Important facts Flashcards
1
Q
What factors increase respiratory depression with a PCA?
A
-Basal infusion rate
-Administration of other sedative medications
-Old age
-OSA and pulmonary disease
Respiratory depression is NOT higher when compared to other opioid routes
2
Q
What opioid is not recommended with PCA pumps?
A
-Meperidine
3
Q
What meds
target perception ?
A
General Anesthetics, opioids, and Alpha-2
4
Q
What drugs target modulation ? Where is the most important site?
A
Neuraxial
NMDA
Alpha 2
AchE
SSRI
SNRI
Substantia Gelatinosa
5
Q
What is the order of block onset for fiber types?
A
B
C
A (gamma and delta)
A (Alpha and Beta
6
Q
What concept is analogous to ED50?
A
Minimum effective concentration.
Lower are more easily blocked
Higher are harder to block
7
Q
Do local anesthetics affect the RMP or TP?
A
NO
8
Q
Where do local anesthetics bind to?
A
Alpha subunit INSIDE the sodium channel.
9
Q
What are the three building blocks of a local anesthetic ?
A
benzene ring - lipophilic
Intermediate chain - determines class
Tertiary amine- hydrophilic
10
Q
What is the primary determinant of potency ?
A
Lipid solubility
Intrinsic vasodilating effect is a secondary effect of potency
11
Q
What determines the duration of action of a local anesthetic?
A
- Protein binding
- Lipid solubility and intrinsic vasodilating activity
12
Q
Which local has a high intrinsic vasodilating effect?
A
Lidocaine
13
Q
Which locals have low protein binding
A
- Chloroprocaine - 0
- Procaine - 6
- Prilocaine - 55
- Lidocaine - 65
14
Q
What factors influence vascular uptake into the blood?
A
- Site of injection
- Tissue blood flow
- Properties of local
- Metabolism
- Adding a vasoconstrictor
15
Q
Rank the injection sites from most vascular to least
A
IV
Tracheal
Interpleural
Intercostal
Caudal
Epidural
Brachial Plexus
Femoral
Sciatic
Subq
***Femoral is low
16
Q
What is the most common sign of LAST?
A
Seizure
Except cardiotoxicity with Bupivacaine
17
Q
What conditions increase the risk of CNS toxicity with LAST?
A
Hypercarbia - Increases blood flow to brain and increases the free fraction to enter the brain
Hyperkalemia - Raises RMP
Metabolic acidosis - Decreases the convulsion threshold
18
Q
What drug has the highest cardiotoxicity ? Why?
A
Bupivacaine, Levobupivacaine, Ropivacaine, Lidocaine
Affinity for the voltage gated channel
19
Q
What’s the drug of choice for resuscitation from LAST? What to avoid ?
A
Amiodarone
Avoid vaso, lido, and procainamide
20
Q
Treatment for LAST?
A
Lipid emulsion therapy
Bolus 100mL over 2-3 minutes
Infusion of 250mL over 20 minutes
Repeat and/or double
If under 70kg
1.5mL/kg of LBW
0.25mL/kg/min
Repeat
MAX DOSE 12mL/kg
21
Q
Max dose age for tumescent anesthesia ?
A
- 50mg/kg
22
Q
What two locals produce a leftward shift in the oxyhemoglobin curve?
A
Prilocaine and benzocaine which creates anemia
ALSO
EMLA and cetacaine
23
Q
Treatment for methemoglobinemia ?
A
Methylene blue 1-2mg/kg over 5 minutes
24
Q
What patients are at risk for methemoglobinemia ?
A
Glucose-6 phosphate reductase deficiency
and
Fetal hgb
25
Max dose for EMLA cream?
0-3 , 1g - 10cm
3-12 months , 2g - 20cm
1-6 years ,10g - 100cm
7-12 years , 20g - 200cm
26
How does bicarbonate affect local ?
Shortens the onset time and reduces pain
27
WHAT DRUG REDUCES THE EFFECTIVNESS OF OPIOIDS?
Chloroprocaine
28
What drugs offer supplemental analgesia to locals?
Clonidine, Epi, Opioids
29
What can improve the diffusion through tissue?
Hyaluronidase, used in eye blocks frequently
30
What conditions allow extrajunctional receptors to populate in the myocyte?
