Chapter 3
Regional Anesthesia MCQS
1) Contraindication(s) for neuraxial blockade
include(s)
A. Severe aortic stenosis
B. Severe bleeding tendency
C. Existing severe hypotension
D. All of the above
2)During epidural placement using a midline
approach, the epidural needle penetrates all the following anatomical layers,
except
A. Ligamentum flavum
B. Subarachnoid membrane
C. Supraspinous ligament
D. Intraspinous ligament
3) The correct statement for human neuraxial
anatomy is?
A. Adult
spinal cord ends at L2
B. Spinal cord in children ends at L3
C. The dural sac and subarachnoid space in adults end at S1
D. The dural sac and subarachnoid space in children end at S2
3) The principal site of action of local anesthetics
placed into the epidural space is the?
A. Spinal
cord
B. Nerve roots
C. Epidural space
D. Subarachnoid space
4)As an adjuvant in epidural anesthesia,
epinephrine can?
A. Prolong
duration of blockade
B. Improve the quality of blockade
C. Decrease the peak plasma levels of local anesthetic concentration
D. All of above
5)Factors that can affect the level of an
epidural anesthetic include
A. Patient
weight, amount of local anesthetic injected, patient position
B. Patient height, amount of local anesthetic injected, patient position
C. Patient age, amount of local anesthetic injected, patient
D. B and C
6) Addition of sodium bicarbonate to epidural
local anesthetics may accelerate the onset of blockade with all of the local
anesthetics, except
A. Lidocaine
B. Chloroprocaine
C. Mepivacaine
D. Bupivacaine
7) Factors influencing the level of spinal
anesthesia achieved include all of the following, except
A. Baricity
of anesthetic solution
B. Patient age
C. Volume of anesthetic solution
D. Patient gender
8)Complications from neuraxial blockade may
include all of the following, except
A.
Radiculopathy
B. Anterior spinal artery syndrome
C. Arachnoiditis
D. Constipation
9)Neuraxial block complications using local
anesthetics alone include all of the following, except
A Post-dural puncture
B. Urinary retention
C. Postoperative cognitive dysfunction
D. High spinal
11)
A spinal
neuraxial anesthetic was given 20 minutes earlier to a 28-year-old G3P2
parturient scheduled for repeat cesarean section. Alcohol swab exam revealed
that she has lost temperature sensation up to T2 level. At what level do you
anticipate the block will reach to provide adequate pain control?
A. T2
B. T3
C. T4
D. T5
12)
You performed
an epidural anesthetic for an elective open-abdominal aneurysm repair. You are
asked to advise the surgeon when it would be considered safe to administer
intraoperative intravenous heparin:
A. Not at all
B. One hour after epidural placement
C. Two hours after epidural placement
D. Four hours after epidural placement
13)
Following
performance of spinal anesthesia at the L4-L5 level with 3 mL of 5% lidocaine,
you suspect a potential injury to the conus medullaris. Which of the following
symptoms is least likely to be associated with cauda equina syndrome?
A. Urinary incontinence
B. Saddle anesthesia
C. Quadriceps weakness
D. Biceps femoris weakness
14)
The
most likely reason for dyspnea in a patient experiencing the effects of a high
neuraxial blockade is:
A. Phrenic nerve palsy when the neuraxial level
reaches T3-T5
B. Patient is experiencing an anxiety attack
C. Medullary hypoperfusion
D. congestive heart failure
15)
All of the following
local anesthetic systemic toxicity (LAST) treatment
measures should be performed when caring for a patient who may be experiencing
toxicity, except:
A. Stop epidural medication administration
B. Support the airway with 100% oxygen
C. Administer intravenous epinephrine
according to ACLS protocols
D. Administer an intralipid bolus and continuous
infusion
16)
A
higher-than-expected spinal level achieved or greater dermatomal spread of
local anesthetic can be associated with all of the following clinical
situations, except:
A. Pregnancy
B. Ascites
C. Elderly
D. Female gender
17)
Which
of the following techniques is LEAST effective in the
treatment of pruritus from administration of neuraxial opiates?
A. Nalbuphine 5 mg intravenous (IV)
B. Dexmedetomidine 30 μg IV
C. Diphenhydramine 50 mg IV
D.
Propofol 10 mg IV
18)
All
of the following are symptoms of a
developing epidural hematoma EXCEPT:
A. Radicular back pain
B. Bowel and bladder dysfunction
C. Motor deficits
D. Fever
19)
Which
of the following is the EARLIEST sign of lidocaine toxicity from a high blood
level?
A. Shivering
B. Nystagmus
C. Light-headedness and dizziness
D. Tonic-clonic seizures
20)
Three
days after knee arthroscopy under spinal anesthesia, a 55-year-old patient complains
of double vision and difficulty hearing. The other likely finding would be:
A. Headache
B. Fever
C. Weakness in legs
D. Mental status changes
21)
An intradural
mass lesion at the tip of a drug infusion catheter is LEAST likely to present
as
A. Increasing pain
B. Development of numbness in T8 dermatomal pattern
C. Hypopnea
D. Perianal numbness
22)
In addition
to C nerve fibers, which nerve fibers carry pain impulses?
