Local Anaesthetics and Regional Anaesthesia (Spinal, Epidural, Nerve Blocks) MCQs

Anaesthesia · 50 free questions with answers & explanations.

1. A patient develops sudden cardiovascular collapse with refractory VF after an inadvertent intravascular injection during an interscalene brachial plexus block. The anaesthetic agent most likely responsible and the specific first-line lipid rescue dose is:
2. In a spinal anaesthetic for a lower limb procedure, heavy bupivacaine 0.5% 3 mL is injected at L3-L4 with the patient in the right lateral decubitus position. The baricity of the solution and patient positioning determine spread. If the patient is kept lateral with right side down for 10 minutes, the block will be predominantly:
3. Total spinal anaesthesia following epidural top-up is a recognised complication when epidural catheter has migrated intrathecally. Compared to a standard spinal, total spinal has rapid progression to high cervical block because epidural doses contain:
4. A post-dural puncture headache (PDPH) is characterised by postural worsening in upright position. The most effective definitive treatment after failed conservative management is:
5. In a transversus abdominis plane (TAP) block, local anaesthetic is deposited in the fascial plane between which two muscle layers?
6. Bupivacaine is more cardiotoxic than lidocaine at equivalent doses. Which cellular mechanism explains bupivacaine's disproportionate cardiac toxicity?
7. During spinal anaesthesia for a Caesarean section, the block level must reach which dermatomal level to ensure adequate visceral anaesthesia, particularly for uterine manipulation?
8. In epidural anaesthesia, a test dose containing 3 mL of 1.5% lidocaine with 1:200,000 epinephrine is administered. What constitutes a positive intravascular test dose response?
9. Transient neurological symptoms (TNS) following spinal anaesthesia are most strongly associated with which local anaesthetic agent and patient positioning?
10. Post-dural puncture headache (PDPH) after inadvertent dural tap in obstetric epidural anaesthesia has which characteristic feature that distinguishes it from other causes of postoperative headache?
11. An epidural catheter is placed at L2–L3 for post-operative analgesia. The patient suddenly develops loss of consciousness, severe hypotension, and ventricular fibrillation after a test dose. The most likely cause and immediate priority treatment are:
12. Hyperbaric bupivacaine 0.5% heavy is used for spinal anaesthesia in a patient undergoing LSCS. What makes this formulation 'hyperbaric' and how does baricity affect spread?
13. Which ion channel property best explains why myelinated C fibres mediating pain are more readily blocked by local anaesthetics than myelinated A-alpha fibres mediating motor function?
14. Post-dural puncture headache (PDPH) occurs after unintentional dural puncture with an epidural needle. Which of the following correctly identifies the mechanism and optimal therapeutic measure when conservative treatment fails?
15. An interscalene brachial plexus block is performed under ultrasound guidance. Which of the following complications is unique to this approach due to the proximity of specific anatomical structures?
16. Ropivacaine produces less motor blockade than bupivacaine at equivalent analgesic concentrations. The pharmacological basis for this differential blockade is:
17. During epidural anaesthesia for labour, the patient suddenly develops hypotension, bradycardia, loss of consciousness, and bilateral arm weakness 20 minutes after top-up with 15 mL of 0.5% bupivacaine. The MOST likely cause is:
18. In spinal anaesthesia for a Caesarean section, hyperbaric bupivacaine 0.5% 2.2 mL is injected at L3–4 with the patient sitting upright. The patient is immediately placed supine. What determines the final spread of the block?
19. Transient neurological symptoms (TNS) following spinal anaesthesia occur most commonly after which agent and in which patient position?
20. A 65-year-old hypertensive man undergoes an interscalene brachial plexus block for right shoulder arthroplasty. Despite successful motor and sensory block, he develops ipsilateral ptosis, miosis, anhidrosis, and enophthalmos. This is due to:
21. During spinal anaesthesia for lower limb surgery, the block is at T10. Suddenly the patient develops bradycardia to 38 bpm with hypotension and nausea. The most likely cause of bradycardia in this clinical setting is:
22. In comparing hyperbaric versus isobaric bupivacaine for spinal anaesthesia in a patient positioned in the lateral decubitus position, which statement is MOST accurate?
23. A patient undergoes lumbar epidural anaesthesia. The test dose contains 3 mL of 1.5% lidocaine with 1:200,000 adrenaline (15 mcg). Three minutes after injection, the patient's heart rate increases from 75 to 100 bpm. This finding indicates:
24. Local anaesthetic systemic toxicity (LAST) has occurred after an interscalene nerve block. After initial seizure control with benzodiazepines, the patient develops pulseless ventricular tachycardia. The FIRST definitive treatment per current guidelines is:
25. The differential sensory-to-motor block ratio that makes bupivacaine preferred for labour analgesia at low concentrations relates primarily to which property?
