General Anesthesia
اسلاید 1: General AnesthesiaAnesthesiology Lecture SeriesSurgery Module Level III
اسلاید 2: Lecture OutlinePrinciples of General AnesthesiaPharmacology in General AnesthesiaConduct of General AnesthesiaComplications of General Anesthesia
اسلاید 3: General Anesthesia“General Anesthesia is a drug-induced loss of consciousness during which patients are not arousable, even by painful stimulation. The ability to independently maintain ventilatory function is often impaired. Patients often require assistance in maintaining a patent airway, and positive pressure ventilation may be required because of depressed spontaneous ventilation or drug-induced depression of neuromuscular function. Cardiovascular function may be impaired.” PRINCIPLES CONTINUUM OF DEPTH OF SEDATION: DEFINITION OF GENERAL ANESTHESIA AND LEVELS OF SEDATION/ANALGESIA*. Approved by ASA House of Delegates on October 13, 1999, and amended on October 27, 2004
اسلاید 4: Minimal SedationAnalgesiaModerate Sedation (Conscious Sedation)Deep Sedation (Anxiolysis)General Anesthesia / AnalgesiaResponsivenessNormal response to verbal stimulationPurposeful response to verbal or tactile stimulationPurposeful response following repeated or painful stimulationUnarousable even with painful stimulusAirwayUnaffectedNo intervention requiredIntervention may be requiredIntervention often requiredRespiratory FunctionUnaffectedAdequateMay be inadequateFrequently inadequateCardiovascular FunctionUnaffectedUsually maintainedUsually maintainedMay be impairedCONTINUUM OF DEPTH OF SEDATION: DEFINITION OF GENERAL ANESTHESIA AND LEVELS OF SEDATION/ANALGESIA* Approved by ASA House of Delegates on October 13, 1999, and amended on October 27, 2004
اسلاید 5: Stages of General AnesthesiaStage 1 (amnesia) From induction of anesthesia to loss of consciousness (loss of eyelid reflex)Pain perception threshold is not lowered. Stage 2 (delirium/excitement) Characterized with uninhibited excitation, agitation, delirium, irregular respiration and breath holdingPupils are dilated and eyes are divergentResponses to noxious stimuli: vomiting, laryngospasm, hypertension, tachycardia, and uncontrolled movements PRINCIPLES Morgan, et al. Clinical Anesthesiology, 4th ed. 2006Ezekiel. Handbook of Anesthesiology, 2005
اسلاید 6: Stages of General AnesthesiaStage 3 (surgical anesthesia) characterized by central gaze, constricted pupils, and regular respirationsPainful stimulation does not elicit somatic reflexes or deleterious autonomic responses. Stage 4 (impending death/overdose) characterized by onset of apnea, dilated and nonreactive pupils, and hypotensionmay progress to circulatory failure PRINCIPLES Morgan, et al. Clinical Anesthesiology, 4th ed. 2006Ezekiel. Handbook of Anesthesiology, 2005
اسلاید 7: Principles of General AnesthesiaMinimum Alveolar Concentration (MAC) the minimum concentration necessary to prevent movement in 50% of patients in response to a surgical skin incisionThe lower the MAC, the more potent the agent PRINCIPLES Morgan, et al. Clinical Anesthesiology, 4th ed. 2006Ezekiel. Handbook of Anesthesiology, 2005AnesthesiaUK.comSummary of physical properties of volatile anestheticsSummary of physical properties of volatile anestheticsSummary of physical properties of volatile anestheticsSummary of physical properties of volatile anestheticsSummary of physical properties of volatile anestheticsSummary of physical properties of volatile anestheticsHalothaneIsofluraneEnflurane DesfluraneSevofluraneMolecular weight197 184 184 168 200 Boiling point (°C)50.248.556.522.858.5 Saturated vapor pressure at 20°C243 238 175 669 157 MAC in 100% O20.751.151.86 2.05 % Biotransformation20 0.22<0.13 - 5Blood / gas 2.2 1.361.910.450.6 Oil / gas224 98 98.528 47
