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Chapter 15 General Anesthesia Elsevier items and derived items © 2006 by Saunders, an imprint of Elsevier Inc. Objective 1 Define terminology related to anesthesia. Amnestic Agent that causes memory impairment Depolarization Reversal of charges at a cell membrane, caused by a rapid inflow of sodium ions Elsevier items and derived items © 2006 by Saunders, an imprint of Elsevier Inc. Objective 1. Terms Emulsion Endotracheal (ET) tube A mixture of two liquids not mutually soluble An airway catheter inserted in the trachea to assure patency of the upper airway and provide ventilation Extubation Process of removing a previously inserted endotracheal tube Elsevier items and derived items © 2006 by Saunders, an imprint of Elsevier Inc. Objective 1. Terms Intubation LMA Laryngeal masked airway; an airway that is placed over the larynx Opioid Insertion of an endotracheal tube Any synthetic narcotic not derived from opium Repolarization Restoration of the polarized state at the cell membrane Elsevier items and derived items © 2006 by Saunders, an imprint of Elsevier Inc. Review basics of anesthesia Review pain impulses Nerve endings Nerves • Sensory and motor Spinal cord Brain Elsevier items and derived items © 2006 by Saunders, an imprint of Elsevier Inc. Review of process of pain Nerve endings stimulated Transmit via sensory nerve To spinal cord (motor loop) To brain for interpretation and response Elsevier items and derived items © 2006 by Saunders, an imprint of Elsevier Inc. Objective 2 Discuss indications for general anesthesia. Elsevier items and derived items © 2006 by Saunders, an imprint of Elsevier Inc. Objective 2. Indications The surgical procedure to be performed Multiple sites Need for motionless field Long duration Elsevier items and derived items © 2006 by Saunders, an imprint of Elsevier Inc. Objective 2. Indications The individual patient Age (all pediatrics) Cognitive ability Mental/emotional state Preference Elsevier items and derived items © 2006 by Saunders, an imprint of Elsevier Inc. Objective 3 Identify anesthesia equipment. Elsevier items and derived items © 2006 by Saunders, an imprint of Elsevier Inc. Objective 3. Equipment Anesthesia machine Manual and automatic ventilation systems Oxygen and nitrous oxide (N2O) central pipeline hoses and back up tanks Elsevier items and derived items © 2006 by Saunders, an imprint of Elsevier Inc. Objective 3. Equipment Vaporizers For volatile gases Flowmeters Breathing circuits Gas scavenging systems Elsevier items and derived items © 2006 by Saunders, an imprint of Elsevier Inc. Objective 4 Explain the basic components of a general anesthetic. Elsevier items and derived items © 2006 by Saunders, an imprint of Elsevier Inc. Objective 4. Basic components Patient is: Unconscious Pain-free No memory of the event Immobile Maintains normal cardiovascular function Elsevier items and derived items © 2006 by Saunders, an imprint of Elsevier Inc. Objective 4. Basic components Explain each: Unconscious Unaware, does not respond to stimuli Pain-free (analgesia) Does not experience pain Elsevier items and derived items © 2006 by Saunders, an imprint of Elsevier Inc. Objective 4. Basic components Explain: Retains no memory of the event (amnesia) No explicit recall No awareness under anesthesia Elsevier items and derived items © 2006 by Saunders, an imprint of Elsevier Inc. Objective 4. Basic components Immobile Muscles relaxed Old term: “paralyzed” Cardiovascular function Goal: stable throughout Elsevier items and derived items © 2006 by Saunders, an imprint of Elsevier Inc. Objective 5 List methods of inducing general anesthesia. Elsevier items and derived items © 2006 by Saunders, an imprint of Elsevier Inc. Objective 5. Methods of general Most common are: Intravenous (IV) Inhalation Balanced • Combination of inhalation and intravenous Elsevier items and derived items © 2006 by Saunders, an imprint of Elsevier Inc. Objective 5. Methods of general Rare, but possible: Regional block used as an adjunct to a light general • High-risk patients Elsevier items and derived items © 2006 by Saunders, an imprint of Elsevier Inc. Objective 6 Define the phases