Pharmacology DH206 Chapter 10: General Anesthetics Lisa Mayo, RDH, BSDH Copyright © 2011, 2007 Mosby, Inc., an affiliate of Elsevier. All rights reserved.

Application to Dentistry Drugs in this category produce CNS depression & analgesia Reversible loss of consciousness Absence to painful stimuli DH = Nitrous Dentist = training & license to use moderate sedation and/or general anesthesia

Copyright © 2011, 2007 Mosby, Inc., an affiliate of Elsevier. All rights reserved. Chapter 10 Outline General Anesthetics 1. Terminology 2. Types of anesthesia 3. ASA Classification 4. Nitrous Oxide 5. General Anesthesia

Copyright © 2011, 2007 Mosby, Inc., an affiliate of Elsevier. All rights reserved. Terminology

Copyright © 2011, 2007 Mosby, Inc., an affiliate of Elsevier. All rights reserved. Terminology 1. Minimal sedation (anxiolysis = anti-anxiety) Drug-induced state. Pt can respond to commands Ventilation & cardiovascular unaffected 2. Moderate sedation (formerly called conscious sedation) Drugs used to induce sedation, lack of awareness, amnesia, analgesia Patient can respond to commands Monitor vitals, no intubation Licensed dentist can administer 3. Deep sedation Drug-induced depression of consciousness, pt cannot be easily aroused Monitor vitals, respiration closely 4. General anesthesia Unconsciousness, ventilator needed, hospital ONLY

Copyright © 2011, 2007 Mosby, Inc., an affiliate of Elsevier. All rights reserved. Types of Anesthesia

Copyright © 2011, 2007 Mosby, Inc., an affiliate of Elsevier. All rights reserved. Types of Anesthesia 1. Oral (enteral): need large initial dose, absorption NOT predictable 2. Inhalation: sedation obtained via lungs, allows for rapid recovery 1)Nitrous oxide: anxiolysis ONLY, not for anesthesia 2)Volatile liquids: halogenated hydrocarbons or halogenated ethers (p.118, TABLE 10-3) 3. IV Most predictable sedation IV moderate sedation = general anesthesia (don’t confuse the 2) 4. Combo: inhalation + Enteral (used in dentistry)

Copyright © 2011, 2007 Mosby, Inc., an affiliate of Elsevier. All rights reserved. NBQ All of the following statements are true about moderate sedation EXCEPT which one? a. Complete loss of protective reflexes b. Total unconsciousness c. Patent airway d. Responds to physical stimulation

Copyright © 2011, 2007 Mosby, Inc., an affiliate of Elsevier. All rights reserved. NBQ All of the following statements are true about moderate sedation EXCEPT which one? a. Complete loss of protective reflexes b. Total unconsciousness c. Patent airway d. Responds to physical stimulation

Copyright © 2011, 2007 Mosby, Inc., an affiliate of Elsevier. All rights reserved. NBQ Which of the following procedures is used for anxiety reduction, pain control and amnesia in the dental patient while remaining responsive and cooperative during the dental procedure? a. Deep sedation b. Local anesthesia c. Moderate sedation d. Minimal sedation

Copyright © 2011, 2007 Mosby, Inc., an affiliate of Elsevier. All rights reserved. NBQ Which of the following procedures is used for anxiety reduction, pain control and amnesia in the dental patient while remaining responsive and cooperative during the dental procedure? a. Deep sedation b. Local anesthesia c. Moderate sedation d. Minimal sedation

Copyright © 2011, 2007 Mosby, Inc., an affiliate of Elsevier. All rights reserved. ASA Classification

Copyright © 2011, 2007 Mosby, Inc., an affiliate of Elsevier. All rights reserved. ASA Classification ASA I – II Medically stable & able to receive anesthesia ASA III – IV Medical consult necessary

Copyright © 2011, 2007 Mosby, Inc., an affiliate of Elsevier. All rights reserved. NBQ Which ASA class described a patient with mild hypertension? a. I b. II c. III d. IV e. V

Copyright © 2011, 2007 Mosby, Inc., an affiliate of Elsevier. All rights reserved. NBQ Which ASA class described a patient with mild hypertension? a. I b. II c. III d. IV e. V

Copyright © 2011, 2007 Mosby, Inc., an affiliate of Elsevier. All rights reserved. Nitrous Oxide

