Lippincott's Anesthesia Review: 1001 Questions and Answers
Chapter 8. Peripheral Nerve Blocks
1. An 85-year-old male is scheduled for a right distal radius and ulnar open reduction interior fixation at the wrist. Medical history is significant for chronic obstructive pulmonary disease dependent on 2 L of oxygen, hypertension, diabetes mellitus, and coronary artery disease with a stent inserted one year ago. Given that the surgeon plans to use a forearm tourniquet, the regional anesthesia technique that would be most appropriate for this patient is
A. An interscalene brachial plexus block plus an intercostal brachial nerve block
B. A supraclavicular approach to the brachial plexus plus an intercostal brachial nerve block
C. An infraclavicular block of the brachial plexus at the cords plus an intercostal brachial nerve block
D. Superficial cervical plexus blockade plus an intercostal brachial nerve block
2. While performing an axillary brachial plexus block, all of the following nerves are spared, except
A. Musculocutaneous nerve
B. Ulnar nerve
C. Lateral brachial cutaneous nerve
D. Medial brachial cutaneous nerve
3. Contraindications to safely perform peripheral regional anesthesia include all of the following, except
A. Patients who may not provide absolute cooperation during nerve block placement (mental retardation) without administration of sedation
B. Patient refusal
C. Severe coagulopathy while anticipating a deep nerve plexus blockade
D. Evidence of infection at injection site
4. While performing a peripheral nerve block in an awake patient, access and/or use of all of the following should be considered mandatory, except
A. Administer supplemental oxygen
B. Apply standard ASA monitors
C. Access to resuscitation medications and equipment
D. Immediate access to a mechanical ventilator
5. The most correct statement regarding the appropriate use of ultrasound equipment during performance of regional anesthesia is
A. Higher frequency ultrasound probes are used for deeper penetration
B. High-frequency ultrasound probes provide for higher image resolution
C. Liner array probes are typically used for imaging deeper anatomical structures
D. The curvilinear probe is designed to best image superficial structures
6. Which of the following nerves is typically spared during performance of an interscalene brachial plexus block?
7. Following successful performance of a right interscalene block for surgical rotator cuff repair in a 27-year-old patient with no other medical issues, you are called to the recovery room (post–anesthesia care unit) 3 hours later to evaluate the patient. The patient’s symptoms include drooping of the right eyelid, redness of the conjunctiva, and pupillary constriction. The most likely diagnosis is
A. Spinal anesthesia
B. Subdural injection of local anesthetic
C. Horner syndrome
D. Cerebrovascular accident (CVA)
8. A supraclavicular block of the brachial plexus does not provide consistent surgical anesthesia for shoulder surgery secondary to potential sparing of which of the following nerve branches of the brachial plexus?
A. Musculocutaneous and axillary nerve branches
B. Axillary and suprascapular nerve branches
C. Ulnar and axillary nerve branches
D. Suprascapular and supraclavicular nerve branches
9. Performing an infraclavicular approach for brachial plexus blockade would deposit local anesthetics at which of the following anatomical levels of the plexus?
10. A supraclavicular approach for brachial plexus blockade would deposit local anesthetics at which of the following anatomical levels of the plexus?
11. When performing an axillary block of the brachial plexus for distal upper extremity surgery, which of the following nerves most often needs to be targeted separately?
12. Anatomical location of the musculocutaneous nerve in the upper forearm is most frequently found within which of the following muscles?
A. Triceps brachii
B. Biceps brachii
13. While performing an ultrasound-guided axillary nerve block along with a nerve stimulator, your needle tip is imaged inferior to the pulsating axillary artery, and you see evidence of flexion of fourth and fifth digits. The stimulating needle tip is in closest proximity to which of the following peripheral nerve branches of the brachial plexus?
14. During placement of an ultrasound-guided and nerve stimulator–assisted axillary nerve block, your needle tip is imaged superiorly to the axillary artery. You also see pronation of the patient’s forearm. The needle tip is in closest proximity to which of the following branches of the brachial plexus?
