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Pharmacology for Anesthesia > 05 - Clinical Pharm of Inhalationals > Flashcards

05 - Clinical Pharm of Inhalationals Flashcards

0
Q

MAC is the concentration that prevent movement in ___ of patients in response to a certain stimulus

A

50%

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1
Q

Minimal alveolar concentration is really a

A

Median

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2
Q

MAC is best used to compare

A

Different agents

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3
Q

What are the other MACs?

A

MACawake (0.1 x MAC)
MACbar (1.7-2.0 x MAC)
MACrecall (0.3-0.5 x MAC)

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4
Q

T or F. MAC is additive.

A

True

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5
Q

Factors that increase MAC

A 
Younger age
Chronic alcoholism
Anxiety?
Acute sympathetic increase - COCAINE
Hyper metabolic state (thyroid? High fever)
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6
Q

Factors that decrease MAC

A 
Premedication
Older age
Pregnancy
Acute alcohol usage
Hypothermia
Hypercarbia/hypoxia
Sympathetic blockade
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7
Q

How much does MAC decrease with age?

A

Six percent per decade after age 40

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8
Q

Look at that chart

A

LOOK AT IT

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9
Q

Nitrous oxide is inorganic, _______, sweet smelling! and relatively insoluble

A

Non volatile

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10
Q

NO2 is non flammable but supports

A

Combustion

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11
Q

Nitrous cause CV _____ but stimulates

A

Depression

Catecholamines

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12
Q

Respiratory effects of NO2

A

Increased RR
Decreased TV
No change in MV
Very decreased hypoxic drive

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13
Q

Has analgesic properties but is not complete anesthesia?

A 
Nitrous
Increased ICP (CBF, CBV, CMRO2)
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14
Q

Which inhalational has no muscle relaxant properties?

A

Nitrous

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15
Q

T or F. NO2 can induce malignant hyperthermia.

A

False

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16
Q

Renal effects of NO2

A

Decreased GFR

Decreased urine output (due to decreased RBF)

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17
Q

Hepatic effects of NO2

A

Slightly decreased hepatic blood flow

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18
Q

GI effects of NO2

A

PONV (activates CTZ)

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19
Q

Elimination of NO2 is almost

A

100% exhalation

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20
Q

How does NO2 inactivate methionine synthetase?

A

It oxidizes the Co atom in B12

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21
Q

What are the toxicities of NO2?

A 
Inactivates methionine synthetase
Affects myelin formation
Homocysteine accumulation
Inhibits thymidylate synthetase (DNA synthesis)
Bone marrow depression
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22
Q

What effects are seen with disturbed myelin formation?

A

Peripheral neuropathies

Neurotoxicity

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23
Q

Teratogenicity is caused by

A

Inhibition of thymidylate synthetase (DNA synthesis) which is one of the effects of NO2

