Pharmacology - General Anesthesia (Exam 3) Flashcards

1
Q

Medically induced loss of consciousness w/ concurrent loss of protective reflexes due to anesthetic agents

A

Anesthesia

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2
Q

Three goals of balanced anesthesia

A

1) calm
2) decrease pain
3) reduce adverse effects of anesthetics

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3
Q

Combined anesthetics from different drug classes to take advantage of the best properties to minimize side effects

A

Balanced anesthesia

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4
Q

Two main categories of anesthetics

A

Inhalation
IV

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5
Q

Name some scenarios where you would want to use general anesthesia in dentistry

A
  1. Highly invasive and long dental procedures
  2. Complicated Wisdom tooth removal
  3. Dental implants
  4. Facial and jaw reconstruction
  5. Treatment of traumatic facial injuries
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6
Q

MOA of general anesthetics

A

Block Excitatory Receptors (ketamine, nitrous oxide)

Amino butyric acid GABA receptor (benzodiazepines, etomidate)

Block G protein-coupled Receptors (halothane)

Perturb ion channels (e.g,. Calcium, potassium, sodium)

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7
Q

Name the 4 stages of anesthesia

A

1: analgesia
2: delirium and excitement
3: surgical anesthesia
4: medullary paralysis (overdose & death)

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8
Q

T/F: you can start surgery during Stage II

A

FALSE

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9
Q

This stage of anesthesia starts from loss of consciousness to beginning of irregular respiration

A

Stage II

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10
Q

Which stage is divided into 4 planes?

A

Stage III

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11
Q

Which stage is this?

Starts from onset of irregular resp to cessation of spontaneous breathing

A

Stage III

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12
Q

Return of regular respiration, muscle relaxation, and normal heart/pulse rates. Eyelid and swallowing reflexes are lost

A

Plane I from Stage III - surgical anesthesia

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13
Q

Begins with disappearance of respiratory function

A

Stage IV - medullary paralysis

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14
Q

Concentration of inhaled anesthetic needed to prevent movement in 50% of patients in response to a surgical stimuli

A

MAC - minimum alveolar concentration

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15
Q

Potency of inhaled anesthetic is inversely related to?

A

MAC and lipid solubility

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16
Q

The more lipid soluble an inhalant is….

A

The higher its potency (lipid/gas partition coefficient)

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17
Q

The concentration ratio of the inhaled anesthetic in the blood phase to the gas phase when equilibrium is achieved

A

Blood/gas partition coefficient

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18
Q

The higher the blood:gas partition coefficient…

A

The greater the blood solubility

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19
Q

What does an anesthetic with low blood solubility indicate?

A

Equilibrium is achieved rapidly
Quickly saturates the blood
Results in a rapid induction and recovery

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20
Q

Name that anesthetic!

Physical Characteristics: Colorless, Odorless

Very insoluble in blood and other tissues

Rapid induction of anesthesia 2-3 minutes

Quick recovery

Blood/Gas coef = 0.47

Completely eliminated by the lungs

Weak anesthetic and powerful analgesic

Low potency with MAC = 104%

Lipid solubility = 2.3

A

Nitrous oxide

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21
Q

Why do you usually have to administer nitrous with another anesthetic?

A

It’s a weak anesthetic but powerful analgesic

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22
Q

Pharmacological effects of nitrous

A

Induces conscious sedation, anxiety relief, analgesia, amnesia

May increase heart rate and respiration

Mild myocardial depression and hypoventilation

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23
Q

T/F: Nitrous oxide undergoes metabolism in the body.

A

FALSE

24
Q

Adverse effects of nitrous oxide

A

-Nausea, Vomiting
-Oxidizes vit B12; renders methionine synthase inactive; decrease in methionine and B12 function; degenerative nervous system changes
-megablastic anemia

25
Q

Nitrous oxide can be detrimental in patients who are deficient in? (on exam)

A

vitamin B12 -> can lead to degenerative nervous system changes

26
Q

Contraindications of nitrous oxide

A

COPD
Methytetrahydrofolate deficiency

27
Q

Name 2 inhalational general anesthetics

A

Nitrous oxide (gas)
Halogenated hydrocarbons (volatile liquid)

28
Q

Name that anesthetic!

Induces anesthetic state rapidly with a quick recovery

Blood/gas partition coeff (2.3) & high lipid solubility (51)

Very potent; High Potency (MAC = ~1) but a weak analgesic (pain reliever)

A

Halogenated hydrocarbons

29
Q

Which anesthetic sensitizes the heart to catecholamines which can lead to cardiac arrhythmias?