A. A-alpha (Aα)
B. A-beta (Aβ)
C. A-delta (Aδ)
D. B
23)
All of the
following are symptoms of a developing epidural hematoma Except
A. Radicular back pain
B. Bowel and bladder dysfunction
C. Motor deficits
D. Fever
24)
The structure
MOST likely to be blocked during placement of an interscalene block in addition
to the brachial plexus is the
A. Phrenic nerve
B. Vertebral artery
C. Recurrent laryngeal nerve
D. Vagus nerve
25)
An axillary
block is performed on a healthy 19-year-old athlete. A 30-mL quantity of 0.75%
bupivacaine is injected incrementally. Five minutes after the bupivacaine injection,
the patient has a seizure and experiences CV collapse. Which of the measures
below is NOT indicated?
A. Begin chest compressions at 100 per minute
B. Ventilate with 100% oxygen
C. Bolus propofol to bind local anesthetic
D. Infuse 20% lipid emulsion
26)
The only
technique shown to prevent anesthetic-related nerve injury during placement of
peripheral nerve blocks is
A. Ultrasound-guided regional technique
B. Transarterial technique
C. Nerve stimulator
D. None of the above
27)
Nerves that
originate from the sacral plexus include each of the following EXCEPT
A. Femoral nerve
B. Tibial nerve
C. Sciatic nerve
D. Common peroneal nerve
28)
The reason
that ropivacaine is marketed as pure S enantiomers is because the S form is
associated with
A. Increased potency
B. Longer duration
C. Reduced cardiac toxicity
D. Reduced incidence of anaphylaxis
29)
During
placement of an interscalene block, the patient becomes hypotensive,
bradycardic, apneic, and cyanotic. The MOST likely cause is
A. Vertebral artery injection
B. Phrenic nerve blockade
C. Total spinal
D. Stellate ganglion block
30) During an
airway examination, a 53-year-old patient mentions that his right thumb tingles
and then becomes numb if he extends his head for more than a few seconds. This
symptom MOST likely represents a(n)
A. Unstable C-spine
B. Lhermitte’s phenomenon
C. C6 nerve root irritation
D. C8 radiculopathy
31) Which of the following nerves can be
electrically stimulated at the ankle to produce flexion of the toes?
A. Posterior tibial nerve
B. Saphenous nerve
C. Deep peroneal nerve
D. Superficial peroneal nerve
32) Discontinuation of which of the following
antiplatelet medications, for 14 days, would be necessary before a spinal could
be safely administered?
A. Aspirin
B. Clopidogrel
C. Ticlopidine
D. Abciximab (GPIIb/IIIa)
33) Which is NOT a potential complication of a
stellate ganglion block?
A. Recurrent laryngeal nerve paralysis
B. Subarachnoid block
C. Brachial plexus block
D. Increased heart rate
34) A caudal block (performed under
sevoflurane general anesthesia) with 0.25% bupivacaine and 1:200,000
epinephrine is planned for postoperative analgesia after bilateral inguinal
hernia repair in a 5-month-old patient. Each of the following would be
consistent with an intravascular injection EXCEPT
A. Systolic blood pressure increase by greater than 15 mm Hg
B. Heart rate decrease by greater than 10 beats/min
C. Ventricular extrasystoles
D. Increase in T-wave amplitude > 25% over baseline
3 35) Discharge criteria from the PACU would be
reached FASTEST after a 20- to 30-mL volume of which of the following
epidurally administered local anesthetics?
A. 3% 2-Chloroprocaine
B. 2% Lidocaine
C. 0.75% Ropivacaine
D. 0.5% Levobupivacaine
36) Which of the following local anesthetics is
inappropriately paired with a clinical application because of its properties or
toxicity?
A. Tetracaine, topical anesthesia
B. Bupivacaine, IV anesthesia
C. Prilocaine, infiltrative anesthesia
D. Chloroprocaine, epidural anesthesia
37) Each of the following additives to a spinal
anesthetic possesses analgesic properties EXCEPT
A. Clonidine
B. Hydromorphone
C. Epinephrine
D. All of the above have analgesic properties
38) Addition of bicarbonate to local anesthetics
results in
A. Delayed onset of action
B. Reduced toxicity
C. Increased duration of action
D. Reduced pain with skin infiltration
39) How long should a patient be off clopidogrel
(Plavix) before a central neuraxial block is performed?
A. 24 hours
B. 7 days
C. 14 days
D. No waiting necessary
40) Para-aminobenzoic acid is a metabolite of
A. Mepivacaine
B. Ropivacaine
C. Bupivacaine
D. Procaine
41)
A 35-year-old
woman receives a popliteal block for ankle and foot surgery. Which other nerve
must be blocked in order to have complete anesthesia of the foot?
A. Superficial peroneal
nerve
B. Sural nerve
C. Saphenous nerve
D. Posterior tibial nerve
42)
Which of the
following blocks has the LONGEST duration of action when bupivacaine with
epinephrine is administered?
