Exam 10: General Anesthetics Flashcards Preview

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Flashcards in Exam 10: General Anesthetics Deck (63):
1

purpose of atropine pre-op

Prevent bradyarrhythmias that can be caused by general anesthesia

2

Fast acting IV agent used to induce anesthesia

Propofol

3

Inhaled anesthetics used to maintain anesthesia after propofol

N2O plus another inhaled general anesthetic (-flurane)

4

emergence excitement

5-30% of patients experience restlessness, crying, moaning, thrashing when they come out of anesthesia

5

Drug that can be used to combat shivering due to hypothermia post-up

Merperidine

6

What property of inhaled anesthetics greatly affects how fast they work?

Water (blood) solubility
High solubility = slow induction
Low solubility = fast induction

7

Measurement of water solubility

Blood/gas partition coefficient
(concentration in blood)/(concentration in lung) when gas is in equilibrium

8

how quickly does N2O work? Why?

Fast
poorly soluble in blood (low blood/gas partition coefficient

9

How do we measure potency of inhaled general anesthetics?

MAC
Minimum Alveolar Concentration
Inhaled concentration for 50% of patients to not respond to pinprick pain

10

How does MAC relate to lipid solubility?

More lipid soluble = more potent
Less lipid soluble = less potent

11

What's weird regarding lipid/water solubility of anesthetics?

Poorly water-soluble agents aren't necessarily highly lipid soluble
Ex. N2O has low lipid and water solubility (fast induction, but low potency)

12

What's a really good way to find out how conscious a sleeping patient is?

BIS
Bispectral Index
real time computer analysis of patient EEG
Give you a 0-100 scale from deep coma to awake

13

N2O side effects (3)

1. air pockets (middle ear)
2. Blood pressure change
3. Depresses ventillary response to hypoxia

14

What is one side effect that N2O does NOT have compared to the other inhaled GAs/

Malignant hyperthermia

15

Inhaled anesthetic still used in 3rd world. Side effects?

Diethyl ether
Cheap, effective but irritates airway and is flammable

16

Problem with cyclopropane

Spontaneous combustion

17

Side effect of halothane

decreased BP at 1 MAC
Vasodilation
Decreased cardiac output
bradycardia
Decreased GFR
Decreased ventilation rate
Halothane hepatitis

18

Pharmacokinetics of halothane

Blood:Gas partition = 2.3
Slowest induction, recovery

19

Rare, 50% fatal side effect of halothane

Halothane Hepatitis

20

Enflurane odor

Sweet

21

Halothane metabolism

liver

22

Enflurane side effects

Produces electrical seizure activity, though no
evidence, contraindicated for epileptics

23

Isoflurane odor

Pungent

24

Where is isoflurane excreted?

99% unchanged excreted from lungs

25

Preferred inhaled GA for neurosurgery? Why?

Isoflurane
Modest vasodilation in cerebral vasculature, but metabolic rate of brain is decreased

26

Desflurane disadvantage

Irritating- causes coughing, secretions
you have to induce with IV before giving them this

27

Where is desflurane excreted?

99% unchanged excreted from lungs

28

Sevoflurane excretion

99% unchanged excreted from lungs

29

Potential danger of sevoflurane

Causes CO2 absorber to heat up, could potentially cause a fire

30

Advantage of sevoflurane over desflurane?

Non-irritating to airway, so you can use it to induce

31

Preferred inhaled GA for patients prone to myocardial ischemia? why?

sevoflurane
does not change cardiac output

32

2 characteristics of IV general anesthetics

1. Act fast (

33

Sodium thiopental mechanism

Barbiturate
Enhances effects of GABA at GABAA receptors

34

Sodium thiopental metabolism

Liver

35

Sodium thiopental side effects

Decreases brain metabolic rate, ICP, and cerebral blood flow
Decreases heart contractility and causes vasodilation
Decreases ventilation

36

Interesting use of Sodium thiopental

Lethal injection

37

Propofol constitution

Super fatty (white)
Careful with patients with high triglyceride levels
Not water soluble

38

Most common agent of induction of anesthesia in the USA

Propofol

39

Advantage of propofol over Sodium thiopental

no hangover (faster discharge, better outcomes)

40

propofol mechanism

Enhances effects of GABA at GABAA receptors

41

Side effects of propofol

1. Decreased ventilation (even more than Sodium Thiopental)
2. Major decrease in BP (vasodilation and less heart contractility)
3. May hurt on injection

42

Advantages of propofol

Safe in pregnant women
Anti-emetic properties

43

Who might be good patients with whom to use Etomidate?

Those prone to hypotension

44

Mechanism of Etomidate

Enhances effects go GABA at GABAA receptors
Also activates GABAA receptors without GABA being present

45

Side effects of etomidate

Pain on injection
Myoclonic movements
Nausea/vomiting
Inhibit adrenal gland synthetic enzymes

46

Advantage of Etomidate over propofil

It doesnt decrease BP or cardiac output

47

Ketamine advantage

Produces profound analgesia

48

Ketamine mechanism

NDMA antagonist
Inhibits voltage sensitive Na, K channels

49

Side effects of ketamine

Increased cerebral blood flow
Emergence delerium (1 hr post emergence, hallucinations, vivid dreams)

50

Ketamine effects of ventilation

Modest decrease in ventilation
Bronchodilation

51

Ketamine effects of CV system

Increases BP, CO and HR
useful for patients at risk of hypotension

52

Ketamine effects of urogenital system

Caron abuse leads to severe deterioration of the urinary bladder

53

What is the point of GA adjuncts

Decrease the dose of GA needed to reach desired anesthesia
"Balanced anesthesia"

54

Best benzo pre-op sedation (amnesia)

Midazolam (versed)
it is water soluble, the others aren't
also doesn't irritate blood vessels

55

Role of opioids in anesthesia

Minimize vascular reflex to noxious, painful stimuli
Potent analgesics, since only ketamine of the anesthetics has effective analgesic properties

56

Side effects of opioids

Nausea, vomiting
Decreased ventilation, HR, BP

57

What opioid has the shortest duration of action?

Remifentanil

58

Dexmedetomidine use in anesthesia

Alpha 2 agonist
Used for sedation (off label)
Does not decrease ventilation, so it is useful in non-intubated patients

59

How does anesthesia contribute to hypothermia?

Vasodilation is a side effect of most of the anesthetics we talked about (convective heat loss)

60

Mechanism of malignant hyperthermia

Ryanodine calcium channels do not close, leading to uncontrolled muscle contraction and heat generation

61

How can malignant hyperthermia kill you fast

Myocytes eventually lyse, releasing potassium which can cause fatal cardiac effects

62

Treatment for malignant hyperthermia

Dantrolene

63

Dantrolene mechanism

Ryanodine receptor inhibitor