اسلاید 8: Minimum Alveolar Concentration PRINCIPLES Morgan, et al. Clinical Anesthesiology, 4th ed. 2006Ezekiel. Handbook of Anesthesiology, 2005
اسلاید 9: Minimum Alveolar ConcentrationFactor that increase/decrease PRINCIPLES
اسلاید 10: Meyer-Overton HypothesisThe MAC of a volatile substance is inversely proportional to its lipid solubility (oil:gas coefficient)High MAC equals low lipid solubilityBacktrack: MAC is inversely related to potency (high MAC equals low potency) PRINCIPLES
اسلاید 11: Meyer-Overton HypothesisCorrelation between lipid solubility with potency onset of anesthesia occurs when sufficient molecules of the agent have dissolved in the cells lipid membranesHigh lipid solubility equals high potency (and low MAC) PRINCIPLES Summary of physical properties of volatile anestheticsSummary of physical properties of volatile anestheticsSummary of physical properties of volatile anestheticsSummary of physical properties of volatile anestheticsSummary of physical properties of volatile anestheticsSummary of physical properties of volatile anestheticsHalothaneIsofluraneEnflurane DesfluraneSevofluraneMolecular weight197 184 184 168 200 Boiling point (°C)50.248.556.522.858.5 Sat’d vapor pressure 20°C243 238 175 669 157 MAC in 100% O20.751.151.86 2.05 MAC in 70% N2O0.290.560.572.50.66 % Biotransformation20 0.22<0.13 - 5Blood / gas 2.2 1.361.910.450.6 Oil / gas224 98 98.528 47
اسلاید 12: Meyer-Overton HypothesisFactors Affecting the Meyer - Overton HypothesisConvulsant propertiesHalogenation results in decreased anesthetic potency and appearance of convulsant activitySpecific Receptors e.g. opioid receptorsthere is reduction of MAC by opioidsDexmedetomidinean alpha-2- agonist, results in marked reduction in MACHydrophilic site of actioncorrelation between ability to form clathrates and anesthetic potencyClathrates (of water) are postulized to alter membrane ion transport
اسلاید 13: II. OVERVIEW OF PHARMACOLOGIC AGENTS USED IN GENERAL ANESTHESIA Inhaled AnestheticsIntravenous induction AgentsNeuromuscular Blocking AgentsOpioidsBenzodiazepinesAnticholinergic agents Anticholinesterases
اسلاید 14: Inhalational AgentsUsed in the induction and maintenance of anesthesiaHalogenated alkane or ether-derived compoundsNitrous oxide (N2O; laughing gas) is the only inorganic anesthetic gas in clinical useProduce dose-dependent systemic effectsAssociated with Malignant Hyperthermia PHARMACOLOGIC AGENTSExamples:Ether HalothaneMethoxyfluraneEnfluraneIsofluraneSevofluraneDesfluraneNitrous OxideXenon
اسلاید 15: Inhalational AgentsPHARMACOLOGIC AGENTSMorgan, et al. Clinical Anesthesiology, 4th ed. 2006Ezekiel. Handbook of Anesthesiology, 2005Townsend, et al. Sabiston, Textbook of Surgery, 17th ed. 2004
اسلاید 16: Intravenous Induction AgentsUsed as premedications, sedatives, intravenous induction agents and in the maintenance of anesthesia.Total intravenous anesthesia (TIVA)PHARMACOLOGIC AGENTSMorgan, et al. Clinical Anesthesiology, 4th ed. 2006Ezekiel. Handbook of Anesthesiology, 2005Townsend, et al. Sabiston, Textbook of Surgery, 17th ed. 2004Examples:Barbiturates (Thiopental)Benzodiazepines (Midazolam)KetamineEtomidatePropofol
اسلاید 17: Intravenous Induction AgentsThiopentalREVIEW: RedistributionHepatic eliminationCan cause hypotension, vasodilation and cardiac depression Can precipitate bronchospasm in patients with reactive airway diseaseDecreases CMRO2 in neuroanesthesiaPHARMACOLOGIC AGENTSMorgan, et al. Clinical Anesthesiology, 4th ed. 2006Townsend, et al. Sabiston’s Textbook of Surgery, 17th ed. 2004www.3dchem.com
