MSN, RN
Never say that you can’t learn anything new in nursing! I have been an emergency department nurse for most of my nursing profession, so I thought I had heard and seen it all. However, I had never heard of a phenomenon called malignant hyperthermia.
This is seen in surgical centers where minor procedures are performed. Now working in an endoscopy/surgical suite, it is something I had to learn about.
Malignant hyperthermia (MH) is a severe reaction and — dominantly inherited disorder — that occurs in response to certain medications used during general anesthesia.
Exposure to triggering agents, which are volatile anesthesia agents including succinylcholine, can lead to the development of MH in anyone who might be susceptible, according to the Malignant Hyperthermia Association of the United States (MHAUS).
Other potent, volatile anesthetics include halothane, isoflurane, and sevoflurane. These are inhaled anesthetics that are administered as primary therapy for preoperative sedation and work with intravenous sedation agents like midazolam and propofol. All anesthetic gases are administered through inhalation.
Signs and symptoms are characterized by hypermetabolism that produces heat, otherwise known as hyperpyrexia, increased oxygen consumption, carbon dioxide production, and hyperkalemia.
Skeletal muscle rigidity can be localized to the masseter muscle or be generalized. Rhabdomyolysis with myoglobinuria can often occur as well.
The time of onset may vary from patient to patient, ranging from minutes to hours, even though a patient may have had a previously uneventful exposure to anesthetics.
For treatment to be successful, immediate cessation of the anesthetic triggering agent, cooling of the patient, and intravenous administration of Dantrolene must be initiated. Dantrolene inhibits calcium ion release and directly interferes with muscle contractions. It’s the only approved drug for MH.
The prophylactic dose of Dantrolene is 2.5mg/kg administered intravenously over at least one minute, starting about 75 minutes prior to surgical procedure.
The nursing staff have many roles in the immediate management of MH. This includes assessing the patient, administering treatments, and monitoring the patient. Nursing staff must perform risk assessments during a preoperative visit or phone call to identify which patients may be at risk for contracting MH.
If a patient develops an MH episode, nurses may hyperventilate them with 100% oxygen. They can also initiate cooling measures by placing ice packs and hypothermia blankets on the patient’s body, such as the neck, groin, and underarms if the patient’s temperature exceeds 39 degrees Celsius.
Intravenous fluids, either normal saline, dextrose, or lactated ringers, may be hung by nursing staff to replace body fluids and nutrients. Have someone place a call to the MH Hotline.
There should also be at least two medication nurses who mix the Dantrolene, also known as Revonto or Ryanodex. It comes in 36 vials that must be mixed with 60 ml of sterile water for injection, each without a bacteriostatic agent added. The vial should be shaken for approximately 20 seconds until the solution is clear. It will take two nurses to complete and speed up this process.
Nurses then monitor the patient for signs of muscle weakness, nausea, vomiting, and difficulty breathing, along with their cardiac status as tachyarrhythmias and tachypnea may occur. They must monitor the patient’s core body temperature and check for adequate urine output by inserting a foley catheter to measure output hourly. Stop cooling measures once the patient’s core temperature is below 38 degrees Celsius.
While this emergency care is taking place, preparing for immediate transfer to the nearest emergency department is critical. Considering the receiving hospital’s capabilities and staff to handle such an emergency is paramount, along with observing the patient’s stability for the transfer itself.
Nurses can prepare a transfer pack with supplies that may be needed during the transfer, such as extra oxygen supplies, temperature probes, BP cuff, and EKG leads.
The physician or anesthesiologist should provide a report to the receiving hospital, along with proper documentation.
Continuously evaluate the patient for at least 24 hours following the stoppage of signs of MH in case of a relapse. One-fourth of MH events that relapse can be fatal. There can be sudden and unexpected cardiac arrest in young patients. Avoid the use of calcium channel blockers, as they may cause hyperkalemia or cardiac arrest in the presence of Dantrolene.
The Malignant Hyperthermia Hotline number for any institution that has questions concerning MH is 1-800-644-9737 and is staffed 24/7. Callers should provide their name, phone number, and facility so a call back can be made. Would you know what to do if your patient develops malignant hyperthermia? It is important to be aware of the signs and symptoms and how to treat MH promptly.
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