Motor neuron injury
Spinal cord injury
Burns
Cerebrovascular accident
Chemical denervation
Tetanus
Sepsis
Muscular dystrophy
31
How are extra junctional receptors affected by sux and nondepolarizers ?
Sux - remain open longer so have an increased in Potassium
Nondepolarizers - Need an increase dosage
32
Is there fade with Succ? When do you see fade?
No unless high dose or continuous IV infusion
7-10mg/kg
33
What TOF ratio correlates with full recovery from a NMB?
>0.9 at the adductor pollicis
34
Best location to measure the onset and recovery for NMB?
Onset - Orbicularis Oculi
Recovery - Adductor pollicis
35
What is the best test to assess recovery from NMB?
Tongue blade. Max 50% of receptors are occupied
36
What other tests are used to assess NMB recovery?
No fade (60% of receptors)
Sustained head lift and hand grip (50% of receptors)
Tidal volume >5mL/kg (80)
Vital Capacity>20mL (70)
Ins force better than negative 40 (50)
37
How does succ affect HR, IOP, Renal failure, intragastric pressure?
Tachy and Bradycardia
Increase IOP
Okay to give in renal failure if K is normal, however caution with elevated K
Increases intragastric but is canceled out by esophageal sphincter tone
38
What are the three variants of pseudocholinesterase ?
Homo (Dibucaine of 80) 8 min duration of succ
Hetero (Dibucaine of 50) 25 min duration of succ
Atypical Homo (dibucaine of 25) 5 hour duration of succ
39
What is the treatment for hyperkalemia cardic arrest ?
Calcium to raise the Threshold Potential
40
How is hyperkalemia treated when from Succ?
Calcium
Hyperventilation, glucose and insulin, sodium bicarb, albuterol
Diuretics, dialysis, volume
41
Who is at the highest risk for myalgia?
Young adults, women more than men, those who do not exercise
42
How can myalgia be reduced?
HIGH dose of succ
Lidocaine
NSAIDS
NOT opioids
43
What populations are at increased risk with succ?
Charcot - Marie - Tooth
Hyperkalemic paralysis
Duchenne's
Guillain Barre
Upregulation of extra junctional
Amyotrophic lateral sclerosis
MS
44
Rank the NMB smallest to largest ED95 ( dose which there is a 95% decrease in twitch height )
Cis
Vec
Miv and Panc
Atra
Roc
Need 3x for intubating dose
45
What NBM are metabolized through Hoffman?
-Atracurium 33% (66% by non specific plasma esterase (different that Pseudo))
-Cisatracurium 100%
46
Which NMB is metabolized by pseudocholinesterase? what other paralytic is ?
Mivacurium and Succ
47
What does Hoffman rely on ? how does it change the reaction?
Normal blood pH
Faster with alkalosis and hyperthermia
Slower with acidosis and hypothermia
48
What is the active metabolite of cis and atracurium ?
Laudanosine - CNS stimulant
49
How is roc metabolized and eliminated? Any metabolite?
No metabolite
70% through liver
50
How is vec metabolized and eliminated? Any metabolite?
Liver
50% Liver and 50% kidney
3-OH vec
51
How is panc metabolized and eliminated? Any metabolite?
Liver
15% Liver and 85% kidney
3-OH panc
52
What drugs potentiate (increase the effect) NMB
Antibiotics, antidysrhythmics, locals, diuretics, dantrolene, cyclosporine
53
How do electrolytes potentiate NMB?
Increased Lithium and Mag
Decreased Ca and K
54
Which NMB have a histamine release
Succ, atra, mivacurium
55
What NMB can block the heart?
Panc and a little roc
56
What NMB has a vagolytic effect?
Panc - Increases HR while no effect on SVR
57
What NMB should be avoided with hypertrophic cardiomyopathy
Panc
Atra
Miva
58
What NMB is most likely to cause anaphylaxis?
Succ
59
3 examples ways to inhibit acetylcholinesterase ?
Competitive through electrostatic attachment - Edrophonium
Formation of carbamyl esters (competitive) - neostigmine, pyridostigmine
Phosphorylation - noncompetitive inhibition - organophosphates and echothiopate
60
How does renal failure affect the dosing of acetylcholinesterase?