اسلاید 18: www.3dchem.comIntravenous Induction AgentsKetamineProduces dissociative state of anesthesiaOnly IV induction agent that increases blood pressure and heart rateDecreases bronchomotor toneMay be used as sole anesthetic for short proceduresProduces profound amnesia and analgesiaIncreases intracranial pressureProduces emergence delirium and bad dreamsPHARMACOLOGIC AGENTSMorgan, et al. Clinical Anesthesiology, 4th ed. 2006Townsend, et al. Sabiston’s Textbook of Surgery, 17th ed. 2004www.bedfordlabs.com
اسلاید 19: Intravenous Induction AgentsPropofol, (2,6-diisopropylphenol) Short-acting induction agentAvailable as oil-in-water emulsion containing soybean oil, glycerol, and egg lecithinIdeal for ambulatory surgeryCan decrease blood pressure in susceptible patientsProduces bronchodilatationAssociated injection painPHARMACOLOGIC AGENTSMorgan, et al. Clinical Anesthesiology, 4th ed. 2006Townsend, et al. Sabiston’s Textbook of Surgery, 17th ed. 2004jchemed.chem.wisc.eduwww.psimeds.com
اسلاید 20: Intravenous Induction AgentsEtomidateImidazole compoundProduces minimal hemodynamic changes (ideal for patients with cardiovascular disease)Produces pain on injection, abnormal muscular movements and adrenal suppressionMidazolamA benzodiazepine (Other BZD: Diazepam, Lorazepam)Because of minimal cardiovascular effects, used for anesthesia inductionProduces anxiolysis and profound amnesiaAlso used as a premedicantPHARMACOLOGIC AGENTSMorgan, et al. Clinical Anesthesiology, 4th ed. 2006Townsend, et al. Sabiston’s Textbook of Surgery, 17th ed. 2004www.bedfordlabs.comwww.bedfordlabs.com
اسلاید 21: OpioidsUsed as part of general anesthesia, and in patients receiving regional anesthesiaProduces profound analgesia and minimal cardiac depressionCause ventilatory depressionExamples: (REVIEW CLASSIFICATION OF OPIOIDS AND RECEPTORS)Agonists: Morphine, Fentanyl, MeperidineAntagonists: Naloxone Agonist-Antagonist: Nalbuphine, ButorphanolPHARMACOLOGIC AGENTSMorgan, et al. Clinical Anesthesiology, 4th ed. 2006Townsend, et al. Sabiston’s Textbook of Surgery, 17th ed. 2004
اسلاید 22: OpioidsUses in General AnesthesiaReduces MAC of potent inhalational agentsBlunt the sympathetic response (increase in BP and HR) to direct laryngoscopy, intubation and surgical incisionProvide analgesia extending into postoperative periodMay be used as complete anesthetics (may provide analgesia, hypnosis and analgesia)May be added in local anesthetic solutions in regional anesthesia to improve quality of analgesiaPHARMACOLOGIC AGENTSTownsend, et al. Sabiston’s Textbook of Surgery, 17th ed. 2004
اسلاید 23: Neuromuscular Blocking AgentsUses in anesthesia:Facilitates endotracheal intubationProvides muscle relaxation necessary for the conduct of surgeryTypes: (Review Pharmacology)DEPOLARIZING (non-competitive) AGENTSSuccinylcholine: mimics the action of acetylcholine by depolarizing the postsynaptic membrane at the neuromuscular junction (non-competitive antagonism)NON-DEPOLARIZING Produces reversible competitive antagonism of AchMaybe aminosteroid or benzylisoquinoline compounds PHARMACOLOGIC AGENTSMorgan, et al. Clinical Anesthesiology, 4th ed. 2006Townsend, et al. Sabiston’s Textbook of Surgery, 17th ed. 2004
اسلاید 24: Neuromuscular Blocking AgentsAdvantages of SuccinylcholineRapid onset, short duration of actionUsed in rapid-sequence inductionAdverse effects of SuccinylcholineBradycardia (esp. in pediatrics)Life-threatening hyperkalemia in burn patientsMay trigger malignant hyperthermiaMyalgia (from fasciculations) and myoglobinuria Increased ICP, CBF, IOPIncreased intragastric pressureProlonged blockade in susceptible individuals (in decreased plasma cholinesterase activity, myopathies)PHARMACOLOGIC AGENTSMorgan, et al. Clinical Anesthesiology, 4th ed. 2006Townsend, et al. Sabiston’s Textbook of Surgery, 17th ed. 2004www.buyemp.com
