Pharmacology Week 4 Ppt Review

Front 1

What are General Anesthetics

Back 1

• A hetrogeneous group of potent CNS depressants
• Reversible loss of consciousness and insensibility to painful stimuli

Front 2

What is Balanced anesthesia?

Back 2

• A combination of drugs to minimize adverse effects

Front 3

Stages of Anesthesia - Stage I

Back 3

Analgesia
Reduces pain sensation
Patient is conscious & responsive to command
Reflexes present, normal respiration

Front 4

Stages of Anesthesia - Stage II

Back 4

Delirium or Excitment

• Uncoscousness w/ involuntary movement/ excitement
• Irregular respiration, ^ muscle tone, sympathetic stimulation (tachycardia, mydriasis, hypertension)
• Emesis and incontinence may occur

Front 5

Stages of Anesthesia - Stage III

Back 5

Surgical Anesthesia

• Resumes regular respiration, muscle relaxation, normal heart & pulse rates

Front 6

Stages of Anesthesia - Stage IV

Back 6

Medullary/Respiratory Paralysis

• Pupils dilated, blood pressure falls, respiration stops

Front 7

What are the Levels of Anesthesia
(Flagg's Approach)

Back 7

Induction -
• Includes all preparation and pre-op meds
Maintenance -
• Begins when patient is at depth of anesthesia needed for procedure --> completion
Recovery -
• Starts when surgical procedure is complete --> patient is fully responsive

Front 8

What are the Adverse Reactions/ Hazards of General Anesthetics?

Back 8

• Cardiovascular collapse/cardiac arrest
• Arrhythmia
• Hypertension (Stage II only); hypotension
• Depressed respiration; respiratory arrest
• Explosions w/ inhaled gases

Front 9

What are the types of General anesthesia?

Are they removed through respiration?

Back 9

• Inhalation anesthetic - Respiration
• Intravenous Anesthetic - NOT Respiration

Front 10

Inhalation Anesthetics-

What are the subcategories?

What do they consist of?

Back 10

Inhalation Gases

• Nitrous Oxide

Inhalation Volatile Liquids

• Ether - no longer in use
• Halogenated Hydrocarbons:

-- Enflurane and isoflurane most popular

Front 11

Intravenous Anesthetics-

What are the subcategories?

What is an example of each?

Back 11

• Barbiturates: thiopental
• Dissociative: ketamine
• Neuroleptanalgesic: fentanyl

Front 12

How Are Inhalation Anesthetics used?
What do they do?
What is their MOA?

Back 12

Vaporized from liquid form and inhaled to produce general anesthesia
Inhaled Gas
Depress spontaneous/evoked activity of neurons
Influence GABAA receptor-chloride channel

Front 13

What are examples of Inhaled Anesthetics?

Back 13

• Nitrous Oxide
• Halothane (Halogenated Hydrocarbon)
• Isoflurane (Halogenated Ether)
• Enflurane
• Sevoflurane
• Methoxyflurane
• Desflurane

Front 14

What is Nitrous Oxide?

- Solubility?

-Potency and use?

-What is it intended for and does it produce?

Back 14

• Colorless, odorless gas
• Least solubility in blood
• Low potency - not for Single Agent General Anesthesia

-- Used alone to reduce anxiety

• Used in combination w/ other general anesthetics

-- Intention: relax and slightly sedate patient

• Produces Stage I (Analgesia) level

Front 15

What is Nitrous Oxide's MOA?
What is it's Onset of Action?
What is it used for?
How is it metabolized?

Back 15

MOA - Not truely known - Potentiation of neurotransmitter GABA
Rapid onset of action
Use - light sedation/relaxation
Not metabolized in the body--- Safe even in poor liver function

Front 16

What are the advantages of Nitrous Oxide?

Back 16

• Rapid onset of action
• Elevates pain threshold
• Pleasant induction
• Titratable (adjustable)
• Rapid and complete recovery
• Virtually no adverse effects
• Therapeutic for medically compromised patients
• Suitable for ALL ages

Front 17

Keys to Nitrous Oxide Safety:

How is it administered?

What does 100% nitrous oxide cause and how?

What is scavenging?

What should patients do?

What is done if nitrous indicator is triggered?

Back 17

• Always administered combined w/ oxygen

--- ("Fail Safe" on flow meter)

• 100% Nitrous causes Hypoxia - binds to hemoglobin, kicks off oxygen
• Scavenging: removes exhaled gas; (double mask by Porter)
• Patients should not talk when administered
• Do not leave room/op to find the leak

Front 18

Keys to Nitrous Oxide safety:

What is cause in adults? By what?

What is cause in children? By what?

Who has higher resistance?

How is Diffusion Hypoxia avoided?

Back 18

• Nausea and vomiting - associated with adjusting the nitrous dose
• Nausea and vomiting - Eating 1 hr before
• Higher resistance - patients who are alcoholics, drug addicts, chronic cigarette smokers
• Avoid - administer 100% oxygen for at least 5 min. after terminating nitrous oxide

Front 19

Keys to Nitrous Oxide Safety:

What is Chronic Exposure? What monitors it?

