anesthesia Flashcards
(104 cards)
1
Q
what does an anesthetic do?
A
depresses the CNS to cause a lack of consciousness, lack of responsiveness to sensory stimuli (like pain), and relaxation of muscles
2
Q
how are anesthetics administered?
A
- volatile liquids or gases are vaporized in oxygen and administered by inhalation
- nonvolatile liquids are injected
3
Q
an anesthetic is usually what?
A
a mix of several agents that cause the desired effects
4
Q
what are the 5 things that a general anesthesia involves?
A
1) analgesia (opioids)
2) amnesia (barbiturates)
3) inhibition of reflexes (a variety of drugs)
4) skeletal ms relaxation (NMJ blocking agents)
5) rapid hypnosis (barbiturates and other drugs)
5
Q
in a general anesthetic, what causes analgesia?
A
opioids
6
Q
in a general anesthetic, what causes amnesia?
A
barbiturates
7
Q
in a general anesthetic, what causes skeletal ms relaxation?
A
NMJ blocking agents
8
Q
in a general anesthetic, what causes rapid hypnosis?
A
barbiturates and other drugs
9
Q
what are the reasons that general anesthetics are usually a mix? (the benefits)
A
- no one drug can cause all 5 necessary responses
- combo can reduce requirement for inhaled anesthetics=reduced side effects, increased safety
- reduced barbiturates, opioid, NMJ blocking agents means increased safety
10
Q
how many stages of general anesthesia are there?
A
4
11
Q
what is stage 1 of general anesthesia?
A
analgesia or loss of pain
12
Q
what is stage 2 of general anesthesia?
A
excitement and hyperactivity
13
Q
what is stage 3 of general anesthesia?
A
surgical anesthesia
14
Q
what is stage 4 of general anesthesia?
A
imminent death or paralysis of the medulla
15
Q
what stage of general anesthesia is desired for surgery?
A
a plane of stage 3, the plane depends on type of surgery (open heart vs. minor surgery)
16
Q
what are the adverse side effects of nitrous oxide gas?
A
dizziness drowsiness nausea euporia vomiting malignant hyperthermia apnea cyanosis
17
Q
what are the adverse side effects of volatile liquid general anesthesia?
A
drowsiness nausea vomiting myocardial depression hypotension pulmonary vasoconstriction hepatotoxicity
18
Q
what does MAC stand for?
A
minimum alveolar concentration
19
Q
what is minimum alveolar concentration?
A
concentration at which 50% of the patients do not move during surgery. This is the percent of the gas mixture or percent of 760 mm Hg pressure
20
Q
Inhaled general anesthetics are administered as _______.
A
gases
21
Q
the dosage of inhaled general anesthetics are expressed in _________.
A
alveolar concentration
22
Q
MAC is also and index of what?
A
potency of an inhaled anesthetic
23
Q
The MAC has a very _______and is inversely proportional to ________.
A
very steep dose-response curve
proportional to anesthetic potency
24
Q
what is the number one thing that effects MAC (and in what direction?)
A
Age
MAC is lower in the elderly
25
MAC is not affected by what factors?
sex
height
weight
26
what does ED50 mean?
mean effective dose
27
which anesthetic is more potent?
| 1MAC=10% or 1MAC=20%
1MAC=10%
| the higher the required MAC (which is the amount of the drug in the lung air), the less potent.
28
should stage 2 of general anesthesia be long or short?
short
29
why is a steep dose response curve an issue?
need to get the person up to surgical anesthesia quickly so must inject a large volume of agent administered
30
what is the mechanism of action for general anesthetics?
lipophilicity
extreme lipophilicity disrupts plasma membrane
disruption increases threshold needed to fire
31
The more lipid soluble an agent is, the more or less potent an anesthetic it is?
more potent (more disruption to membrane, more increase of threshold)
32
what is MAC influenced by?
pulmonary ventilation
pulmonary blood flow
water solubility (lipophilicity?)
33
pulmonary ventilation affects what? how
speed of induction
the more rapidly air is exchanged, the more rapidly anesthesia will be achieved
34
what does pulmonary blood flow affect?
how quickly an anesthetic leaves the alveolus and enters the blood
35
The faster blood flows by the alveolus the______it takes to increase blood concentration of anesthetic.
longer
| converse relationship!
36
what are 2 reasons that pulmonary blood flow might be low?
decreased BP
| decreased blood volume
37
a more water soluble drug will mix with what first?
blood reservoir
38
a more water soluble drug will require _______ to achieve unconsciousness.
more because it stays in the watery blood reservoir
39
how do different drugs work? 5
Block flow of sodium into neurons
Enhance the inhibitory action of GABA
Delays impulses and reduces neural activity
Produces unconsciousness
Produces lack of responsiveness to painful stimuli
40
when are intravenous anesthetics used?
- situations that require short duration anesthesia, like outpatient surgery (think "oscopy")
- to supplement inhalation anesthetics
41
how are intravenous anesthetics primary used?
as adjuncts to inhalations agents
42
are intravenous anesthetics administered before or after inhaled anesthetics?
before
43
intravenous anesthetics ________ induce unconsciousness
rapidly
44
what are some examples of IV anesthetics?