اسلاید 25: Neuromuscular Blocking AgentsNondepolarizing AgentsUsed when succinylcholine is contraindicatedChoice of agent Based on mode of excretionHoffman degradation (atracurium, cis-atracurium)RenalHepaticBased on duration of actionShort acting: MivacuriumIntermediate: Atracurium, RocuroniumLong-acting: Pancuronium PHARMACOLOGIC AGENTSMorgan, et al. Clinical Anesthesiology, 4th ed. 2006Ezekiel. Handbook of Anesthesiology, 2005Townsend, et al. Sabiston, Textbook of Surgery, 17th ed. 2004
اسلاید 26: Neuromuscular Blocking AgentsConcerns in anesthesiaParalysis can mask signs of inadequate anesthesiaHigher doses required for intubation than for surgical relaxationOther drugs can potentiate effects of non-depolarizing agentsVariable individual responsesResidual blockade may result to postoperative problemsTOF monitoringClinical assessmentPHARMACOLOGIC AGENTSMorgan, et al. Clinical Anesthesiology, 4th ed. 2006Ezekiel. Handbook of Anesthesiology, 2005Townsend, et al. Sabiston, Textbook of Surgery, 17th ed. 2004
اسلاید 27: Anticholinergicscompetitively inhibits the action of acetylcholine at muscarinic receptors with little or no effect at nicotinic receptors. Examples:Atropine*, Scopolamine§, Glycopyrrolate¤Uses in anesthesia:Amnesia and Sedation§Antisialogogue effect §*¤Tachycardia* Bronchodilation*PHARMACOLOGIC AGENTSMorgan, et al. Clinical Anesthesiology, 4th ed. 2006Ezekiel. Handbook of Anesthesiology, 2005Townsend, et al. Sabiston, Textbook of Surgery, 17th ed. 2004www.ci.springfield.or.us
اسلاید 28: AnticholinesterasesInactivate acetylcholinesterase by reversibly binding to the enzyme increasing the amount of acetylcholine available to compete with the nondepolarizing agent Increases acetylcholine at both nicotinic and muscarinic receptorsMuscarinic side effects can be blocked by administration of atropine or glycopyrrolate Examples: edrophonium, neostigmine, pyridostigmine, physostigmineUse in anesthesia: reversal of neuromuscular blockadePHARMACOLOGIC AGENTSMorgan, et al. Clinical Anesthesiology, 4th ed. 2006Ezekiel. Handbook of Anesthesiology, 2005Townsend, et al. Sabiston, Textbook of Surgery, 17th ed. 2004www.comparestoreprices.co.uk
اسلاید 29: GENERAL ANESTHESIAInduction TechniquesIntubationMaintenanceEmergence and ExtubationCONDUCT OF GENERAL ANESTHESIA
اسلاید 30: Patient Monitoring in AnesthesiaRoutinePulse oximetryAutomated BPECGCapnographyOxygen analyzerVentilator pressure monitorThermometrySpecializedFoley catheterArterial catheterVentral venous catheterPulmonary artery catheterPrecordial dopplerTransesophageal EchocardiographyEsophageal DopplerEsophageal and Precordial StethoscopeCONDUCT OF GENERAL ANESTHESIATownsend, et al. Sabiston, Textbook of Surgery, 17th ed. 2004
اسلاید 31: Airway ExaminationMallampati ScoreThe patient is asked to maximally open his mouth and protrude his tongue while in the sitting positionCONDUCT OF GENERAL ANESTHESIAwww.acilveilkyardim.comClass 1Faucial pillars, uvula, soft palate seenClass 2Uvula masked by tongue baseClass 3Only soft and hard palate visualizedClass 4Only hard palate
اسلاید 32: Airway ExaminationInterdental Distance (3)Measures the distance between the 2 incisors, with the mouth fully openedThyromental Distance (3)Measures the distance between the chin (mentum) and the thyroid cartilageThyrohyoid Distance (2)Measures the distance between the hyoid and the thyroid cartilageCONDUCT OF GENERAL ANESTHESIAkvyouth.blogspot.comwww.unige.chwww.emedicine.com
اسلاید 33: Airway ExaminationBellhouse-Doremaximal flexion and extension of the neck will identify limitations that might prevent optimal alignment of the OPL axes. Normal atlanto-occipital joint: 35 degrees of extension CONDUCT OF GENERAL ANESTHESIAwww.emedicine.com
