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

Objective 1. Terms Emulsion Endotracheal (ET) tube Extubation A mixture of two liquids not mutually soluble Endotracheal (ET) tube 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

Objective 1. Terms Intubation LMA Opioid Repolarization Insertion of an endotracheal tube LMA Laryngeal masked airway; an airway that is placed over the larynx Opioid Any synthetic narcotic not derived from opium Repolarization Restoration of the polarized state at the cell membrane

Review basics of anesthesia Review pain impulses Nerve endings Nerves Sensory and motor Spinal cord Brain

Review of process of pain Nerve endings stimulated Transmit via sensory nerve To spinal cord (motor loop) To brain for interpretation and response

Objective 2 Discuss indications for general anesthesia.

Objective 2. Indications The surgical procedure to be performed Multiple sites Need for motionless field Long duration

Objective 2. Indications The individual patient Age (all pediatrics) Cognitive ability Mental/emotional state Preference

Objective 3 Identify anesthesia equipment.

Objective 3. Equipment Anesthesia machine Manual and automatic ventilation systems Oxygen and nitrous oxide (N2O) central pipeline hoses and back up tanks

Objective 3. Equipment Vaporizers Flowmeters Breathing circuits For volatile gases Flowmeters Breathing circuits Gas scavenging systems

Objective 4 Explain the basic components of a general anesthetic.

Objective 4. Basic components Patient is: Unconscious Pain-free No memory of the event Immobile Maintains normal cardiovascular function

Objective 4. Basic components Explain each: Unconscious Unaware, does not respond to stimuli Pain-free (analgesia) Does not experience pain

Objective 4. Basic components Explain: Retains no memory of the event (amnesia) No explicit recall No awareness under anesthesia

Objective 4. Basic components Immobile Muscles relaxed Old term: “paralyzed” Cardiovascular function Goal: stable throughout

Objective 5 List methods of inducing general anesthesia.

Objective 5. Methods of general Most common are: Intravenous (IV) Inhalation Balanced Combination of inhalation and intravenous

Objective 5. Methods of general Rare, but possible: Regional block used as an adjunct to a light general High-risk patients

Objective 6 Define the phases of general anesthesia.

Objective 6. Phases Pre-induction Induction Maintenance Emergence Recovery

Objective 6. Define phases Pre-induction Preoperative area Assessment Patient preparation Up to admit to OR

Objective 6. Define phases Induction Preoxygenation Administration of agents Through airway management

INDUCTION ALERT! Patients are highly reactive to noise during this phase. Pay attention to this when setting up your instruments.

Objective 6. Define phases Maintenance Starts when airway is secured/stable Continues until end of procedure Agents given PRN

Objective 6. Define phases Emergence Begins at end of procedure Agents discontinued or allowed to wear off Patient begins to awaken Airway removed (PRN)

EMERGENCE ALERT! Patients are highly reactive to noise in this phase. Be quiet and attentive to the patient when cleaning up.

Objective 6. Define phases Recovery Leave OR – go to PACU Patient fully awakens Vital signs must be stable before discharge

Objective 7 Discuss options for airway management.

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

Objective 7. Airway options LMA Laryngeal masked airway

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

Objective 7. Airway options Endotracheal (ET) tube

Objective 7. Airway options Endotracheal (ET) tube Maximum airway control Administer gases and inhalation agents Longer procedures

Objective 7. Airway options Endotracheal (ET) tube When deep muscle relaxation is needed Prone or lateral position

Objective 7. Airway options Endotracheal (ET) tube Variations: RSI (rapid sequence) Nasal Patient awake

Objective 8 Describe the process of endotracheal intubation.

Objective 8. Intubation Patient’s muscles relaxed Laryngoscope inserted View vocal cords

Objective 8. Intubation Intubate (insert ET tube) Inflate cuff PRN Ventilate (O2 & agents)

Objective 9 Discuss the concept of awareness under anesthesia.

Objective 9. Awareness Rare Idiosyncratic 0.1-0.2% of all patients Unpredictable Unknown cause

Objective 9. Awareness Some patients do NOT demonstrate characteristic physiologic responses to pain and/or inadequate depth of consciousness during surgery.

Objective 9. Awareness Result: the patient may have direct recall of events during surgery. Also called explicit memory See Insight 15-4 in book

Objective 9. Awareness Risk is  when it is necessary to use the lowest possible dose of anesthesia medications to avoid undesirable side effects.

Objective 9. Awareness Risk is  for: Trauma patients Cardiac patients Obstetric patients

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

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.