```
barbiturate
benzodiazepines
opioids
propofol
ketamine
```
45
which IV anesthetics has its own category?
propofol
46
2 barbiturates
Thiopental
| Methohexital
47
barbituates have ______onset and are ______, but no _________.
rapid onset
potent
no analgesia
48
3 Benzodiazepines
Diazepam
Lorazepam
Midazolam
49
Benzodiazepines produce ______and _____ but not _______
yes sedation
yes amnesia
no analgesia
50
1 opioid
fentanyl
51
opioids are good for _______ for ________
analgesia
| intra-operative pain
52
propofol is used for what?
sedation during procedures or in the ICU
53
how is ketamine used? adverse effects?
rarely used in adults
good analgesia for children
produces delusions and can increase ms tone
54
what drug is used prophylactically before surgery and why?
atropine prevents bradycardia induced by surgery and for drying of secretions
55
adverse effects of barbiturates
```
drowsiness
lethargy
hangover
respiratory depression
laryngospasm
```
56
opioids
```
sedation
circulatory depression
cardiac arrest
respiratory depression
respiratory arrest
```
57
anticholinergics
salivation
abdominal cramping
sweating
transient complete heart block
58
dopamine blockers
```
drowsiness
extrapyramidal symptoms
hypotension
tachycardia
laryngospasm
bronchospasm
```
59
phenothiazine
blurred vision
dry mouth
respiratory depression
agranulocytosis
60
NMJ blocker succinylcholine
ms fasciculations
bradycardia
respiratory depression
malignant hypothermia
61
NMJ blocker tubocurarine
```
hypotension
respiratory depression
malignant hypothermia
apnea
circulatory collapse
```
62
what techniques are used to apply local anesthetics
```
topical
nerve block
infiltration
spinal
epidural
```
63
2 types of local anesthetics
ester
| amide
64
example of ester
procaine
65
example of amide
lidocaine
66
how do esters and amides work?
stop axonal conduction of action potentials by blocking sodium channels
67
what is the effect of esters and amides?
rapid loss of sensation in limited part of the body
68
what was the first local anesthetic used?
cocaine
69
Local anesthetics may be contraindicated in which patients? why
patients with cardiovascular conditions because they have antiarrhythmic properties
70
what is the most commonly used local anesthetics?
lidocaine
71
short acting local anesthetic? time frame
procaine
| 1 hour
72
intermediate acting local anesthetic? time frame
lidocaine
| 1 to 2.5 hours
73
long acting local anesthetic? time frame
tetracaine
| 3-9 hours
74
local anesthetics may be administered with what? why
Vasoconstrictor substances such as norepinephrine so as to limit absorption and concentrate them at the site of injection
75
how are topical anesthetics administered?
directly to skin or mucous membranes
76
what is the major topical anesthetic used?
benzocaine
| followed by lidocaine and tetracaine
77
why are topical anesthetics used?
to relieve or prevent pain from minor burns, irritation, itching or to numb an area before an injection is given
78
what are the adverse effects of topical anesthetics?
skin irritation and hypersensitivity reactions (rare)
79
what are ms relaxants?
drugs that affect skeletal muscle
80
what are the 2 categories of ms relaxants?
```
Neuromuscular blockers (NMJ)- used in intensive care units to cause paralysis and as an adjunctive to anesthesia
spasmolytics
```
81
how are NMJs used?
in intensive care units to cause paralysis and as an adjunctive to anesthesia
82
how are spasmolytics used?
to reduce spasticity in a variety of neurologic disorders
83
why are ms relaxants used during surgery?
to reduce the intensity of muscle spasms in electrically-induced convulsions
to manage patients who are fighting mechanical ventilation
84
how do nondepolarizing NMJ blocking agents work?
They block neurotransmitter action of acetylcholine. but do not cross the blood–brain barrier or have any action on the CNS.
85
5 curare alkaloids nondepolarizing NMJ blocking agents
tubocurarine
pancuronium bromide
pipecuronium
vecuronium
86
when nondepolarizing NMJ blocking agents are used in surgery, when is anesthesia induced?
before neuromuscular blockade is started
87
tubocurarine effects can be reversed with what?
anticholinesterases: neostigmine, pyridostigmine, and edrophonium
88
example of depolarizing NMJ blocking agents
succinylcholine
89
how do depolarizing NMJ blocking agents work?
excessive depolarization which desensitizes muscles and renders them unresponsive
90
where does curare come from?
poisonous frogs
91
spasticity causes what?
Increase in tonic stretch reflexes
Increased flexor muscle spasm
Muscle weakness
92
what are involved with spasticity?
reflex arcs
| upper motor neurons (higher centers) affecting descending pathways
93
what drugs are used against spasticity?
spasmolytics
94
what do spasmolytics do (therapeutically)?
relax skeletal ms, relieve acute musculoskeletal pain, spasm or spasticity
95
what is GABAb?
subtype of GABA
96
how do anesthetic drugs work? 5
Block flow of sodium into neurons
Enhance the inhibitory action of GABA
Delays impulses and reduces neural activity
Produces unconsciousness
Produces lack of responsiveness to painful stimuli
97
tetrodotoxin, batrachotoxin, and local anesthetics prevent what physiological process?
action potential
98
hemicholinuim, botulinus toxin, procaine prevent what physiological process?
acetylcholine release
99
curare alkaloids and snake toxins prevent what physiological process?
depolarization
100
cholinesterase inhibitors prevent what physiological process?
hydrolysis of acetylcholine
101
quinine and tetrodotoxin prevent what physiological process?
muscle action potential
102
metabolic poisons, Ca++ deficiency, procaine and dantrolene prevent what physiological process?
ms contraction
103
calcium enhances what 2 physiological processes?
acetylcholine release and muscle action potentials
104
veratridine enhances what physiological process?
muscle action potential