Copyright © 2011, 2007 Mosby, Inc., an affiliate of Elsevier. All rights reserved. Nitrous oxide Low potency IV + N 2 O/O 2 + volatile anesthetic = excellent balanced anesthesia produced Indications for use 1) Fearful patient 2) Cognitively, physically, medically compromised person Gag reflex 3) Profound local anesthesia CANNOT be obtained 4) Cardiac conditions, HBP, asthma, cerebral palsy

Copyright © 2011, 2007 Mosby, Inc., an affiliate of Elsevier. All rights reserved. Nitrous Oxide Effects CNS sedation  Resulting in analgesia and amnesia Cardiovascular effects  Peripheral vasodilation Gastrointestinal effects  Nausea and vomiting are uncommon but may occur Vitals remain wnl Pt conscious, reflexes intact Anxiety reduction BOOK CORRECTION: N2O2 DOES NOT CAUSE AMNESIA P.120

Copyright © 2011, 2007 Mosby, Inc., an affiliate of Elsevier. All rights reserved. Nitrous Oxide: Contraindications Pregnancy: NEVER in 1 st trimester but controversy on nitrous use after that Communication difficulties Emotional instability Respiratory obstruction (nasal, blocked eustachian tubes) COPD (Emphysema, Bronchitis) Reformed drug and alcohol abusers

Copyright © 2011, 2007 Mosby, Inc., an affiliate of Elsevier. All rights reserved. Nitrous Oxide Abuse Neuropathy Liver, kidney problems Inhibit function & absorption of B 12 (NBQ) Not in your book, but need to know

Copyright © 2011, 2007 Mosby, Inc., an affiliate of Elsevier. All rights reserved. General Anesthesia

Copyright © 2011, 2007 Mosby, Inc., an affiliate of Elsevier. All rights reserved. General Anesthesia Dental Office IV sedation Dentist needs separate license to administer Use a combo of meds to achieve goal (all highly lipid soluble = FAST onset of action) 1)Benzodiazepines (Valium, Versed) 2)Opioids (fentanyl, morphine, meperidine) 3)Sedative/Hypnotic (propfol, ketamine) 4)Barbiturates (pentobarbital) if cannot use Benzo’s

Copyright © 2011, 2007 Mosby, Inc., an affiliate of Elsevier. All rights reserved. General Anesthesia Used in OMS Administration: IV drugs 1 st then Inhalation Drugs rapidly produce unconsciousness and total analgesia Progressive process that occurs in distinct stages (Guedel’s signs) NEXT SLIDE

Copyright © 2011, 2007 Mosby, Inc., an affiliate of Elsevier. All rights reserved. General Anesthesia GUEDEL Stages & Planes of Anesthesia: p.117, Table Stage I: analgesia The patient is still conscious and can respond The end of stage I is marked by loss of consciousness Nitrous oxide in dental office 2. Stage II: Delirium or Excitement Begins as loss of consciousness, irregular respiration, hyper-responsiveness 3. Stage III: Surgical Anesthesia Return to regular respiration, 4 planes 4. Stage IV: Respiratory or medullary paralysis Cessation of respiration, circulatory failure

Copyright © 2011, 2007 Mosby, Inc., an affiliate of Elsevier. All rights reserved. General Anesthesia Stage III: Surgical Anesthesia Most surgical procedures require this stage Guedel’s 4 signs you are in stage III (NBQ) 1)Pupil dilation 2)Tachycardia 3)Hypotension 4)Skeletal muscle relaxation

Copyright © 2011, 2007 Mosby, Inc., an affiliate of Elsevier. All rights reserved. NBQ At which of the following stages of anesthesia is surgical anesthesia attained? a. 1 b. 2 c. 3 d. 4

Copyright © 2011, 2007 Mosby, Inc., an affiliate of Elsevier. All rights reserved. NBQ At which of the following stages of anesthesia is surgical anesthesia attained? a. 1 b. 2 c. 3 d. 4

Copyright © 2011, 2007 Mosby, Inc., an affiliate of Elsevier. All rights reserved. General Anesthesia Drugs Injectable Anesthetics TYPICAL SEQUENCE FOR IV SEDATION 1. IV agent 1 st 2. Inhalation agents: N 2 O 2, Halogenated hydrocarbon