Teratogenicities are abnormalities of physiological development

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24
What results from the bone marrow depression seen with NO2?
Megoloblastic anemia (anemia that results from DNA synthesis) Specifically, pernicious anemia which causes alteration to the secretion of intrinsic factor, a protein essential for the absorption of B12 in the ileum
25
How long does it take to recover from NO2?
>4 days
26
T or F. It is OK to harvest bone marrow from someone with megaloblastic anemia.
True???
27
_______ exposure to NO2 is particularly harmful
Serial
28
Other problems with NO2
Added cost of installation/management of pipeline Added complexity to anesthesia machine Concerns about exposure to workers Risks of low FiO2 and catastrophic hypoxia
29
NO2 is ____ more soluble in the blood than N2
35x
30
NO2 diffuses out of blood and into ________ faster than air can diffuse into blood which can cause
Closed airspaces Pneumothorax, trauma, venous air embolism, intracranial air, acute GI obstruction, intraocular air, tympanic membrane, blebs/bullae
31
Some other contraindications to NO2
Inborn errors of single carbon metabolism (and untested family members), antifolate chemotherapeutics, pernicious anemia, megaloblastic anemia, serial anesthetics
32
NO2 is recommended to be avoided for maintenance, especially in the ______ pregnancy and
First trimester Extremes of age Consider? Avoiding in patients with cardiac, vascular, neurogenerative disease
33
A halogenated alkane
Halothane
34
Halothane is cheap, safe, used worldwide. It is
Sweet | Non pungent odor
35
CV effects of halothane
Myocardial depression
36
By how much can halothane decrease blood pressure and cardiac output?
Up to 50%
37
Halothane ______ electrical conduction of the heart. It is sensitive to
Slows catecholamines
38
Respiratory effects of halothane
``` Increased RR Very decreased TV Decreased MV Very decreased hypercapnic drive Potent bronchodilator ```
39
Why does halothane cause blunted autoregulation?
It dilates vessels and increases cerebral blood flow but decreases CMRO2
40
What must be done before starting halothane?
Hyperventilate
41
Neuromuscular effects of halothane
Muscle relaxation Potentiates NMB Triggers MH
42
Renal effects of halothane
Decreased RBF, GFR, and UO (partially due to decreased CO)
43
T or F. Halothane causes impaired hepatic clearance of drugs
True, it decreases hepatic blood flow
44
Halothane is oxidized in the liver by CYP to
Trifluoroacetic acid (TFA)
45
What percent of halothane is metabolized in the liver?
20%
46
1 in 5 adults develop ______ from halothane
Mild hepatotoxicity (lethargy, nausea, fever) Likely related to changes in hepatic blood flow
47
What is halothane hepatitis? Why?
A rare condition of massive hepatic necrosis/death | Likely an immune mechanism (eosinophilia, rash, fever); genetic?
48
What causes centrilobar necrosis?
Hypoxia of reductive metabolites? | Associated with halothane
49
Contraindications to halothane
Liver dysfunction after prior exposure Intracranial HTN Pheochromocytoma, severe cardiac disease Beta blockers, Ca channel blockers, aminophylline
50
Non pungent, low solubility - excellent for inhalation induction
Sevoflurane
51
Sevoflurane and desflurane allow for fast emergence but it can lead to
Post op delirium, especially in peds
52
CV effects of sevoflurane
Minimal changes in contractility and HR
53
Respiratory effects of sevoflurane
``` Increased RR Very decreased TV Decreased MV Blunts hypercapnic drive Bronchodilator ```
54
Neuro effects of sevo fluorine
Increased CBF, ICP (responds to hyperventilation) | Decreases CMRO2
55
Neuromuscular effects of sevoflurane
Muscle relaxation Potentiates NMB Triggers MH
56
Allows for enough muscles relaxation for peds intubation
Sevoflurane
57
Renal effects of sevo fluorine
Slightly decreases RBF
58
Can cause the formation of compound A
Sevoflurane
59
Hepatic effects of sevoflurane
No significant changes
60
How much sevoflurane is metabolized in the liver?
5%
61
Inorganic fluoride ion of sevoflurane can lead to
Nephrotoxicity? | Not clinically seen
62
BaOH or soda lime used with sevoflurane produces compound A which caused nephrotoxicity in rats. What is the recommendation to avoid this?
FGF at least 2 L/min if exposure will exceed 2 MAC-hr | Avoid flows <1 L/min
63
What causes higher incidence of compound A?