26. A patient develops sudden cardiovascular collapse during interscalene brachial plexus block with bupivacaine 0.5%. The MOST likely mechanism and appropriate resuscitation is:
27. For combined spinal-epidural (CSE) anaesthesia in a parturient undergoing elective LSCS, which complication is SPECIFICALLY associated with the epidural component compared to a spinal alone?
28. Isobaric ropivacaine 0.5% 3 mL is administered intrathecally for spinal anaesthesia. Compared to hyperbaric bupivacaine, the MOST important practical difference is:
29. A 28-year-old parturient receives epidural bupivacaine 0.5% (20 mL) for labour analgesia. Thirty seconds after injection she becomes obtunded, develops generalised convulsions, followed by cardiovascular collapse with a wide QRS complex on ECG. Intralipid 20% is prepared. What is the recommended loading dose of Intralipid for local anaesthetic systemic toxicity (LAST)?
30. Post-dural puncture headache (PDPH) following spinal anaesthesia is characterised by its postural nature. An epidural blood patch is indicated when conservative management fails. The success rate of a well-placed epidural blood patch is approximately:
31. A patient receives epidural analgesia via an L2–3 catheter and 2 hours later develops sudden severe back pain, bilateral leg weakness, bladder dysfunction and saddle anaesthesia. The MOST urgent diagnosis to exclude and the action required is:
32. Which statement correctly describes the mechanism of differential nerve block by local anaesthetics?
33. A patient receiving a supraclavicular brachial plexus block for forearm surgery develops sudden hypotension, bradycardia, and reports ringing in the tinnitus, perioral tingling, and metallic taste 2 minutes after injection of 30 mL of 0.5% bupivacaine. What is the correct initial treatment?
34. Intravascular injection of 3 mg/kg of bupivacaine causes cardiovascular toxicity that is more refractory to resuscitation than that of lignocaine. What is the primary mechanism responsible for bupivacaine's enhanced cardiotoxicity?
35. A patient undergoing spinal anaesthesia for elective hip replacement develops sudden hypotension (BP 80/50 mmHg) and bradycardia (HR 42 bpm) 10 minutes after intrathecal injection of hyperbaric bupivacaine 15 mg. The MOST appropriate initial management sequence is:
36. What is the maximum safe dose of plain lignocaine (lidocaine) for infiltration anaesthesia in adults, and how does the addition of adrenaline (epinephrine) 1:200,000 affect this limit?
37. A 55-year-old man receives a spinal anaesthetic with 0.5% hyperbaric bupivacaine 2.5 mL at L3–L4 for a right total knee replacement. Ten minutes later his blood pressure drops from 130/80 to 80/50 mmHg and he feels nauseated. His block level is T6. What is the PRIMARY mechanism of this hypotension?
38. A patient develops sudden cardiovascular collapse with wide complex bradycardia immediately after injection of local anaesthetic for an infraclavicular brachial plexus block. The MOST appropriate immediate treatment is:
39. A spinal needle is being inserted at L4–L5 in the midline. Correct order of ligaments pierced from superficial to deep is:
40. A 34-year-old parturient receives an epidural block for labour analgesia. The anaesthetist withdraws the epidural catheter 3 cm and is surprised to find that sensory testing reveals a unilateral block. What is the MOST likely explanation?
41. Which local anaesthetic has the HIGHEST cardiotoxic to neurotoxic ratio, making its inadvertent intravascular injection particularly dangerous?
42. A post-dural puncture headache (PDPH) classically differs from other headaches by which feature?
43. A 25-year-old parturient receiving epidural bupivacaine develops sudden cardiovascular collapse with ventricular fibrillation. The MOST likely explanation is:
44. The baricity of a spinal anaesthetic solution determines its spread within the intrathecal space. A hyperbaric solution (e.g., heavy bupivacaine) is prepared by adding:
45. A patient develops post-dural puncture headache (PDPH) after spinal anaesthesia with a 25-gauge Quincke needle. The headache is characteristically:
46. The maximum safe dose of lignocaine (lidocaine) without epinephrine for infiltration anaesthesia in an adult is:
47. A 40-year-old patient undergoing upper limb surgery receives an axillary brachial plexus block. The nerve most likely to be missed with this approach, requiring supplemental blockade, is:
48. Combined spinal-epidural (CSE) anaesthesia is used for labour analgesia. The Tuohy needle is inserted at L2–L3, a 27G pencil-point spinal needle passed through it 1.5 cm beyond the tip into the subarachnoid space, and fentanyl 25 mcg with bupivacaine 2.5 mg injected intrathecally. Which advantage is unique to CSE over either technique alone?
49. A patient receiving epidural analgesia via infusion develops sudden onset of bilateral lower limb weakness, urinary retention, and back pain 18 hours post-operatively. The most critical diagnosis to rule out, and the time-sensitive intervention, is:
50. Ropivacaine has greater cardiosafety compared to bupivacaine for regional anaesthesia. Which pharmacological property explains this differential toxicity?