31290855 Anestesi Umum Dan Lokal

GENERAL ANESTHETICSI WAYAN SUMARDIKA Department of Pharmacology,Faculty Of Medicine, Udayana University

IntroductionThe goal of general anesthesia is to create a reversible condition of comfort, quiescence, and physiological stability before, during, and after a surgical procedure.

IntroductionCharacteristics of an ideal general anestheticProvide a smooth and rapid induction of unconsciousnessProduce amnesiaBlock troublesome reflexesProduce skeletal muscle relaxationProduce analgesiaProvide a smooth and rapid emergence and recovery without long lasting adverse effects

IntroductionCombination AnesthesiaSince a single anesthetic agent will not meet the ideal, a combination of drugs is used to take advantage of their best properties and minimize the undesirable side effects.

PreanestheticsPreanesthetic medications drugs given generally prior to anesthesia (may be given during or after, as well) in order to:Decrease anxiety without producing excessive drowsinessFacilitate a rapid, smooth induction without prolonging emergenceProvide amnesia for the perioperative periodRelieve pre-and post-operative painMinimize undesirable side effects of anesthetics

Preanesthetic Agents

Drug ClassificationGeneric NameDesired EffectBenzodiazepinesDiazepam MidazolamReduce anxiety, Sedation, Amnesia, Conscious sedationAntihistaminesHydroxyzineSedationOpioid analgesicsMorphine Meperidine Fentanyl RemifentanilSedation to decrease tension, anxiety, and provide analgesiaPhenothiazinesPromethazineSedation, antihistaminic, antiemetic, decreased motor activityAnticholinergicsAtropine GlycopyrollateInhibit secretion, bradycardia, vomiting, and laryngospasmsGI DrugsOndansetron Cimetidine MetoclopramideAntiemetic Decrease gastric acidity Decrease stomach contents

Signs and StagesThese signs and stages are only partly recognizable with modern balanced anesthesia. ECG, HR, body temp, pulse oximetry, BP are routinely used to evaluate depth of anesthesia in practice. EEG now being used, too.

Stages of General AnesthesiaStage I: Loss of painStage II: Excitement and hyperactivityStage III: Surgical anesthesiaStage IV: Paralysis of the medulla

Anesthetics divide into 2 classes:Inhalation Anesthetics

Gasses or VaporsUsually Halogenated Intravenous Anesthetics

InjectionsAnesthetics or induction agents

Inhalation Anesthetic AgentsGeneral pharmacological effectsCNS dose dependent depression of all portions of CNS. Order of sensitivity (most to least) is RAS and cortex hippocampus basal ganglia cerebellum spinal cord medulla (irregularly descending anesthesia)Autonomic nervous systemInhibition of sympatheticsStimulation of parasympatheticsNausea and vomiting

Inhalation Anesthetic AgentsGeneral pharmacological effectsCardiovascularDose related negative inotropic effect BPArrhythmiasSensitization to circulating catecholaminesRespiration Dose dependent depression of medullary respiratory center

Inhalation Anesthetic AgentsGeneral pharmacological effectsHypothermiaAltered thermoregulatory control and reduced metabolic rateMiscellaneousDecrease lower esophageal sphincter toneMalignant hyperthermiaHalothane hepatitisPost-operative cognitive dysfunction

Inhalation Anesthetic AgentsAnesthetic gases only one is Nitrous OxideVolatile liquidsHalothane (Fluothane) Isoflurane (Forane) commonly used anesthetic for adultsEnflurane (Ethrane) like isoflurane, except increased risk of seizures. Rarely usedDesflurane (Suprane) similar to isoflurane except for more rapid emergence, and more irritating to airwaySevoflurane (Ultane) similar to desflurane except not irritating to airway

Anesthetic AgentsIntravenous agentsBarbiturates sodium thiopentalPropofol (Diprivan) similar to thiopental except that it can be used for longer periods of anesthesiaDissociative ketamineBenzodiazepines diazepam, midazolamEtomidate (Amidate)Dexmedetomidine (Precedex)