A. Axillary
B. Epidural
C. Infiltration
D. Spinal
43)
Each of the
following is associated with an increased incidence of PDPHs EXCEPT
A. Younger adults
B. Early ambulation
C. Pregnancy
D. Large needle size
44)
Transient
neurologic symptoms (TNS) after spinal anesthesia are associated with each of
the following EXCEPT
A. Lidocaine
B. Lithotomy position
C. Ambulatory anesthesia
D. Concentration of local anesthetic injected
45)
Each of the
following drugs has been used to treat neuropathic pain. Selective inhibition
of serotonin and norepinephrine reuptake is the mechanism of which drug?
A. Duloxetine
B. Mexiletine
C. Gabapentin
D. Carbamazepine
46)
Which of the
following procedures for treatment of chronic pain requires localization of the
epidural space with an epidural needle as part of technique?
A. Radio-frequency ablation of a lumbar facet joint
B. Spinal cord stimulation
C. Percutaneous disk decompression
D. Vertebroplasty
47)
The only
technique shown to prevent anesthetic-related nerve injury during placement of
peripheral nerve blocks is A. Ultrasound-guided regional
technique
B. Transarterial technique
C. Nerve stimulator
D. None of the above
48)
Three days
after knee arthroscopy under spinal anesthesia, a 55-year-old patient complains
of double vision and difficulty hearing. The other likely finding would be
A. Headache
B. Fever
C. Weakness in legs
D. Mental status changes
49)
Each of the
following is a potential complication of thoracic paravertebral blocks EXCEPT
A. Pneumothorax
B. Epidural spread of local anesthetic
C. Hypertension
D. Total spinal
50)
The most
common complication of a celiac plexus block is
A. Hypotension
B. Seizure
C. Retroperitoneal hematoma
D. Constipation
Correct answers and explanations
Chapter 3rd
Regional anesthesia
MCQS
MCQ 1 Explanation
Correct Answer: D Neuraxial
block is a great alternative to general anesthesia for many surgical procedures
below the diaphragm and an excellent choice for postoperative pain control.
However, there are conditions where neuraxial block needs to be used with
caution. Neuraxial blocks are associated with a sympathectomy and can therefore
worsen existing hypotension and hypovolemia. Hypotension in combination with
aortic and/or mitral valve stenosis may not be very well tolerated. Although
spinal/epidural hematoma is rare yet possible, the risk of bleeding is
significantly higher in patients with a known coagulopathy.
MCQ 2 Explanation
Correct Answer: B To perform
an epidural block, the needle passes through several layers, including skin,
subcutaneous tissue, supraspinous ligament, intraspinous ligament, and ligament
flavum. To perform a spinal anesthesia, the needle goes deeper to penetrate the
dura and frequently the subarachnoid membrane.
MCQ 3 Explanation
Correct Answer: B The spinal
cord typically ends around L1 in adults, and around L3 in children. This is the
reason why neuraxial blocks are performed below these levels and carry a lower
risk of direct spinal cord injury. The dural sac and subarachnoid spaces end at
S2 in adults and S3 in children.
MCQ 4 Explanation
Correct Answer: B Major site
of action of neuraxial blockade takes place on the nerve roots. Local
anesthetics act on nerve roots in the subarachnoid space in the case of a
spinal blockade and on the nerve roots in the epidural space in the case of
epidural anesthesia.
MCQ 5 Explanation
Correct Answer: D During
epidural anesthesia, epinephrine in the dose of 5 µg/mL will improve the quality
of an epidural anesthetic. Additionally, epinephrine can also prolong blockade
duration, delays local anesthetic intravascular absorption, and decreases peak
plasma local anesthetic concentration(s).
MCQ 6 Explanation
Correct Answer: D It is
currently believed that body weight alone does not influence the level of an
epidural block (although extreme obesity may). Patient height (vertebral levels
covered decrease with height) and age (vertebral levels covered increase with
age) along with local anesthetic volume (about 1 to 2 mL local anesthetic
medication per segment) and patient position (theory of gravity) can play
significant roles.
MCQ 7 Explanation
Correct Answer: D Addition of
a base with acidic local anesthetic medications will increase the amount of
uncharged local anesthetic molecules injected and can therefore increase
diffusion of local anesthetic molecules through the lipid layer of the cell
membrane. However, sodium bicarbonate is not used with bupivacaine as it can
precipitate in solutions of a pH above 6.8.
MCQ 8 Explanation
Correct Answer: D Major
factors influencing the level of spinal anesthesia includes baricity of local
anesthetic solution, patient position immediately following spinal block
placement, drug dose used, site of injection, patient age and spine anatomy, pH
of the CSF, drug volume used, needle orifice direction, patient height, and
patients being pregnant.
MCQ 9 Explanation
Correct Answer: D
Complications from neuraxial blockade can be diverse and range from death,
cardiac arrest, seizures, paraplegia, radiculopathy, anterior spinal artery
syndrome, high/total spinal anesthesia, arachnoiditis, post-dural puncture
headache, back pain, epidural hematoma, epidural abscess, and urinary
retention. However, the complication rates are typically low and may even
improve bowel function and decrease constipation.
