Exam 4: 7 Apr Local Anesthetics Part I & II Flashcards
1
Q
What is the first local anesthetic discovered?
A
Cocaine
Discovered in 1884 for its vasoconstrictive effects and stimulating qualities.
2
Q
What are the two classifications of local anesthetics?
A
- Esters
- Amides
3
Q
When was procaine, the first synthetic ester, discovered?
A
1905
4
Q
What is the standard local anesthetic against which others are compared?
A
Lidocaine
5
Q
What is the primary mechanism of action for local anesthetics?
A
Sodium channel blockers
6
Q
List the uses of local anesthetics.
A
- Anesthesia
- Acute and chronic pain management
- Peripheral nerve blocks
- Walking epidurals
- Spinal anesthesia
7
Q
True or False: Local anesthetics block only the sensory components of anesthesia.
A
False
8
Q
What happens to motor function when local anesthetics are administered in the right dosage?
A
Motor function can be blocked, leading to inability to lift legs.
9
Q
What is the typical dose range for lidocaine in an intraoperative setting?
A
1 to 2 mg per kg
10
Q
Fill in the blank: The initial bolus of lidocaine is given over ____ to ____ minutes.
A
2 to 4
11
Q
What is the recommended infusion duration for lidocaine?
A
12 to 72 hours
12
Q
What should be monitored when administering lidocaine?
A
- Cardiac function
- Hepatic function
- Renal function
13
Q
What is a common side effect of lidocaine that patients may experience?
A
Circumoral numbness and metallic taste
14
Q
What is the target plasma concentration for lidocaine to achieve analgesia?
A
1 to 5 mcg per ml
15
Q
What effect does lidocaine have when used for IV starts on hard stick patients?
A
Vasodilation
16
Q
When should lidocaine be administered for intubation preparation?
A
1 mg per kg
17
Q
What can happen if a patient is overdosed with lidocaine?
A
Myocardial depression
18
Q
What is the significance of the range of dosages for paralytic agents?
A
Correct answers will fall within a specific range, while incorrect answers will be out of range.
19
Q
What is advised regarding the sequence of care plans?
A
Do not disarrange the sequence of the care plan.
20
Q
What can propofol cause in patients?
A
Skeletal muscle twitching
This can complicate the differentiation between effects caused by propofol and lidocaine.
21
Q
What are the potential severe consequences of overdosing patients with lidocaine?
A
- Myocardial depression
- Seizures
- Unconsciousness
- Apnea
- Cardiovascular depression
These are critical adverse effects that require careful monitoring during administration.
22
Q
What is the primary focus of the lecture mentioned?
A
Local anesthetics
The lecture will primarily discuss local anesthetics rather than intravenous components.
23
Q
What are the three main structures of local anesthetics?
A
- Lipophilic component
- Hydrocarbon chain (intermediate chain)
- Hydrophilic component
The classification of local anesthetics as either esters or amides is based on the intermediate chain.
24
Q
What distinguishes an ester from an amide in local anesthetics?
A
The hydrocarbon chain
This is the intermediate chain that classifies local anesthetics as either esters or amides.
25
How many eyes do esters and amides have in their names?
* Esters: one eye
* Amides: two eyes
## Footnote
This is a mnemonic to help differentiate between the two classes of local anesthetics.
26
What is the pH range of the human body?
7.35 to 7.45
## Footnote
This is relevant for understanding the solubility and effectiveness of local anesthetics.
27
What effect does sodium bisulfite have on local anesthetics?
Increases solubility with epinephrine
## Footnote
It prevents precipitation and maintains clarity in local anesthetic solutions.
28
What are the two classifications of local anesthetics?
* Esters
* Amides
## Footnote
This classification is based on their chemical structure and properties.
29
What is a characteristic of local anesthetics in terms of their composition?
Most are weak bases
## Footnote
This affects their solubility and interaction with the body.
30
What does a higher non-ionized component indicate about a local anesthetic?
Higher lipid solubility
## Footnote
Lipid solubility is crucial for the potency and effectiveness of the anesthetic.
31
Which local anesthetic has the highest potency among esters?
Tetracaine
## Footnote
This is based on its lipid solubility and non-ionized fraction.
32
What role does lipid solubility play in local anesthetics?
It determines potency
## Footnote
Higher lipid solubility allows better penetration through cell membranes.
