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Myotonic dystrophy for laparoscopic cholecystectomy44-year-old man, 70 kg, for elective laparoscopic cholecystectomy for recurrent biliary colic

From memory: the diagnosis and the notes are hidden. Answer each question aloud, then press Show.

Know this first

  • Suxamethonium can trigger myotonia that relaxants and anaesthesia can't reverse.
  • Cold, shivering, diathermy and nerve stimulation provoke myotonia.
  • Very sensitive to the respiratory depression of opioids, benzodiazepines and propofol.
  • Local anaesthetic infiltrated into the contracted muscle may relax it.
  • AV block may not respond to atropine; pacing must be ready.

The patient

44-year-old man, 70 kg, for elective laparoscopic cholecystectomy for recurrent biliary colic. Myotonic dystrophy type 1: facial weakness, ptosis, grip myotonia, mild dysphagia and daytime sleepiness. ECG: first-degree heart block, PR 260 ms, QRS 118 ms. Echo normal. No regular drugs. Vitals: BP 124/76, HR 64, SpO2 95% on air, RR 14; VC 2.6 L.

The examiner asks

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  1. Consider

    What are your concerns?

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    • A 44-year-old with myotonic dystrophy type 1, for elective laparoscopic cholecystectomy. Patient
    • It's multisystem: muscle, cardiac conduction, lungs, gut and endocrine glands. Disease
    • His long PR and wide QRS predict sudden death from heart block.
    • Dysphagia, a weak pharynx and slow gastric emptying: high aspiration risk. Airway
    • Daytime sleepiness and weak breathing make sedatives and opioids risky for him. Disease
    • Upper abdominal surgery raises his risk of lung complications. Surgery

  2. Prepare

    How do you prepare him?

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    • Cardiology review of his ECG; he may need a pacemaker-defibrillator. Disease
    • Pacing pads on before induction; his block may not respond to atropine. Crisis
    • Glucose, thyroid function and calcium checked. Disease
    • Aspiration prophylaxis with a non-particulate antacid and an H2 blocker. Airway
    • Warm theatre, warmed fluids, forced-air warming, temperature probe. Stem trigger
    • Monitored bed afterwards with pulse oximetry and capnography. After surgery

  3. Plan

    How will you anaesthetise him?

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    • RSI with propofol, carefully titrated; he's sensitive to hypnotics. Airway
    • Rocuronium at a reduced dose; no suxamethonium.
    • Twitch monitoring can mislead: stimulation may provoke myotonia that mimics tetany. Disease
    • Short-acting drugs; paracetamol and an NSAID to spare opioids.
    • Reverse with sugammadex rather than neostigmine.
    • Extubate fully awake; long recovery stay with oximetry and capnography. After surgery

  4. Crisis

    As the surgeon uses diathermy on the gallbladder, his abdominal wall goes rigid and his jaw clenches; ventilation is difficult. What do you do?

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    • Myotonic spasm from diathermy; more relaxant won't release it. (Crisis)
    • Diathermy stops; I check he isn't cold or shivering.
    • Deepen with propofol, which has ended myotonic crises in case reports.
    • Surgeon infiltrates the contracted muscle with local anaesthetic.
    • Persisting: phenytoin; I avoid quinine and procainamide with his conduction disease.
    • A high volatile concentration also works, but depresses his heart.

  5. Crisis

    In recovery his HR drops to 32 with broad QRS complexes and P waves unrelated to them; BP 74/40. What do you do?

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    • Bradycardia algorithm: complete heart block from his conduction disease. Crisis
    • Atropine is unlikely to work when the block is below the AV node.
    • Pace now through the transcutaneous pads already in place.
    • Bridge with isoprenaline 2–10 mcg/min or adrenaline 2–10 mcg/min.
    • Pacing not capturing: correct acidaemia and potassium.
    • Cardiology for transvenous, then permanent, pacing. After surgery

Fatal mistakes

  • Suxamethonium.
  • No pacing ready despite his PR 260 and QRS 118.
  • Unmonitored opioids on the ward afterwards.

