malignant hyperthermia
| Life-threatening drug reaction | |
|---|---|
| Etiology | Causative drugs: suxamethonium, sevoflurane... |
| Epidemiology | 1:15000 in children; 1:50000 in adults |
| Clinical presentation | Unexplained increase in ETCO2 AND tachycardia AND increased oxygen consumption Perioperative hyperthermia - LATE sign |
| Pathogenesis | Uncontrolled Ca release from sarcoplasmic reticulum due to genetic defect |
| Management | Paraphrased from QRH - in order of importance 1. Stop surgery, note time 2. Get help and get cardiac arrest trolley + dantrolene box 3. A-E resuscitation, addressing the hypermetabolic state 4. Eliminate potential triggers 1. Turn off vaporisers and remove from anaesthesia workstation 2. Set fresh gas flow to 100% oxygen, maximum flow 3. Hyperventilate (2-3 x normal minute ventilation) 4. Place activated charcoal filters on both limbs of the breathing circuit 5. Change soda lime and breathing circuit if/when feasible (not a priority) 5. Dantrolene (muscle relaxant binding to ryanodine receptor) 1. which will need a whole army to make up and draw up 2. 2-3 mg.kg-1 immediate i.v. bolus (Adult approx. 200 mg) 3. Repeat 1 mg.kg-1 every 5 mins, until ETCO2 <6 kPa and temp <38.5C 4. Pause and observe 5. Repeat 1 mg.kg-1 to maintain ETCO2 <6 kPa and temp <38.5C, even if exceeds 10mg/kg dose 6. Active cooling 1. Stop active warming (duh) 2. Ice to axilla and groin (no evaporative cooling?) 3. Cold IV fluids, peritoneal lavage 7. Additional monitoring- invasive BP, core + peripheral temp 8. Initial investigations: arterial blood gases, U&E, glucose, FBC, coagulation, urinary pH, creatine kinase (peak 12-24h) 9. Off to ICU 1. Avoid CCBs - interaction with dantrolene 10. Reporting: 1. Emergency hotline 07947 609601 or 0113 243 3144 2. UK MH Registry website: www.ukmhr.ac.uk |