33
What happens to lidocaine when injected for dental procedures?
It has vasodilatory capacity
## Footnote
This can affect its effectiveness in remaining at the site of action.
34
What is the significance of liposomal local anesthetics?
They provide prolonged release and decreased toxicity
## Footnote
Liposomal formulations allow for extended action of local anesthetics.
35
Fill in the blank: The main characteristic that distinguishes local anesthetics is the _______.
Intermediate chain
## Footnote
This is crucial for classifying the anesthetic as either an ester or an amide.
36
True or False: The non-ionized fraction of a local anesthetic is not important for its potency.
False
## Footnote
The non-ionized fraction is a major determinant of potency.
37
What are examples of amide local anesthetics?
* Lidocaine
* Bupivacaine
* Ropivacaine
## Footnote
These are commonly used amide local anesthetics with varying properties.
38
What is the advantage of using a higher amount of local anesthetic in a controlled release system?
It provides a consistent release of local anesthetic into tissues, similar to an extended release capsule, leading to prolonged duration of action
## Footnote
This method decreases toxicity by controlling plasma levels compared to a large injection.
39
What is the impact of local anesthetics on plasma levels?
Local anesthetics in controlled release systems have decreased toxicity due to controlled plasma levels
## Footnote
This prevents high plasma levels that can traverse from intracellular to interstitial to intravascular spaces.
40
How does the FDA's approval of expert rail impact surgical procedures?
It has facilitated the transition of many procedures from hospitals to outpatient surgery, reducing costs for patients
## Footnote
Procedures like right shoulder arthroscopy can be significantly cheaper in ambulatory surgical care centers.
41
What is the maximum duration of action for the local anesthetic mentioned?
Up to 96 hours
## Footnote
This extended duration is particularly beneficial in outpatient surgical settings.
42
What is the role of the non-ionized form of local anesthetic?
The non-ionized form is crucial for blocking sodium passage through voltage-gated sodium channels, inhibiting action potentials
## Footnote
This mechanism prevents sensory reactions and pain transmission.
43
What does the term 'minimum effective concentration' (MEC) refer to?
The concentration required to numb or introduce local anesthetic effectively at a distance of one centimeter
## Footnote
This concentration covers three nodes of Ranvier in myelinated nerves.
44
What factors affect the blockade effectiveness of local anesthetics?
* Diameter of the nerve
* Myelination status
* Repetitive stimulation of the nerve
* Ionization state of the anesthetic
## Footnote
Larger and myelinated nerves require higher concentrations for effective blockade.
45
True or False: The ionized form of local anesthetic is preferred for nerve blockade.
False
## Footnote
The ionized form is less effective and contributes to toxicity.
46
What are the types of channels that local anesthetics can target besides sodium channels?
* Potassium channels
* Calcium ion channels
* G protein-coupled channels
## Footnote
These channels are involved in propagating electrical impulses.
47
What is the relationship between nerve diameter and local anesthetic dosage?
Larger nerves require higher doses of local anesthetics for effective blockade
## Footnote
Myelinated nerves also need more anesthetic due to their structure.
48
Fill in the blank: The minimum effective concentration of local anesthetics is at least _______ to cover three nodes of Ranvier.
one centimeter
49
What is the effect of increased sensitivity to local anesthetics during pregnancy?
Pregnant patients may require lesser amounts of local anesthetics due to lower plasma concentrations
## Footnote
This increased sensitivity should be considered in pain management.
50
How does the pKa value of local anesthetics influence their onset of action?
Local anesthetics with pKa values closer to physiologic pH (7.35 - 7.45) have a more rapid onset of action
## Footnote
This is due to a higher proportion of the non-ionized form being available.
51
What is the relationship between protein binding and metabolism of local anesthetics?
Higher protein binding correlates with lower metabolism and clearance rates
## Footnote
Lidocaine has lower protein binding compared to bupivacaine, leading to faster clearance.
52
List the local anesthetics in order of protein binding capacity from highest to lowest.
* Bupivacaine
* Ropivacaine
* Lidocaine
## Footnote
This order affects their metabolism and systemic absorption.
53
What factors influence the absorption of local anesthetics?
* Site of injection
* Dose of the anesthetic
* Vascularity of the area
## Footnote
Absorption varies greatly depending on these factors.
