Regional Anesthesia and Pain Management Flashcards

Which nerve is most commonly injured during interscalene brachial plexus block?

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.

The transversus abdominis plane (TAP) block primarily targets which fascial plane?

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.

Which local anesthetic has the longest duration of action for peripheral nerve blocks?

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.

A patient develops sudden hypertension, bradycardia, and loss of consciousness during spinal anesthesia. What is the most likely cause?

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.

What is the maximum recommended dose of lidocaine with epinephrine for peripheral nerve block in adults?

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.

Which landmark is used for the posterior approach to the lumbar plexus (psoas compartment) block?

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.

In chronic pain management, what mechanism underlies the analgesic effect of tricyclic antidepressants (TCAs)?

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.