Checked against: Stoelting 8e · Miller 10e · Barash 9e · Faust

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Same topic, another patient

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Another patient · Medical and endocrine disease. Myotonic dystrophy for inguinal hernia repair. Same myotonic dystrophy for open hernia: shivering rigidity in recovery

Know this first

  • Prolonged PR and QRS predict sudden death; AV block may not respond to atropine, so have pacing ready.
  • Suxamethonium causes contractures that can make intubation and ventilation impossible.
  • Relaxants cannot relieve myotonia; its mechanism is beyond the junction.
  • Triggers: shivering, cold, surgical and electrical stimulation; sugammadex is the preferred reversal.

The patient

38-year-old man, 70 kg, for elective open repair of an inguinal hernia. Myotonic dystrophy type 1: facial and neck weakness, chokes on solids, daytime sleepiness; ECG shows PR 260 ms and QRS 130 ms. Drugs: none regular. Vitals: BP 122/74, HR 62, SpO2 95% on air, RR 16. FVC 55% predicted.

The examiner asks

Answer aloud, then press Show.

  1. Consider

    What are the issues?

    Show the answerHide the answer
    • A 38-year-old with type 1 myotonic dystrophy, bulbar weakness and conduction disease, for elective hernia repair. Patient
    • It is multisystem: his muscles, heart, lungs, gut and endocrine glands. Disease
    • His long PR and QRS predict sudden death; his heart block may not respond to atropine.
    • A weak pharynx and slow gastric emptying make him likely to aspirate.
    • Restrictive lungs, blunted response to CO2, and sleepiness from obstructive apnoea.
    • He is very sensitive to sedatives, opioids and muscle relaxants.

  2. Prepare

    How will you prepare him?

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    • Cardiology review first; his ECG changes may warrant a pacemaker or defibrillator. Disease
    • Pacing pads on and pacing ready in theatre.
    • His FVC of 55% and weak cough raise his risk of chest complications; I explain this.
    • Glucose, thyroid function and calcium checked.
    • Non-particulate antacid and an H2 blocker before anaesthesia. Airway
    • Sedative premedication avoided, given his sensitivity. Disease

  3. Plan

    What anaesthetic will you give?

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    • A spinal or ultrasound-guided block avoids sedatives, opioids and relaxants. Disease
    • Ultrasound rather than nerve stimulation, which can set off myotonia. Stem trigger
    • If general: rapid sequence, titrated propofol, reduced-dose rocuronium; never suxamethonium. Airway
    • Sugammadex preferred; neostigmine's myotonia risk is disputed, but incomplete reversal is the real danger. Disease
    • Temperature monitored and active warming; cold and shivering trigger myotonia. Stem trigger
    • Paracetamol and an NSAID rather than opioids; monitored bed with oximetry and capnography. After surgery

  4. Crisis

    In recovery he is shivering, his jaw and limbs are rigid, SpO2 is 86% and he breathes shallowly at 8/min. What do you do?

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    • A myotonic crisis set off by shivering, with hypoventilation; oxygen, help, and active warming now. Crisis
    • More relaxant won't help: myotonia arises beyond the neuromuscular junction.
    • Jaw support and bag-mask breaths; NIV risks inflating his stomach.
    • Propofol has ended myotonic crises; phenytoin or mexiletine treat ongoing myotonia.
    • I check for residual block, opioid and CO2 retention, and reverse what I can.
    • Still hypoxic: reintubate with propofol and rocuronium, never suxamethonium.
    • ICU or HDU with oximetry and capnography until fully recovered. After surgery

Fatal mistakes

  • Suxamethonium given.
  • Leaving him partly reversed.
  • An opioid-heavy plan on a general ward.

Checked against: Barash 9e · Faust · Miller 10e

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