Pharm A Test 3 Flashcards
1
Q
What value do we use to compare potencies of neuromuscular blockers?
A
ED95
2
Q
What is ED95?
A
Dose needed to produce 95% suppression of single twitch response
3
Q
How is the ED95 of neuromuscular blockers changed in the presence of volatile anesthetics?
A
Decreased
4
Q
What do we use to dose neuromuscular blockers?
A
Nerve stimulator
5
Q
Which muscles are affected first by neuromuscular blockers?
A
Small, rapidly moving muscles are paralyzed first
6
Q
What factors determine the onset of the neuromuscular block?
A
- Fiber type
- Density of Ach receptors
7
Q
Why do neuromuscular blockers have a limited volume of distribution?
A
- Highly ionized
- Limited lipid solubility
- Don’t cross blood brain barrier or placenta
8
Q
How are neuromuscular blockers excreted?
A
Unchanged by the kidneys
9
Q
How is the pharmacokinetics of NMB changed in elderly patients?
A
They may stick around longer because there is decreased blood flow to the liver and kidneys
10
Q
How is the pharmacokinetics of NMB changed in ESRD/liver disease patients?
A
Longer effect because of a slower clearance
11
Q
Action of succinylcholine at NMJ
A
Binds to postsynaptic receptor and activates it
12
Q
Action of non-depolarizing blockers at NMJ
A
Binds to postsynaptic receptor and blocks it
13
Q
How is acetylcholine cleared from the NMJ?
A
Hydrolyzed by acetylcholinesterase in the NMJ
14
Q
Where does succinylcholine bind to in order to exert its effect?
A
Alpha subunit of nicotinic receptor
15
Q
Dose of succinylcholine
A
1-2mg/kg
16
Q
Onset time of succinylcholine
A
30-60 seconds due to low lipid solubility
17
Q
Duration of succinylcholine
A
3-5 min
18
Q
How is succinylcholine cleared from circulation?
A
Plasma cholinesterase
19
Q
What is the effect of high doses of succinylcholine?
A
Phase II block
20
Q
How does succinylcholine affect amplitude during tetany?
A
Decreases amplitude
21
Q
How is the Phase I blockade caused by succinylcholine affected by an anticholinesterase like neostigmine?
A
Phase I blockade is enhanced
22
Q
With succinylcholine, is the amplitude of each twitch in a TOF the same or different?
A
Each TOF twitch has the same amplitude
23
Q
What is a phase II blockade with succinylcholine?
A
The nerve response resembles a non-depolarizing blocker, causing fade with TOF and tetany and posttentanic potentiation
24
Q
What causes a phase II blockade?
A
- Repeated doses
- Prolonged infusion
25
What variables can decrease activity of plasma cholinesterase?
- Hepatic failure
- Low levels of circulation cholinesterases
- Anticholinesterases
- Metoclopramide (Reglan)
- Atypical types
26
In large male patients with lots of muscle mass, what can be a side effect of the fasciculations caused by sux?
Myoglobinuria
27
How does succinylcholine affect intragastric/intraocular pressure?
It increases both - so don't use if a patient has an open globe injury or if these pressures are already high
28
What muscular effect is an early sign of MH?
Masseter muscle rigidity
29
Why would you NOT use succinylcholine in patients presenting with the following: muscular dystrophy, T4-T6 lesions, renal failure
Because succinylcholine increases K+ release and can cause hyperkalemia
30
Why would you NOT use succinylcholine in patients presenting with the following: small bowel obstruction, pyloric stenosis, bleeding varices
Because succinylcholine increases intragastric pressure
31
Why would you NOT use succinylcholine in patients presenting with the following: open globe, intracranial hemorrhage
Because succinylcholine increases intracranial pressure
32
What conditions cause susceptibility to succinylcholine-induced hyperkalemia?
- Prolonged total body immobilization i.e. ICU patients
- Burns
- Massive trauma
- Spinal cord injury
- Stroke
- Severe Parkinson's
- Myopathies
33
What type of non-depolarizer is cisatracurium?
Benzylisoquinolinium
34
What type of non-depolarizer is rocuronium and vecuronium?
Aminosteroid
35
Non-depolarizing muscle blockers cause a TOF ratio less than __
0.7
36
Which neuromuscular blockers cause fade - depolarizing or nondepolarizing?
Nondepolarizing
37
What is the effect of using aminosteroids and benzylisoquinoliniums together?
Flipping between them can prolong the block
38
Which nondepolarizing muscular blocker has autonomic effects?