What is there potential for?

What must the clinician do?

How do you remove nitrous gas

What does chronic exposure cause?

What is associated with chronic exposure?

Back 19

• 8 hrs of 50ppm, monitored by Nitrous badges
• Potential for abuse
• Don't Leave Op! Constantly monitor patient
• Heavy gas difficult to remove; fans, open windows
• Reduces fertility w/ chronic exposure
• Associated w/ miscarriages during pregnancy

Front 20

When is Nitrous Contraindicated?

Back 20

• Upper respiratory infection
• COPD
• Pregnancy
• Communication barrier
• Contagious disease such as hepatitis if tubing cannot be completely sterilized
• Epilepsy
• Emotional Instability
• Previous negative experience w/ nitrous

Front 21

Besides Nitrous Oxide, what are

other General Anesthetics?

Back 21

• Halogenated Hydrocarbon
• Barbiturates
• Propofol
• Ketamine

Front 22

What do Hydrogenated Hydrocarbons contain?

What is it's potency/solubility?

How is it turned to gas?

Back 22

• Fluorine, chlorine, or bromine
• Potent w/ limited solubility in tissues
• Very low boiling point - evaporates easily @ room temp.

Front 23

What gases are Hydrogenated Hydrocarbons?

Back 23

• Halothane
• Enflurane
• Isoflurane
• Desflurane
• Sevoflurane

Front 24

Hydrogenated Hydrocarbon: Halothane

Volatility?

Induction/recovery?

MAC?

Who is it good for? Why?

Back 24

• Nonflammable / nonexplosive
• relatively rapid induction / recovery
• MAC - 0.77; 0.29 combo w/ 70% N2O
• Asthmatics - Not irritating to mucous membranes

Front 25

Hydrogenated Hydrocarbon: Halothane

Muscle relaxation?

Effect on Heart/Vessels?

Sensitizes?

Can lead to?

Back 25

• Incomplete muscle relaxation
• Depresses heart rate, increases peripheral vasodilation
• sensitizes myocardium to Epi and NE which can lead to arrhythmias
• Can lead to post anesthetic hepatitis

Front 26

Hydrogenated Hydrocarbon: Enflurane

Induction/recovery?

MAC?

Effect on Respiration?

Muscle relaxation?

Back 26

• Rapid induction / recovery
• MAC - 0.57 combo w/ N2O
• Depresses Respiration - use assisted ventilation
• Incomplete muscle relaxation - requires additional muscle relaxents

Front 27

Hydrogenated Hydrocarbon: Enflurane

Effect on Heart/Vessels?

What does it alter?

Metabolism?

Back 27

• CB and BP depression, less sensitivity to Epi than Halothane
• Alters electroencephalographic activity leading to more motor activity
• lower amounts of metabolites, no hepatotoxicity

Front 28

Hydrogenated Hydrocarbon: Isoflurane

Induction/Recovery?

MAC?

Effect on Heart/vessels?

Back 28

• Rapid induction/recovery
• MAC - 0.5 combo w/ 70% N2O
• Reduced BP

Front 29

Hydrogenated Hydrocarbon: Isoflurane

Metabolism?

Sensitizaiton?

Effect on respiration?

Back 29

• Limited amounts metabolized, low if any liver toxicity
• Limited sensitization of myocardium to Epi
• Respiratory acidosis w/ deeper anesthesia

Front 30

Hydrogenated Hydrocarbon: Desflurane

Onset/duration?

volatility?

Effect on respiration?

Induction?

Speed?

Back 30

• More rapid onset and shorter duration

- Lower blood/gas partition coefficient

• Low volatility, requires special vaporizer
• Causes cought/laryngospasm
• Cannot use for induction
• Not faster than older agents

Front 31

Hydrogenated Hydrocarbon: Sevoflurane

Onset/duration?

Stability?

Metabolism?

Back 31

• More rapid onset and shorter duration

- Lower blood/gas partition coefficient

• Chemically unstable
• Potential for renal toxicity due to release of fluoride when metabolized

Front 32

Ultrashort Acting Barbiturates:

Duration of action?

Use?

Solubility?

Analgesic ability?

Example?

Back 32

• 5-20 min (IV Administration)
• Used for induction of general anesthesia due to rapid onset (30 sec)
• Highest lipid solubility, accumulates in fat leading to prolonged recovery w/ repeated doses
• Not good as sole anesthetic - NO analgesia if using does that allows spontaneous respiration.
• Thiopental, methohexital

Front 33

Ultrashort Acting Barbiturates:

Complications?

Back 33

• Extravascular injection-necrosis or sloughing
• Inraarterial injection can lead to ischemia due to arteriospasm
• Laryngospasm and bronchospasm

Front 34

Ultrashort Acting Barbiturates:

Overdose is?

Back 34

• Respiratory Failure

Front 35

Ultrashort Acting Barbiturates:

Contraindications?

Back 35

• Absence of good veins forinjection
• Status asthmaticus
• Porphyrias
• Known hypersitivity

Front 36

Propofol:

What is it?