اسلاید 34: Strategies in General AnesthesiaQuestions to ask prior to conduct of anesthesia:Is the patient’s condition or scheduled surgery require additional monitoring techniques?Does the patient have conditions that contraindicate certain drugsIs endotracheal intubation required?Are there anticipated difficulties in oral translaryngeal intubation?Are NMBs required during surgery?Are there special surgical requirements that mandate use of or avoidance of specific interventions? (e.g. NMBs)Is substantial blood loss or fluid shifts anticipated?CONDUCT OF GENERAL ANESTHESIATownsend, et al. Sabiston, Textbook of Surgery, 17th ed. 2004
اسلاید 35: Induction of AnesthesiaSequence of interventions during induction vary depending on the patient and type of surgeryConcernsLoss of consciousnessInability to maintain a natural airwayReduction or cessation of spontaneous ventilationUse of drugs that may depress the myocardium and change vascular toneCONDUCT OF GENERAL ANESTHESIATownsend, et al. Sabiston, Textbook of Surgery, 17th ed. 2004
اسلاید 36: Awake IntubationMay be supplemented with sedatives, opioids, and topical or local anesthesiaAccomplished via “blind” nasal, fiberoptic bronchoscopy, and direct visualizationCONDUCT OF GENERAL ANESTHESIATownsend, et al. Sabiston, Textbook of Surgery, 17th ed. 2004picasaweb.google.comwww.pbase.comIndications:inadequate mouth openingfacial traumacervical spine injurychronic cervical spine diseaselesions in the upper airway
اسلاید 37: Awake IntubationNasal IntubationEndotracheal tube (ET) is inserted through the nose and guided into the tracheal by listening to the transmitted breath soundFiberoptic intubationPassing an ET through the nose or mouth into the pharynx, then passing a bronchoscope through the tube. The larynx and the trachea are visualized and the ET is thread over the bronchoscopeCONDUCT OF GENERAL ANESTHESIATownsend, et al. Sabiston, Textbook of Surgery, 17th ed. 2004groups.msn.comwww.ispub.com
اسلاید 38: Intravenous InductionPreoxygenation with 100% oxygen+/- IV opioid or BZDAdministration of rapid-acting IV induction agentsAnesthesiologist ensures patient can be manually ventilatedYes? Patient is given NMBDirect Laryngoscopy and IntubationTECHNIQUECONDUCT OF GENERAL ANESTHESIATownsend, et al. Sabiston, Textbook of Surgery, 17th ed. 2004tumj.tums.ac.ir
اسلاید 39: Intravenous InductionDisadvantagesSpontaneous ventilation is abolished without certainty that patient can be manually ventilatedEndotracheal intubation is performed while the patient is lightly anesthetized, precipitating hypertension, tachycardia, or bronchospasmCONDUCT OF GENERAL ANESTHESIATownsend, et al. Sabiston, Textbook of Surgery, 17th ed. 2004
اسلاید 40: Inhalational InductionPreoxygenation (100% O2)O2 + Volatile agent via face maskAnesthesiologist ensures patient can be manually ventilatedDirect Laryngoscopy and IntubationTECHNIQUEGeneral Anesthesia via Face MaskIn children (induction)In patients at severe risk of bronchospasmShort ProceduresDifficult airwayYes? Patient is given NMB+/- IV opioid or BZDOptionOptionCONDUCT OF GENERAL ANESTHESIATownsend, et al. Sabiston, Textbook of Surgery, 17th ed. 2004
اسلاید 41: Inhalational InductionMay be used in children and cooperative adultsDisadvantagesDepending on the induction agent, patients progress from the awake state to surgical level of anesthesia.Stage 2 anesthesia prodispose the patient to laryngospasm, vomiting and aspirationAgents used for Inhalational induction: SevofluraneHalothaneCONDUCT OF GENERAL ANESTHESIATownsend, et al. Sabiston, Textbook of Surgery, 17th ed. 2004www.cuhk.edu.hk
