange. Respiration is driven by different muscular systems in different species. Mammals, reptiles and birds use their musculoskeletal systems to support and foster breathing. In early tetrapods, air was driven into the lungs by the pharyngeal muscles via buccal pumping, a mechanism still seen in amphibians. In humans, the primary muscle that drives breathing is the Thoracic diaphragm, diaphragm. The lungs also provide airflow that makes Animal communication#Auditory, vocalisation including speech possible. Humans have two lungs, a ri ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
GABA
GABA (gamma-aminobutyric acid, γ-aminobutyric acid) is the chief inhibitory neurotransmitter in the developmentally mature mammalian central nervous system. Its principal role is reducing neuronal excitability throughout the nervous system. GABA is sold as a dietary supplement in many countries. It has been traditionally thought that exogenous GABA (i.e., taken as a supplement) does not cross the blood–brain barrier, but data obtained from more recent research (2010s) in rats describes the notion as being unclear. The carboxylate form of GABA is γ-aminobutyrate. Function Neurotransmitter Two general classes of GABA receptor are known: * GABAA in which the receptor is part of a ligand-gated ion channel complex * GABAB metabotropic receptors, which are G protein-coupled receptors that open or close ion channels via intermediaries (G proteins) Neurons that produce GABA as their output are called GABAergic neurons, and have chiefly inhibitory action at receptors in t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chloroform
Chloroform, or trichloromethane (often abbreviated as TCM), is an organochloride with the formula and a common solvent. It is a volatile, colorless, sweet-smelling, dense liquid produced on a large scale as a precursor to refrigerants and polytetrafluoroethylene (PTFE). Chloroform was once used as an inhalational anesthetic between the 19th century and the first half of the 20th century. It is miscible with many solvents but it is only very slightly soluble in water (only 8 g/L at 20°C). Structure and name The molecule adopts a tetrahedral molecular geometry with C3v symmetry. The chloroform molecule can be viewed as a methane molecule with three hydrogen atoms replaced with three chlorine atoms, leaving a single hydrogen atom. The name "chloroform" is a portmanteau of ''terchloride'' (tertiary chloride, a trichloride) and ''formyle'', an obsolete name for the methylylidene radical (CH) derived from formic acid. Natural occurrence Many kinds of seaweed produce chlor ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Halothane
Halothane, sold under the brand name Fluothane among others, is a general anaesthetic. It can be used to induce or maintain anaesthesia. One of its benefits is that it does not increase the production of saliva, which can be particularly useful in those who are difficult to intubate. It is given by inhalation. Side effects include an Heart arrhythmia, irregular heartbeat, respiratory depression, and hepatotoxicity. Like all volatile anesthetics, it should not be used in people with a personal or family history of malignant hyperthermia. It appears to be safe in porphyria. It is unclear whether its usage during pregnancy is harmful to the fetus, and its use during a cesarean section, C-section is generally discouraged. Halothane is a Chirality (chemistry), chiral molecule that is used as a racemic mixture. Halothane was discovered in 1951. It was approved for medical use in the United States in 1958. It is on the WHO Model List of Essential Medicines, World Health Organization ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Isoflurane
Isoflurane, sold under the brand name Forane among others, is a halogenated ether used as a general anesthetic. It can be used to start or maintain anesthesia; however, other medications are often used to start anesthesia, due to airway irritation with isoflurane. Isoflurane is given via inhalation. Isoflurane was approved for medical use in the United States in 1979. It is on the World Health Organization's List of Essential Medicines. Medical uses Isoflurane is always administered in conjunction with air or pure oxygen. Often, nitrous oxide is also used. Although its physical properties imply that anaesthesia can be induced more rapidly than with halothane, its pungency can irritate the respiratory system, negating any possible advantage conferred by its physical properties. Thus, it is mostly used in general anesthesia as a maintenance agent after induction of general anesthesia with an intravenous agent such as thiopentone or propofol. Mechanism of action Similar to many ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Enflurane
Enflurane (2-chloro-1,1,2-trifluoroethyl difluoromethyl ether) is a halogenated ether. Developed by Ross Terrell in 1963, it was first used clinically in 1966. It was increasingly used for inhalational anesthesia during the 1970s and 1980s but is no longer in common use. Enflurane is a structural isomer of isoflurane. It vaporizes readily, but is a liquid at room temperature. Physical properties Pharmacology The exact mechanism of the action of general anaesthetics has not been delineated. Enflurane acts as a positive allosteric modulator of the GABAA, glycine, and 5-HT3 receptors, and as a negative allosteric modulator of the AMPA, kainate, and NMDA receptors, as well as of nicotinic acetylcholine receptors. Side effects Clinically, enflurane produces a dose-related depression of myocardial contractility with an associated decrease in myocardial oxygen consumption. Between 2% and 5% of the inhaled dose is oxidised in the liver, producing fluoride ions and difluoro ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sevoflurane