54
True or False: Administering local anesthetics intratracheally results in lower blood concentrations compared to intravenous administration.
True
## Footnote
Intratracheal administration is highly vascularized but does not maintain high local concentrations.
55
What is the relationship between protein binding capacity and metabolism of local anesthetics?
Higher protein binding capacity leads to slower metabolism
## Footnote
Examples: Bupivacaine has the highest protein binding, followed by Nipivicaine and Lidocaine.
56
Which local anesthetic has the fastest metabolism?
Lidocaine
## Footnote
Lidocaine is cleared fastest among Lidocaine, Nipivicaine, and Bupivacaine due to its lower protein binding.
57
What is the primary route of metabolism for ester local anesthetics?
Hydrolysis by cholinesterase enzymes in the plasma
## Footnote
Cocaine is an exception, as it is metabolized more in the liver.
58
What is the metabolite responsible for allergies associated with ester local anesthetics?
Para-aminobenzoic acid (PABA)
## Footnote
PABA is a metabolite of Tetracaine and can cause allergic reactions.
59
True or False: The more lipid soluble a local anesthetic is, the greater its potency.
True
60
Which property of local anesthetics is most important for determining duration of action?
Protein binding capacity
## Footnote
Clearance from the site of action is also important.
61
What physiological changes in pregnancy affect local anesthetic metabolism?
Lower levels of plasma cholinesterase
## Footnote
This results in a need for lower doses of local anesthetics, especially esters.
62
What adverse effect can prilocaine cause?
Methemoglobinemia
## Footnote
This condition reduces oxygen carrying capacity in the blood.
63
What is the treatment for methemoglobinemia caused by prilocaine?
Methylene blue
## Footnote
Administer 1-2 mg/kg IV over 5 minutes, total dose not to exceed 7-8 mg/kg.
64
What is the maximum infiltration dose of Lidocaine without epinephrine?
300 mg
65
What is the maximum infiltration dose of Lidocaine with epinephrine?
500 mg
66
What local anesthetic is preferred for longer procedures due to its longer duration of action?
Mepivacaine
## Footnote
It is not a vasodilator, which contributes to its extended duration.
67
What is the primary elimination route for local anesthetics?
Urine
## Footnote
About 5% for most local anesthetics, but higher for cocaine at 10-12%.
68
What is the primary concern with ion trapping of local anesthetics in pregnancy?
Non-ionized form converts to ionized form in the fetal acidic environment
## Footnote
This can lead to seizures or bradycardia in the fetus.
69
What is the effect of increased systemic vascular resistance on local anesthetic clearance?
Prolonged clearance
## Footnote
This is seen in conditions like pregnancy-induced hypertension.
70
What type of protein do local anesthetics bind to in plasma?
Alpha-1 acid glycoprotein
## Footnote
This is different from how some opioids bind to albumin.
71
What is the main reason why dibucaine is not commonly used as a local anesthetic?
It inhibits normal cholinesterase activity by more than 70%
## Footnote
This affects the metabolism of other drugs that rely on cholinesterase.
72
What is a potential complication of using local anesthetics in patients with renal impairment?
Accumulation of metabolites
## Footnote
This can occur with drugs like bupivacaine.
73
What is the primary use of diabucaine?
To diagnose patients with true allergies to succinylcholine
## Footnote
Succinylcholine can cause prolonged block in patients deficient in plasma esterases.
74
What is the metabolism rate of chloroprocaine compared to other anesthetics?
Three to five times faster than other anesthetics
## Footnote
This rapid metabolism contributes to its short duration of action.
75
Why is chloroprocaine preferred for outpatient procedures?
It is fast acting and fast off, minimizing recovery time
## Footnote
Commonly used in urology procedures.
76
What are the considerations for using chloroprocaine in patients with bad lungs or cardiac issues?
It only affects from the belly down, not the heart or lungs
## Footnote
Suitable for patients with COPD or recent myocardial infarction.
77
How should the dosage of chloroprocaine be adjusted in pregnant patients?
Decreased by up to 40%
## Footnote
This adjustment is due to changes in metabolism affecting plasma cholinesterase levels.
78
Rank the metabolism speed of ester local anesthetics from fastest to slowest.
1. Chloroprocaine
2. Procaine
3. Tetracaine
4. Benzocaine
## Footnote
Understanding metabolism speeds is crucial for clinical applications.