Copyright © 2011, 2007 Mosby, Inc., an affiliate of Elsevier. All rights reserved. General Anesthesia Drugs Injectable Drug Class Drugs BenzodiazepineValium, Versed OpioidsFentanyl, Morphine, Meperidine Sedative/HypnoticPropfol, Ketamine BarbituratePhenobarbital, Thiopental, Methohexital(Brevital) Inhalation Anesthetics Halothane(Fluothane) PROTYPE Desflurane(Suprane) NEWER Sevoflurane(Ultane) NEWER Isoflurane(Forane) Enflurane(Ethrane)

Copyright © 2011, 2007 Mosby, Inc., an affiliate of Elsevier. All rights reserved. General Anesthesia Drugs Injectable Drug Class DrugNotations BenzodiazepineValium, Versed OpioidsFentanyl, Morphine, Meperidine Sedative/HypnoticPropfol, KetamineCatatonic state, no loss consciousness BarbituratePhenobarbital, Thiopental, Methohexital(Brevital) ALL pose risk for resp depression!

Copyright © 2011, 2007 Mosby, Inc., an affiliate of Elsevier. All rights reserved. General Anesthesia Drugs Inhalation Anesthetics Inhalation Anesthetics Halothane(Fluothane) PROTYPE Desflurane(Suprane) NEWER Sevoflurane(Ultane) NEWER Isoflurane(Forane) Enflurane(Ethrane)

Copyright © 2011, 2007 Mosby, Inc., an affiliate of Elsevier. All rights reserved. General Anesthesia Drugs Inhalation Anesthetics 2 classes: gases or volatile liquids 1. Nonhalogenated drugs 2. Halogenated drugs: only used by dentist or anesthesiologists in hospital setting (next slide) Uses Maintenance after induction of IV agent Measured in terms of partial pressure (not mg/mL like oral agents) MAC (minimal alveolar concentration) Inspired concentration of anesthetic to induce surgical anesthesia in 50% of patients Used to measure & compare potency of the different drugs

Copyright © 2011, 2007 Mosby, Inc., an affiliate of Elsevier. All rights reserved. NBQ Which of the following agents is considered to be a gas? a. Nitrous oxide b. Fentanyl c. Propofol d. Diazepam

Copyright © 2011, 2007 Mosby, Inc., an affiliate of Elsevier. All rights reserved. NBQ Which of the following agents is considered to be a gas? a. Nitrous oxide b. Fentanyl c. Propofol d. Diazepam

Copyright © 2011, 2007 Mosby, Inc., an affiliate of Elsevier. All rights reserved. NBQ Which of the following inhalation anesthetics does not cause respiratory depression and hypotension? a. Nitrous oxide b. Enflurane c. Isoflurane d. Halothane

Copyright © 2011, 2007 Mosby, Inc., an affiliate of Elsevier. All rights reserved. NBQ Which of the following inhalation anesthetics does not cause respiratory depression and hypotension? a. Nitrous oxide b. Enflurane c. Isoflurane d. Halothane

Copyright © 2011, 2007 Mosby, Inc., an affiliate of Elsevier. All rights reserved. General Anesthesia Drugs Adverse Reactions: Table 10-2,p Cardio Hypotension Hypertension Arrhythmias 2. CNS Pain Muscle weakness Sleepy 3. GI Constipation Nausea, vomiting 4. Respiration Difficulty breathing Sore throat Hypoxia (low oxygen)

Copyright © 2011, 2007 Mosby, Inc., an affiliate of Elsevier. All rights reserved. NBQ Propofol is preferred over thiopental as an IV anesthetic because of its a. Recovery characteristics b. Can be taken orally c. Long onset of action d. Prolonged duration of action

Copyright © 2011, 2007 Mosby, Inc., an affiliate of Elsevier. All rights reserved. NBQ Propofol is preferred over thiopental as an IV anesthetic because of its a. Recovery characteristics b. Can be taken orally c. Long onset of action d. Prolonged duration of action

Copyright © 2011, 2007 Mosby, Inc., an affiliate of Elsevier. All rights reserved. NBQ Which of the following side effects is common after general anesthesia? a. Diarrhea b. Esophageal reflux c. Nausea and vomiting d. Muscle weakness

Copyright © 2011, 2007 Mosby, Inc., an affiliate of Elsevier. All rights reserved. NBQ Which of the following side effects is common after general anesthesia? a. Diarrhea b. Esophageal reflux c. Nausea and vomiting d. Muscle weakness