A. Median nerve
B. Axillary nerve
C. Musculocutaneous nerve
D. Interscalene nerve
15. While performing an axillary nerve block by both ultrasound guidance and nerve-stimulator assistance, the image of your needle tip is seen posterior to axillary artery, and you observe supination of the forearm. The needle tip is closest to which of the following brachial plexus nerve branches?
A. Infraclavicular nerve
C. Intercostal brachial nerve
D. Radial nerve
16. After performing an axillary peripheral nerve block, your ultrasound probe moves to scan laterally and you see what appears to be an oval and hyperechoic nerve structure within the belly of the coracobrachialis muscle. When the needle tip is advanced closer to this structure and the nerve stimulator is activated, you notice that the elbow begins to flex. The most likely nerve branch that is being stimulated is
A. Median nerve
B. Triceps brachii nerve
C. Musculocutaneous nerve
D. Radial nerve
17. You successfully perform a right supraclavicular nerve block for a right wrist open reduction interior fixation. You are called to the post–anesthesia care unit 2 hours later because the patient is complaining of pain on the back of the wrist, which extends distal to the index, middle, and ring fingers on the dorsal surface of the hand. You consent the patient to perform a terminal branch nerve block to supplement the initial block. The nerve that would be needed to be blocked is
A. Median nerve
B. Radial nerve
C. Infraclavicular nerve
D. Interscalene nerve
18. You have just successfully performed a Bier block using 50 mL 0.5% lidocaine for carpal tunnel release surgery in a 45-year-old male (height, 6 ft; weight, 200 lb). The patient was sedated with 2 mg of midazolam upon arrival to the OR. Ten minutes following the local anesthetic placement, the surgeon indicates that the surgery is finished. At the surgeon’s request, the nurse releases the tourniquet that was placed on the upper arm. The patient soon becomes agitated, and you notice twitching of the patient’s arms and legs. The most likely diagnosis is
A. Anaphylaxis to midazolam
B. New-onset seizure disorder
C. Allergic reaction to the local anesthetic
D. Local anesthetic systemic toxicity (LAST)
19. A properly performed lumbar plexus block will result in blockade of all the following nerve branches, except
A. Femoral nerve
B. Lateral femoral cutaneous nerve
C. Obturator nerve
D. Sciatic nerve
20. Electrical nerve stimulation of which of the following nerves will produce quadriceps muscle contraction?
A. Femoral nerve
B. Sciatic nerve
C. Lateral femoral cutaneous nerve
D. Obturator nerve
21. You have just performed a femoral nerve block in preparation for a tibial plateau fracture repair using 20 mL 0.5% ropivacaine. Three hours postsurgery in the recovery room, the patient complains of lateral thigh pain. Was the femoral nerve block a failure and what would be the most appropriate action?
A. Yes, repeat the femoral nerve block due to a failed block
B. No, repeat the femoral nerve block as the effectiveness of the local anesthetic has worn off after 4 hours
C. No, the pain expressed is not located within the distribution of the femoral nerve, supplement with a lateral femoral cutaneous nerve block
D. Yes, the pain is due to a failed femoral block, but do not repeat the block as there exists a high risk of nerve injury
22. A properly placed psoas compartment block or posterior lumbar plexus block can be associated with any of the following complications, except
A. Retroperitoneal hematoma
B. Spinal anesthesia
C. Local anesthetic systemic toxicity
D. Sciatic nerve injury
23. You are consulted on an ASA IV patient for a right-ankle surgery. The patient has a known history of difficult intubation and status post–spinal fusion surgery. The surgeon is requesting for a peripheral nerve block that will provide for surgical anesthesia. Which of the following nerves will need to be blocked in order to provide for complete anesthesia during performance of foot and ankle surgery?
