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Anaesthesia, drugs & pain MCQs with answers

12 single-best-answer questions on muscle relaxants, local anaesthetic dosing, analgesia and perioperative drugs. Try each one, then open the answer to see the explanation, why the other options are wrong, and the guideline or trial behind it.

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Written by , consultant surgeon, Jerusalem. Updated .

  1. A patient who had a complete thoracic spinal cord injury 3 weeks ago needs an emergency laparotomy with rapid sequence induction. Which muscle relaxant should be avoided?

    1. Suxamethonium (succinylcholine), because it can cause life-threatening hyperkalaemia; use rocuronium instead
    2. Cisatracurium
    3. All relaxants are equally safe
    4. Vecuronium
    5. Rocuronium
    Show the answer and explanation

    Answer: A. Suxamethonium (succinylcholine), because it can cause life-threatening hyperkalaemia; use rocuronium instead. After denervation (spinal cord injury or stroke after about 72 hours), burns (after about 24 hours), major crush injury, prolonged immobility and some neuromuscular diseases, extra acetylcholine receptors spread over muscle membranes. Suxamethonium then releases large amounts of potassium, which can cause cardiac arrest. High-dose rocuronium allows rapid sequence induction, and sugammadex can reverse it.

    Why not the others? Suxamethonium is also a trigger for malignant hyperthermia.

    References

    1. Martyn JA, Richtsfeld M. Succinylcholine-induced hyperkalemia in acquired pathologic states. Anesthesiology 2006

  2. A woman with myasthenia gravis received rocuronium for an emergency appendicectomy. At the end of surgery she remains weak. Which reversal agent is preferred?

    1. Suxamethonium
    2. Naloxone
    3. Sugammadex, which encapsulates rocuronium directly
    4. Neostigmine in high doses
    5. Flumazenil
    Show the answer and explanation

    Answer: C. Sugammadex, which encapsulates rocuronium directly. Sugammadex binds rocuronium (and vecuronium) and reverses even deep block quickly and predictably. It does not act through acetylcholinesterase, so it avoids the problems of neostigmine in myasthenia, where response is unpredictable and cholinergic crisis is possible. It is also used in “cannot intubate” situations after rocuronium.

    Why not the others? Naloxone reverses opioids; flumazenil reverses benzodiazepines.

    References

    1. Hristovska AM et al. Efficacy and safety of sugammadex versus neostigmine in reversing neuromuscular blockade in adults. Cochrane Database Syst Rev 2017

  3. You are excising a lipoma under local anaesthetic in a 70-kg adult using plain 1% lidocaine. What is the maximum volume you can safely use?

    1. About 21 mL (3 mg/kg = 210 mg; 1% = 10 mg/mL)
    2. There is no maximum
    3. 7 mL
    4. 70 mL
    5. 50 mL
    Show the answer and explanation

    Answer: A. About 21 mL (3 mg/kg = 210 mg; 1% = 10 mg/mL). The usual maximum for plain lidocaine is about 3 mg/kg (up to about 7 mg/kg with adrenaline). A 1% solution contains 10 mg/mL. Calculating the maximum dose before starting, and aspirating before injecting, prevents local anaesthetic toxicity.

    Why not the others? Percentage × 10 gives mg/mL: 1% = 10 mg/mL, 2% = 20 mg/mL.

    References

    1. Neal JM et al. The third American Society of Regional Anesthesia and Pain Medicine practice advisory on local anesthetic systemic toxicity. Reg Anesth Pain Med 2018

  4. A man who takes buprenorphine for opioid use disorder needs an elective open hernia repair. What is the recommended approach?

    1. Switch him to tramadol only
    2. Stop buprenorphine 2 weeks before surgery in every case
    3. Give no analgesia because of addiction risk
    4. Cancel surgery
    5. Generally continue buprenorphine, use multimodal and regional analgesia, and add short-acting opioids if needed under close monitoring
    Show the answer and explanation

    Answer: E. Generally continue buprenorphine, use multimodal and regional analgesia, and add short-acting opioids if needed under close monitoring. Stopping buprenorphine risks relapse, overdose and very difficult pain control. Current multisociety guidance supports continuing it in most cases, maximising non-opioid and regional analgesia, and planning with the patient’s addiction team.