A

halogenated hydrocarbons

30
Q

Pharmacodynamics of halogenated hydrocarbons

A

Decrease BP, pulse, respiration, pain
Muscle relaxation

31
Q

T/F: Halogenated hydrocarbons are no longer used in the US

A

True

32
Q

Metabolism of halothane

A

~15% of the drug is metabolized by the liver by CYP2E1 and to a lesser extent CYP3A4 and CYP2A6

33
Q

Halothane is primarily eliminated through the?

A

Lungs

34
Q

Pharmacodynamics of halogenated ethers (enflurane)

A

Greater muscle relaxant than halothane

Cause dose dep myocardial depression similar to halothane

Less sensitizing of the heart to catecholamines than halothane

35
Q

Contraindications of halogenated ethers

A

pts with renal disorder/seizures

-renal toxicity!!!!!

36
Q

Halogenated ethers are toxic to the heart and kidneys but not the?

A

Lungs

37
Q

Name that anesthetic!*

Replaced enflurane (chemically similar) – combines the desirable cardiovascular properties of enflurane with a freedom from seizure activity, less resp depression, less hepatic metabolism

Does not sensitize the heart to catecholamines, Does not induce arrhythmias

More likely to cause coughing, salivation, and laryngospasm in children compared to sevoflurane – prevented by i.v. admin induction agent

Respiratory depression, reduced bp, muscle relax.

A

Halogenated ether - Isoflurane

38
Q

Describe the metabolism of isoflurane

A

Minimal metabolism; less than 2%

39
Q

Name that anesthetic!

Rapid uptake, induction, distribution, elimination – rapidly absorbed into the blood via the lungs

Low blood/gas solubility = 0.42

Relatively potent (MAC = 6% in middle aged adults)

Less potent than other volatile agents

Its rapid induction is offset by its tendency to irritate airways&raquo_space;> coughing and laryngospasm

A

Halogenated hydrocarbon - desflurane

40
Q

Pharmacodynamics of desflurane

A

Malignant hyperthermia

Respiratory adverse reactions, neurotoxicity, and postoperative agitation in pediatric patients,

41
Q

This anesthetic has a slow duration due to high fat/blood solubility of 48

A

Sevoflurane

42
Q

Name that anesthetic!

Relatively potent MAC = ~2% (3x’s more potent than desflurane, less potent than halothane and isoflurane)

Nephrotoxic

Renal Damage

Reproductive toxicity

A

Sevoflurane

43
Q

_______________ is a potent anesthetic but weak analgesic

A

Thiopental

44
Q

Very short acting barbituate (enters CNS in a minute)

Can cause coughing, chest wall spasm

A

Thiopental

45
Q

Not a potent pain reliever

Widely used and has replaced thiopental as the 1st choice for anesthesia induction and sedation, because it produces a euphoric feeling in the patient and does not cause postanesthetic nausea and vomiting

A

Propofol

46
Q

Adverse effects of propofol

A

Hypotension caused mainly by vasodilation rather than cardiac depression

Non-analgesic

Reduces cerebral blood flow

47
Q

Name that anesthetic!

Produces amnesia and analgesia without actual loss of consciousness.

Induces a dissociated state in which the patient is unconscious but appears to be awake and does not feel pain.

A

Ketamine

48
Q

T/F: ketamine is highly lipid soluble

A

True

49
Q

This anesthetic

Increases pulmonary vascular resistance and may exacerbate pulmonary hypertension

Increases cerebral blood flow and stimulates the heart to increase in heart rate, cardiac output, and blood pressure.

A

Ketamine

50
Q

Contraindications for ketamine

A

Pts with high BP/HR

51
Q

This anesthetic

Primarily used for conscious sedation and preanesthetic medication

Undergoes metabolism that leads to metabolites that offer additional sedation

First water-soluble benzodiazepine

A

Midazolam

52
Q

Above a pH of 4, midazolam becomes?

A

very lipid-soluble!

(causes it to have rapid onset of action)

53
Q

The most potent inhalant based on low MAC and high lipid solubility

A

Halothane

54
Q

Which anesthetics become more toxic following metabolism?

A

Halothane

55
Q

These 2 anesthetics have the highest lipid solubility

A

Sevoflurane
Isoflurane

56
Q

Rank these from highest to lowest blood solubility:

Desflurane, Sevoflurane, Nitrous oxide

A

Desflurane > nitrous oxide > sevolfuran

57
Q

This anesthetic:

Greater muscle relaxant than halothane

Causes dose deep myocardial depression similar to halothane

Less sensitizing of the heart to catecholamines than halothane

A

Enflurane