MCQ 10 Explanation
Correct Answer: C Potential
complications of neuraxial blockade can be diverse and range from death,
cardiac arrest, seizures, paraplegia, radiculopathy, anterior spinal artery
syndrome, high/total spinal anesthesia, arachnoiditis, post-dural puncture
headache, back pain, epidural hematoma, and epidural abscess. However,
complication rates are low and patients do not typically experience delirium
unless systemic opioid analgesics have been used.
MCQ 11 Explanation
Correct Answer: C In spinal
and epidural anesthesia, differential blockade is frequently reported to
observe the “two segments rule,” namely, sympathetic block is two segments
higher than sensory block, and sensory block is two segments higher than motor
block. In this spinal block, alcohol swab tested the level of
sensory/sympathetic blockade.
MCQ 12 Explanation
Correct Answer: B Subcutaneous
heparin prophylaxis at once or twice daily is not a contraindication to
neuraxial anesthesia placement or prior to epidural catheter removal. Systemic
heparin administration can be considered safe if given 1 hour or longer
following neuraxial blockade according to the ASRA guidelines.
MCQ 13 Explanation
Correct Answer: C Cauda equina
syndrome is usually secondary to neurotoxic effects from local anesthetics on
the sacral nerve roots. All of above symptoms, with the exception of the
quadriceps muscles, could be explained by the cauda equina syndrome (innervated
by the sacral plexus). Quadriceps muscles are innervated by lumbar plexus and
lumbar nerve roots and are rarely involved in the cauda equine syndrome.
MCQ 14 Explanation
Correct Answer: C Hypotension
associated with a high spinal may be worsened as a result of effects on the
cardiac accelerator fibers at the T1–T4 levels. Therefore, a vasopressor that
can simultaneously increase both HR and BP would be the most ideal medication
to administer. All of the above drugs, except phenylephrine, can be used to
treat severe bradycardia in the management of a high neuraxial block associated
with a decreasing heart rate.
MCQ 15 Explanation
Correct Answer: C In LAST
management, steps taken toward advanced life support still need to be followed
despite evidence that intralipid administration is the definitive treatment.
Administration of epinephrine as well vasopressin in the treatment of LAST
should be avoided as it has not been shown to be associated with improved
patient outcomes.
MCQ 16 Explanation
Correct Answer: D Factors
associated with a decreased CSF volume include pregnancy, large abdominal
tumor, ascites, and the elderly, and can be associated with an exaggerated
spread of neuraxial local anesthetic (volume and amount of local anesthetic
injected remain constant).
MCQ 17 Explanation
Correct Answer: B The
treatment of pruritus, the most common side effect of neuraxial opiates, is
primarily with opioid antagonists, mixed opioid agonist–antagonists, and
antihistamine drugs (by their sedating effects). Nalbuphine is a mixed opioid
agonist– antagonist; diphenhydramine has antihistamine properties. Propofol at
very low doses (e.g., 10 mg) has been useful to treat pruritus, not only
induced by neuraxial opiates but also the pruritus associated with cholestatic
liver disease. Propofol does not affect analgesia, whereas opioid antagonists
and mixed agonist– antagonists may reverse some or all of the analgesia,
depending on dose. Dexmedetomidine is a highly selective α2 -receptor agonist
that has a faster onset and shorter duration of action compared with clonidine.
Dexmedetomidine has analgesic properties, can potentiate neuraxial analgesia
when injected spinally, and can perhaps.
MCQ 18 Explanation
Correct Answer: D Epidural
hematomas are rare complications of spinal anesthesia (1:220,000) and epidural
anesthesia (1:150,000). However, in the presence of LMWH, the incidence is much
higher: 1:40,000 with spinal anesthesia and 1:3000 with continuous epidural
catheter. Clinical symptoms include radicular back pain, bowel and bladder
dysfunction, and sensory or motor deficits. An MRI is the diagnostic test of
choice, and prompt (< 8 hours) decompressive laminectomy is the treatment of
choice. Epidural abscesses typically progress slowly compared with epidural hematomas
and are also associated with fever.
MCQ 19 Explanation
Correct Answer: C Toxic
reactions to local anesthetics are usually due to intravascular or intrathecal
injection or to an excessive dosage. The initial symptoms of local anesthetic
toxicity from high blood levels (inadvertent IV injection or excessive dosages)
are light-headedness and dizziness, and numbness of the tongue. Patients also
may note perioral numbness and tinnitus. Progressive central nervous system
(CNS) excitatory effects include visual disturbances (difficulty focusing),
auditory disturbances (tinnitus), shivering, muscular twitching, and,
ultimately, generalized tonic-clonic seizures. CNS depression can ensue,
leading to respiratory depression or arrest. Higher levels can lead to cardiovascular
(CV) collapse. To help prevent excessively high levels of local anesthetic,
common practice is to aspirate for blood and inject the local anesthetic slowly
and incrementally, looking for signs of toxicity (and, if appropriate, adding
epinephrine to use as an intravascular marker as noted by an increase in heart
rate and blood pressure) (Miller: Miller’s Anesthesia, ed 8, pp 1048–1052).