    Why not the others? Untreated pain is also a trigger for relapse.

    References

    1. Kohan L et al. Buprenorphine management in the perioperative period: educational review and recommendations from a multisociety expert panel. Reg Anesth Pain Med 2021

  5. A 72-year-old on amitriptyline and sertraline is given tramadol after rib fractures. He becomes agitated, sweaty and tremulous, with fever and brisk reflexes with clonus. What is the cause and action?

    1. Anxiety; reassure
    2. Serotonin syndrome from tramadol combined with serotonergic antidepressants; stop the serotonergic drugs and give supportive care
    3. Sepsis only; add antibiotics and continue tramadol
    4. Malignant hyperthermia; dantrolene
    5. Alcohol withdrawal; give more tramadol
    Show the answer and explanation

    Answer: B. Serotonin syndrome from tramadol combined with serotonergic antidepressants; stop the serotonergic drugs and give supportive care. Tramadol inhibits serotonin reuptake and, with SSRIs or tricyclics, can cause serotonin syndrome (agitation, hyperthermia, clonus, hyperreflexia). It also lowers the seizure threshold. Treatment is stopping the drugs, supportive care, benzodiazepines and, in severe cases, cyproheptadine.

    Why not the others? Clonus and hyperreflexia help distinguish it from neuroleptic malignant syndrome.

    References

    1. Boyer EW, Shannon M. The serotonin syndrome. N Engl J Med 2005

  6. Which approach best describes recommended postoperative pain management after major abdominal surgery?

    1. High-dose opioids alone as first-line
    2. Analgesia only when the patient asks
    3. No analgesia, to allow assessment of complications
    4. Intramuscular pethidine every hour
    5. Multimodal analgesia: regular paracetamol and an NSAID (if no contraindication), regional or wound techniques, and opioids only for breakthrough pain
    Show the answer and explanation

    Answer: E. Multimodal analgesia: regular paracetamol and an NSAID (if no contraindication), regional or wound techniques, and opioids only for breakthrough pain. Combining drugs with different mechanisms, plus regional techniques (epidural, transversus abdominis plane or wound catheters), improves pain relief and reduces opioid needs and side effects such as ileus, nausea, sedation and respiratory depression, supporting early mobilisation.

    Why not the others? Good analgesia does not mask important surgical complications.

    References

    1. Chou R et al. Management of postoperative pain: a clinical practice guideline from the APS, ASRA and ASA. J Pain 2016

  7. A postoperative patient on a morphine PCA is very drowsy, with a respiratory rate of 7 and pinpoint pupils. What is the immediate treatment?

    1. Let him sleep and recheck in 4 hours
    2. Give a large naloxone dose of 2 mg at once in every case
    3. Stop the opioid, support the airway with oxygen, and give naloxone in small titrated intravenous doses (for example 100–200 µg), repeating as needed
    4. Flumazenil
    5. Increase the PCA dose
    Show the answer and explanation

    Answer: C. Stop the opioid, support the airway with oxygen, and give naloxone in small titrated intravenous doses (for example 100–200 µg), repeating as needed. Opioid-induced respiratory depression is treated by stopping the opioid, supporting breathing and titrating naloxone to restore breathing without completely reversing analgesia. Naloxone is short-acting, so repeated doses or an infusion may be needed.

    Why not the others? Large boluses can cause abrupt withdrawal, severe pain and pulmonary oedema.

    References

    1. Boyer EW. Management of opioid analgesic overdose. N Engl J Med 2012

  8. Shortly after induction and antibiotic administration, a patient becomes severely hypotensive, with bronchospasm and a widespread rash. What is the first-line drug?

    1. Atropine
    2. Adrenaline (intravenous boluses of about 50 µg in adults under anaesthesia), with fluids and stopping the suspected trigger
    3. Salbutamol alone
    4. Hydrocortisone alone
    5. Chlorphenamine alone
    Show the answer and explanation

    Answer: B. Adrenaline (intravenous boluses of about 50 µg in adults under anaesthesia), with fluids and stopping the suspected trigger. Perioperative anaphylaxis is most often caused by neuromuscular blocking drugs, antibiotics (especially teicoplanin and penicillins) and chlorhexidine. Adrenaline is the key treatment. Mast cell tryptase is measured, and the patient is referred for allergy testing afterwards.