Pancuronium
39
Which class of nondepolarizing muscular blockers has hepatic and renal clearance?
Aminosteroids
40
How do volatiles, aminoglycosides (mycin antibiotics), and high doses of local anesthetics affect ND-NMBs?
Prolong the block
41
How does Phenytoin and other seizure meds affect ND-NMBs?
They decrease the duration of the block because of the increase in CYP450
42
How do ganglionic blockers such as trimethaphan affect ND-NMBs?
They delay onset and prolong the block
43
How do diuretics affect ND-NMBs?
Prolong the block
44
How do anti-dysrhythmics affect ND-NMBs?
Prolong block
45
How does hypothermia affect ND-NMBs?
Increases the duration because it slows hepatic enzymes
46
How does hypokalemia affect both succinylcholine and ND-NMBs?
It hyperpolarizes the cell so patients are resistant to succinylcholine and sensitive to ND-NMBs
47
How does hyperkalemia (burn patients) affect both succinylcholine and ND-NMBs?
- Sensitive to succinylcholine
| - Resistant to ND-NMB
48
If a patient has paresis on the right, where should you put the peripheral nerve stimulator?
Left
49
How does magnesium affect ND-NMBs?
Enhances the block because Mg2+ decreases Ach release
50
How will a large dose of ND-NMB given in combination succinylcholine affect the block?
The block will be prolonged
51
Maintenance dose of pancuronium
0.01mg/kg (same as vec)
52
Onset of pancuronium
3-5 minutes
53
Duration of pancuronium
60-90 minutes
54
Cardiovascular effects of pancuronium
- Tachycardia
- Increased MAP
- Increased cardiac output
55
How is clearance of pancuronium affected in patients with renal failure?
Decreased up to 50%
56
Dose of atracurium
0.5mg/kg
57
Onset for intermediate acting NDNBMs (atra, cis, vec, roc)
2-5 minutes
58
Duration for intermediate acting NDNBMs (atra, cis, vec, roc)
20-45 minutes
59
Clearance of atracurium
- Hoffmann elimination
- Ester hydrolysis
- Degraded at high pH
60
Side effects of atracurium
Histamine release and the subsequent drop in BP
61
Considerations for the pH of atracurium
The pH is 3.2 so do not mix with thiopental or it will crystallize
62
How does temperature affect atracurium
Hypothermia increases the duration of action because it decreases Hoffmann elimination
63
How does the dose of atracurium change in pediatrics?
Reduced by 50%
64
What is the metabolite of atracurium that can evoke seizures?
Laudanosine
65
Dose of cisatracurium
0.1-0.15mg/kg
66
Which NDNMB is great to use for ESRD and liver failure patients?
Cisatracurium because it is not metabolized by kidneys or liver
67
How is cisatracurium metabolized
Hoffman elimination
68
Maintenance dose of vecuronium
0.01mg/kg
69
Clearance of vecuronium
Excreted unchanged by the liver
70
How does the action of vecuronium change in pediatrics?
The onset is quicker and the duration is longer
71
How does the action of vecuronium change in elderly?
The duration is longer due to decreased liver/kidney blood flow
72
Intubating dose of rocuronium
0.6-1.2mg/kg
73
Maintenance dose of rocuronium
0.1mg/kg
74
What dose of roc must you use in order to mimic the onset time of succinylcholine?
1.2mg/kg
75
What is the only short acting NDNMB?
Mivacurium
76
Which NDNMBs should be considered in patients with renal and severe hepatic failure?
- Mivacurium
- Cisatracurium
- Atracurium
77
Which NDNMB should be considered in extremely long cases?
Pancuronium
78
Which NDNMBs should be considered in patients with pseudocholinesterase deficiency?
- Rocuronium
| - Vecuronium
79
What allergy correlates with pseudocholinesterase deficiency?
Anectine
80
Anticholinesterase drug used to diagnose myasthenia gravis
Edrophonium
81
Anticholinesterase drug that crosses the blood/brain barrier and treats overdose of anticholinergics
Physostigmine
82
Anticholinesterase drug that is paired with atropine
Edrophonium
83
Anticholinesterase that is paired with glycopyrrolate
Neostigmine
84
Recovery from neuromuscular blocker results from what?
Elimination of the drugs from the body
85
Why can neostigmine prolong the block if you overdose it?
Because there is a ceiling effect of anti-cholinesterases on acetylcholinesterase
86
Which anticholinesterase reversibly inhibits AChase electrostatically?