79
What is the main use of benzocaine?
To numb the airway of the patient
## Footnote
Caution is advised when using benzocaine due to potential risks.
80
True or False: Chloroprocaine affects the heart and lungs.
False
## Footnote
Chloroprocaine is designed to minimize systemic effects.
81
Fill in the blank: The metabolization of chloroprocaine is primarily through _______.
[plasma cholinesterase]
82
What condition could be worsened by administering succinylcholine to patients with certain deficiencies?
Prolonged neuromuscular block
## Footnote
Patients with deficiencies in plasma esterases are at risk.
83
What is the typical delivery amount of benzocaine from one spray for one second?
200 to 300 milligrams
84
What is benzocaine primarily used for?
Topical anesthesia of mucous membranes
85
What is the duration of action for benzocaine?
30 to 60 minutes
86
What is the maximum dose of methylene blue for a 120-pound male patient?
432 milligrams
87
How do you convert pounds to kilograms for a patient weighing 120 pounds?
Divide by 2.2
88
What condition can benzocaine and prilocaine cause if overdosed?
Methemoglobinemia
89
What is the antidote for methemoglobinemia?
Methylene blue
90
What is the peak time for cocaine when used as a local anesthetic?
30 to 45 minutes
91
How long does cocaine's effect last after its peak?
60 minutes
92
What are some patient conditions that require caution when using cocaine?
* Coronary vasospasm
* Ventricular dysrhythmias
* Hypertension
* Tachycardia
* Coronary heart disease
93
What procedures can cocaine be used for?
* ENT procedures
* Awake nasal intubation
* Functional endoscopic sinus surgery
94
What is one way to enhance the efficacy of local anesthetics?
Mixing with sodium bicarbonate
95
What is the effect of alkalinizing local anesthetics with sodium bicarbonate?
* Faster onset of action
* Enhanced depth of anesthesia
* Increased spread
96
What is the pKa of local anesthetics generally around?
8
97
What happens to local anesthetics in a more alkaline environment?
They become more non-ionized
98
Which local anesthetic would have more non-ionized form at a body pH of 7.4, one with a pKa of 9.1 or 4.5?
pKa of 9.1
99
True or False: Patients develop tolerance to local anesthetics.
False
100
What is the approximate conversion of 120 pounds to kilograms using a quick mental math trick?
54 kilograms
101
What is the elimination time frame for cocaine?
24 to 36 hours
102
What is the primary mechanism of action for local anesthetics?
Blocking sodium channels
103
Fill in the blank: The more alkaline the pKa of a drug, the more _______ it becomes.
non-ionized
104
What is one disadvantage of using local anesthetics in spinal procedures?
Increased spread
105
What is the role of sodium bicarbonate when mixed with local anesthetics?
To alkalinize and increase lipid solubility
106
What mental math method can be used to calculate 20% of a total bill?
Calculate 10% and multiply by 2
107
What does a lower pH indicate about ionization in local anesthetics?
A lower pH indicates more ionized components.
108
What is the effect of mixing adjuvant anesthetics with local anesthetics?
It increases the duration of both motor and sensory block.
109
Name an analgesic that can be administered after spinal anesthesia.
Dexmedetomidine.
110
Fill in the blank: ______ can prolong the duration of arachnoid blocks.
Magnesium.
111
True or False: IV lidocaine can be used as spinal lidocaine.
False.
112
What is an example of a local anesthetic that has a rapid onset compared to lidocaine?
Chloroprocaine.
113
What is the recommended concentration of sodium bicarbonate to mix with local anesthetics?
8.4% sodium bicarbonate, 1 ml to 30 ml of local anesthetic.
114
What can cause local anesthetics to precipitate when mixed?
Using more than the intended amount of sodium bicarbonate.
115
How does the use of vasoconstrictors affect local anesthetics?
It prolongs the duration of action by increasing contact time with nerve fibers.
116
What are the potential side effects of systemic absorption of epinephrine?
Hypertension and tachycardia.
117
Fill in the blank: The concentration of epinephrine in a 1:200,000 solution is ______ per ml.
5 mcg.
118
What does an 'epi wash' refer to?
Mixing epinephrine with local anesthetic before administration.
119
What is the formula to convert percent concentration to milligrams per ml for local anesthetics?