of general anesthesia. Elsevier items and derived items © 2006 by Saunders, an imprint of Elsevier Inc. Objective 6. Phases Pre-induction Induction Maintenance Emergence Recovery Elsevier items and derived items © 2006 by Saunders, an imprint of Elsevier Inc. Objective 6. Define phases Pre-induction • • • • Preoperative area Assessment Patient preparation Up to admit to OR Elsevier items and derived items © 2006 by Saunders, an imprint of Elsevier Inc. Objective 6. Define phases Induction • Preoxygenation • Administration of agents • Through airway management Elsevier items and derived items © 2006 by Saunders, an imprint of Elsevier Inc. INDUCTION ALERT! Patients are highly reactive to noise during this phase. Pay attention to this when setting up your instruments. Elsevier items and derived items © 2006 by Saunders, an imprint of Elsevier Inc. Objective 6. Define phases Maintenance Starts when airway is secured/stable Continues until end of procedure Agents given PRN Elsevier items and derived items © 2006 by Saunders, an imprint of Elsevier Inc. Objective 6. Define phases Emergence Begins at end of procedure Agents discontinued or allowed to wear off Patient begins to awaken Airway removed (PRN) Elsevier items and derived items © 2006 by Saunders, an imprint of Elsevier Inc. EMERGENCE ALERT! Patients are highly reactive to noise in this phase. Be quiet and attentive to the patient when cleaning up. Elsevier items and derived items © 2006 by Saunders, an imprint of Elsevier Inc. Objective 6. Define phases Recovery Leave OR – go to PACU Patient fully awakens Vital signs must be stable before discharge Elsevier items and derived items © 2006 by Saunders, an imprint of Elsevier Inc. Objective 7 Discuss options for airway management. Elsevier items and derived items © 2006 by Saunders, an imprint of Elsevier Inc. Objective 7. Airway options Mask Placed over patient’s nose and mouth Oxygen and inhalation agents given Very short procedures • e.g., Myringotomy and tubes Elsevier items and derived items © 2006 by Saunders, an imprint of Elsevier Inc. Objective 7. Airway options LMA Laryngeal masked airway (pg 331) Elsevier items and derived items © 2006 by Saunders, an imprint of Elsevier Inc. Objective 7. Airway options LMA Sits on top of larynx Administer oxygen and inhalation agents Contraindications • Oral procedures, obesity, hiatal hernia, GERD, and low pulmonary compliance Elsevier items and derived items © 2006 by Saunders, an imprint of Elsevier Inc. Objective 7. Airway options Endotracheal (ET) tube (pg 331) Elsevier items and derived items © 2006 by Saunders, an imprint of Elsevier Inc. Objective 7. Airway options Endotracheal (ET) tube Maximum airway control Administer gases and inhalation agents Longer procedures Elsevier items and derived items © 2006 by Saunders, an imprint of Elsevier Inc. Objective 7. Airway options Endotracheal (ET) tube When deep muscle relaxation is needed Prone or lateral position Elsevier items and derived items © 2006 by Saunders, an imprint of Elsevier Inc. Objective 7. Airway options Endotracheal (ET) tube Variations: • RSI (rapid sequence) • Nasal • Patient awake Elsevier items and derived items © 2006 by Saunders, an imprint of Elsevier Inc. Objective 8 Describe the process of endotracheal intubation. Elsevier items and derived items © 2006 by Saunders, an imprint of Elsevier Inc. Objective 8. Intubation Patient’s muscles relaxed Laryngoscope inserted • View vocal cords • Image pg 332 Elsevier items and derived items © 2006 by Saunders, an imprint of Elsevier Inc. Objective 8. Intubation Intubate (insert ET tube) • Inflate cuff PRN Ventilate (O2 & agents) Image pg 334 Elsevier items and derived items © 2006 by Saunders, an imprint of Elsevier Inc. Objective 9 Discuss the concept of awareness under anesthesia. Elsevier items and derived items © 2006 by Saunders, an imprint of Elsevier Inc. Objective 9. Awareness Rare 0.1-0.2% of all patients Idiosyncratic Unpredictable Unknown cause Elsevier items and derived items © 2006 by Saunders, an imprint of Elsevier Inc. Objective 9. Awareness Some patients do NOT demonstrate characteristic physiologic responses to pain and/or inadequate depth of consciousness