3-8. Malignant hyperthermia crisis

Objectives

Unexplained increase in ETCO2 AND tachycardia AND increased oxygen requirement.  Temperature rise is a late sign.  MH is rare.  Always consider other, more common causes (see 2.8 Peri-operative hyperthermia).

START

❶ Call for help and inform theatre team of problem, note the time.

❷ Allocate tasks as scenario develops (see Box A).

❸ Aim to abandon or finish surgery as soon as possible.

❹ Call for MH treatment pack/dantrolene and cardiac arrest trolley.

❺ Remove vaporisers from machine.

❻ Give highest possible fresh gas flow and hyperventilate lungs: • Change breathing system is NOT a priority.

❼ Maintain anaesthesia with intravenous hypnotic agent and muscle relaxation with a nondepolarising neuromuscular blocking agent.

❽ Give dantrolene (see Box B).  Delegate mixing – it is time and labour intensive

❾ Begin active cooling: • Reduce the operating room ambient temperature. • Cooling jackets or blankets. • Ice packing in groin, axillae and anterior neck. • Bladder, gastric or peritoneal lavage with boluses 10 ml.kg-1 iced water.

❿ Begin continuous monitoring of: core and peripheral temperature, invasive BP, CVP.

⓫ Send urgent blood samples and repeat as indicated (Box C).

⓬ Treat complications (see Box D).

⓭ Plan admission to critical care.

EMERGENCY HELP:

Leeds MH Hotline: Direct 0113 206 5270, Switchboard: 0113 243 3144, Out of hours mobile 07947 609601

 

Box A: SUGGESTED TASK ALLOCATION

1st nurse/ODP: Collect MH treatment pack/dantrolene and cold saline and insulin. Set up lines (arterial/CVC).  Runner for resuscitation drugs/equipment

2nd nurse/ODP (ideally two people): Draw up dantrolene as directed, keep notes of times of key events

Surgeon:   Complete/abandon surgery ASAP, catheterise, commence cooling manoeuvres 

2nd anaesthetist: Give dantrolene, start TIVA, manage hyperkalaemia, arrhythmias, acidosis. Renal protection (forced alkaline diuresis) 3rd anaesthetist: Arterial line. Send bloods. Central venous access. Urinary myoglobin. Monitor core and peripheral temperatures

Box B: DANTROLENE

2.5 mg.kg-1 immediate i.v. bolus (Adult approx. 200 mg) Repeat 1 mg.kg-1 every 10-15 mins thereafter as required  Maximum dose 10 mg.kg-1

Box C: INVESTIGATIONS

Arterial blood gases every 30 mins, U&E, CK, FBC, coagulation screen, group and save/cross-match blood as indicated 

Box D: COMPLICATIONS AND OUTLINE TREATMENTS

AVOID calcium channel blockers - interaction with dantrolene Hyperkalaemia: calcium chloride, glucose/insulin, bicarbonate Arrhythmias:  magnesium/ amiodarone/ metoprolol Metabolic acidosis: hyperventilate, sodium bicarbonate Myoglobinaemia: forced alkaline diuresis (mannitol/furosemide + bicarbonate); may require renal replacement therapy later DIC: FFP, cryoprecipitate, platelets

Editorial Information

Last reviewed: 30/09/2018

Author(s): The Association of Anaesthetists of Great Britain & Ireland 2018.-19. www.aagbi.org/qrh Subject to Creative Commons license CC BY-NC-SA 4.0. You may distribute original version or adapt for yourself and distribute with acknowledgement of source. You may not use for commercial purposes. Visit website for details. The guidelines in this handbook are not intended to be standards of medical care. The ultimate judgement with regard to a particular clinical procedure or treatment plan must be made by the clinician in the light of the clinical data presented and the diagnostic and treatment options.

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