Percent concentration x 10 = milligrams per ml.
120
If a surgeon injected 20 ml of 0.25% bupivacaine with 1:200,000 epinephrine, how much bupivacaine was administered?
50 mg.
121
What is the relationship between lipid solubility and onset time of local anesthetics?
High lipid solubility does not necessarily mean rapid onset.
122
True or False: All forms of local anesthetics are interchangeable.
False.
123
What are the effects of alpha-adrenergic effects of local anesthetics?
They can provide some level of analgesia.
124
What should be checked when using local anesthetics with adjuvants?
The label for mixability with epidural or spinal use.
125
What is the total amount of anesthetic given if 150 mg of lidocaine is followed by 100 mg and then another 100 mg?
350 mg
## Footnote
The total exceeds the recommended maximum amount.
126
What is the maximum recommended dose of lidocaine for a patient?
300 mg
## Footnote
This is the maximum amount for a healthy adult.
127
True or False: Epinephrine should be given in high doses to patients with a history of angina.
False
## Footnote
High doses can be dangerous for patients with cardiac issues.
128
What is the concentration of epinephrine used in the discussed anesthetic?
1:200,000
## Footnote
This concentration equates to 5 mcg/ml.
129
Fill in the blank: The maximum recommended single dose of bupivacaine is ______.
225 mg
## Footnote
This is the maximum amount with epinephrine.
130
What are the different sizes of vials for local anesthetics mentioned?
Multi-dose and single-dose vials
## Footnote
Multi-dose vials can be punctured multiple times, while single-dose should not.
131
What is EMLA and what does it consist of?
Eutectic mixture of local anesthetics, comprising 2.5% lidocaine and 2.5% prilocaine
## Footnote
It is used for topical anesthesia.
132
What can happen if local anesthetics are given in excess?
Toxicity leading to symptoms such as circumoral numbness or aystole
## Footnote
Careful calculations are necessary to avoid this.
133
What is the onset time for EMLA?
45 minutes
## Footnote
This is the time required for adequate effect before procedures.
134
What is the risk of using epinephrine in certain areas?
Ischemia and necrosis
## Footnote
Areas like the ears, toes, fingers, and nose are particularly vulnerable.
135
What local anesthetic is commonly used for topical anesthetic applications?
Cocaine
## Footnote
It is effective for mucous membranes and produces localized vasoconstriction.
136
What is the mechanism of action of local anesthetics on peripheral nerves?
They diffuse from the outer mantle to the central core along a concentration gradient
## Footnote
This affects sensory and motor functions in a specific order.
137
What is the effect of adding epinephrine to local anesthetics?
Increases duration of anesthesia
## Footnote
It helps to prolong the effect by reducing blood flow to the area.
138
Fill in the blank: The typical volume of local anesthetic used for peripheral nerve blocks is ______.
30 ml
## Footnote
This volume is commonly used to achieve effective blocks.
139
What is the impact of sodium bicarbonate when mixed with lidocaine?
Increases the onset speed
## Footnote
This combination can enhance the effectiveness of lidocaine.
140
What should be assessed in patients regarding allergies to local anesthetics?
Distinguish between true allergies and reactions to epinephrine
## Footnote
Cross-sensitivity exists between amides and esters.
141
What is the typical volume of local anesthetic used for infiltration?
30 mls
## Footnote
The duration of anesthesia depends on the dose or amount infiltrated.
142
What can be mixed with local anesthetics to increase duration?
* EPI
* Fentanyl or clonidine
* Magnesium
* Dexmedetomidine
* Ketamine
## Footnote
These additives can extend the duration of anesthesia to more than 12 to 18 hours.
143
What is Exparel?
A liposomal formulation of bupivacaine
## Footnote
It provides pain relief for 24 to 72 hours.
144
Name three types of peripheral nerve blocks.
* Interscalene
* Axillary
* Femoral
## Footnote
Sciatic is also a common type of peripheral nerve block.
145
What is the purpose of a continuous infusion block?
To provide prolonged pain relief
## Footnote
A catheter is left in place for continuous delivery of anesthetic.
146
What are the effects of spinal anesthesia on blood pressure?
Blood pressure decreases
## Footnote
This occurs due to vasodilation from sympathetic block.
147
What is the sequence of blockade in spinal anesthesia?