Edrophonium
87
Which anticholinesterases inhibit AChase via the formation of carbamyl esters?
- Neostigmine
- Physostigmine
- Pyridostigmine
88
Which anticholinesterase inhibits AChase via irreversible activation?
Echothiophate
89
Onset time of neostigmine for 50% antagonism of AChase
3 minutes
90
Onset time of neostigmine for 100% antagonism of AChase
7-11 minutes
91
Onset time of pyridostigmine for 100% antagonism of AChase
12 minutes
92
What accounts for 50-75% of anticholinesterase elimination
Renal clearance
93
How does a decrease in renal and hepatic blood flow affect neostigmine?
The effects of neostigmine are increased
94
Pharmacologic effects of anticholinesterases
- BLUDS
- Increased intraocular pressure
- Can be therapeutic for myasthenia gravis
95
Treatment of anticholinesterase overdose
- Atropine
| - Pralidoxime
96
Dose of neostigmine
0.04-0.07mg/kg
97
How does neostigmine affect a phase 1 block from succinylcholine?
It potentiates the block because it inhibits acetylcholinesterase
98
Post-op risk of neostigmine
PONV
99
Onset of neostigmine
5-10 minutes
100
Peak effect of neostigmine
10 minutes
101
Duration of neostigmine
1 hour
102
Which anticholinergics are very lipid soluble?
- Atropine
| - Scopolamine
103
Which anticholinergics cause sedation?
- Atropine
| - Scopolamine
104
Which anticholinergic is the strongest antisialagogue?
Scopolamine
105
Which anticholinergic does not cross the blood/brain barrier?
Glycopyrrolate
106
Duration of atropine and glycopyrrolate
30-60 minutes
107
Clearance of anticholinergics
Excreted unchanged by the liver and kidneys
108
With which patients should you use caution when considering using anticholinergics?
- Glaucoma
| - Pregnant
109
Anticholinergic used as a pre-operative amnestic
Scopolamine
110
IV dose of scopolamine
0.4mg
111
Which anticholinergic is best for the treatment of bradycardia due to its quick onset?
Atropine
112
How do anticholinergics affect the airways?
Cause bronchodilation in the medium/large airways, thus decreasing resistance and increasing deadspace
113
What is Ipratropium?
An inhaled anticholinergic that works directly on the airways
114
What is Combivent?
A combination of albuterol and ipratropium
115
What are the symptoms of central anticholinergic syndrome?
- Restlessness
- Hallucinations
- Somnolence
- Unconsciousness
116
What is the treatment for central anticholinergic syndrome?
Physostigmine
117
What patients are at risk for central anticholinergic syndrome?
- Elderly patients on glaucoma medication or with scope patches
- Children
118
What are the symptoms of an anticholinergic overdose?
- Dry mouth
- Blurred vision
- Tachycardia
- Increased temp
- Flushing
- Irritability
119
For a safe extubation, the TOF ratio must be greater than...
0.7
120
For a safe extubation, patients must produce a negative inspiratory pressure greater than...
20cmH2O
121
On what nerves do we monitor neuromuscular blockade?
- Ulnar
- Posterior tibial
- Peroneal
- Facial
122
How is residual paralysis from NMB defined?
A TOF less than 90% at adductor pollicis
123
How is sugammadex cleared?
Renally
124
How is sugammadex supplied?
100mg/ml
125
Dose of sugammadex for 0/4 twitches and a PTC of 1-2
4mg/kg
126
Dose of sugammadex for 2/4 twitches
2mg/kg
127
Dose of sugammadex after an RSI dose of rocuronium
16mg/kg
128
What are the side effects caused by sugammadex?
- Bradycardia
- Hypersensitivity
- Prolonged PTT/PT
- Decreased hormonal contraception effectiveness
129
Onset of action of sugammadex
~3 minutes
130
Contraindication to sugammadex
A prior hypersensitivity reaction to it
131
Cellular membrane resting potential
-70mV
132
Cellular membrane threshold potential
-55mV
133
Method of action of local anesthetics
Bind to Na+ channels in the activated state to prevent achievement of threshold potential and decrease rate of depolarization
134
Which nerve fibers are easier to block - small or large?
Small fibers
135
Which nerves are easier to block - motor or sensory?
Sensory because they are smaller
136
Which nerves are easier to block - myelinated or non-myelinated?
Myelinated
137
How many nodes of Ranvier need to be blocked in order to stop the action potential?
2-3
138
What makes nerve bundles difficult to block?