A. Both sciatic and femoral nerve blockade
B. Sciatic nerve block alone
C. Femoral nerve block alone
D. Sciatic, femoral, and obturator nerve blocks
24. All of the following nerves provide sensory innervation to the foot, except
A. Lateral femoral cutaneous nerve
B. Sural nerve
C. Deep peroneal nerve
D. Superficial peroneal nerve
25. The most correct statement concerning a unilateral paravertebral block is
A. Such a block is always associated with a similar degree of sympathectomy as with an epidural block
B. Such a block is often associated with a higher serum level of local anesthetic than that achieved with an intercostal nerve block due to high vascularity
C. It is not likely to be associated with a pneumothorax
D. Such a block may be associated with epidural spread of local anesthetic
26. The most incorrect statement regarding transversus abdominis plane (TAP) block is
A. TAP blocks can provide analgesia following hernia repair surgeries
B. TAP blocks can often alleviate both somatic and visceral pain
C. One potential complication includes liver injury
D. Unilateral TAP blocks never cross over the midline
27. When performing a transversus abdominis plane (TAP) block, the goal is to deposit/inject local anesthetic between which of the following two muscle layers?
A. External oblique and internal oblique muscles
B. Internal oblique and transversus abdominis muscles
C. Transversus abdominis and external oblique muscles
D. Rectus abdominis and external oblique muscles
28. While performing the popliteal approach for a sciatic nerve block under ultrasound guidance, you are able to identify the popliteal artery adjacent to two hyperechoic nerve structures that appear to become one nerve structure upon proximal movement of the ultrasound probe placed within the popliteal fossa. The correct identity of the two nerve branches is
A. The nerve on the lateral side is the common peroneal nerve, and the nerve on the medial side is the tibial nerve (combined nerve is the sciatic nerve)
B. The nerve on the lateral side is the sciatic nerve, and nerve on the medial side is the deep peroneal nerve (combined nerve is the femoral nerve)
C. The nerve on the lateral side is the common tibial nerve, and nerve on the medial is the superficial peroneal nerve (combined nerve is the sciatic nerve)
D. The nerve on the lateral side is the common posterior tibial nerve, and the nerve on the medial side is the superficial peroneal nerve (combined nerve is the femoral nerve)
29. The most appropriate statement regarding the function of the saphenous nerve is
A. It serves as both a motor nerve and a sensory nerve
B. It is the motor terminal branch of the femoral nerve
C. It is the sensory terminal branch of the femoral nerve
D. It is a sensory terminal branch of the sciatic nerve
30. An interscalene block will typically deposit the local anesthetic between which of the following two muscles?
A. Anterior and middle scalene muscles
B. Middle and posterior scalene muscles
C. Anterior and posterior scalene muscles
D. Sternocleidomastoid and anterior scalene muscles
31. A 45-year-old healthy male is scheduled for bilateral elbow open reduction interior fixation secondary to a motor vehicle accident. Successful bilateral supraclavicular blocks were planned and performed under ultrasound guidance, with 20 mL 0.5% ropivacaine injected for each block on each side. In the operating room, the patient is receiving 25 μg/kg/min of a propofol infusion and oxygen via a non-rebreather bag. The patient also received 2 mg of midazolam, but no opioids. Thirty minutes after incision, the patient is experiencing progressive respiratory depression, and the oxygen saturation decreases from 100% to 85%. The most likely diagnosis is
A. Local anesthetic systemic toxicity (LAST)
B. Dysfunction of the diaphragm (diaphragm palsy)
D. Aspiration pneumonia
32. The most appropriate treatment for the patient in the above scenario is
A. Methylene blue due to local anesthetic systemic toxicity
B. Flumazenil to antagonize midazolam (oversedation)
C. Endotracheal intubation to provide respiratory support
D. Antibiotics to treat aspiration pneumonia
33. A 56-year-old woman is scheduled for a right total knee replacement. She has a medical history of hypertension, diabetes mellitus, obesity, and is status post L1–L5 vertebral fusion. The regional anesthetic technique that will provide her the most optimal perioperative pain management is
A. A femoral nerve block and an epidural
B. A femoral and proximal sciatic nerve block
C. Both a femoral and popliteal sciatic nerve block
D. A sciatic nerve block and a spinal
34. A 65-year-old female is scheduled for a right total shoulder replacement. Under ultrasound guidance, you perform a right interscalene nerve block and place a catheter for continuous local anesthetic infiltration planned for 3 days. One week later, the patient complains of persistent parasthesia of the entire right arm, including the wrist, hand, and all fingers (from the shoulder to the fingers). An MRI shows a diffuse swelling of the brachial plexus at the level of the cords. The most likely diagnosis is