    Why not the others? Steroids and antihistamines are second-line and slow to act.

    References

    1. Harper NJN et al. Anaesthesia, surgery, and life-threatening allergic reactions: epidemiology and clinical features of perioperative anaphylaxis in NAP6. Br J Anaesth 2018

  9. A patient on prophylactic-dose enoxaparin (given once daily) is due to have an epidural catheter placed. How long after the last dose should the epidural be inserted?

    1. At least 12 hours
    2. No interval is needed
    3. 1 hour
    4. 30 minutes
    5. 7 days
    Show the answer and explanation

    Answer: A. At least 12 hours. Neuraxial procedures in anticoagulated patients risk spinal epidural haematoma, which can cause paraplegia. Guidance recommends waiting at least 12 hours after a prophylactic LMWH dose (24 hours after a treatment dose) before insertion or catheter removal, and timing the next dose after removal.

    Why not the others? New weakness or back pain after an epidural needs urgent MRI.

    References

    1. Horlocker TT et al. Regional anesthesia in the patient receiving antithrombotic or thrombolytic therapy: ASRA evidence-based guidelines (fourth edition). Reg Anesth Pain Med 2018

  10. Which measures reduce postoperative ileus after colorectal surgery?

    1. Large volumes of intravenous fluid
    2. Opioid-sparing analgesia, avoiding fluid overload, early oral intake, early mobilisation, chewing gum, and avoiding routine nasogastric tubes
    3. High-dose morphine
    4. Bed rest
    5. Routine nasogastric tubes for 5 days
    Show the answer and explanation

    Answer: B. Opioid-sparing analgesia, avoiding fluid overload, early oral intake, early mobilisation, chewing gum, and avoiding routine nasogastric tubes. Postoperative ileus is worsened by opioids, salt and water overload, and gut handling. Enhanced recovery measures reduce it. Peripheral opioid antagonists (such as alvimopan) are used in some countries.

    Why not the others? Routine nasogastric decompression does not speed recovery.

    References

    1. Gustafsson UO et al. Guidelines for perioperative care in elective colorectal surgery: ERAS Society recommendations 2018. World J Surg 2019

  11. A 60-year-old with insulin-treated diabetes, stable angina and well-controlled hypertension is assessed before surgery. What is his ASA physical status?

    1. ASA II
    2. ASA V
    3. ASA III (severe systemic disease)
    4. ASA I
    5. ASA IV
    Show the answer and explanation

    Answer: C. ASA III (severe systemic disease). ASA I is a healthy patient; ASA II mild systemic disease; ASA III severe systemic disease that limits activity; ASA IV severe disease that is a constant threat to life; ASA V moribund; ASA VI brain-dead organ donor. “E” is added for emergency surgery. The classification predicts risk but is subjective.

    Why not the others? Multiple well-controlled conditions may still be ASA II; functional limitation pushes towards III.

    References

    1. American Society of Anesthesiologists. ASA Physical Status Classification System (updated 2020)

  12. Two days after a spinal anaesthetic for a hernia repair, a patient has a severe headache that is much worse when sitting up and relieved by lying flat. What is the diagnosis and the most effective treatment if it persists?

    1. Migraine; triptans
    2. Subarachnoid haemorrhage; CT angiography in every case
    3. Post-dural puncture headache; simple analgesia, fluids and caffeine first, then an epidural blood patch if it persists
    4. Meningitis; lumbar puncture again
    5. Tension headache; reassurance only
    Show the answer and explanation

    Answer: C. Post-dural puncture headache; simple analgesia, fluids and caffeine first, then an epidural blood patch if it persists. A postural headache after dural puncture is caused by CSF leak and low pressure. Many resolve with conservative measures, but an epidural blood patch is the most effective treatment for persistent or severe cases. Red flags (fever, neurological signs, non-postural headache) require investigation for other causes.

    Why not the others? Thinner, pencil-point spinal needles reduce the risk.

    References

    1. Uppal V et al. Consensus practice guidelines on postdural puncture headache from a multisociety, international working group. JAMA Netw Open 2023

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