They are surrounded by sheath
139
Which local anesthetic is most likely to cause cardiac arrest?
Bupivicaine
140
What is the lipophilic group on local anesthetics?
Benzene ring
141
What is the hydrophilic group on local anesthetics?
Tertiary amine
142
What anesthetic class has an "i" before caine?
Amides
143
How are amides metabolized?
Hepatically
144
How are esters metabolized?
Plasma cholinesterases
145
What is the only ester that has some hepatic metabolism?
Cocaine
146
What determines the potency of local anesthetics?
Lipid solubility - the more lipid soluble, the more potent
147
Which class of local anesthetics are more potent?
Esters
148
What factors determine the onset of local anesthetics?
- Lipid solubility
| - pKa
149
What can be added to local anesthetics to speed up their onset?
Sodium bicarb because it brings the solution closer to physiologic pH
150
What parameter is the measurement of a local anesthetic's local potency?
Cm (minimum concentration)
151
What affects Cm of local anesthetics?
1) Fiber size
2) Type
3) Myelination
4) pH
5) Frequency of stimulation
152
Are nerves that fire a lot easier or harder to block with local anesthetics?
Easier
153
Are local anesthetics weak acids or bases?
Weak bases
154
What affects the absorption of local anesthetics?
- Dosage
- Site of injection
- Local blood flow
- Vasoconstrictors
- Drug-tissue binding
155
Why is placental transfer of local anesthetics an issue?
When the baby gets stressed, they become acidotic so the local anesthetic shifts towards this acidic environment and becomes trapped in its ionized form
156
What is the metabolite of ester anesthetics that patients may be allergic to?
PABA
157
What other allergy may indicate that the patient has an allergy to PABA?
Sunscreen because there is PABA in it
158
What 2 local anesthetics produce ortholuidine, the metabolite that causes methemoglobin?
- Prilocaine
| - Benzocaine
159
What is the normal metHgB level?
Less than 1%
160
What is methemoglobinemia?
There is a decrease in oxygen carrying capacity of hemoglobin due to the presence of increased methemoglobin
161
What are the signs and symptoms of methemoglobinemia?
- Sat 85%
| - Dark brown blood
162
What is the treatment for methemoglobinemia?
Methylene blue 1-2mg/kg
163
How does the addition of vasoconstrictors affect the action of local anesthetics?
- Increases duration of action
- Limits systemic absorption
- Maintains drug concentration at the nerve
- Decreases possibility of systemic toxicity
164
What is the common concentration of epi added to local anesthetics?
5mcg/ml (1:200,000)
165
List the vascularity of local injection sites from most to least vascular (I Think I Can Pass Emory But School Sucks)
Intravenous > tracheal > intercostal > caudal > paracervical > epidural > brachial plexus > sciatic > subQ
166
CNS symptoms of local anesthetic systemic toxicity
- Circumoral numbness
- Tinnitus
- Restlessness
- Slurred speech
- Seizure
167
CV symptoms of local anesthetic systemic toxicity
- Hypotension
- Decreased cardiac conduction
- Ventricular arrhythmias
168
What is the treatment for seizures assc. with local anesthetic systemic toxicity?
Benzodiazepines
169
First sign of local anesthetic toxicity
Circumoral numbness
170
Toxic dose of lidocaine without epi
5mg/kg
171
Toxic dose of lidocaine with epi
7mg/kg
172
Toxic dose of bupivicaine
2.5mg/kg
173
Sequence of events for treatment of LAST (local anesthetic systemic toxicity)
1) Get help
2) 100% O2
3) Suppress seizures with benzos
4) Manage arrhythmias
5) Lipid emulsion therapy
174
What cardiovascular drugs should be avoided when a patient is having arrhythmias due to LAST?
Any drug that interferes with the cardiac conduction system...vasopressin, calcium channel blockers, beta blockers
175
What is the dose of IntraLipid to treat LAST?
1.5mg/kg bolus
176
Infusion rate for intralipid
0.25ml/kg/min (~18mL/min)
177
What is the recommended upper limit for IntraLipid administration for LAST?
10mL/kg over the first 30 minutes
178
What receptors does cocaine block?
- Na+ receptors
- Alpha 2
- Dopamine
179
How does cocaine affect NE and DA levels?
Increases NE and DA levels by blocking their reuptake
180
What are the most common clinical uses for cocaine?
