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About General Anesthetics PowerPoint Presentation

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Description : Check out this medical PowerPoint presentation titled "General anesthetics" by Amber Johnson.

This medical PowerPoint presentation talks about General anesthetics. General anesthetics are drugs that cause a reversible loss of consciousness, sensation, and memory during medical procedures. They work by suppressing activity in the central nervous system, leading to unconsciousness and a lack of response to pain stimuli.

There are two main types of general anesthetics: intravenous (IV) and inhalational. IV anesthetics are administered through a vein and act quickly, while inhalational anesthetics are breathed in through a mask or tube and act more slowly.

Tags : General Anaesthetics, reversible loss of consciousness, central nervous system, Anesthesiology

Published on : Mar 16, 2023 | Views : 646 | Downloads : 1

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Slide 1-

General Anesthetics Amber Johnson
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What are General Anesthetics? A drug that brings about a reversible loss of consciousness. These drugs are generally administered by an anesthesiologist in order to induce or maintain general anesthesia to facilitate surgery.
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Background General anesthesia was absent until the mid-1800’s William Morton administered ether to a patient having a neck tumor removed at the Massachusetts General Hospital, Boston, in October 1846. The discovery of the diethyl ether as general anesthesia was the result of a search for means of eliminating a patient’s pain perception and responses to painful stimuli. (CH3CH2)2O
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Anesthetics divide into 2 classes: Inhalation Anesthetics Gasses or Vapors Usually Halogenated Intravenous Anesthetics Injections Anesthetics or induction agents
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Inhaled Anesthetics Halothane Enflurane Isoflurane Desflurane Halogenated compounds: Contain Fluorine and/or bromide Simple, small molecules
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Physical and Chemical Properties of Inhaled Anesthetics Although halogenations of hydrocarbons and ethers increase anesthetic potency, it also increase the potential for inducing cardiac arrhythmias in the following order F
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Overview
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Intravenous Anesthetics Used in combination with Inhaled anesthetics to: Supplement general anesthesia Maintain general anesthesia Provide sedation Control blood pressure Protect the brain
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Essential Components of Anesthesia Analgesia- perception of pain eliminated Hypnosis- unconsciousness Depression of spinal motor reflexes Muscle relation * These terms together emphasize the role of immobility and of insensibility!
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Hypotheses of General Anesthesia Lipid Theory: based on the fact that anesthetic action is correlated with the oil/gas coefficients. The higher the solubility of anesthetics is in oil, the greater is the anesthetic potency. Meyer and Overton Correlations Irrelevant 2. Protein (Receptor) Theory: based on the fact that anesthetic potency is correlated with the ability of anesthetics to inhibit enzymes activity of a pure, soluble protein. Also, attempts to explain the GABAA receptor is a potential target of anesthetics acton.
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Other Theories included Binding theory: Anesthetics bind to hydrophobic portion of the ion channel
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Mechanism of Action UNKNOWN!! Most Recent Studies: General Anesthetics acts on the CNS by modifying the electrical activity of neurons at a molecular level by modifying functions of ION CHANNELS. This may occur by anesthetic molecules binding directly to ion channels or by their disrupting the functions of molecules that maintain ion channels.
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Cont on Mechanism Scientists have cloned forms of receptors in the past decades, adding greatly to knowledge of the proteins involved in neuronal excitability. These include: Voltage-gated ion channels, such as sodium, potassium, and calcium channels Ligand-gated ion channel superfamily and G protein-coupled receptors superfamily.
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Anesthetic Suppression of Physiological Response to Surgery
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Pharmacokinetics of Inhaled Anesthetics Amount that reaches the brain Indicated by oil:gas ratio (lipid solubility) Partial Pressure of anesthetics 5% anesthetics = 38 mmHg Solubility of gas into blood The lower the blood:gas ratio, the more anesthetics will arrive at the brain Cardiac Output Increased CO= greater Induction time
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Pathway for General Anesthetics
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Variables that Control Partial Pressure in Brain Direct Physician's Control Solubility of agent Concentration of agent in inspired by air Magnitude of alveolar ventilation Indirect Physician’s Control Pulmonary blood flow-function of CO Arteriovenous concentration gradient
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Rate of Entry into the Brain: Influence of Blood and Lipid Solubility
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MAC A measure of potency 1MAC is the concentration necessary to prevent responding in 50% of population. Values of MAC are additive: Avoid cardiovascular depressive concentration of potent agents.
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Increase in Anesthetic Partial Pressure in Blood is Related to its Solubility
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General Actions of Inhaled Anesthetics Respiration Depressed respiration and response to CO2 Kidney Depression of renal blood flow and urine output Muscle High enough concentrations will relax skeletal muscle
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Cont’ Cardiovascular System Generalized reduction in arterial pressure and peripheral vascular resistance. Isoflurane maintains CO and coronary function better than other agents Central Nervous System Increased cerebral blood flow and decreased cerebral metabolism
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Depression of respiratory drive Decreased CO2 drive (medullary chemoreceptors), Takes MORE CO2 to stimulate respiration Depressed cardiovascular drive Gaseous space enlargement by NO Fluoride-ion toxicity from methoxyflurane Metabolized in liver = release of Fluoride ions Decreased renal function allows fluoride to accumulate = nephrotoxicity Toxicity and Side Effects
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Toxicity and Side Effects Malignant hyperthermia Rapidly cool the individual and administer Dantrolene to block S.R. release of Calcium