اسلاید 42: Rapid Sequence InductionIndicated for patients at high risk for acid aspirationExamplesObese patientsPregnant patientsHistory of gastroesophageal reflux diseasePatients with bowel obstructionCONDUCT OF GENERAL ANESTHESIATownsend, et al. Sabiston, Textbook of Surgery, 17th ed. 2004Sellick’s Maneuver: pressure on the cricoid cartilage to occlude the esophagus, thus preventing passive regurgitation from the stomach to the pharynxwww.johnshopkins.org
اسلاید 43: Rapid Sequence InductionPreoxygenation (100% O2)Administration of rapid-acting IV induction agents*Succinylcholine IVDirect Laryngoscopy and Intubation*TECHNIQUESELLICK’S MANEUVER*Patient is NOT ventilatedConfirm ET placementCricoid Pressure RemovedOther concerns: Consequences of difficult intubation and hypoxia3-person* techniqueCONDUCT OF GENERAL ANESTHESIATownsend, et al. Sabiston, Textbook of Surgery, 17th ed. 2004www.ispub.com
اسلاید 44: Combined intravenous and inhalational anesthesiaAgents are combined to gain advantage of smooth and rapid hypnosis but still permit establishment of deep level of inhalational anesthesia prior to airway instrumentationCONDUCT OF GENERAL ANESTHESIATownsend, et al. Sabiston, Textbook of Surgery, 17th ed. 2004
اسلاید 45: Combined Intravenous and Inhalational AnesthesiaPreoxygenation (100% O2)+/- IV opioid or BZDAdministration of rapid-acting IV induction agentsAnesthesiologist ensures manual ventilationDirect Laryngoscopy and IntubationAnesthesiologist deepens anesthesia with O2 + Volatile agent (+ N2O) via face maskYes? Patient is given NMBTECHNIQUECONDUCT OF GENERAL ANESTHESIATownsend, et al. Sabiston, Textbook of Surgery, 17th ed. 2004
اسلاید 46: Techniques in Managing Airway ObstructionChin tiltExtension of neckAnterior displacement of mandibleUse of airway adjuncts (oral and nasal airway)Use of supraglottic airway (e.g. LMA)CONDUCT OF GENERAL ANESTHESIAwww.charlydmiller.comwww.mdconsult.comReview 2nd Year Airway Management Lectureswww.shilog.commedical-dictionary.thefreedictionary.comwww.cuhk.udu
اسلاید 47: Orotracheal Intubation TechniqueCONDUCT OF GENERAL ANESTHESIABarash, et al. Clinical Enesthesiology,2006www.emedicine.comPosition the PatientOpen the mouthInsert the laryngoscope bladeSweep the tongue from right to leftIdentify landmarksAdvance the laryngoscope bladewww.medgear.orgIdentify and elevate the epiglottisVisualize the vocal cords and glottic openingemsresponder.comSniffing PositionPads and PillowsMacintosh blade: valleculaMiller blade: epiglottis
اسلاید 48: Orotracheal Intubation TechniqueCONDUCT OF GENERAL ANESTHESIAInsert the endotracheal tube from the corner of the mouthAdvance the tube into the glottic openingWithdraw laryngoscope bladeVentilateConfirm tube placementInflate ET balloon cuffSecure the endotracheal tubewww.dhmc.orgservices.epnet.comPeriodically check tube
اسلاید 49: Confirmation of Successful Endotracheal IntubationDirect visualization of the ET tube passing though the vocal cords. Carbon dioxide in exhaled gases (documentation of end-tidal CO2 in at least three consecutive breaths). Maintenance of arterial oxygenation.Bilateral breath sounds. Absence of air movement during epigastric auscultation. Condensation (fogging) of water vapor in the tube during exhalation. Refilling of reservoir bag during exhalation. Chest x-ray: the tip of ET tube should be between the carina and thoracic inlet or approximately at the level of the aortic notch or at the level of T5.CONDUCT OF GENERAL ANESTHESIAMorgan, et al. Clinical Anesthesiology, 4th ed. 2006Ezekiel. Handbook of Anesthesiology, 2005www.vet.uga.eduwww.capnography.comwww.chmeds.ac.nzwww.sai.net.inwww.ispub.com
