EDAIC Regional Anesthesia and Pain Management 4 — Questions and Answers
Question 1: What is the primary advantage of ropivacaine over bupivacaine for continuous peripheral nerve blocks?
- Longer duration of action
- Greater motor sparing at equivalent analgesic concentrations (Correct answer)
- Lower cost
- Faster onset of action
Correct answer: Greater motor sparing at equivalent analgesic concentrations
Ropivacaine has less lipid solubility than bupivacaine, resulting in more differential sensory-motor block and a significantly lower risk of cardiotoxicity with accidental intravascular injection.
Question 2: In ultrasound-guided femoral nerve block, where is the nerve typically located relative to the femoral artery?
- Medial to the femoral artery, within the femoral sheath
- Lateral to the femoral artery, beneath the fascia iliaca (Correct answer)
- Posterior to the femoral vein
- Deep to the femoral artery within the adductor canal
Correct answer: Lateral to the femoral artery, beneath the fascia iliaca
The femoral nerve lies lateral to the femoral artery and deep to the fascia iliaca (but outside the femoral sheath) at the inguinal level.
Question 3: Which opioid is most appropriate for a patient with severe renal impairment requiring analgesia?
- Morphine
- Codeine
- Fentanyl (Correct answer)
- Hydromorphone
Correct answer: Fentanyl
Fentanyl has no active renally-cleared metabolites, making it the preferred opioid in renal failure; morphine-6-glucuronide accumulates in renal failure and can cause profound sedation.
Question 4: The erector spinae plane (ESP) block deposits local anesthetic in which anatomical location?
- Within the paravertebral space
- Between the erector spinae muscle and the transverse process (Correct answer)
- Between the internal intercostal membrane and the parietal pleura
- Within the epidural space via paramedian approach
Correct answer: Between the erector spinae muscle and the transverse process
The ESP block injects local anesthetic into the fascial plane between the erector spinae muscles (multifidus/longissimus) and the tip of the transverse process, where it can spread to block dorsal and ventral rami.
Question 5: A patient develops ringing in the ears, perioral numbness, and metallic taste during a scalp nerve block. What is the immediate management priority?
- Administer IV diphenhydramine for allergic reaction
- Stop injection, administer IV lipid emulsion if seizures develop (Correct answer)
- Increase the rate of local anesthetic injection to dilute the dose
- Perform immediate endotracheal intubation
Correct answer: Stop injection, administer IV lipid emulsion if seizures develop
These are early CNS signs of local anesthetic systemic toxicity (LAST); injection should be stopped immediately and 20% lipid emulsion (1.5 mL/kg bolus) should be prepared for administration if cardiovascular or neurological deterioration occurs.
Question 6: Which mechanism explains the analgesic effect of intrathecal clonidine?
- Mu-opioid receptor activation in the dorsal horn
- Alpha-2 adrenergic receptor activation inhibiting substance P release in the spinal cord (Correct answer)
- NMDA receptor blockade at the dorsal horn
- Sodium channel blockade of primary afferent fibers
Correct answer: Alpha-2 adrenergic receptor activation inhibiting substance P release in the spinal cord
Clonidine activates spinal alpha-2 adrenergic receptors on presynaptic C-fiber terminals, inhibiting substance P and glutamate release, and on postsynaptic dorsal horn neurons, producing hyperpolarization and analgesia.
Question 7: What is the correct definition of 'chronic pain' according to the International Association for the Study of Pain (IASP)?
- Pain persisting for more than 3 months
- Pain that is unresponsive to opioid therapy
- Pain associated with identifiable tissue damage only
- Pain persisting for more than 6 months or beyond expected healing time (Correct answer)
Correct answer: Pain persisting for more than 6 months or beyond expected healing time
The IASP defines chronic pain as pain that persists beyond normal tissue healing time (usually 3 months) or recurs over more than 3-6 months, often reclassified to >3 months in updated criteria.
EDAIC Regional Anesthesia and Pain Management 4
What is the primary advantage of ropivacaine over bupivacaine for continuous peripheral nerve blocks?