Prolongs the duration
Also prolongs the duration of NMB
61
Is neostigmine faster or slower in children or adults?
Faster in children
62
What acetylcholinesterase inhibitor passes through the BBB.
Physostigmine
The rest do NOT
63
Common side effects of acetylcholinesterase inhibitors includes
DUMBBELLS - Increases parasympathetic nervous system
Diarrhea
Urination
Miosis
Bradycardia
Bronchoconstriction
Emesis
Lacrimation
Laxation
Salvation
64
Which anticholinergic does not pass through the BBB?
Glyco
65
When can atropine cause paradoxical bradycardia?
small IV dose.
<0.5 mg in adult
66
What are two ways AchE inhibitors increase Ach?
-Enzyme inhibition
-Presynaptic effects
67
What AchE inhibitor is mainly presynaptic ? What is it also used for ?
Edrophonium
Tensilon test, symptoms get better with MG and will get worse if in cholinergic crisis
68
Which AchE inhibitors inhibit pseudocholinesterase?
Neostigmine and pyridostigmine
69
How is edrophonium metabolized and eliminated? Neostigmine?
75% renal
50/50
70
Onset of AchE inhibitors is directly related to?
Depth of block
They also have an additive effect and more isn't always better
71
Which AchE inhibitor passes the BBB?
Physostigmine because it goes through more physiologic membranes
72
What can small doses of atropine cause? Why?
Paradoxical bradycardia through the blockage of M1 receptor on vagal nerve endings which normal reduce Ach
73
Roc dosage for reintubation after 4mg/kg or less of roc in the last 4 hours? more than 4 hours?
5 min to 4 hours - 1.2mg/kg
4+ hours. 0.6mg/kg or vec 0.1mg/kg
74
After an injection of an LA, it rapidly dissociates into a ...
Uncharged base and an ionized conjugate acid
75
What form of the LA binds to the LA binding site?
ionized conjugate acid
76
What are the two common reasons for LA allergies ?
esters - Para aminobenzoic Acid
Amides - Methylparaben
77
What is the primary variable contributing to LA onset of action? Secondary variables?
pKa
-Dose and concentration
78
What is the primary variable contributing to LA potency? Secondary variables?
Lipid solubility
Intrinsic vasodilating effect
79
What is the primary variable contributing to LA duration of action? Secondary variables?
Protein binding
Lipid solubility, intrinsic vasodilating effect, vasoconstrictors
80
Lipid solubility of an LA is increased with?
Alkyl group substitution
81
How does stereoselectivity play a role in LA?
Potency
82
Which LA has the highest degree of protein binding?
Levo bupivacaine 98&
Bupivacaine 96%
82
What determines the final plasma concentration of an LA?
TOTAL DOSE
not
concentration or speed of injection
83
What else acts as a reservoir and limits plasma concentration of LAs?
Lungs which remove LA from circulation
84
Which block does dexamethasone extend?
Brachial plexus
85
How does hypercapnia affect LAST?
Increases the free fraction
Decreases protein binding
Increases cerebral blood flow
86
How does metabolic acidosis affect LAST?
Favors Ion trapping and decreases the convulsion threshold
87
How do LA effect the myocardium?
Depresses it by altering the calcium regulation
88
How do LAs disrupt hemodynamics?
Alter the cardiac action potential, decrease automaticity, conduction velocity, AP duration, and vascular resistance
89
How do LAs affect vascular smooth muscle?
Low doses causes constriction
Normal and higher doses produce vasodilation
90
What determines the extent of cardiotoxicity?
Affinity for the receptor
Rate of dissociation from receptor
91
With cocaine toxicity, what should be given?
Nitro
Best beta blocker choice would be a selective
92
What can be given if seizure can not be broken?
Succ
but won't stop seizures in the brain
Do NOT use propofol
93
What is the max dose for lipid emulsion ? When should it be stopped?
Stopped ten minutes after hemodynamic stability
Max dose -10mL/kg in the first 30 min
94
Most common cause of death with liposuction? What is contained in tumescent anesthesia?
PE
Lidocaine, epi, bicarb
95
Max dosage for tumescent? When does it peak? When is it out?
50mg/kg
12 hours
36 hours
96
How is methemoglobin formed? how is it diagnosed?
