Guideline sources The following summarized guidelines for the evaluation and management of malignant hyperthermia (MH) are prepared by our editorial team based on guidelines from the Association of Anaesthetists (AA 2021) and the European Malignant Hyperthermia Group (EMHG 2021; 2010). 1 2 3 Guidelines 1. Screening and diagnosis Diagnosis: suspect MH in case of an unexplained and unexpected progressive increase in CO production as evidenced in end-tidal CO . E 2. Respiratory support Hyperventilation therapy: https://web.pathway.md/diseases/recSrCd4r0C7Ntnat 1/5 6/29/23, 6:19 AM Malignant hyperthermia Pathway Initiate hyperventilation (use a minute volume 2-3 times normal) with 100% oxygen at high flow immediately in patients with MH crisis. E Initiate hyperventilation to normocapnia in patients with acidosis. E 3. Medical management General principles: As per AA 2021 guidelines: Aim the management of an MH reaction towards immediately reversing the reaction and treating the consequences of the reaction. E Refer patients with suspected MH reaction to a tertiary assessment unit for MH. E As per EMHG 2010 guidelines: Initiate treatment as soon as an MH crisis is suspected. Declare an emergency and call for help. E Modify treatment according to the clinical presentation of MH. E Elimination of triggers: As per AA 2021 guidelines, eliminate the triggering agent in patients with MH. E As per EMHG 2010 guidelines, stop all trigger agents immediately as soon as MH is suspected. E Show 2 more Dantrolene: As per AA 2021 guidelines, administer IV dantrolene in patients with MH initially at 2-3 mg/kg with a further 1 mg/kg every 5 minutes until treatment goals are reached (until the end-tidal CO is < 6 kPa with normal minute ventilation and the core temperature is < 38.5 C). E As per EMHG 2010 guidelines, administer IV dantrolene 2 mg/kg (ampoules of 20 mg mixed with 60 mL sterile water) in patients with MH. Repeat dantrolene infusions until the cardiac and respiratory systems stabilize. Avoid exceeding the maximum dose of 10 mg/kg. E Management of electrolyte abnormalities: Administer 50 mL of 50% dextrose with 50 IU insulin (adult dose) and IV CaCl2 0.1 mmol/kg for the treatment of hyperkalemia. Consider offering dialysis if needed. E Administer IV sodium bicarbonate if pH is < 7.2. Hyperventilate to normocapnia. E Management of arrhythmia: administer IV amiodarone 3 mg/kg for the management of arrhythmias. Administer -blockers (such as propranolol, metoprolol, or esmolol) if tachycardia persists. E Prevention of kidney injury: administer IV crystalloids (such as lactated Ringer's solution or 0.9% saline), furosemide 0.5 mg/kg, and mannitol 1 g/kg to maintain urinary output > 2 mL/kg/hour in patients with MH. E https://web.pathway.md/diseases/recSrCd4r0C7Ntnat 2/5 6/29/23, 6:19 AM Malignant hyperthermia Pathway 4. Inpatient care Monitoring during acute crisis: Monitor the following during acute crisis of MH: routine anesthetic parameters (ECG, noninvasive arterial pressure, SaO , end-tidal CO ) core temperature blood potassium, CK, arterial blood gases, myoglobin, and glucose renal and hepatic function coagulation signs of compartment syndrome. E Show 2 more 5. Nonpharmacologic interventions Body cooling: As per AA 2021 guidelines, initiate active body cooling in patients with MH. E As per EMHG 2010 guidelines, administer 2-3 L of cold (4 C) IV 0.9% saline in patients with MH. E Show 2 more 6. Perioperative care Perioperative assessment: As per AA 2021 guidelines, elicit a personal and family history of anesthetic problems as part of the preoperative assessment in all patients requiring general or regional anesthesia. E As per EMHG 2021 guidelines, do not obtain specific preoperative or postoperative blood tests in MH-susceptible patients. D 7. Patient education General counseling: inform the patient and their primary care physician before discharge from the hospital about the suspected diagnosis of MH and its implications. E 8. Preventative measures Avoidance of triggers: As per AA 2021 guidelines: Ensure the availability of activated charcoal filters at all locations where general anesthesia is administered. E https://web.pathway.md/diseases/recSrCd4r0C7Ntnat 3/5 6/29/23, 6:19 AM Malignant hyperthermia Pathway Do not expose patients at increased risk of developing MH to potent inhalation anesthetics or suxamethonium. D As per EMHG 2021 guidelines, administer only trigger-free anesthesia in MH-susceptible patients. Do not obtain any extra monitoring during anesthesia if trigger-free anesthesia is administered. A Show 8 more Clinical findings Symptoms Past medical history Dark urine AKI Fever Acute limb compartment syndrome Sweating Exposure to succinylcholine Medication history Rhabdomyolysis Exposure to inhalation anesthetics Family history Malignant hyperthermia Vital signs Neurological exam Hypertension Tachycardia Masseter spasm Tachypnea Muscular rigidity body temperature Lab findings Respiratory exam Metabolic acidosis end-tidal CO2 Respiratory acidosis minute ventilation arterial partial pressure of CO2 Hematological findings serum CK serum calcium Coagulopathy serum myoglobin DIC serum potassium urine myoglobin Genetic testing serum pH Cacna1s gene mutation ECG findings Ryr1 gene mutation Stac3 gene mutation Premature ventricular contractions Ventricular arrhythmia Histological findings https://web.pathway.md/diseases/recSrCd4r0C7Ntnat 4/5 6/29/23, 6:19 AM Malignant hyperthermia Pathway caffeine-halothane contracture test References 1. K P E Glahn, F R Ellis, P J Halsall et al. Recognizing and managing a malignant hyperthermia crisis: guidelines from the European Malignant Hyperthermia Group. Br J Anaesth. 2010 Oct;105 4 417 20. Open 2. P M Hopkins, T Girard, S Dalay et al. Malignant hyperthermia 2020 Guideline from the Association of Anaesthetists. Anaesthesia. 2021 May;76 5 655 664. Open 3. Henrik R ffert, B rge Bastian, Diana Bendixen et al. Consensus guidelines on perioperative management of malignant hyperthermia suspected or susceptible patients from the European Malignant Hyperthermia Group. Br J Anaesth. 2021 Jan;126 1 120 130. Open https://web.pathway.md/diseases/recSrCd4r0C7Ntnat 5/5