Onset?

Use?

Back 36

• General Anesthetic
• Rapid onset (about 30 sec)
• Used for induction and maintenance of anesthesia

Front 37

Propofol:

Heart/Vessels?

Analgesic ability?

Back 37

• Vasodilator leading to large decreases in blood pressure
• NO Analgesic Effects

-- Must provide supplemental pain relief

Front 38

Ketamine:

Anesthetic effect?

Analgesic ability?

Onset?

Back 38

Dissociative anesthetic, causes amnesia

Analgesia w/o loss of consciousness

Onset 1-2 min - IV or IM

Front 39

Ketamine:

Heart/Vessels?

Other effects?

Back 39

• increased cerebral blood flow
• increased cardiac output
• Excess salivation - pretreat w/ atropine
• Can cause hallucinations and delirium during recovery

-- reduce audio/video stimulation

Front 40

Ketamine:

Contraindications

Back 40

• Cerebrovascular disease
• Hypertension
• Hypersensitivity

Front 41

Barbiturates:

MOA

Back 41

• Binds to components of GABA receptor present in neuronal membranes in the CNS.

--GABA receptor is transmembrane chloride ion channel composed of 5 protein subunits.

• Binding to receptor by barbiturates cause hyperpolarization of neuron to suppress nerve function

Front 42

Barbiturates:

What are the 4 classifications?

Back 42

• Long acting (8-12 hrs)
• Intermediate acting (6-8 hrs)
• Short acting (4-6 hrs)
• Ultrashort acting (1-2 hrs) - for surgury - IV stops = shorter recovery

Front 43

Long Acting Barbiturates:

Duration?

Solubility?

Use?

Examples?

Back 43

• Duration of action 6-10 hrs
• Least lipid soluble
• Used for daytime sedation and anticonvulsant
• Examples: Phenobarbitol, primidone (both antiseizure), Mephobarbitol (sleep, anxiety)

Front 44

Intermediate Acting Barbiturates:

Duration?

Use?

Examples?

Back 44

• Duration of action 3-6 hrs
• Used to treat insomnia

--Not used very often

• Amobarbital, butabarbital (not commonly used today)

Front 45

Short Acting Barbiturates:

Duration?

Solubility?

Use?

Examples?

Back 45

• Duration of action 1-3 hrs
• Increased lipid solubility
• Used to treat insomnia
• Rarely used anymore

-- Replaced by Benzodiazepine hypnotics such as valium due to safety

• Addiction and toerance
• Secobarbital, pentobarbital

Front 46

Barbiturates:

Duration?

MOA?

Metabolism?

Interactions?

Analgesic ability?

Back 46

• Duration of action related to lipid solubility

-- More lipid soluble = acts on CNS more easily

• Medication has to cross blood brain barrier to have action
• Metabolized by liver (decrease dose for cirrhosis)
• Potential interactions by long term use.

-- Liver increases enzymes for metabolism (upregulation)

• NO analgesic action - agitation may result if analgesic is not also given

Front 47

Benzodiazepines:

MOA

Action?

Use?

Back 47

• Binds to GABA receptor causing CNS depression (3 types omega 1-3)
• Enhance the action of GABA
• Action on CNS depends on which GABA receptor subunit drug binds to and where the receptor is located

-- Limbic, cortical, thalamic, hypothalamus

• Similar action as barbiturates, but saver

-- Less respiratory depression

• Therapeutic use has replaced barbiturates

Front 48

Benzodiazepines:

Clinical Uses?

Back 48

• Anti-Anxiety
• Sedative/Hypnotic
• Skeletal Muscle Relaxant - valium
• Anticonvulsant
• Treatment of alcohol withdrawal
• Accounts for 10 of the "top 200"

Front 49

Benzodiazepines:

Uses in Dentistry?

What should patients not do?

Overdose?

Back 49

• Pre-medication
• Anti-anxiety: Diazepam (Valium)
• Conscious Sedation

-- IV Lorazepam, Midazolam, Diazepam

-- Oral Triazolam (Halcion) - Conscious sedation

-- Muscle Relaxation; amnesia

• Patients can not drive while taking
• Overdose - treated with flumazenil (mazicon)

Front 50

Benzodiazepines:

Side Effects?

Interactions?

Contraindications?

Back 50

• Side effects - Drowsiness
• Interactions (enhanced sedation)

-- Nitrous oxide

-- Pain medications

-- Muscle relaxants

• DO NOT TAKE WHILE PREGNANT

-- Most are pregnancy category D or X

Front 51

Other Agents - Chloral Hydrate:

What is it?

Heart/respiration?

Side Effects?

Use?

Back 51

• Inexpensive, sedative-hypnotic w/ rapid onset (20-30 min)
• No pronounced respiratory or cardiovascular depression
• Very irritating to mucosal tissue, may cause aspiration. Unfavorable taste and odor, usually given in syrup form

-- Administer with food or milk

• Used for pre-op sedation of children

-- Benzodiazepines more preferred due to gastrointestinal adverse effects, vasodialation, and hypotension seen with chloral hydrate