* Sympathetic nervous system
* Sensory
* Motor
## Footnote
Sympathetic fibers are affected first, followed by sensory, and then motor fibers.
148
What is the effect of spinal anesthesia on heart rate?
Heart rate increases
## Footnote
This compensatory response occurs due to hypotension.
149
Fill in the blank: The _______ fibers are affected first by spinal anesthesia.
Sympathetic nervous system
150
What is the significance of the T10 dermatome in spinal anesthesia?
It corresponds to the umbilical region
## Footnote
Sensory blockade is assessed at this level.
151
What is the common local anesthetic used in IV regional anesthesia (Beer block)?
Lidocaine
## Footnote
Mepivacaine is also used due to its vasoconstrictive properties.
152
What is the purpose of a double cuff in a Beer block?
To isolate the extremity from systemic circulation
## Footnote
This prevents local anesthetic from entering systemic circulation.
153
True or False: Motor fibers are affected before sensory fibers in spinal anesthesia.
False
## Footnote
Sensory fibers are affected before motor fibers.
154
What are the typical dosages for spinal anesthesia based on patient height?
1 mL of 0.75% solution for every inch over 5 feet
## Footnote
The maximum dose is typically 2 mL.
155
What happens to the sympathetic nervous system level when sensory is at T10?
It is at T8
## Footnote
The sympathetic block is typically two segments higher than the sensory block.
156
What is the common complication associated with local anesthetic toxicity?
Adverse effects due to increased plasma levels
## Footnote
This can occur if local anesthetic is inadvertently introduced into systemic circulation.
157
What is the role of cerebrospinal fluid in spinal anesthesia?
It confirms placement in the subarachnoid space
## Footnote
Proper placement is crucial for effective anesthesia.
158
What should be monitored during spinal anesthesia administration?
Heart rate and blood pressure
## Footnote
These parameters help assess the effectiveness and safety of the anesthesia.
159
What type of segmental anesthesia is injected interspinally for a 5-foot patient?
1 mL of 0.75% local anesthetic
## Footnote
For every inch, it is 0.1 mL of 0.75% VPK.
160
How much local anesthetic is typically administered for a 6-foot patient?
2 mL
## Footnote
This is based on the standard dosing for height.
161
What determines the specific gravity of local anesthetics?
The amount of dextrose or glucose added
## Footnote
This affects patient positioning adjustments.
162
What are the three types of local anesthetics based on specific gravity?
* Hyperbaric
* Hypobaric
* Isobaric
163
What is the primary effect of epidural anesthesia?
Sensory effect
## Footnote
It may have slight sympathetic effects but no motor component.
164
What is the most commonly used local anesthetic in epidurals?
Lidocaine
## Footnote
It is considered the gold standard for epidural anesthesia.
165
What is the onset time for epidural anesthesia?
15 to 30 minutes
## Footnote
This indicates low diffusion before puncturing the dura.
166
What happens if local anesthetic diffuses into intravascular space during epidural anesthesia?
It can affect the fetus
## Footnote
This is due to the placental barrier.
167
Which local anesthetic crosses the transplacental barrier more, lidocaine or bupivacaine?
Lidocaine
## Footnote
Lidocaine is more rapid in onset compared to bupivacaine.
168
What is the recommended concentration of lidocaine used in liposuction?
0.05% to 0.1%
## Footnote
This dilution is used for infiltrating large volumes.
169
What is the effect of epinephrine in local anesthesia during liposuction?
Causes vasoconstriction
## Footnote
This reduces blood supply, making the procedure less bloody.
170
What is the peak effect time for local anesthesia after injection in liposuction?
12 to 14 hours
## Footnote
The local anesthesia continues to be effective post-procedure.
171
What is the maximum recommended dose of lidocaine with epinephrine for regional anesthesia?
35 to 55 mg per kg
## Footnote
This is a change from previous guidelines.
172
What is a potential risk of local anesthesia toxicity?
Fatal bradycardia
## Footnote
Overdosing can lead to severe adverse outcomes.
173
What concept will be discussed in the next session related to local anesthetics?
LA complications and rescue
## Footnote
This includes allergic reactions and other syndromes.
174
True or False: Bupivacaine has a faster onset than lidocaine.
False
## Footnote
Lidocaine has a more rapid onset compared to bupivacaine.