Objective 9. Awareness How does this affect the surgical technologist? Set a good example Be an agent for positive change

Objective 10 List agents used to accomplish general anesthesia.

Objective 10. Agents by category Sedatives/hypnotic agents Analgesics Inhalation agents Neuromuscular blockers Reversal agents

Objective 10. Agents by category

Objective 10. Agents Sedatives: Hypnotics: Benzodiazepines Valium, Versed, Ativan Hypnotics: Barbiturates Pentothal, Brevital

Objective 10. Agents Other hypnotics Ketamine Etomidate Propofol

Objective 10. Agents Analgesics Natural opioid: Synthetic opioids: Morphine Synthetic opioids: Fentanyl Alfentanil Sufentanil Remifentanil

Objective 10. Agents Inhalation agents Nitrous oxide Isoflurane (Forane) Desflurane (Suprane) Sevoflurane (Ultane)

Objective 10. Agents Neuromuscular blockers Depolarizing Succinylcholine Non-depolarizing Tracrium, Mivacron, Pavulon, Zemuron, Curare, Norcuron

Objective 10. Agents Reversal agents For opioids For benzodiazepines Naloxone (Narcan) Nalmefene (Revex) Naltrexone (ReVia, Trexan) For benzodiazepines Flumazenil (Mazicon)

Objective 10. Agents Reversal agents For non-depolarizing muscle relaxants: Neostigmine (Prostigmine) Edrophonium (Tensilon)

Objective 10. Agents

Objective 11 Identify the purposes and categories of agents used in general anesthesia.

Objective 11. Category/purpose Sedatives/hypnotic agents Produce unconsciousness Analgesics Prevent perception of pain Inhalation agents Prevent motor response to painful stimuli

Objective 11. Category/purpose Neuromuscular blockers Relax muscles for intubation and surgical procedure Reversal agents Counteract the action of various agents

Objective 12 Identify generic and trade names of common agents used in anesthesia. Make drug cards Generic name on one side Trade name on other side

Objective 13 State the phase of anesthesia in which various agents are administered. Make drug cards Agent on one side Phase on other side

Objective 13. Phase/agents Induction Benzodiazepines Versed, Valium, Ativan Barbiturates Thiopental, methohexital Ketamine Etomidate Propofol

Objective 13. Phase/agents Induction and maintenance Analgesics (PRN only) Morphine Sublimaze Alfenta Sufenta Ultiva

Objective 13. Phase/agents Induction and maintenance Inhalation agents Nitrous oxide Forane Suprane Ultane

Objective 13. Phase/agents Induction and maintenance Inhalation agents

Objective 13. Phase/agents Induction and maintenance Depolarizing muscle relaxant Succinylcholine Non-depolarizers Tracrium, Mivacron Pavulon, Zemuron Curare, Norcuron

Objective 13. Phase/agents Emergence Reversal agents: Narcan, Revex, ReVia, Trexan Mazicon Prostigmine, Tensilon

Objective 14 Compare and contrast depolarizing and non-depolarizing muscle relaxants. How are they alike? How are they different?

Objective 14. C/C muscle relaxants Basics – review physiology of muscle contraction - anatomy Brain to motor nerve Neuromuscular junction Muscle fiber

Objective 14. C/C muscle relaxants Basics – review physiology of muscle contraction – chemical level Neurotransmitter Acetylcholine (ACh) Binds to receptor Release Ca+

Objective 14. C/C muscle relaxants Basics – review physiology of muscle contraction – chemical level Depolarize (contract) Acetylcholine (ACh) unhooks Acetylcholinesterase removes ACh Repolarize (resting)

Objective 14. C/C muscle relaxants Depolarizers Cause contractions (sustained) Non-depolarizers Prevent contractions

Objective 14. C/C muscle relaxants

Objective 14. C/C muscle relaxants Similarities between depolarizing and non-depolarizing muscle relaxants Both types paralyze muscles to allow intubation and surgical exposure Both types are given IV

Objective 14. C/C muscle relaxants How are they different? Only 1 depolarizer Many non-depolarizers Depolarizer causes sustained contraction Non-depolarizer prevents contraction

Objective 14. C/C muscle relaxants How are they different? Depolarizer Rapid onset Short duration Not reversible

Objective 14. C/C muscle relaxants How are they different? Non-depolarizers Vary in onset and duration Reversible

Objective 14. C/C muscle relaxants How are they different? Depolarizer Trigger for Malignant Hyperthermia (see Chapter 16) Non-depolarizers Not implicated in MH