pharmacology dh206 chapter 10: general anesthetics lisa mayo, rdh, bsdh copyright © 2011, 2007...

Pharmacology DH206Chapter 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


Chapter 10 Outline

General Anesthetics

1. Terminology

2. Types of anesthesia

3. ASA Classification

4. Nitrous Oxide

5. General Anesthesia


Terminology


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


Types of Anesthesia


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)


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


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


ASA Classification


ASA Classification

ASA I – II• Medically stable & able to receive anesthesia

ASA III – IV• Medical consult necessary


NBQ

Which ASA class described a patient with mild hypertension?a. I

b. II

c. III

d. IV

e. V


Nitrous Oxide


Nitrous oxide• Low potency

• IV + N2O/O2 + volatile anesthetic = excellent balanced anesthesia produced

• Indications for use1) Fearful patient2) Cognitively, physically, medically compromised person

Gag reflex3) Profound local anesthesia CANNOT be obtained4) Cardiac conditions, HBP, asthma, cerebral palsy


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


Nitrous Oxide: Contraindications • Pregnancy: NEVER in 1st 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


Nitrous Oxide Abuse

• Neuropathy• Liver, kidney problems

• Inhibit function & absorption of B12 (NBQ)

• Not in your book, but need to know


General Anesthesia


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


General Anesthesia• Used in OMS• Administration: IV drugs 1st then Inhalation• Drugs rapidly produce unconsciousness and total

analgesia• Progressive process that occurs in distinct stages

(Guedel’s signs) NEXT SLIDE


General AnesthesiaGUEDEL Stages & Planes of Anesthesia: p.117, Table 10-1

1. 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


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


NBQ

At which of the following stages of anesthesia is surgical anesthesia attained?

a. 1

b. 2

c. 3

d. 4


General Anesthesia DrugsInjectable Anesthetics

TYPICAL SEQUENCE FOR IV SEDATION1.IV agent 1st

2.Inhalation agents: N2O2, Halogenated hydrocarbon


General Anesthesia DrugsInjectable Drug Class

Drugs

Benzodiazepine Valium, Versed

Opioids Fentanyl, Morphine, Meperidine

Sedative/Hypnotic Propfol, Ketamine

Barbiturate Phenobarbital, Thiopental, Methohexital(Brevital)

Inhalation Anesthetics

Halothane(Fluothane) PROTYPE

Desflurane(Suprane) NEWER

Sevoflurane(Ultane) NEWER

Isoflurane(Forane)

Enflurane(Ethrane)


General Anesthesia DrugsInjectable Drug Class

Drug Notations

Benzodiazepine Valium, Versed

Opioids Fentanyl, Morphine, Meperidine

Sedative/Hypnotic Propfol, Ketamine Catatonic state, no loss consciousness

Barbiturate Phenobarbital, Thiopental, Methohexital(Brevital)

ALL pose risk for resp depression!


General Anesthesia DrugsInhalation Anesthetics

Inhalation Anesthetics

Halothane(Fluothane) PROTYPE

Desflurane(Suprane) NEWER

Sevoflurane(Ultane) NEWER

Isoflurane(Forane)

Enflurane(Ethrane)


General Anesthesia DrugsInhalation 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


NBQ

Which of the following agents is considered to be a gas?a. Nitrous oxide

b. Fentanyl

c. Propofol

d. Diazepam


NBQ

Which of the following inhalation anesthetics does not cause respiratory depression and hypotension?

a. Nitrous oxide

b. Enflurane

c. Isoflurane

d. Halothane


General Anesthesia DrugsAdverse Reactions: Table 10-2,p.129

1. Cardio• Hypotension• Hypertension• Arrhythmias

2. CNS• Pain• Muscle weakness• Sleepy

3. GI• Constipation• Nausea, vomiting

4. Respiration• Difficulty breathing• Sore throat• Hypoxia (low oxygen)


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


NBQ

Which of the following side effects is common after general anesthesia?

a. Diarrhea

b. Esophageal reflux

c. Nausea and vomiting

d. Muscle weakness

pharmacology dh206 chapter 10: general anesthetics lisa mayo, rdh, bsdh copyright © 2011, 2007...

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