Suspect Malignant Hyperthermia
Clinical signs during/after anesthesia with triggering agents (volatile anesthetics, succinylcholine)
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AnesthesiologyEmergency
Malignant Hyperthermia Crisis Management (AAGBI 2020)
Malignant Hyperthermia Crisis Management (AAGBI 2020): Suspect Malignant Hyperthermia → Clinical Signs Present? → STOP All Trigger Agents IMMEDIATELY → ...
Pathway Overview
13 steps
Algorithm Steps
13 total
01Start 02Decision Clinical Signs Present?
Early signs: unexplained tachycardia, rising ETCO2, muscle rigidity. Late: hyperthermia, arrhythmias, acidosis
- Unexplained rapid rise in ETCO2
- Unexplained tachycardia
- Masseter muscle rigidity after succinylcholine
- Generalized muscle rigidity
- Temperature rise (may be late sign)
- Arrhythmias, unstable BP
- Dark blood in surgical field
- Cola-colored urine (myoglobinuria)
03Action STOP All Trigger Agents IMMEDIATELY
Discontinue volatile anesthetics and succinylcholine
- Turn OFF vaporizer
- Increase fresh gas flow to 10+ L/min
- Do NOT change anesthesia machine/circuit (wastes time)
- Switch to IV anesthesia (propofol, opioids)
- Hyperventilate with 100% O2
04Action Call for Help
Activate MH protocol and get dantrolene
- Declare MH emergency
- Call MHAUS Hotline: 1-800-644-9737 (US)
- Assign roles: mixing dantrolene, labs, cooling
- Send for MH cart/dantrolene immediately
- Delegate tasks - requires team effort
05Action Administer Dantrolene
Initial dose: 2.5 mg/kg IV bolus
- Initial: 2.5 mg/kg IV push
- Mix each 20mg vial with 60mL sterile water (shaken, not stirred)
- Repeat 1 mg/kg every 5-10 min until signs resolve
- No maximum dose - continue until effective
- Typical total: 2.5-10 mg/kg
- Monitor for muscle weakness, respiratory depression
06Warning ⚠️ CONTRAINDICATION
Do NOT give calcium channel blockers with dantrolene - causes severe hyperkalemia and cardiovascular collapse
07Action Supportive Measures
Manage hyperkalemia, acidosis, arrhythmias
- Sodium bicarbonate 1-2 mEq/kg for acidosis
- Calcium chloride 10-20 mg/kg for hyperkalemia
- Insulin/glucose (10U regular + 50mL D50)
- Treat arrhythmias (avoid calcium channel blockers with dantrolene!)
- Insert Foley - monitor for myoglobinuria
08Action Laboratory Monitoring
Serial labs every 15-30 minutes initially
- ABG (acidosis, hypercarbia)
- Potassium (hyperkalemia common)
- CK (will rise - peak 12-24 hours)
- Myoglobin (serum and urine)
- Lactate
- Coagulation studies (DIC possible)
09Decision Response to Dantrolene?
Signs of improvement: decreasing ETCO2, HR, muscle rigidity
10Action Continue Dantrolene
Repeat 1 mg/kg every 5-10 min
- Continue until all signs resolve
- No upper limit - give what's needed
- Prepare more dantrolene
- Path rejoins step 09Shared downstream outcome
11Action ICU Admission
All MH patients require ICU monitoring
- Continue dantrolene 1 mg/kg IV q4-6h x 24-48h
- Monitor for recrudescence (25% of cases)
- Serial CK, K+, renal function
- Urine output >2 mL/kg/hr (prevent AKI)
- Mannitol/furosemide if myoglobinuria
- Refer for MH susceptibility testing
12Outcome MH Crisis Managed
Continue monitoring, arrange genetic testing
13Action Active Cooling
Target temperature <38.5°C
- Cold IV saline (not through blood warmer)
- Ice packs to groin, axillae, neck
- Cooling blanket
- Gastric/bladder lavage with cold saline if refractory
- STOP cooling at 38°C to prevent overshoot
- Path rejoins step 08Shared downstream outcome
Guideline Source
Malignant hyperthermia 2020: Guideline from the Association of Anaesthetists
Clinical Safety Information
Clinical Decision Support — Not a Substitute for Clinical Judgment
Individual patient factors may require deviation from these recommendations.
Known Limitations
- Dantrolene must be readily available (36 vials minimum)
- Requires MH-trained personnel
- Does not cover post-crisis management in detail
- Local protocols may vary
Applicable Regions
USEUglobal
UK: Based on AAGBI 2020 guidelines
US: Compatible with MHAUS recommendations
Version 1Next review: 2027-01-01
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Related Resources
Frequently Asked Questions
What is the Malignant Hyperthermia Crisis Management (AAGBI 2020)?
The Malignant Hyperthermia Crisis Management (AAGBI 2020) is a emergency clinical algorithm for Anesthesiology. It provides a structured decision tree to guide clinical decision-making, based on Malignant hyperthermia 2020: Guideline from the Association of Anaesthetists.
What guideline is the Malignant Hyperthermia Crisis Management (AAGBI 2020) based on?
This algorithm is based on Malignant hyperthermia 2020: Guideline from the Association of Anaesthetists (DOI: 10.1111/anae.15317).
What are the limitations of the Malignant Hyperthermia Crisis Management (AAGBI 2020)?
Known limitations include: Dantrolene must be readily available (36 vials minimum); Requires MH-trained personnel; Does not cover post-crisis management in detail; Local protocols may vary. Individual patient factors may require deviation from these recommendations.
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