MCQ 20 Explanation
Correct Answer: A Postdural
puncture headaches (PDPHs) (spinal headaches) usually develop within 12 to 72
hours after a dural puncture but may develop immediately or take months to
develop. The most characteristic symptom is a postural component in which the
headache occurs in the upright position and is usually completely gone when the
patient is in the supine position. The headache is typically frontal and/or
occipital in location. Other symptoms include nausea, vomiting, anorexia,
visual disturbances (blurred vision, double vision, photophobia), and
occasionally hearing loss (routinely found with auditory testing).
MCQ 21 Explanation
Correct Answer: C Overdose of
intrathecal opiates would not be a sign of an intradural mass lesion.
Granulomas at the tip of intrathecal catheters used with intrathecal drug
delivery systems are gaining increased attention. Granulomas are more
frequently associated with high concentrations and doses of either morphine
(> 10 mg/day) or hydromorphone (> 10 mg/day). Most patients who will
develop granulomas receive the intrathecal medications for more than 6 months. Presenting
symptoms may include loss of drug effect, new pain or paresthesias, or
neurologic deficits. Patients should be routinely screened for signs and
symptoms of granuloma formation at scheduled intrathecal pump refill
appointments. In suspicious cases, patients should undergo prompt diagnostic
imaging, and neurosurgical consultation should be considered (Miller: Miller’s
Anesthesia, ed 8, pp 1911–1912).
MCQ 22 Explanation
Correct Answer: C Aα fibers
are efferent to the skeletal muscles. Aβ fibers are afferent from the skin and
joints to provide touch and proprioception sensations. A-gamma (Aγ) fibers are
3 to 6 μm in diameter, have conduction velocities of 15 to 35 m/sec, and are
efferent to the muscle spindles to provide muscle tone. A-delta (Aδ) fibers are
1 to 4 μm in diameter and have conduction velocities of 5 to 25 m/sec and are
afferent fibers, which provide sharp localized pain and temperature and touch
sensations. B fibers are myelinated, preganglionic sympathetic nerve fibers
that are less than 3 μm in diameter, have medium conduction velocities 3 to 15
m/sec, and are involved with various autonomic nervous system control. C fibers
are nonmyelinated, postganglionic sympathetic nerves that are 0.3 to 1.3 μm in
diameter and have slow conduction velocities of 0.1 to 2 m/sec. C fibers are
afferent sensory nerves involved with nonlocalized pain, temperature, and touch
sensations (Miller: Miller’s Anesthesia, ed 8, pp 1013–1014).
MCQ 23 Explanation
Correct Answer: D Epidural
hematomas are rare complications of spinal anesthesia (1:220,000) and epidural
anesthesia (1:150,000). However, in the presence of LMWH, the incidence is much
higher: 1:40,000 with spinal anesthesia and 1:3000 with continuous epidural
catheter. Clinical symptoms include radicular back pain, bowel and bladder
dysfunction, and sensory or motor deficits. An MRI is the diagnostic test of
choice, and prompt (< 8 hours) decompressive laminectomy is the treatment of
choice. Epidural abscesses typically progress slowly compared with epidural
hematomas and are also associated with fever. See also explanation for Question
814 (Miller: Miller’s Anesthesia, ed 8, p 1049).
MCQ 24 Explanation
Correct Answer: A When
performing an interscalene block, the needle is usually inserted where the line
extending lateral to the cricoid cartilage (C6 level) intersects the
interscalene groove. The needle is inserted perpendicular to the skin and is
slowly advanced in a medial, caudal, and slightly posterior direction. The
caudal direction is used to decrease the chance of injecting the local
anesthetic into the vertebral artery, or obtaining a spinal or epidural block.
Injecting into the vertebral artery may lead to an immediate convulsion, since
the local anesthetic would go directly to the brain. The phrenic nerve is
routinely blocked (100% of the time) and, in healthy patients, rarely leads to
symptoms. However, in patients with borderline respiratory insufficiency,
respiratory compromise can result. Occasionally the recurrent laryngeal nerve
is blocked. Unilateral paralysis rarely is clinically significant, but if
contralateral recurrent paralysis existed preoperatively, then complete airway
obstruction may develop. The vagus nerve can also be blocked but is rarely
clinically significant.
MCQ 25 Explanation
Correct Answer: C Local
anesthetic systemic toxicity (LAST) is a multisystem phenomenon, but the most
crucial manifestation involves the heart (atrioventricular conduction block,
arrhythmias, myocardial depression, and cardiac arrest). In this case of CV collapse,
treatment consists of getting help with the initial focus of airway management
and CV support (i.e., basic and advanced cardiac life support). BUT AVOID the
use of vasopressin, calcium channel blockers, β-blockers, or local anesthetics.