A. Direct nerve injury/trauma from the block needle used
B. Irritation of the brachial plexus at the level of the branches from the continuous peripheral nerve catheter
C. Surgical trauma/manipulation of the brachial plexus at the level of the cords
D. Local anesthetic toxicity of the brachial plexus at the level of the roots/trunks
35. The foot is supplied mainly by which of the following nerve(s)?
A. Sciatic nerve
B. Obturator and tibial nerves
C. Femoral and lateral femoral cutaneous nerves
D. Saphenous and common peroneal nerves
36. The following local anesthetic medication is associated with the highest risk for cardiovascular collapse in the event of local anesthetic systemic toxicity (LAST)
37. The most appropriate nerve block for pain management in a patient scheduled for a total hip replacement is
A. Femoral nerve block
B. Lumbar plexus block
C. Femoral and obturator nerve block
D. Femoral and lateral femoral cutaneous nerve block
38. The femoral nerve provides sensory innervation to the
A. Lower extremity below the knee
B. Anterior and medial thigh
C. Posterior and medial thigh
D. Almost the entire ankle
39. Sciatic nerve blockade provides sensory loss of the
A. Anterior and lateral thigh
B. Posterior thigh and majority of the leg below the knee
C. Medial and posterior thigh
D. Medial leg below the knee
40. You perform a right-side T3–T5 paravertebral blockade for a patient who is to undergo a right mastectomy with axillary lymph node dissection. Medical history of the patient includes alcohol abuse and panic attacks. After the surgery in the post–anesthesia care unit, the patient complains of a new-onset right-arm paresthesia. Vital signs remain stable along with strong and equal upper extremity bilateral pulses. The most likely diagnosis is
A. Surgery-related brachial plexus nerve injury and/or positional injury
B. The patient is experiencing withdrawal from alcohol
C. Side effects/complications of the paravertebral block on the brachial plexus
D. Patient is having a panic attack
41. You successfully perform and place a bilateral T8 continuous paravertebral block catheters for an open–partial hepatectomy. Eighteen hours postoperatively, the patient complains of 7/10 pain. To improve postoperative analgesia, 10 mL of 0.2% ropivacaine is administered through each catheter. Twenty minutes later, the patient indicates that the pain has decreased to 4/10. The most likely aspect of paravertebral blockade that can account for the reason why the patient did not achieve a pain-free condition is
A. The block level was too high; it should have been placed at the T10 level
B. The block level is too low; it should have been placed at the T6 level
C. Paravertebral blockade analgesia provides for mostly somatic blockade and does not provide for complete coverage of visceral pain
D. The local anesthetic volume administered is too small
42. A patient is to undergo surgery to create an arteriovenous fistula for hemodialysis on the antecubital area of the right upper extremity. You perform a right supraclavicular block uneventfully using 20 mL 0.5% ropivacaine. The patient has a medical history significant for hypertension and end-stage renal disease. Three days following the surgery, the patient complains that she has no sensation from the right elbow to the tips of all her fingers, but she can move all of her fingers normally. The most likely etiology is
A. Neurotoxicity of the trunks/divisions of the brachial plexus secondary to the ropivacaine
B. Nerve injury secondary to the regional block needle used
C. Prolonged effect of the local anesthetic secondary to the patient’s renal failure
D. Possible surgery-related injury at the elbow that may warrant an electrophysiology study
43. While performing an axillary brachial plexus blockade, the goal is to deposit local anesthetic medications at what location of the brachial plexus and to target which specific nerve structures?
A. Level of the branches and targeting the radial, median, and ulnar peripheral nerves
B. Level of the trunks and targeting the interscalene, radial, and ulnar peripheral nerves
C. Level of the divisions and targeting the supraclavicular, median, and radial peripheral nerves
D. Level of the cords and targeting the infraclavicular, ulnar, and radial peripheral nerves
44. Which of the following approaches to blockade of the brachial plexus is associated with the highest incidence of a pneumothorax?
