45 Pharmacology_ General Anesthetics (Chen).pptx - Pharmacology 14 General Anesthetics Andy Chen Ph.D [email protected] 814-866-8449 Case Study A

45 Pharmacology_ General Anesthetics (Chen).pptx -...

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Pharmacology 14 General Anesthetics Andy Chen, Ph.D. [email protected] 814-866-8449
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Case Study A 18-year-old male is in the intensive care unit after suffering from a fall. Injuries include multiple facial lacerations and fractures. He was intubated due to combativeness and for airway protection. Initial sedation was with midazolam and fentanyl, but switched to another drug to facilitate neurologic exam. Fentanyl and morphine were given as bolus to maintain analgesia. He became unstable on day 5 and required phenylephrine and epinephrine infusions. Lab findings show hyperkalemia, metabolic acidosis, hyperlipidemia, increased creatine kinase, and acute kidney injury. Liver enzymes were also elevated. Later he developed cardiac arrhythmia progressing to cardiac arrest. He was unable to be resuscitated. What happened?
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Learning Objectives 1. Describe the reason for using multiple general anesthetics in combination 2. Compare potency and rate of induction/elimination of inhalation anesthetics based on partition coefficient and minimal alveolar concentration 3. Discuss and compare the limitations of individual inhalation anesthetics 4. Explain the importance of context-sensitive halftime of intravenous anesthetics with relations to clinical uses of induction or maintenance 5. Compare and contrast the mechanism of action, side effects, advantages, and disadvantages of intravenous anesthetics
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Outline I. History II. General Anesthetics 1. Inhalation Anesthetics A. Stages of Anesthesia B. Uptake and Distribution C. Minimal Alveolar Concentration D. Rate of Induction/ Elimination E. Partition Coefficient F. Analgesic Index G. Mechanism of Action H. Side Effects 2. Intravenous Anesthetics III. Summary
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I. History For centuries, surgeries were limited to rapid procedures (limb amputations) 1846, 1 st public demonstration of anesthesia using diethyl ether was performed at Massachusetts General Hospital (revolutionary event) Diethyl ether is no longer used in US due to slow rate of induction, postoperative nausea and vomiting, and high inflammability 1847, chloroform introduced, which has a more pleasant odor and is nonflammable; causes severe hepatotoxicity and cardiac depression 1929, cyclopropane introduced, which is pleasant- smelling and has rapid induction and recovery; highly explosive 1956, halothane introduced, nonflammable hydrocarbon
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II. General Anesthetics Two main types of general anesthetics: 1. Inhalation 2. Intravenous Five desired effects of general anesthetics: 1. Analgesia 2. Amnesia (benzo/barbiturates) 3. Immobility 4. Inhibition of autonomic reflexes 5. Unconsciousness None of the current general anesthetics can achieve all five desired effects when used as monotherapy Modern practice uses combination of inhalation and intravenous general anesthetics Balanced anesthesia
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II.1.A. Stages of Anesthesia Anesthetic states are traditionally (diethyl ether) divided into four stages Modern anesthesia have faster induction and avoids stage II Stage III is the stage where surgery
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