Epinephrine doses should be reduced to less than 1 µg/kg. Lipid emulsion
therapy should be started; the initial bolus of 20% Intralipid is 1.5 mL/kg
(lean body mass) over 1 minute, followed by a continuous infusion of 0.25
mL/kg/min. Repeat the bolus one or two times for persistent CV collapse, and
double the continuous infusion rate if the blood pressure remains low. Continue the infusion for at least 10 minutes after CV stability
is attained. The upper limit of 20% Intralipid is 10 mL/kg over 30 minutes.
Failure to respond with the above treatment should prompt consideration for
cardiopulmonary bypass. Although propofol is formulated as a lipid emulsion and
as such would bind bupivacaine to some degree, the cardiac depressant effects
of propofol would far overshadow any therapeutic benefit of binding
bupivacaine.
MCQ 26 Explanation
Correct Answer: D Anesthetic-related nerve injuries to the brachial plexus
are rare and poorly understood. The only way to minimize nerve injury is to
minimize trauma to neural fibers. Although ultrasound-guided technique is
promising, currently there is no clinical evidence for this (Neal et al:
Upper extremity regional anesthesia: Essentials of our current understanding,
2008, Reg Anesth Pain Med 34:134–170, 2009; Miller: Miller’s Anesthesia, ed 8, p 1049).
MCQ 27 Explanation
Correct Answer: A Nerves to the lower extremity emerge from the L1-S4 nerve
roots. The upper roots (mainly L1-L4) form the lumbar plexus, which gives rise to
the genitofemoral (L1-L2), lateral femoral cutaneous (L2-L3), obturator
(L2-L4), and the femoral (L2-L4) nerves. A branch from the lumbar plexus (L4),
along with the sacral plexus (L4-S3), gives rise to the sciatic nerve. Branches
of the sciatic nerve include the common peroneal (branches to make the
superficial and deep) and the tibial, and the sural nerves (Miller: Miller’s
Anesthesia, ed 8, p 1736).
MCQ 28 Explanation
Correct Answer: C The pipecoloxylidide local anesthetics (mepivacaine, bupivacaine,
ropivacaine, and levobupivacaine) are chiral drugs, which means that they have
an asymmetric carbon atom (i.e., have a left or S and a right or R hand
configuration). Mepivacaine and bupivacaine are produced as racemic mixtures
(50% S:50% R). The pure S forms show reduced neurotoxicity and reduced
cardiotoxicity (e.g., ropivacaine and
levobupivacaine). Clinical studies suggest that the pure S forms have a slight
decrease in potency and a shorter duration of action compared with racemic
mixtures. Lidocaine is an achiral compound (i.e., has no chiral carbon atom)
(Barash: Clinical Anesthesia, ed 8, pp 1189–1190).
MCQ 29 Explanation
Correct Answer: C With an intravascular injection, the main symptoms would
most likely be CNS toxicity (e.g., seizures), as blood flow is directly to the
brain. The Bezold-Jarisch reflex (hypotension and bradycardia) has been
reported in awake, sitting patients undergoing shoulder surgery with an
interscalene block. This may be related to intracardiac mechanoreceptors being
stimulated by the decreased venous return in the
sitting position. This leads to decreased sympathetic tone and increased
parasympathetic tone. Breathing is still present with this reflex. Block of the
stellate ganglion would produce Horner
syndrome, which is not associated with breathing abnormalities. Injection into
the intrathecal space is uncommon, but possible (especially if the needle is
not pointed in the caudal direction), and would lead to a total spinal block
with little local anesthetic injected (e.g., hypotension, bradycardia, and
respiratory paralysis that would lead to cyanosis).
MCQ 30 Explanation
Correct Answer: C Unilateral numbness or paresthesia in the upper extremity
during extension of the neck usually represents nerve root impingement at the
vertebral foramina. C6 nerve distribution is the thumb. Specifically,
unilateral degenerative changes restrict the foramen to such a degree that it
compresses and irritates the nerve root traversing the vertebral foramen when
the head is extended. Treatment ranges from NSAIDs to steroids and may require
surgical intervention if there is muscle weakness. Lhermitte sign, named after Jean Lhermitte, occurs when head flexion causes
shooting sensations down the back and into the lower limbs. It is a sign of
posterior column disease (Miller: Miller’s Anesthesia, ed 8, p 1725).
MCQ 31 Explanation
Correct Answer: A
·
Five nerves
are blocked for an ankle block: saphenous, superficial peroneal, sural,
posterior tibial, and deep peroneal. The first three are purely sensory and are
not used for nerve stimulation localization.
·
The posterior
tibial nerve is the primary target for localization using a nerve stimulator
(causing toe flexion/abduction) and is essential for plantar foot sensation. It
is often difficult to block or stimulate in patients with diabetic neuropathy.
·
The deep
peroneal nerve is motor (causing toe extension) and sensory to the first
interdigital cleft. Many anesthesiologists opt for a pure infiltration block
for all nerves for practical reasons.