Lower flow Higher temp Higher conc Longer case
64
Sevoflurane is unlikely to form
CO
65
Contraindications to sevoflurane
Nothing unique
66
CV effects of isoflurane
Minimal cardiac depression (increased HR) | Some coronary artery dilation (?steal syndrome)
67
Respiratory effects of isoflurane
Increased RR Very decreased TV Decreased MV Blunts hypoxic/hypercapnic drives
68
Isoflurane is an irritant, but
Bronchodilator
69
Neuro effects of isoflurane
Increased CBF, ICP (>1 MAC) | Decreased CMRO2
70
At 2 MAC, isoflurane can cause
EEG silence
71
Renal effects of isoflurane
Decreased RBP, GFR, UOP
72
Isoflurane decreases hepatic blood flow but has better _____ than with halothane
Perfusion
73
Isoflurane is metabolized to
TFA | Increased fluoride levels but nephrotoxicity unlikely
74
Contraindications to isoflurane
Nothing unique
75
Desflurane is similar in structure to isoflurane but
Less soluble and potent
76
Why does desflurane require a special vaporizer?
Des has a high vapor pressure and can boil at normal OR temps. Changes in temperature or altitude can change concentration of delivered gas.
77
CV effects of desflurane
Increased HR Decreased BP No change in coronary blood flow
78
Respiratory effects of desflurane
Increased RR Very decreased TV Decreased MV
79
Which inhalants are irritants but bronchodilators?
Desflurane | Isoflurane
80
Pungency of desflurane can cause
Salivation Breath holding Coughing Laryngospasm
81
Neuro effects of desflurane
Increased CBF, ICP (responds to hyperventilation) | Decreased CMRO2
82
All inhalationals cause muscle relaxation, potentiate NMB, and trigger MH except
NO2 and xenon
83
Renal and hepatic effects of desflurane
No effects
84
Contraindications to desflurane
Nothing unique (maybe asthma)
85
Elimination of desflurane
Minimal metabolism
86
Advantages of xenon
``` Inert CV stability Insoluble Fast induction/recovery No MH trigger ```
87
Disadvantages to xenon
``` Expensive Low potency (MAC = 70%) ```
88
Formula for cost of volatile agents
Cost = (conc x FGF x duration x MW x cost/mL) / ( 2412 x density)
89
Where does malignant hyperthermia occur?
Skeletal muscles
90
MH is a genetic defect with
Autosomal dominant inheritance
91
MH related deaths have occurred even though patients have undergone
Multiple prior uneventful surgeries
92
What is the gold standard for definitive diagnosis of MH?
Caffeine-halothane contracture test Requires muscle biopsy at a specialized biopsy center
93
There is a ______ association between heat stroke and susceptibility for MH
Small
94
Triggers of MH
All volatile agents and succinylcholine
95
For prevention of MH, avoid triggers and
Flush anesthesia machine STOP TRIGGERING AGENTS, CALL FOR HELP Dantrolene High flow O2, active cooling, treatment of acidosis and electrolytes, ICU mgmt
96
What can be administered for MH and how does it work?
Dantrolene 2.5 mg/kg IV It is a MR that reduces Ca release by muscle sarcoplasmic reticulum
97
MH causes an abnormal release of calcium that causes
Sustained muscle contraction, including masseter muscle rigidity Hypermetabolism - heat production, hypoxemia, acidosis, increased PaCO2, tachycardia Rhabdomyolysis - increased serum K and creatinine kinase, arrhythmia, myoglobinuria, renal failure
98
Rate of recurrence of MH
25% within 24-36 hours
99
What's the problem with using succinylcholine in young patients?
They could have undiagnosed muscular dystrophy an using sux can lead to hyperkalemic cardiac arrest.
100
Does Neuroleptic Malignant Syndrome require MH precautions?
No/ It is related to the administration of antipsychotic drugs. It causes hyperthermia, muscular hypertonicity, autonomic instability, mental status changes
101
What percent of children receiving halothane/sevo and sux develop MMR?
1%
102
What is MMR?
Masseter Muscle Rigidity - trismus making it difficult/impossible to open jaw Mild MMR with sux is normal
103
T or F? We do not assume that MMR or peripheral muscle rigidity is MH. Continue the surgery.
False. Assume it is MH and begin treatment. Postpone the surgery.
104
Succinylcholine induced MMR can lead to _____. Patients should remain in the hospital for
rhabdomyolysis | 12-24 hours
105
What are signs of rhabdomyolysis?
myoglobinuria | myoglobinemia
106
With sux induced MMR, CK and electrolyte levels should be checked every
8 hours

Pharmacology for Anesthesia (9 decks)

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