Regional Anesthesia and Nerve Blocks Flashcards

What is the first-line treatment for local anesthetic systemic toxicity (LAST) presenting with cardiovascular collapse?

Answer: 20% lipid emulsion (Intralipid) IV

20% lipid emulsion acts as a 'lipid sink' to sequester the lipophilic local anesthetic from cardiac tissues and is the definitive pharmacologic treatment for LAST with cardiovascular collapse, per ASRA guidelines.

Following an epidural top-up dose, a patient develops rapid onset of apnea, unconsciousness, and cardiovascular collapse. What has most likely occurred?

Answer: Total spinal anesthesia from inadvertent subarachnoid injection

Total spinal anesthesia from inadvertent intrathecal injection of an epidural dose causes rapid cephalad spread, blocking respiratory muscles and cardioaccelerator fibers, resulting in apnea and cardiovascular collapse requiring immediate airway management.

Which brachial plexus approach carries the highest risk of pneumothorax?

Answer: Supraclavicular

The supraclavicular block is performed directly above the clavicle at the apex of the lung (historically called the 'bloody corner'), and pneumothorax occurs in up to 6% of cases without ultrasound guidance.

According to ASRA guidelines, what is the minimum time to wait after the last prophylactic dose of LMWH (e.g., enoxaparin 40 mg daily) before performing neuraxial anesthesia?

Answer: 12 hours

ASRA recommends a minimum 12-hour interval after the last prophylactic LMWH dose before neuraxial needle placement to reduce the risk of epidural hematoma.

Ipsilateral Horner syndrome (ptosis, miosis, anhidrosis) following an interscalene block is caused by inadvertent blockade of which structure?

Answer: Stellate (cervicothoracic) ganglion

The stellate ganglion, which provides sympathetic innervation to the ipsilateral head and neck, lies adjacent to the brachial plexus at the interscalene level and is frequently blocked, producing the classic Horner triad.

What is the primary advantage of ultrasound guidance over nerve stimulator technique for peripheral nerve blocks?

Answer: Provides real-time visualization of needle tip, nerve, and local anesthetic spread

Ultrasound guidance provides real-time imaging of the needle, target nerve, and local anesthetic spread, allowing the practitioner to avoid intraneural or intravascular injection and confirm adequate perineural distribution.

Post-dural puncture headache (PDPH) is best characterized by which clinical feature?

Answer: Positional headache that worsens upright and improves supine

PDPH results from CSF leakage through the dural defect causing intracranial hypotension; the hallmark is a positional headache that is exacerbated in the upright position (increased CSF loss) and relieved by lying supine (reduced traction on pain-sensitive structures).