MCQ 32 Explanation
Correct Answer: C Spinal
hematomas can have catastrophic consequences, and knowledge of the waiting time
after cessation of the various antiplatelet and anticoagulant drugs is
paramount. American Society of Regional Anesthesia (ASRA) has published
guidelines for anticoagulants and neuraxial anesthesia. Ticlopidine should be
stopped 14 days, clopidogrel for 7 days, and abdiximab for 8–48 hours before
the administration of a spinal or epidural anesthetic. No delay is needed for a
patient taking aspirin or NSAIDs (Miller: Basics of Anesthesia, ed 7, p 282).
MCQ 33 Explanation
Correct Answer: D All of the
choices listed are potential complications of stellate ganglion blockade except
an increase in heart rate. The stellate ganglion supplies sympathetic fibers to
the upper extremity and head and some to the heart. Loss of the cardiac
accelerator fibers may slow the heart rate, not speed it up. Other potential
complications of stellate ganglion blockade include accidental injection of the
local anesthetic into a vertebral artery, resulting in seizure, phrenic nerve
paralysis, and inadvertent cervical epidural (Miller: Miller’s Anesthesia, ed
8, p 1732).
MCQ 34 Explanation
Correct Answer: B Under
sevoflurane general anesthesia, an increase in the T-wave amplitude of 25%
(usually in lead II), an increase in heart rate of 10 beats/min, or a systolic
blood pressure increase of greater than 15 mm Hg is considered a positive dose
response to an epinephrine-containing local anesthetic solution. As always,
slow incremental dosing is safer than a large bolus dose (Miller: Miller’s
Anesthesia, ed 8, p 2721).
MCQ 35 Explanation
Correct Answer: A Procaine and
2-chloroprocaine have a short duration of action; lidocaine, mepivacaine, and
prilocaine have an intermediate duration of action; and etidocaine,
bupivacaine, levobupivacaine, tetracaine, and ropivacaine have a long duration
of action. For similar sensory anesthesia, a higher concentration of local
anesthetic is needed for the short duration of local anesthetics compared with
both the intermediate- and long-duration agents,
because they are less potent (Miller: Miller’s Anesthesia, ed 8, pp 1710–1711).
MCQ 36 Explanation
Correct Answer: B
·
Topical
Use: Lidocaine, tetracaine, cocaine, dibucaine, benzocaine, and EMLA are
effective. Most local anesthetics are suitable for infiltration/epidural use, except for
cocaine and benzocaine.
·
IV
Regional Anesthesia (Bier Block): Lidocaine and prilocaine are preferred for
safety. Esters (due to breakdown/thrombophlebitis) and bupivacaine (due to risk
of CV collapse) are contraindicated for this
technique.
MCQ 37 Explanation
Correct Answer: D
·
Opioids
(Fentanyl, Morphine, etc.) are the primary adjuncts, enhancing surgical
anesthesia and providing post-op relief; short-acting agents are used for
outpatient surgery, while long-acting agents are used for inpatients.
·
alpha-Agonists
(Phenylephrine, Clonidine, Epinephrine) provide mild analgesic activity (less
than opioids) and may enhance local anesthetic effects, but carry a risk of
hypotension; Clonidine is effective as a sole analgesic.
MCQ 38 Explanation
Correct Answer: D Adding sodium bicarbonate to local anesthetic solutions
hastens the onset of action of the local anesthetics, especially when the local
anesthetic solution contains epinephrine (which is produced at a lower pH). By
raising the pH, more of the local anesthetic is in the nonionized, more
lipid-soluble state. Raising the pH too much (i.e., > 6.05-8) would cause
precipitation of the local anesthetic. Some studies have shown that
alkalization of the local anesthetic may decrease the duration of a
peripheral block, especially if epinephrine was not added. It also seems to
decrease pain with skin infiltration. Pain on injection can also be decreased
by a slow injection of the local anesthetic (Miller: Miller’s Anesthesia, ed 8,
p 1040).
MCQ 39 Explanation
Correct Answer: B (B) NSAIDs,
ticlopidine, and clopidogrel exert effects on platelet function. NSAIDs are not
a problem if given alone before epidural or spinal anesthesia; however, before
having a neuraxial block placed, patients taking ticlopidine should wait 14
days, and patients taking clopidogrel should wait 7 days, because of the
increased risk of spinal hematoma formation. Keep in mind that caution is
always needed and that the ASRA statement “Careful preoperative assessment of
the patient to identify alterations of health that might contribute to bleeding
is crucial” is important (Miller: Basics of Anesthesia, ed 7, p 282, Table
17-1; Barash: Clinical Anesthesia, ed 8, pp 570–571).
MCQ 40 Explanation
Correct Answer: D Para-aminobenzoic acid is a metabolite of the ester-type local
anesthetics. Local anesthetics may be placed into two distinct categories based
on their chemical structure: amino esters or amino amides. The amides (two i’s
in the name), which are ropivacaine, lidocaine, etidocaine, prilocaine, mepivacaine, and bupivacaine, are metabolized in the
liver. The ester local anesthetics (one i in the name) are cocaine, procaine,
chloroprocaine, tetracaine, and benzocaine. These drugs are metabolized by the
enzyme pseudocholinesterase found in the blood. Para-aminobenzoic acid is a
metabolic breakdown product of ester anesthetic and is responsible for allergic
reactions in some individuals (Barash: Clinical Anesthesia, ed 8, p
569).