A. Interscalene and axillary approaches
B. Supraclavicular and interscalene approaches
C. Infraclavicular and axillary approaches
D. Axillary and interscalene approaches
45. All of the following medication adjuvants can be used in combination with local anesthetic solutions during performance of a peripheral nerve blockade to extend the duration/effectiveness of nerve blockade, except
46. While performing a femoral nerve block guided with a nerve stimulator, you observe a strong sartorius muscle twitch that disappears at 0.2 mA. What does this mean and how should you proceed further?
A. The stimulating block needle tip is in the correct position, and the local anesthetic can be injected
B. The needle tip is likely superficial to the femoral nerve, and the block needle needs to be readjusted (twitch may not be from stimulation of the femoral nerve) prior to local anesthetic injection
C. Sartorius muscle twitch indicates that the needle tip is in the correct location, but you need to get closer to the nerve as 0.2 mA stimulus is too high
D. The block needle needs to be repositioned more medially, and a paresthesia must be elicited prior to local anesthetic injection
47. The trauma team in the ICU did not want a thoracic epidural placed on a trauma patient with bilateral rib fractures secondary to concerns about the potential hemodynamic instability that may result. Therefore, both right T7 and left T5 continuous paravertebral catheters were successfully placed for this patient under ultrasound guidance. Twenty minutes following the administration of 10 mL of 0.2% ropivacaine administered through each catheter (following evidence of negative aspiration), the systolic blood pressure dropped by 50 mm Hg. The most likely diagnosis is
A. Performance of paravertebral blockade creates identical concerns about potential hemodynamic compromise as do thoracic epidural blocks
B. Local anesthetic toxicity as the paravertebral space is very vascular
C. Possible epidural spread of local anesthetics from either one or both the paravertebral catheters
D. Venous bleeding into the paravertebral space resulting in large volumes of local anesthetic absorption from the paravertebral blocks
CHAPTER 8 ANSWERS
1. C. In a patient with severe pulmonary compromise, performing either an interscalene or supraclavicular block of the brachial plexus should be approached with caution secondary to the increased risk of an ipsilateral phrenic nerve palsy. Placement of an interscalene block for wrist surgery may also not be optimal as it may not effectively block the ulnar nerve distribution to the wrist. A superficial cervical plexus block (C1–C4) will not effectively provide anesthesia/analgesia to the wrist. Both infraclavicular and axillary approaches to the brachial plexus would be appropriate for wrist surgery, along with a reduced incidence of adverse effects on the phrenic nerve. Intercostobrachial nerve blockade is added to cover the T2 dermatome distribution that is not included in a properly performed brachial plexus block and will contribute to alleviating tourniquet discomfort in the medial portion of the upper arm.
2. B. The musculocutaneous and medial brachial cutaneous nerves branch from the brachial plexus at a more proximal location than can be consistently anesthetized with an axillary nerve block approach of the brachial plexus. Therefore, these nerve branches need to be blocked separately if they innervate the planned surgical area. The lateral brachial cutaneous nerve is a branch of musculocutaneous nerve.
3. A. Patient refusal is an absolute contraindication following informed consent. Evidence of anticipated injection-site infection and severe coagulopathy are considered relative contraindications, and risk-to-benefit analysis needs to be carefully considered. Non-cooperative patients can often pose an increased risk to patient/operator safety, but it is not an absolute contraindication to performing regional anesthesia.
4. D. Regional anesthesia should be administered in a monitored location where standard ASA monitors. Supplemental oxygen along with resuscitative medications and equipment should be readily accessible and immediately available. However, immediate access to a functioning anesthesia ventilator is not always necessary.
5. B. High-frequency ultrasound probes are typically manufactured with a liner probe design and provide high image resolution used for superficial anatomical structures. Low-frequency ultrasound probe equipment is typically produced with a curvilinear probe design and reveals a lower image resolution, but is used for visualizing deeper anatomical structures secondary to better penetration.
6. D. The ulnar nerve branch originates from the C8–T1 nerve roots. Properly performed interscalene approach to brachial plexus blockade can provide for a dense blockade of the C5–C7 nerve roots/trunks and less consistent blockade of the C8–T1 nerve roots/trunks. Therefore, an interscalene approach to blockade of the brachial plexus for distal upper extremity surgical procedures may not be the most ideal approach.
