What is the anesthetic management for a patient with Malignant Hyperthermia (MH)?

From the Guidelines

The anesthetic management for a patient with Malignant Hyperthermia (MH) requires avoiding triggering agents and being prepared for rapid intervention if a crisis occurs, as recommended by the European Malignant Hyperthermia Group guidelines 1. All volatile anesthetics (sevoflurane, desflurane, isoflurane) and succinylcholine must be strictly avoided as they are the primary triggers of MH. Instead, use a total intravenous anesthesia (TIVA) technique with propofol, opioids like fentanyl or remifentanil, and non-depolarizing muscle relaxants such as rocuronium or cisatracurium. The anesthesia machine should be prepared by removing all vaporizers if possible, replacing the CO2 absorbent, changing the circuit, and flushing with high flow oxygen (10 L/min) for at least 20 minutes, as suggested by the Association of Anaesthetists guidelines 1. Dantrolene sodium must be immediately available (minimum 36 vials or 720 mg for a 70 kg patient), along with sterile water for reconstitution, as recommended by the European Malignant Hyperthermia Group guidelines 1. If an MH crisis occurs, immediately discontinue triggering agents, hyperventilate with 100% oxygen, administer dantrolene (2.5 mg/kg initially, repeated until symptoms resolve) 1, provide active cooling (cold IV fluids, ice packs), treat hyperkalemia with calcium, insulin/glucose, and sodium bicarbonate, and manage acidosis and arrhythmias. Continuous monitoring of core temperature, end-tidal CO2, arterial blood gases, electrolytes, creatine kinase, and urine output is essential. MH is a pharmacogenetic disorder causing uncontrolled calcium release in skeletal muscle, leading to hypermetabolism, hyperthermia, acidosis, and potentially death if not treated promptly. Some key points to consider in the anesthetic management of MH include:

• Avoiding triggering agents
• Preparing the anesthesia machine to minimize the risk of exposure to triggering agents
• Having a plan in place for rapid intervention in case of an MH crisis
• Administering dantrolene promptly and in adequate doses
• Providing active cooling and managing hyperkalemia, acidosis, and arrhythmias
• Continuously monitoring the patient's vital signs and laboratory values.

From the FDA Drug Label

As soon as the malignant hyperthermia reaction is recognized, all anesthetic agents should be discontinued; the administration of 100% oxygen is recommended Dantrolene Sodium for Injection should be administered by continuous rapid intravenous push beginning at a minimum dose of 1 mg/kg, and continuing until symptoms subside or the maximum cumulative dose of 10 mg/kg has been reached. Preoperatively Dantrolene Sodium for Injection and/or Dantrolene Sodium Capsules may be administered preoperatively to patients judged malignant hyperthermia susceptible as part of the overall patient management to prevent or attenuate the development of clinical and laboratory signs of malignant hyperthermia.

The anesthetic management for a patient with Malignant Hyperthermia (MH) involves:

• Discontinuing all anesthetic agents as soon as the MH reaction is recognized
• Administering 100% oxygen
• Giving Dantrolene Sodium for Injection by continuous rapid intravenous push, starting at a minimum dose of 1 mg/kg and continuing until symptoms subside or the maximum cumulative dose of 10 mg/kg is reached
• Preoperative administration of Dantrolene Sodium for Injection and/or Dantrolene Sodium Capsules to prevent or attenuate the development of clinical and laboratory signs of MH 2
• Monitoring for early clinical and metabolic signs of MH, and administering additional Dantrolene as needed 2

From the Research

Anesthetic Management for Malignant Hyperthermia (MH)

The anesthetic management for a patient with Malignant Hyperthermia (MH) involves several key considerations to prevent triggering the condition and to manage it effectively if it occurs.

• Precautions before anesthesia include the prohibition of the use of triggering agents such as potent volatile anesthetics and succinylcholine 3.
• Monitoring of central body temperature and expired CO2 is crucial, along with the immediate availability of dantrolene sodium, a nonspecific muscle relaxant 3.
• Careful cleansing of the anesthesia machine of vapors of halogenated agents is recommended to prevent triggering MH 3.

Triggering Agents and Treatment

• MH can be triggered by volatile inhalational anesthetics and/or succinylcholine, a muscle relaxant 4.
• Early signs of MH include unexplained hypercarbia, tachycardia, and muscle rigidity, with the body temperature potentially rising rapidly 4.
• Treatment involves discontinuation of the triggering agents, administration of intravenous dantrolene, and reduction of the body temperature 4.
• Dantrolene must be readily available wherever MH triggering agents are used for anesthesia 5.

Safe Anesthesia Practices

• Anaesthesia can be safely performed with i.v. anaesthetics, nitrous oxide, nondepolarizing muscle relaxants, local anaesthetics, as well as xenon in MH-susceptible patients 6.
• Preparation of the anaesthetic machine is critical, and modern workstations may require longer cleansing times or the use of activated charcoal to eliminate volatile anaesthetics 6.
• Day case surgery can be performed in MH-susceptible patients if all safety aspects are considered 6.

Importance of Prompt Recognition and Treatment

• Prompt recognition and treatment of MH are crucial to prevent a potentially fatal outcome 3, 4.
• Delayed dantrolene treatment increases the likelihood of MH complications, emphasizing the need for immediate action upon suspicion of MH 7.
• The availability of dantrolene and adherence to guidelines for its use are critical in managing MH crises effectively 7, 5.