MCQ 41 Explanation
Correct
Answer: C All of the nerves of the foot (with the exception of the
saphenous) are derived from the sciatic nerve. The sciatic nerve distally becomes
the tibial and peroneal nerves, which can be blocked at the popliteal fossa for
surgery below the knee. The saphenous nerve is a branch of the femoral nerve
and provides sensory innervation along the medial aspect of the lower leg
between the knee and the medial malleolus, and must also be blocked for surgery
below the knee (Barash: Clinical Anesthesia, ed 8, pp 991–993).
MCQ 42 Explanation
Correct
Answer: A The duration of regional blocks differs among local anesthetics,
as well as among block locations. When bupivacaine with epinephrine (1:200,000) is used, epidural anesthesia may last 180 to 350 minutes;
infiltration anesthesia may last 180 to 240 minutes; and major nerve blocks
such as axillary block may last 360 to 720 minutes. Spinal bupivacaine without
epinephrin
MCQ
43 Explanation
Correct
Answer: B Younger adults have a higher incidence of PDPH than older adults
or children. Women have a slightly higher incidence than men. Pregnant women
have a higher incidence than nonpregnant women. Since the incidence and
severity of PDPH relate to the amount of CSF leakage through the dural hole, it
makes sense that the larger the needle and the more holes in the dura, the
greater the incidence of PDPH. In addition, the shape of the tip of the needle
is important: A cutting needle (e.g., Quincke) has a greater incidence of PDPH
than a noncutting needle (e.g., Whitacre, Sprotte).
MCQ 44 Explanation
Correct
Answer: D TNS, previously called transient radicular irritation (TRI), can
occur in 4% to 40% of patients after spinal anesthesia
with lidocaine, in ambulatory patients undergoing surgery in the lithotomy
position, or undergoing knee arthroscopy. The baricity, concentration injected
(lidocaine 0.5%-5%), addition of epinephrine, presenc
MCQ
45 Explanation
Correct
answer A
Duloxetine belongs to a class of medications known as Serotonin-Norepinephrine Reuptake Inhibitors (SNRIs).
Its mechanism of action in treating neuropathic pain is as follows:
·
Mechanism of Action: Duloxetine
works by selectively inhibiting the reuptake of both serotonin and
norepinephrine in the central nervous system. By keeping higher levels of these
neurotransmitters in the synaptic cleft, it enhances the descending inhibitory pain
pathways in the spinal cord, which helps dampen the transmission of pain
signals.
·
Clinical Use: In the field of anesthesia and
pain management, it is frequently used to treat conditions like diabetic
peripheral neuropathy, fibromyalgia, and chronic musculoskeletal pain.
MCQ 46 Explanation
Correct
Answer: B Radiofrequency needles are placed along posterior vertebral
elements, avoiding the epidural space; spinal cord stimulation requires a trial
followed by permanent implantation if successful. For stimulation, a Touhy
needle places electrodes in the epidural space under fluoroscopy, while
vertebroplasty treats compression fractures by injecting 2–6 mL of
polymethylmethacrylate cement.
MCQ 47 Explanation
Correct
Answer: D Anesthetic-related nerve injuries to the brachial plexus are rare
and poorly understood. The only way to minimize nerve injury is to minimize
trauma to neural fibers. Although ultrasound-guided technique is promising,
currently there is no clinical evidence for this (Neal et al: Upper extremity
regional anesthesia: Essentials of our current understanding, 2008, Reg Anesth
Pain Med 34:134–170, 2009; Miller: Miller’s Anesthesia, ed 8, p 1049).
MCQ 48 Explanation
Correct
Answer: A Postdural puncture headaches (PDPHs) (spinal headaches) usually
develop within 12 to 72 hours after a dural puncture but may develop
immediately or take months to develop. The most characteristic symptom is a
postural component in which the headache occurs in the upright position and is
usually completely gone when the patient is in the supine position. The
headache is typically frontal and/or occipital in location. Other symptoms
include nausea, vomiting, anorexia, visual disturbances (blurred vision, double
vision, photophobia), and occasionally hearing loss (routinely found with
auditory testing) (Barash: Clinical Anesthesia, ed 8, pp 938–939).
MCQ 49 Explanation
Correct
Answer: C Thoracic paravertebral blocks provide anesthesia and
postoperative analgesia for breast, axillary, and chest wall surgery, with
pneumothorax as the major risk. Typical dosing is 5 mL at three sites for
unilateral blocks or 3 mL at six sites for bilateral blocks; epidural or
intrathecal spread may occur if large volumes or medial needle placement are
used. Sympathetic chain blockade can develop, making hypotension more likely
than hypertension.
MCQ 50 Explanation
Correct
Answer: A Celiac plexus block–induced sympathectomy may cause hypotension
from reduced preload, preventable with IV fluid loading; unopposed
parasympathetic activity can cause transient diarrhea and increased GI
activity. Back pain is common, while rare but serious complications include
paraplegia, seizures from intravascular injection, and retroperitoneal
hematoma.
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