36: General Anesthetic Agents Flashcards Preview

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Flashcards in 36: General Anesthetic Agents Deck (55):
1

anesthesia =

loss of sensation or a state without any feeling

2

advantages and disadvantages of general v. local anesthesia

local: minimal system disturbance, but may not be adequate

general: body wide anesthesia, but disturbance of all organ systems

3

general anesthesia =

clinical state where there is an induced loss of consciousness or total insensibility in a reversible manner

4

general anesthesia is associated with _____ respiration and __________ blood pressure

decreased; decreased

myocardial depression and vasodilation

5

"triad of anesthesia"

asleep
pain-free
still

6

6 characteristics of ideal anesthetic agent

- unconsciousness
- amnesia
- analgesia
- skeletal muscle relaxation
- areflexia
- good minute-to-minute control

7

why are adjuvant drugs used prior to anesthesia?

to make it more safe and pleasant

1. relieve anxiety = benzodiazepines
2. prevent allergic reactions = antihistaminics
3. prevent nausea and vomiting = antiemetics
4. provide analgesia = opiods
5. prevent bradycardia and secretion = atropine and glycopyrrolate

8

what kinds of clinical conditions might be important to know about when a patient is to undergo anesthesia?

**prior anesthetic history of patient and blood relatives

- family history of malignant hypothermia
- cardiovascular problems
- respiratory disease
- allergies to medicine and food

9

4 phases of general anesthesia

- induction
- maintenance
- emergence
- recovery

10

4 stages of general anesthesia

I: analgesia
II: excitement
III: surgical anesthesia
IV: medullary depression

11

what are inhalable anesthetics generally used for?

maintenance of anesthesia

can be used for induction in pediatrics

12

what are IV or fixed anesthetics generally used for?

induction and short surgical procedures

13

what ion channels may anesthetics alter?

- increase GABAa receptor Cl- channel activity
- activate voltage-gated K channels
- inhibit glutamate NMDA receptors

14

advantages of inhalable anesthetic agents over IV

+ easy to control depth of anesthesia
+ readily reversible, minute-to-minute control

- induction not as fast or smooth as with fixed agents

15

increasing inspired anesthetic concentration in inspired air ---> _________ partial pressure in lungs --->

increased

faster achievement of anesthetic concentration in the blood

16

increasing alveolar ventilation ---> ____ gas molecules/time --->

more

faster anesthesia onset; better ventilation results in more rapid onset of anesthesia

17

partial pressure of anesthetics with higher solubility are affected by _______

ventilation rate

18

what does the otswald coefficient tell you?

solubility in blood

19

lower otswald coefficient --> _____ soluble ---> ______ rise in partial pressure in blood ---> ______ equilibration with brain and induction

less; more rapid; faster

ex: NO which is less soluble reaches a higher partial pressure in the blood faster and thus is able to reach anesthetic concentrations in the brain more rapidly

20

brain:blood partition coefficient is related to...

solubility in lipid

more soluble = more potent

21

high pulmonary blood flow = ______
lower pulmonary blood flow = _________

slower onset
faster onset

22

the greater the uptake of an agent, the alveolar concentration rises _________ ---> ____ rate of induction

slower
slower

ex: insoluble agents are taken up slowly --> alveolar concentration rises fast --> fast induction

23

less soluble per otswald coefficient = ______ elimination

faster

24

what is minimum alveolar concentration MAC?

the concentration of anesthetic in the inspired air at equilibrium when there is no response to noxious stimulus in 50% of patients

25

lower MAC = ____ potent anesthetic

more

26

higher lipid solubility = _______ potent anesthetic

more
(lower MAC)

27

anesthesia is produced when anesthetic px is brain is ____ MAC

greater than or equal to

28

MAC values of inhaled anesthetics are _______

additive

ex: nitrous oxide can be used as a carrier gas producing40% of a MAC, therby decreasing the anesthetic requirement of both volatile and IV anesthetics

29

CNS depressants _______ MAC

decrease

elderly also decreases MAC; young increases

30

"laughing gas"

nitrous oxide

31

pros and cons of nitrous oxide

pro: rapid onset and recovery, good analgesia, safe!

con: incomplete anesthetic; insufficient potency for surgical anesthesia, lack of potency

32

"2nd gas effect"

reduces the induction time for the primary agent

ex: No speeds up mask induction of sevoflurane

decreases: induction time for primary agent, required concentration of primary agent, and toxicity of primary agent

33

2 major side effects of NO2

1. diffusion hypoxia (with abrupt discontinuation it quickly diffuses out of the body into the alveoli and dilutes oxygen)
2. increased risk of spontaneous abortion and decreased probability of conception

34

can NO2 be used as the sole anesthetic agent?

NO

analgesic for minor procedures or EMS
mostly used as complimentary agent

35

effects of halogenating the volatile agents

-nonexplosive and non-flammable
-increased potency
-increased toxicity and side effects

36

systemic effects of halothane

decreased CO and hypotension

37

side effects of enflurane

not as popular as others due to CNS stimulation effects

- EEG convulsive pattern
-jerking
-twitching

38

fastest onset and recovery halogenated agent

desflurane

39

advantages and disadvantages for desflurane

+ fastest onset and recovery
+ excellent minute-minute control
- more irritating to respiratory passages than others --> bronchial irritation with cough and laryngeal spasm

40

why is sevoflurane the most commonly used inhalable anesthetics?

-rapid onset and recovery
- very potent
- excellent controllability due to low solubility and high potency
- low airway irritation --> used for mask induction and those with irritable airway

41

malignant hyperthermia?

occurs in genetically susceptible individuals with inhalable anesthetics combined with paralytics

42

what are IV anesthetic used for?

induction! and maintenance of anesthesia

43

major IV disadvantage

can't reverse the effects, except via metabolism

44

what is thiopental used for?

induction - not maintenance or sole anesthetic

does NOT cause any analgesia

45

"milk of magnesia"

propofol

46

99.9% of all inductions =

propofol

excellent quality of recovery

47

which drug causes dissociative anesthesia?

ketamine

characterized by intense analgesia, catalepsy and amnesia

48

MOA ketamine

non-competetive glutamate NMDA receptor antagonist

49

what is emergence phenomenon?

unpleasant dreams, hallucinations and disorientationduring emergence

side effect of ketamine

50

what agent might you want to use for a patient with compromised cardiac status?

ketamine

51

contraindication for ketamine

psychiatric history

52

pre-anesthetic medication = adjuvant drug. Why use them?

-increase rate of induction
-decrease anxiety
- decrease pre and post operative pain
- decrease side effects of general anesthetics
- reduce amount of general anesthesia required

53

what is midazolam good for?

sedation
amnesia
anxiolytic properties

54

MOA midazolam

potentiation at GABAa receptors

55

what are the uses for midazolam?

sedation for painful procedures, can be used as induction agent, or substitute for thiopental/propofol in high risk patients