اسلاید 50: Maintenance of AnesthesiaGoalsFacilitate surgical exposureEnsure adequate amnesiaEnsure adequate analgesiaParameters used in assuring adequacy of anesthesia:Autonomic signs (BP, HR, RR)Monitoring of Neuromuscular BlockadeBIS Monitoring (for awareness)CONDUCT OF GENERAL ANESTHESIATownsend, et al. Sabiston, Textbook of Surgery, 17th ed. 2004
اسلاید 51: Maintenance of AnesthesiaCONDUCT OF GENERAL ANESTHESIA TITRATABLE COMBINATION OF:IV opioids (e.g. fentanyl)IV sedative-hypnotics (e.g. midazolam) O2+volatile agent Nitrous oxide NITROUS-NARCOTIC TECHNIQUE:IV opioidsIV sedative-hypnotics O2+ Nitrous oxide TOTAL INTRAVENOUS ANESTHESIA: (TIVA) IV sedative-hypnotics (e.g. propofol) via infusion or TCI IV short-acting opioids+ NMBs (in patients requiring intubation/muscle relaxation)Townsend, et al. Sabiston, Textbook of Surgery, 17th ed. 2004
اسلاید 52: Emergence and Extubation“ Emergence and extubation requires the knowledge and experience with the pharmacokinetic and pharmacodynamic principles that underlie the elimination of inhalational and intravenous agents and that govern the reversal of neuromuscular blockade.” CONDUCT OF GENERAL ANESTHESIATownsend, et al. Sabiston, Textbook of Surgery, 17th ed. 2004
اسلاید 53: Emergence and ExtubationParameters for Extubation:Patient follows commandsActive spontaneous respirationAbility to protect the airway (reflexes)Deep extubationUsed in patients at risk for bronchospasm with stimulation of the trachea during emergence from anesthesiaCONDUCT OF GENERAL ANESTHESIATownsend, et al. Sabiston, Textbook of Surgery, 17th ed. 2004
اسلاید 54: Criteria for Extubationawake and responsive patient stable vital signsreversal of paralysisgood hand gripsustained head lift for five secondsNegative inspiratory force > -20 mmHgvital capacity >15 ml/kgCONDUCT OF GENERAL ANESTHESIAMorgan, et al. Clinical Anesthesiology, 4th ed. 2006www.pbase.comOther Concerns: Aspiration riskAirway patency
اسلاید 55: Subjective Clinical Criteria:Follows commandsClear oropharynx/hypopharynx (e.g., no active bleeding, secretions cleared)Intact gag reflexSustained head lift for 5 seconds, sustained hand graspAdequate pain controlMinimal end-expiratory concentration of inhaled anestheticsObjective Criteria:Vital capacity: ≥10 mL/kgPeak voluntary negative inspiratory pressure: >20 cm H2OTidal volume >6 cc/kgSustained tetanic contraction (5 sec)T1/T4 ratio >0.7Alveolar-Arterial Pao2 gradient (on FIO2 of 1.0): <350 mm HgaDead space to tidal volume ratio: ≤0.6aBarash, Clinical Anesthesiology, 2006
اسلاید 56: Complications of general Anesthesia
اسلاید 57: Complications of General AnesthesiaINDUCTIONIndividual variable response to drugsDepression of the CNS / respiratory / cardiovascular systemsHypersensitivity reactionsProblems in Ventilation:HypoxemiaHypercarbiaObstruction Difficult ventilationAspirationCOMPLICATIONS OF GAwww.achi.comwww.medvarsity.com
اسلاید 58: INTUBATIONTracheal Tube PositioningEndobronchial IntubationEsophageal IntubationInadequate insertion depthPhysiologic ResponsesHypertension, TachycardiaLaryngospasmBronchospasmAirway TraumaInjury to teeth and airway tissuesTracheal and laryngeal traumaPost-intubation hoarseness and sore throatDifficult intubationCOMPLICATIONS OF GAwww.resuscitations.inwww.telemedi.netwww.studioshanks.comwww.learningradiology.comwww.worldsmiles.com
اسلاید 59: MAINTENANCEIndividual Variable responseHypersensitivity reactionsDepression of the CNS / respiratory / cardiovascular systemsInadequate depth of anesthesiaAwarenessEXTUBATIONAspirationLaryngospasmAirway traumaResidual Neuromuscular BlockadeDelayed EmergenceCOMPLICATIONS OF GAwww.introtoccnursing.comwww.flatrock.org.nzwww.wilyoth.comwww.pbase.comOthersPeripheral Nerve PalsiesCorneal Abrasions
اسلاید 60: Good Day!
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