What are the management strategies for hyperthermia?

Hyperthermia Management

Immediately stop all triggering agents, administer dantrolene 2-3 mg/kg IV, and initiate aggressive cooling measures—this triad of interventions forms the cornerstone of hyperthermia management and must be implemented simultaneously without delay. 1, 2

Immediate Recognition and Initial Actions

Stop all trigger agents immediately if malignant hyperthermia (MH) is suspected—this includes discontinuing all volatile anesthetic agents and succinylcholine. 1, 3 The vaporizer should be disconnected from the anesthetic machine, but do not waste time changing the entire circuit. 1

• Hyperventilate with 100% oxygen at high flow using 2-3 times normal minute ventilation to reduce end-tidal CO2 and prevent further heat production. 1, 2
• Declare an emergency and call for help—multiple personnel will be needed to reconstitute dantrolene and manage the crisis. 1, 3
• Insert activated charcoal filters on both inspiratory and expiratory limbs of the breathing circuit to rapidly eliminate residual volatile agents. 1, 2, 3
• Switch to total intravenous anesthesia (TIVA) and inform the surgeon to terminate or postpone surgery. 1

Dantrolene Administration (Critical)

Administer dantrolene 2-3 mg/kg IV immediately as the initial bolus—this is the specific antidote for malignant hyperthermia. 1, 2, 3, 4

• Reconstitute each 20 mg vial with 60 mL sterile water (without bacteriostatic agent) and shake vigorously until clear—this may take up to 5 minutes per vial. 1, 3, 4
• Continue administering 1 mg/kg boluses every 5 minutes until end-tidal CO2 falls below 6 kPa with normal minute ventilation AND core temperature drops below 38.5°C. 1, 2, 3
• Obtain dantrolene from all available sources (pharmacy, nearby hospitals)—at least 36-50 ampoules may be needed for an adult patient, and the maximum dose of 10 mg/kg may need to be exceeded. 1, 4
• Do not delay dantrolene administration while awaiting diagnostic confirmation—early intervention is critical for survival. 2, 3

Active Cooling Measures

Initiate aggressive cooling simultaneously with dantrolene administration—cooling should target a core temperature below 38.5°C. 1, 2

• Infuse 2000-3000 mL of chilled (4°C) 0.9% saline IV for internal cooling. 1, 5
• Apply surface cooling with wet, cold sheets, fans, and ice packs placed in the axillae and groin. 1, 2
• Use any available cooling devices including cooling blankets, intravascular cooling catheters, or evaporative cooling methods. 2, 5, 6
• Stop cooling once temperature reaches 38.5°C to prevent overcooling and hypothermia. 1

Comprehensive Monitoring

Establish invasive monitoring early to guide treatment and detect complications. 1, 3, 5

• Insert arterial and central venous lines with wide-bore cannulas for hemodynamic monitoring and medication administration. 1, 3
• Place a urinary catheter and monitor urine output continuously—target output >2 mL/kg/hour. 1
• Measure core temperature continuously using rectal, esophageal, or bladder probes. 1, 2, 5
• Obtain laboratory samples for potassium, creatine kinase (CK), arterial blood gases, myoglobin, glucose, renal function, hepatic function, and coagulation studies. 1, 3
• Continue routine anesthetic monitoring including SpO2, ECG, non-invasive blood pressure, and end-tidal CO2. 1

Treatment of Metabolic Complications

Hyperkalemia Management

Treat hyperkalemia aggressively as it can cause fatal arrhythmias. 1, 3, 5

• Administer calcium chloride 0.1 mmol/kg IV (e.g., 7 mmol = 10 mL for a 70 kg adult) for cardiac membrane stabilization. 1
• Give dextrose 50%, 50 mL with 50 units insulin (adult dose) to shift potassium intracellularly. 1
• Consider dialysis if hyperkalemia is refractory to medical management. 1, 5

Acidosis Management

Correct acidosis through hyperventilation and pharmacologic intervention. 1, 3

• Hyperventilate to normocapnia as the primary method of reducing CO2 and treating respiratory acidosis. 1
• Administer sodium bicarbonate IV if pH <7.2 to treat severe metabolic acidosis. 1

Arrhythmia Management

Treat arrhythmias with specific antiarrhythmic agents. 1, 3

• Give amiodarone 300 mg IV (3 mg/kg) for an adult as first-line antiarrhythmic therapy. 1
• Consider beta-blockers (propranolol, metoprolol, or esmolol) if tachycardia persists despite other interventions. 1

Renal Protection

Maintain high urine output to prevent acute kidney injury from myoglobinuria. 1, 3, 5

• Administer furosemide 0.5-1 mg/kg to promote diuresis. 1
• Give mannitol 1 g/kg for osmotic diuresis and renal protection. 1
• Infuse crystalloids (lactated Ringer's solution or 0.9% saline) to maintain adequate intravascular volume. 1

Post-Crisis Management

Monitor the patient for a minimum of 24 hours in an ICU, high-dependency unit, or recovery unit after the crisis resolves. 1, 3

• Continue dantrolene 4-8 mg/kg/day orally in four divided doses for 1-3 days following the crisis to prevent recurrence. 3, 4
• Monitor for compartment syndrome by checking limbs for swelling and measuring compartmental pressures if suspected. 1, 5
• Refer the patient and family to a regional or national MH center for diagnostic testing (in vitro contracture testing and genetic testing). 1, 3
• Provide comprehensive counseling to the patient and family about the diagnosis, future anesthetic management, and the need to warn all blood relatives about MH risk. 1, 3

Critical Pitfalls to Avoid

Do not delay treatment while awaiting diagnostic confirmation—early recognition and immediate intervention are essential for survival. 2, 3

Do not fail to recognize MH because temperature has not yet risen significantly—unexplained increase in end-tidal CO2 is often the first sign, and temperature may rise rapidly later. 1, 2

Do not underdose dantrolene—continue administering until treatment goals are achieved, even if this exceeds the traditional maximum dose of 10 mg/kg. 1, 4

Do not stop cooling prematurely—maintain cooling efforts until core temperature is stable below 38.5°C. 2, 5