Iron becomes oxidized to ferric acid - fe3+
Co oximeter
97
LAs that can cause methemoglobinemia?
Prilocaine
Benzocaine
Cetacaine
EMLA (prilocaine and lidocaine)
98
What is prilocaine metabolized to?
o-toluidine which oxidizes Hgb to Mhgb
99
Drugs that may prolong the duration of action of LAs?
epi, dexamethasone, dextran
100
Drugs that provide supplemental analgesia with LAs?
Epi, Clonidine, and opioids
101
Drugs that shorten onset time with LAs?
Sodium bicarb
102
Drugs that improve diffusion through tissue with LAs?
Hyaluronidase - has allergic potential
103
What LA reduces the effectiveness of analgesia opioids?
Chloroprocaine
104
What are the two extra junctional receptors? What depolarizes them?
Gamma subunit - succ
7 alpha subunits - stimulated by succ and choline
105
When and how long should succ be avoided?
24 hours after the injury and for one year
EXCEPT BURNS - several years
106
What happens when presynaptic Nn receptors are stimulated by acetylcholine?
More Ach is mobilized inside the presynaptic nerve
107
What does succ do to prejunctional receptors ?
Stimulates them like Ach
108
In adults why does succ produce more tachycardia?
mimics Ach at the sympathetic ganglia
Succ causes brady in children
109
What can be seen before MH caused from succ?
Masseter muscle spasms
Do not need to cancel if Trismus is seen, can open the mouth
110
Where is pseudocholinesterase produced?
liver
NOT located in the CSF but everywhere else
111
Max Percent of receptors occupied when tidal> 5ml/kg
80
112
Max Percent of receptors occupied when head lift is greater than 5 seconds and hand grip is baseline?
50%
113
Max Percent of receptors occupied when inspiratory force is better than NEGATIVE 40?
50%
114
Why does Succ cause bradycardia?
Stimulation of M2 at the SA
Metabolite succinylmonocholine
115
What drugs reduce pseudocholinesterase activity?
Reglan
Neostigmine
MAOI
Esmolol
Nitrogen mustard
Contraceptives
Cyclophosphamide
Echothiopate
116
What conditions reduce pseudocholinesterase activity ?
Atypical PChE
Liver and kidney disease
Burns
Neoplasm
Late pregnancy
Organophosphate poisoning
Malnutrition
Advanced age
117
What is treatment for atypical PChE?
Keep them on the vent
Whole blood, ffp, purified cholinesterase
118
Most common skeletal muscle myopathy in children ? What happens?
Duchenne's- absence of dystrophin protein
Causes hyperkalemic rhabdo NOT MH
119
What is dystrophin
Structural component of cytoskeleton - helps anchor actin and myosin
120
What lab values are elevated when the sarcolemma breaks down?
Creatine phosphokinase and myoglobin
121
Dose of calcium to stabilize myocardium in the presence of hyperkalemia?
C chloride 20mg/kg (contains more Ca)
C gluconate 60mg/kg
122
What shifts K into the cells?
Insulin/Glucose
Albuterol
Calcium
Hyperventilation
Bicarb
123
Dose of glucose to drive potassium into the cells? How much insulin?
0.5g/kg 10% solution
1 unit per 5g of glucose
124
How much bicarb to drive K into the cells?
1-2mmol/kg
125
When using a defasciculating dose of a Non depolarizer, how do you adjust the dose of succ?
Give more
1.5-2mg/kg
126
What disease is resistant to succ?
myasthenia gravis
127
List the NMB potency from least to most
Cis
Vec
Miv
Pan
Atra
Succ
Roc
128
How is mivacurium metabolized? Metabolite?
pseudocholinesterase
NO metabolite
129
What drugs potentiate NMB?
Volatiles
Antibiotics
Antidysrhythmic
Locals
Lasix
Dantrolene
130
What volatile potentiates NMBs the most?
Des
Sevo
Iso
N20
Propofol
131
What test would show an allergic reaction to NMB?
Elevated tryptase peaking at 120 minutes after exposure
132
How is pain inhibited?
1. Spinal neurons release GABA and glycine
2. Descending pathway release norepi, 5HT, and endorphins
133
How is pain augmented?
Central sensitization
Wind up
134
What type of receptors are opioid receptors?