Sevoflurane, sold under the brand name Sevorane, among others, is a sweet-smelling, nonflammable, highly fluorinated methyl isopropyl ether used as an inhalational anaesthetic for induction and maintenance of general anesthesia. After desflurane, it is the volatile anesthetic with the fastest onset. While its offset may be faster than agents other than desflurane in a few circumstances, its offset is more often similar to that of the much older agent isoflurane. While sevoflurane is only half as soluble as isoflurane in blood, the tissue blood partition coefficients of isoflurane and sevoflurane are quite similar. For example, in the muscle group: isoflurane 2.62 vs. sevoflurane 2.57. In the fat group: isoflurane 52 vs. sevoflurane 50. As a result, the longer the case, the more similar will be the emergence times for sevoflurane and isoflurane. It is on the World Health Organization's List of Essential Medicines. Medical uses It is one of the most commonly used volatile a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ethyl Ether
Diethyl ether, or simply ether, is an organic compound with the chemical formula , sometimes abbreviated as . It is a colourless, highly volatile, sweet-smelling ("ethereal odour"), extremely flammable liquid. It belongs to the ether class of organic compounds. It is a common solvent and was formerly used as a general anesthetic. Production Most diethyl ether is produced as a byproduct of the vapor-phase hydration of ethylene to make ethanol. This process uses solid-supported phosphoric acid catalysts and can be adjusted to make more ether if the need arises: Vapor-phase dehydration of ethanol over some alumina catalysts can give diethyl ether yields of up to 95%. : Diethyl ether can be prepared both in laboratories and on an industrial scale by the acid ether synthesis. Uses The dominant use of diethyl ether is as a solvent. One particular application is in the production of cellulose plastics such as cellulose acetate. Laboratory solvent It is a common solvent for the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Desflurane
Desflurane (1,2,2,2-tetrafluoroethyl difluoromethyl ether) is a highly fluorinated methyl ethyl ether used for maintenance of general anesthesia. Like halothane, enflurane, and isoflurane, it is a racemic mixture of (''R'') and (''S'') optical isomers (enantiomers). Together with sevoflurane, it is gradually replacing isoflurane for human use, except in economically undeveloped areas, where its high cost precludes its use. It has the most rapid onset and offset of the volatile anesthetic drugs used for general anesthesia due to its low solubility in blood. Some drawbacks of desflurane are its low potency, its pungency and its high cost (though at low flow fresh gas rates, the cost difference between desflurane and isoflurane appears to be insignificant). It may cause tachycardia and airway irritability when administered at concentrations greater than 10% by volume. Due to this airway irritability, desflurane is infrequently used to induce anesthesia via inhalation techni ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Xenon
Xenon is a chemical element; it has symbol Xe and atomic number 54. It is a dense, colorless, odorless noble gas found in Earth's atmosphere in trace amounts. Although generally unreactive, it can undergo a few chemical reactions such as the formation of xenon hexafluoroplatinate, the first noble gas compound to be synthesized. Xenon is used in flash lamps and arc lamps, and as a general anesthetic. The first excimer laser design used a xenon dimer molecule (Xe2) as the lasing medium, and the earliest laser designs used xenon flash lamps as pumps. Xenon is also used to search for hypothetical weakly interacting massive particles and as a propellant for ion thrusters in spacecraft. Naturally occurring xenon consists of seven stable isotopes and two long-lived radioactive isotopes. More than 40 unstable xenon isotopes undergo radioactive decay, and the isotope ratios of xenon are an important tool for studying the early history of the Solar System. Radioactive xe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nitrous Oxide
Nitrous oxide (dinitrogen oxide or dinitrogen monoxide), commonly known as laughing gas, nitrous, or factitious air, among others, is a chemical compound, an Nitrogen oxide, oxide of nitrogen with the Chemical formula, formula . At room temperature, it is a colourless Flammability#Definitions, non-flammable gas, and has a slightly sweet scent and taste. At elevated temperatures, nitrous oxide is a powerful Oxidising agent, oxidiser similar to molecular oxygen. Nitrous oxide has significant Nitrous oxide (medication), medical uses, especially in surgery and dentistry, for its Anesthesia, anaesthetic and Analgesic, pain-reducing effects, and it is on the WHO Model List of Essential Medicines, World Health Organization's List of Essential Medicines. Its colloquial name, "laughing gas", coined by Humphry Davy, describes the Euphoria, euphoric effects upon inhaling it, which cause it to be used as a recreational drug inducing a brief "Dissociative, high". When abused chronically ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Charles Ernest Overton
Charles Ernest Overton (1865–1933) was a British and Swedish physiologist and biologist, now regarded as a pioneer of the theory of the cell membrane. In the last years of the 19th century Overton did experimental work, allowing the distinction to be drawn between the cell wall of plants and their cytoplasmic membrane. He studied the permeability of a range of biological materials to around 500 chemical compounds. In 1900, Overton proposed a biomembrane model "Overton Biomembrane Model" which stated that biomembranes are made up of lipids. He gave this statement on the basis of observation of transport of lipid soluble substances across the biomembranes. He came to Lund University Lund University () is a Public university, public research university in Sweden and one of Northern Europe's oldest universities. The university is located in the city of Lund in the Swedish province of Scania. The university was officially foun ... in Sweden as a professor, and married Louise ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