during surgery. Elsevier items and derived items © 2006 by Saunders, an imprint of Elsevier Inc. Objective 9. Awareness Result: the patient may have direct recall of events during surgery. Also called explicit memory See Insight 15-4 in book Elsevier items and derived items © 2006 by Saunders, an imprint of Elsevier Inc. Objective 9. Awareness Risk is when it is necessary to use the lowest possible dose of anesthesia medications to avoid undesirable side effects. Elsevier items and derived items © 2006 by Saunders, an imprint of Elsevier Inc. Objective 9. Awareness Risk is for: Trauma patients Cardiac patients Obstetric patients Elsevier items and derived items © 2006 by Saunders, an imprint of Elsevier Inc. Objective 9. Awareness Highly variable, but About 1/2 report auditory recall About 1/2 report sensation of being unable to breathe About 1/3 recall pain Elsevier items and derived items © 2006 by Saunders, an imprint of Elsevier Inc. Objective 9. Awareness How does this affect the surgical technologist? We can no longer assume that the patient is unaware and unaffected by our conversations and comments during surgery. Elsevier items and derived items © 2006 by Saunders, an imprint of Elsevier Inc. Objective 9. Awareness How does this affect the surgical technologist? Set a good example Be an agent for positive change Elsevier items and derived items © 2006 by Saunders, an imprint of Elsevier Inc. Objective 10 List agents used to accomplish general anesthesia. Elsevier items and derived items © 2006 by Saunders, an imprint of Elsevier Inc. Objective 10. Agents by category Sedatives/hypnotic agents Analgesics Inhalation agents Neuromuscular blockers Reversal agents Elsevier items and derived items © 2006 by Saunders, an imprint of Elsevier Inc. Objective 10. Agents by category Table 15-3 pg 340 Elsevier items and derived items © 2006 by Saunders, an imprint of Elsevier Inc. Objective 10. Agents Sedatives: Benzodiazepines • Valium, Versed, Ativan Hypnotics: Barbiturates • Pentothal, Brevital Elsevier items and derived items © 2006 by Saunders, an imprint of Elsevier Inc. Objective 10. Agents Other hypnotics Ketamine Etomidate Propofol (pg 342) Elsevier items and derived items © 2006 by Saunders, an imprint of Elsevier Inc. Objective 10. Agents Analgesics Natural opioid: • Morphine Synthetic opioids: • Fentanyl • Alfentanil • Sufentanil • Remifentanil Elsevier items and derived items © 2006 by Saunders, an imprint of Elsevier Inc. Objective 10. Agents Inhalation agents Nitrous oxide Isoflurane (Forane) Desflurane (Suprane) Sevoflurane (Ultane) Elsevier items and derived items © 2006 by Saunders, an imprint of Elsevier Inc. Objective 10. Agents Neuromuscular blockers Depolarizing • Succinylcholine Non-depolarizing • Tracrium, Mivacron, Pavulon, Zemuron, Curare, Norcuron Elsevier items and derived items © 2006 by Saunders, an imprint of Elsevier Inc. Objective 10. Agents Reversal agents For opioids • Naloxone (Narcan) • Nalmefene (Revex) • Naltrexone (ReVia, Trexan) For benzodiazepines • Flumazenil (Mazicon) Elsevier items and derived items © 2006 by Saunders, an imprint of Elsevier Inc. Objective 10. Agents Reversal agents For non-depolarizing muscle relaxants: • Neostigmine (Prostigmine) • Edrophonium (Tensilon) Elsevier items and derived items © 2006 by Saunders, an imprint of Elsevier Inc. Objective 10. Agents Table 15-8 pg 350 Elsevier items and derived items © 2006 by Saunders, an imprint of Elsevier Inc. Objective 11 Identify the purposes and categories of agents used in general anesthesia. Elsevier items and derived items © 2006 by Saunders, an imprint of Elsevier Inc. Objective 11. Category/purpose Sedatives/hypnotic agents Produce Analgesics Prevent unconsciousness perception of pain Inhalation agents Produce unconsciousness Prevent motor response to painful stimuli Elsevier items and derived items © 2006 by Saunders, an imprint of Elsevier Inc. Objective 11. Category/purpose Neuromuscular blockers Relax muscles for intubation and surgical procedure Reversal agents Counteract the action of various agents Elsevier items and derived items © 2006 by Saunders, an imprint of Elsevier Inc. Objective 12 Identify generic and trade names of common