G protein
turns off adenylate cyclase and decreases cAMP
Ca conductance in decrease (reduces neurotransmitter release)
K conductance is increased (hyperpolarizes the RMP)
135
Where are opioid receptors in the brain?
Periaqueductal gray, locus coeruleus, and rostral ventral medulla
136
What opioid receptors are responsible for pruritus?
Mu and Delta
137
What opioid receptor is responsible for immune supression
Mu - subtype 3
138
What opioid receptor is responsible for dependence and spinal analgesia and constipation ?
Mu 2
Cant go number 2
139
How do opioids affect the Co2 response curve?
Down and to the right
140
How do opioids affect heart contractility?
Doesn't unless combined with nitrous
141
What causes the pupil to constrict with opioids?
Edinger Westphal
Cilia ganglion of oculomotor nerve
142
Where is the CTZ?
Area postrema of medulla
143
Which opioid causes the lowest increase in biliary pressure?
meperidine
144
What are tolerance and physical dependence most likely due to ?
Desensitization and increased cAMP
NOT enzyme induction
145
What are early signs of withdrawal ? late?
Early- diaphoresis, insomnia, restlessness
Late - abd cramping and N/V
146
Withdrawal times of fentanyl and meperidine ?
onset 2- hours
peak 6 -12 hours
last 4-5 days
147
Withdrawal times of morphine and heroin?
onset 6-18 hours
Peak at 36-72 hours
Last 7-10 days
148
Which opioid has the greatest rostral spread when given intrathecal ?
Morphine
149
Which opioids have metabolites? What is the active form ?
Morphine and meperidine
m6G
150
Does m6G cross the BBB? S/S?
NO
Drowsiness, respiratory depression, N/V
151
Which opioid should not be given in a epidural or intrathecal?
Remi - contains glycine and free base
152
What can prevent hyperalgesia from remi?
Mag and Ketamine
153
When should meperidine be avoided?
Elderly, PCA, Dialysis , MAOI
154
What opioid acts like atropine?
Meperidine
155
Which opioids stimulate kappa?
Meperidine
156
Opioid with the largest Vd? Smallest?
Largest fentanyl
Smallest remi
157
pka of opioids?
Alf - 6.5
Remi - 7.2
Morphine 7.9
Su - 8
Fent - 8.4
Meperidine - 8.5
158
Opioids with the highest protein binding ? Lowest?
Remi and Su at 93%
Morphine at 35%
159
Which opioid is sensitive to a low extraction ratio? Also may by inhibited erythromycin
Alf
160
Racemic mixtures of opioids?
Methadone
161
How does methadone reduce pain? What is the oral bioavailability?
MU
NMDA
MAOI
80%
162
Facts about methadone
Good for chronic pain and abuse
Can increase QT
Inhibits K
No metabolite
3-6 hours
163
What causes muscle rigidity with opioids?
Rapid administration
ALL the fentanil's
164
Complications from opioid induced muscle rigidity?
Increased thoracic pressure -
Increased CVP, PAP,PVR
Increased O2
Decreased ventilation, and mixed venous O2
165
Opioid agonist - antagonist FACTS
Provides analgesia with reduced risk of resp depression
Ceiling effect
Decreases other opioids
Can cause acute opioid withdrawal
Lower risk of dependence
166
Facts of buprenorphine
Partial Mu
HARD to reverse
Long duration
Can use patch
167
Facts of nalbuphine
Kappa agonist and Mu antagonist
Revered with Narcan
Does not affect cardiac so good in heart disease
168
Facts of butorphanol
Kappa agonist and weak Mu antagonist
Revered by Narcan
Good for post op shivering
169
Which two agonist provide greater pain relief compared to morphine?
B's
170
Facts about Narcan
Short acting 30-40 minutes
Can causes Pulmonary edema from SNS activation
N/V
All opioid receptors
FIRST PASS LIVER
171
Can Narcan cross the placenta?
Yes careful - can send baby into withdrawal
172
Methylnaltrexone Facts?
Does not cross BBB (quaternary amine)
DOES NOT REVERSE RESP DEPRESSION
good for other effects
173
Nalmefene facts
Long acting, good for abusers
174
Naltrexone
Good for withdrawal and abusers