7. C. A Horner syndrome (miosis, ptosis, and anhidrosis) can be commonly seen following an interscalene block. This syndrome is often due to proximal tracking of local anesthetic and blockade of the sympathetic fibers to the cervicothoracic ganglion. In patients where a CVA may also be within the differential diagnosis, a thorough history and neural exam should always be included.
8. B. A supraclavicular approach to brachial plexus blockade does not consistently and reliably provide anesthesia/analgesia to the axillary and suprascapular nerve branches. Therefore, a supraclavicular block can be used for postoperative analgesia, but may not be ideal for surgical anesthesia during invasive shoulder procedures. Sparing of ulnar nerve during a supraclavicular block may also occur that would not provide effective anesthesia for procedures distal to the mid-humerus.
9. C. At the infraclavicular level, the brachial plexus forms three cords in relation to axillary artery and named according to their position around the artery: medial, lateral, and posterior cords.
10. B. Supraclavicular blockade of the brachial plexus is often referred to as the “spinal anesthesia” of the upper extremity. It provides anesthesia of the brachial plexus distal to the roots and proximal to the cords of the plexus. There has been an increased practice of performing the supraclavicular approach to blockade of the brachial plexus secondary to the introduction of ultrasound into clinical practice as anesthesiologists can now appreciate a decreased incidence of pneumothorax under real-time ultrasound guidance.
11. C. The musculocutaneous nerve typically branches off more proximal to the axillary approach of brachial plexus blockade and is frequently not adequately anesthetized with a traditional axillary block of the plexus (local anesthetics are deposited around the axillary artery). Therefore, the musculocutaneous nerve must be targeted separately when performing an axillary block of the brachial plexus for distal upper extremity surgery.
12. C. Although some anatomical variation can be found with the brachial plexus at the level of the axilla, the musculocutaneous nerve is most commonly positioned within the coracobrachialis muscle or between the bellies of the biceps and coracobrachialis muscles.
13. B. Some anatomical variation can exist, but the ulnar nerve is frequently positioned inferior to the axillary artery. Stimulation of the ulnar nerve will cause wrist flexion, flexion of the fourth and fifth digits, and thumb adduction.
14. A. The median nerve is most frequently positioned superior to the axillary artery (with some anatomical variations). Stimulation of the median nerve will cause muscle stimulation, creating wrist flexion, thumb opposition, and forearm pronation.
15. D. Despite some anatomical variations within the nerve-branch distribution of the brachial plexus around the axillary artery, the radial nerve is most frequently positioned posterior to axillary artery. Stimulator of radial nerve will induce digit/wrist/elbow extension and forearm supination.
16. C. Musculocutaneous nerve is frequently found within coracobrachialis muscle and/or between the biceps and coracobrachialis muscles. Stimulation of the musculocutaneous nerve will characteristically cause elbow flexion.
17. B. The sensory distribution on the dorsal surface of the hand described in the question matches the innervation provided by the radial nerve. Therefore, a terminal nerve block anywhere along the distribution of the radial nerve proximal to the wrist would be an appropriate place to supplement the initial brachial plexus block.
18. D. LAST can occur when a large volume of local anesthetic is absorbed into or directly injected into the systemic circulation. A Bier block can provide surgical anesthesia for short procedures of the extremity, lasting 60 minutes or less. However, patients may complain of tourniquet pain that can become evident as early as 20 minutes following block performance. In order to prevent or reduce the incidence of LAST, the tourniquet needs to remain inflated and in position for a minimum of 15 to 20 minutes even if the surgical procedure finishes early. Even after 15 to 20 minutes has elapsed, cautious, intermittent, and slow release of tourniquet is recommended.
19. D. The three major nerve branches of the lumbar plexus that are affected by such a block include femoral, lateral femoral cutaneous, and obturator nerves. Sciatic nerve originates from the sacral plexus and is not part of the lumber plexus.
