EDAIC Regional Anesthesia and Pain Management 2 — Questions and Answers
Question 1: Which nerve is most commonly injured during interscalene brachial plexus block?
- Phrenic nerve (Correct answer)
- Recurrent laryngeal nerve
- Suprascapular nerve
- Long thoracic nerve
Correct answer: Phrenic nerve
The phrenic nerve (C3-C5) runs adjacent to the brachial plexus at the interscalene level and is blocked in nearly 100% of cases, causing ipsilateral hemidiaphragm paresis.
Question 2: The transversus abdominis plane (TAP) block primarily targets which fascial plane?
- Between external oblique and internal oblique
- Between internal oblique and transversus abdominis (Correct answer)
- Between transversus abdominis and peritoneum
- Between rectus abdominis and posterior rectus sheath
Correct answer: Between internal oblique and transversus abdominis
The TAP block deposits local anesthetic between the internal oblique and transversus abdominis muscles, where the thoracolumbar nerves (T6-L1) travel.
Question 3: Which local anesthetic has the longest duration of action for peripheral nerve blocks?
- Lidocaine
- Ropivacaine
- Bupivacaine (Correct answer)
- Mepivacaine
Correct answer: Bupivacaine
Bupivacaine provides the longest duration (up to 12-18 hours for nerve blocks), though ropivacaine has a similar but slightly shorter duration with a better safety profile.
Question 4: A patient develops sudden hypertension, bradycardia, and loss of consciousness during spinal anesthesia. What is the most likely cause?
- Vasovagal syncope
- Total spinal anesthesia (Correct answer)
- Local anesthetic systemic toxicity
- Anaphylaxis to the local anesthetic
Correct answer: Total spinal anesthesia
Total spinal anesthesia from cephalad spread of intrathecal local anesthetic causes cardiovascular and respiratory depression, including bradycardia from blocking cardiac accelerator fibers and hypotension.
Question 5: What is the maximum recommended dose of lidocaine with epinephrine for peripheral nerve block in adults?
- 3 mg/kg
- 5 mg/kg
- 7 mg/kg (Correct answer)
- 9 mg/kg
Correct answer: 7 mg/kg
With epinephrine (1:200,000), the maximum safe dose of lidocaine is 7 mg/kg due to the vasoconstrictive effect slowing systemic absorption.
Question 6: Which landmark is used for the posterior approach to the lumbar plexus (psoas compartment) block?
- 4 cm lateral to the L4 spinous process
- At the intersection of Tuffier's line and a line 3-4 cm lateral to the spinous processes (Correct answer)
- At the posterior superior iliac spine
- 2 cm medial to the femoral artery at the inguinal ligament
Correct answer: At the intersection of Tuffier's line and a line 3-4 cm lateral to the spinous processes
The Chayen/posterior approach targets the psoas compartment where a needle is inserted at the intersection of Tuffier's line (L4-L5 interspace) and a parasagittal line 3-4 cm lateral to midline.
Question 7: In chronic pain management, what mechanism underlies the analgesic effect of tricyclic antidepressants (TCAs)?
- Opioid receptor agonism
- Inhibition of norepinephrine and serotonin reuptake in descending inhibitory pathways (Correct answer)
- Blockade of voltage-gated sodium channels only
- GABA-A receptor potentiation
Correct answer: Inhibition of norepinephrine and serotonin reuptake in descending inhibitory pathways
TCAs enhance descending pain inhibition by blocking reuptake of norepinephrine and serotonin in the spinal cord, and also have sodium channel blocking properties that contribute to analgesia.
EDAIC Regional Anesthesia and Pain Management 2
Which nerve is most commonly injured during interscalene brachial plexus block?