ENT surgeries
181
Peak effect of cocaine
30 minutes
182
Cocaine metabolism
Liver
183
Adverse effects of cocaine
- HTN
- Arrhythmias
- Catecholamine surge
- Increased O2 demand on the heart
184
How do you treat cocaine toxicity?
Supportive therapy of vitals with beta blockers and NTG
185
Duration of a spinal with 5% lidocaine
~1.5 hours
186
Duration of a spinal with 0.5% bupivicaine
2-2.5 hours
187
Duration of a spinal with 1% tetracaine without epi
2-3 hours
188
Duration of a spinal with 1% tetracaine with epi
up to 5 hours
189
Which local anesthetic is mainly used in obstetrics because it maintains motor function?
Ropivicaine
190
What dose and local anesthetic is commonly used for bier blocks?
50cc 5% lidocaine or prilocaine
191
Which local anesthetics are used for topical anesthesia?
- Tetracaine
- Cocaine
- Lidocaine w/ oxymetazoline
192
What local anesthetic is in hurricaine spray?
20% benzocaine
193
What is EMLA?
Eutectic mixture of local anesthetic - a local anesthetic cream that "melts" into the skin
194
What local anesthetics are usually found in EMLA?
Lidocaine/prilocaine combo
195
Onset of EMLA cream
1 hour
196
Contraindications to EMLA
- Non-intact skin
| - Skin less than a month old
197
Dose of EMLA
1-2g
198
What can occur during retrobulbar blocks due to the inadvertent administration of local anesthetic into the CSF? What are the symptoms?
Brain stem anesthesia - the patient becomes unresponsive and apneic, with hypotension and bradycardia
199
What type of drug is Azathioprine? What is it commonly used to treat?
Immunosuppressive agent commonly used to treat rheumatoid arthritis
200
What is Piperacillin-Tazobectam (Zosyn)?
PCN class antibiotic effective against gram-negative bacteria
201
Typical allergic reaction to paper tape
Contact dermatitis
202
What is Irbesartan? What is it used for?
Angiotensin II Receptor Antagonist used to treat hypertension
203
What drug class is Pyridostigmine?
Anticholinesterase
204
What is Pyridostigmine used to treat?
- Myasthenia gravis
| - Muscle weakness
205
What is myasthenia gravis?
Chronic autoimmune disorder caused by a decrease in functional Ach receptors that causes weakness and rapid exhaustion of voluntary muscles
206
Anesthetic considerations of a patient with myasthenia gravis
- Continue myasthenia gravis meds
- Chance of postop ventilation
- Resistant to succinylcholine
- Sensitive to non-depolarizers
- Potential for phase II block
207
How will a patient with myasthenia gravis react to muscle relaxants if they are on Pyridostigmine?
- Increased sensitivity to nondepolarizers
| - Prolonged response to succinylcholine
208
What is the preferred relaxant for a patient with myasthenia gravis?
Cisatracurium
209
The initial muscle relaxant dose should be titrated to what?
The initial response of the peripheral nerve stimulator
210
Oral dose of morphine
30mg q3-4hr
211
Parenteral dose of morphine
10mg q3-4hr
212
What drug class is Aspirin in?
NSAID
213
Method of action of Aspirin
COX1 inhibitor
214
Drug class of Prednisone
Adrenocortical steroid for short term use (~1 week)
215
What is the recommendation for when to give a a stress dose of steroids?
If the patient has been on a glucocorticoid in the last year
216
Recommended stress dose of hydrocortisone for a major surgery like a colectomy for a 70kg patient
100-150mg
217
Recommended stress dose of hydrocortisone for a minor surgery like a herniorrhapy for a 70kg patient
25-100mg
218
What nerve should you use to monitor neuromuscular blockade in patients with myasthenia gravis?
Temporal branch of the facial nerve to stimulate the orbicularis oculi because it is more sensitive than the ulnar in MG patients
219
List anticholinergics in order of fastest to slowest onset
Edrophonium (fastest) --> neostigmine --> pyridostigmine (slowest)
220
Neuromuscular blocker that causes histamine release
Atracurium
221
Local anesthetic used mainly in ENT surgeries
Cocaine
222
Norepi release is regulated by what receptor
Alpha 2
223
How should the dose of succinylcholine be altered if your patient has myasthenia gravis
Increase the dose
224
Drug class used to treat myasthenia gravis
Anticholinesterase (specifically pyridostigmine)
225
What drugs are combined to make percodan?
Oxycodone + aspirin
226
EMLA definition
Eutectic mixture of local anesthetics
227
EMLA components
Lidocaine + Prilocaine