20. A. The femoral nerve provides motor supply to the quadriceps muscles and sensory supply to portion of the medial thigh. The femoral nerve does not have any motor components below the knee (only a sensory branch, saphenous nerve, below the knee).
21. C. The lateral femoral cutaneous nerve supplies the lateral portion of the thigh. Blockade of the lateral femoral cutaneous nerve is not always consistently blocked with femoral nerve block approach, but can be blocked separately if/when needed.
22. D. A lumbar plexus block is considered a deep block and has been described as an advanced block in regional anesthesia. Some potential complications include retroperitoneal hematoma, local anesthetic systemic toxicity, intrathecal and/or epidural injections of local anesthetics, and renal injury (with potential for subsequent hematoma). The typical approach for lumbar plexus blockade should not cause injury to the sciatic nerve unless an improperly placed or misdirected regional block needle is positioned too caudad that could then result in injury to sacral plexus and the sciatic nerve.
23. A. For complete surgical anesthesia of the foot and ankle, both sciatic and femoral/saphenous nerves need to be anesthetized/blocked. The obturator nerve does not provide sensory or motor nerve distribution to foot or ankle.
24. A. An ankle block can be performed by providing anesthesia and blocking the five nerves that innervate the foot, namely, the superficial and deep peroneal nerve, saphenous nerve, sural nerve, and posterior tibial nerve.
25. D. Advantages of properly placed paravertebral nerve blocks include reduced degrees of local anesthetic–induced sympathectomy compared to epidural or spinal anesthesia and a lower risk of local anesthetic systemic toxicity as compared with intercostal nerve blocks. However, one of the major concerns for potential complications is development of a pneumothorax, and paravertebral blocks can be associated with variable degrees of local anesthetic epidural spread, especially when placing bilateral paravertebral blocks.
26. B. TAP blocks can provide analgesia for peripheral somatic pain of the abdomen and can be associated with a low yet potential risk of bowel perforation and liver injury. For midline ventral hernia surgery, performing bilateral TAP blocks are often needed. TAP blocks do not cover crappy, visceral pain.
27. B. The subcostal (T12), ilioinguinal (L1), and iliohypogastric (L1), and genitofemoral nerves are targeted when performing a TAP block. These nerves have a typical distribution between the internal oblique and transversus abdominis muscles.
28. A. Popliteal approach to the sciatic nerve block is typically performed at the site of bifurcation of the tibial (medial position) and common peroneal (lateral position) nerves. The sciatic nerve is most optimally blocked with local anesthetic at the union (bifurcation) of these two nerves that frequently become one nerve structure approximately 7 to 10 cm proximal to the popliteal crease.
29. C. The saphenous nerve is a terminal sensory nerve branch of the femoral nerve with NO motor components. Under certain clinical situations, the saphenous nerve is preferentially blocked to avoid motor blockade of the anterior quad muscles that can result from performance of a femoral nerve block (increased risk of fall).
30. A. The brachial plexus nerve root/trunk is usually positioned between the anterior and middle scalene muscles. When local anesthetics are placed between these two muscle bundles, it is commonly referred to as an interscalene block.
31. B. Bilateral supraclavicular blockade can significantly increase the risk of symptomatic phrenic nerve palsy. Methemoglobinemia can happen in patients with certain local anesthetics, but usually not from ropivacaine administration. LAST can occur from administration of toxic doses of any local anesthetic, but is most often an acute event from systemic administration.
32. C. The witnessed respiratory depression is most likely due to diaphragm palsy and the urgent need for ventilation assistance until resolution of phrenic nerve dysfunction. An appropriate option would be to intubate the patient and provide any necessary sedation and then extubation upon evidence of recovery of diaphragm function.
33. B. Femoral and proximal sciatic nerve block together can often provide for excellent perioperative pain control and can facilitate physical therapy with a reduced incidence of interference with ambulation. These peripheral regional techniques can be particularly useful in patients with difficulty or contraindications to neuraxial blockade.