Properties of Intravenous Anesthetic Agents

DrugSpeed of Induction and RecoveryMain Unwanted EffectsNotesThiopentalFast (accumulation occurs, giving slow recovery) HangoverCardiovascular and respiratory depressionUsed as induction agent declining. Decreases cerebral blood flow and O2 consumption.EtomidateFast onset, fairly fast recoveryExcitatory effects during induction and recovery, Adrenocortical suppressionLess cardiovascular and respiratory depression than with thiopental, Causes pain at injection sitePropofolFast onset, very fast recoveryCardiovascular and respiratory depression. Pain at injection site.Most common induction agent. Rapidly metabolized; possible to use as continuous infusion. KetamineSlow onset, after-effects common during recoveryPsychotomimetic effects following recovery, Postoperative nausea, vomiting and salivationProduces good analgesia and amnesiaMidazolamSlower than other agentsLittle respiratory or cardiovascular depression

Anesthetic AgentsAnesthetic AntagonistsNaloxone (Narcan) and nalmefene (Revex)Flumazenil (Romazicon)

Thank you!

LOCAL ANESTHETICSI WAYAN SUMARDIKA Department of Pharmacology,Faculty Of Medicine, Udayana University

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Techniques of administrationTopical AnesthesiaInfiltration Peridural Spinal anesthesia

Classes: The rule of iAmidesLidocaine Bupivacaine Levobupivacaine Ropivacaine Mepivacaine Etidocaine Prilocaine

EstersProcaine Chloroprocaine Tetracaine Benzocaine Cocaine

Mechanism of ActionBlocks the sodium channelWide ranging effects on the nervous systemLocal anesthetics blocks the channel from the intracellular sideMust enter the neuron to workincreased lipophilicity is associated with increased potencyIncreased un-ionized fraction increases potencyThe un-ionized molecule crosses the cell membraneAdding bicarbonate increases the un ionized fractionTetrodotoxin binds the sodium channel from the outside

MetabolismAmidesPrimarily hepaticPlasma concentration may accumulate with repeated dosesToxicity is dose related, and may be delayed by minutes or even hours from time of dose.EstersEster hydrolysis in the plasma by pseudocholinesteraseAlmost no potential for accumulationToxicity is either from direct IV injectiontetracaine, cocaineor persistent effects of exposurebenzocaine, cocaine

Duration of ActionRate of systemic absorptionRate of eliminationParticularly for esters, which are metabolized locallyDosePotencyGeneral groups:Short: Procaine, chloroprocaineIntermediate: lidocaine, mepivicaine, prilocaineLong acting: Tetracaine, bupivacaine, etidocaine, ropivacaine, levobupivacaine

Systemic AbsorptionDoseVascularityIntercostal > Caudal > Epidural > Brachial > InfiltrationpHSlower absorption if solution is alkaline, because more is bound into the tissues.LipophilicitySlower absorption for more lipophilic drugs, again because more is bound in the tissuesEpinephrineDecreases local blood flow, decreasing absorption

Drug InteractionsEsters are metabolized by pseudocholinesteraseCompete with succinylcholine for metabolism, so when given together each lasts longerMetabolism slowed by administration of anticholinesterase (e.g., neostigmine)

Acute toxicityMain concern is CNS and cardiac toxicityCNSTinnitus, dizziness, lightheadedness are early signsAnxiety disorientation loss of consciousness seizures respiratory arrestCardiacHypotensionAll local anesthetics are negative inotropesPVC wide QRS Multiform vtach vfib, orPattern with bupivacaineBradycardia asystolePattern with bupivacaine + lidocaine

AllergiesAmidesTrue allergies to amide anesthetics are EXCEEDINGLY rareEstersUncommonAllergic reactions are probably related to PABA.Common ingredient in sun-screen.May also be related to topical benzocaine exposure.

THANK YOU

**Drugs given to induce or maintain general anesthesia are either given as: inhalation or intravenous! Basically extremely diverse group of chemicals which produce a similar endpoint!!!!

The most commonly used methods of administering general anesthetics are inhalation, in which the patient breathes a gas or vapor into the lungs, from which the anesthetic can enter the bloodstream; and injection with a hypodermic needle, usually into a vein. Most commonly there two forms are combined, although its is possible to deliver anesthesia solely by inhalation or injection. *