agents used in anesthesia. Make drug cards Generic Trade name on one side name on other side Elsevier items and derived items © 2006 by Saunders, an imprint of Elsevier Inc. Objective 13 State the phase of anesthesia in which various agents are administered. Make drug cards Agent on one side Phase on other side Elsevier items and derived items © 2006 by Saunders, an imprint of Elsevier Inc. Objective 13. Phase/agents Induction Benzodiazepines • Versed, Valium, Ativan Barbiturates • Thiopental, methohexital Ketamine Etomidate Propofol Elsevier items and derived items © 2006 by Saunders, an imprint of Elsevier Inc. Objective 13. Phase/agents Induction and maintenance Analgesics (PRN only) • Morphine • Sublimaze • Alfenta • Sufenta • Ultiva Elsevier items and derived items © 2006 by Saunders, an imprint of Elsevier Inc. Objective 13. Phase/agents Induction and maintenance Inhalation agents • Nitrous oxide • Forane • Suprane • Ultane Elsevier items and derived items © 2006 by Saunders, an imprint of Elsevier Inc. Objective 13. Phase/agents Induction and maintenance Inhalation agents Image pg 345 Elsevier items and derived items © 2006 by Saunders, an imprint of Elsevier Inc. Objective 13. Phase/agents Induction and maintenance Depolarizing muscle relaxant • Succinylcholine Non-depolarizers • Tracrium, Mivacron • Pavulon, Zemuron • Curare, Norcuron Elsevier items and derived items © 2006 by Saunders, an imprint of Elsevier Inc. Objective 13. Phase/agents Emergence Reversal agents: • Narcan, Revex, ReVia, Trexan • Mazicon • Prostigmine, Tensilon Elsevier items and derived items © 2006 by Saunders, an imprint of Elsevier Inc. Objective 14 Compare and contrast depolarizing and non-depolarizing muscle relaxants. How are they alike? How are they different? Elsevier items and derived items © 2006 by Saunders, an imprint of Elsevier Inc. Objective 14. C/C muscle relaxants Basics – review physiology of muscle contraction - anatomy Brain to motor nerve Neuromuscular junction Muscle fiber Elsevier items and derived items © 2006 by Saunders, an imprint of Elsevier Inc. Objective 14. C/C muscle relaxants Basics – review physiology of muscle contraction – chemical level Neurotransmitter Acetylcholine (ACh) Binds to receptor Release Ca+ Elsevier items and derived items © 2006 by Saunders, an imprint of Elsevier Inc. Objective 14. C/C muscle relaxants Basics – review physiology of muscle contraction – chemical level Depolarize (contract) Acetylcholine (ACh) unhooks • Acetylcholinesterase removes ACh Repolarize (resting) Elsevier items and derived items © 2006 by Saunders, an imprint of Elsevier Inc. Objective 14. C/C muscle relaxants Depolarizers Cause contractions (sustained) Non-depolarizers • Prevent contractions Elsevier items and derived items © 2006 by Saunders, an imprint of Elsevier Inc. Objective 14. C/C muscle relaxants Image pg 31 Elsevier items and derived items © 2006 by Saunders, an imprint of Elsevier Inc. Image pg 31 Elsevier items and derived items © 2006 by Saunders, an imprint of Elsevier Inc. Objective 14. C/C muscle relaxants Similarities between depolarizing and nondepolarizing muscle relaxants Both types paralyze muscles to allow intubation and surgical exposure Both types are given IV Elsevier items and derived items © 2006 by Saunders, an imprint of Elsevier Inc. Objective 14. C/C muscle relaxants How are they different? Only 1 depolarizer Many non-depolarizers Depolarizer causes sustained contraction Non-depolarizer prevents contraction Elsevier items and derived items © 2006 by Saunders, an imprint of Elsevier Inc. Objective 14. C/C muscle relaxants How are they different? Depolarizer Rapid onset Short duration Not reversible Elsevier items and derived items © 2006 by Saunders, an imprint of Elsevier Inc. Objective 14. C/C muscle relaxants How are they different? Non-depolarizers Vary in onset and duration Reversible Elsevier items and derived items © 2006 by Saunders, an imprint of Elsevier Inc. Objective 14. C/C muscle relaxants How are they different? Depolarizer Trigger for Malignant Hyperthermia (see Chapter 16) Non-depolarizers Not implicated in MH Elsevier items and derived items © 2006 by Saunders, an imprint of Elsevier Inc.