34. C. Shoulder surgery is one of the upper extremity procedures that can often be associated with nerve injuries secondary to patient pathology, surgical manipulation(s), surgical trauma, brachial plexus nerve stretching or compression, etc. If such an injury was due to performance of the peripheral nerve block and/or catheter placement, it often tends to involve more isolated nerve roots/trunks of the brachial plexus from the interscalene approach rather than diffuse influences at more distal levels of the plexus. Surgical complications of the brachial plexus often tend to be more diffuse and less selective. Nerve-conduction studies and EMG should be considered rather than merely delineating an etiology of the injury.
35. A. The sciatic nerve supplies all of the motor innervation and the majority of the sensory innervation to the lower extremities below knee except the medial side of the lower extremity that is innervated by the saphenous nerve.
36. B. Bupivacaine is best known for its high cardiovascular toxicity, although any of the local anesthetic medications listed above can result in LAST. One of the reported advantages of ropivacaine over bupivacaine is its relatively lowered incidence of cardiovascular toxicity. The other listed local anesthetic medications tend to have neurological toxicity prior to progressing toward cardiovascular collapse.
37. B. A femoral block for hip surgical procedures have intrinsic limitations as does not completely cover ALL dermatome distributions of the hip. A properly placed and functioning lumbar plexus blockade/catheter will cover the femoral, obturator, and lateral femoral cutaneous nerve and often provides for better pain control of the hip in conjunction with a sciatic/sacral nerve plexus block.
38. B. The femoral nerve provides sensory innervation to the anterior and medial thigh above the knee, and medial side of the lower extremity below the knee. The femoral nerve innervates and supplies motor control of the anterior quadriceps muscles above the knee and no motor innervation below the knee.
39. B. Sciatic nerve blockade provides sensory loss to the posterior thigh by blocking the posterior cutaneous nerve along with everything below the knee, except for the medical lower leg, which is innervated by the saphenous nerve.
40. A. The most likely cause is secondary to axillary lymph node dissection–related brachial plexus injury. The level of paravertebral blocks was at T3–T5; therefore, the brachial plexus should not be affected (C4–T1) by the paravertebral-injected local anesthetic.
41. C. Paravertebral blockade provides mostly for somatic-induced pain with little visceral pain coverage; therefore, hepatectomy patients need additional pain-management modalities such as opioids.
42. D. Neurologic injuries secondary to positional, compressional, ischemic injury often creates a more diffuse type of an injury pattern similar to the one described in the question. If the neurologic injury were due to complications from placement of a single-shot supraclavicular blockade or local anesthetic used during block placement, then these types of injuries would tend to have a more isolated pattern. Peripheral nerve block injuries from a supraclavicular block would be more likely to result in evidence of an injury pattern isolated to the trunks or divisions of the brachial plexus, and the patient would typically reveal symptoms above elbow as well. Without any adjuvant, ropivacaine block will not last as long as 72 hours.
43. A. Axillary block is typically performed at the level of the individual peripheral nerve branches of the brachial plexus, specifically the radial, median, and ulnar nerves.
44. B. Supraclavicular approach to blockade of the brachial plexus carries a high risk of pneumothorax followed by the interscalene approach. This pneumothorax risk has decreased and is believed to be secondary to the more frequent use of ultrasound-guided regional anesthesia. Now the supraclavicular approach to blockade of the brachial plexus is commonly performed with ultrasound guidance.
45. B. All of the above adjuvant medications, except ketamine, are commonly used in peripheral nerve blocks to improve the density and prolong the duration of nerve blockade efficacy. Ketamine, along with ephedrine, when mixed with local anesthetics during a peripheral nerve block has been studied in animal models and was deemed to offer little to no additional benefits or synergistic effects.
46. B. Sartorius muscle twitch could be secondary to stimulation of a small branch from the femoral nerve that innervates the sartorius muscle or secondary to direct muscle stimulation. The femoral nerve is usually positioned more lateral and deeper to this small branch that originates from the femoral nerve which innervates the sartorius muscle.
47. C. A potential advantage of paravertebral blockade compared to neuraxial blockade is a reduced incidence of creating an intense sympathectomy resulting in hemodynamic compromise. However, when bilateral paravertebral blocks are performed, the potential exists that epidural spread could be significant, resulting in an observation of a moderate BP decrease.