Malignant hyperthermia (MH) is a rare and sometimes deadly disease that is difficult to diagnose and treat unless surgery centers have undergone proper training and prepared the right way.

  • Surgery teams might have only minutes to react once the condition is first apparent.
  • MH is triggered by volatile anesthetics and succinylcholine and can be avoided by using the clean technique.
  • Dantrolene is a drug that can be used to reverse symptoms, but ORs must keep the drug in stock to ensure it reaches the patient in time.

Certain patients carry a rare genetic predisposition to a disease that could kill them during surgery.

Called malignant hyperthermia (MH), common anesthesia agents can trigger the pharmacogenetic condition. It is a tricky condition to diagnose as it can appear to be something else and can continue to worsen, unrecognized, until a patient is close to cardiovascular collapse and death.

Surgery teams might have only a few minutes to recognize the symptoms and act to save a patient’s life, says Joseph Tobin, MD, board member with the Malignant Hyperthermia Association of the United States.

MH is a hypermetabolic reaction to volatile anesthetics such as isoflurane, sevoflurane, or desflurane or the administration of succinylcholine with or without the introduction of an inhalation agent.

Although few people die from the disease, thanks to better emergency preparedness among hospitals and surgery centers, any operating room (OR) death can be traumatic for surgery teams. The victims often are young, healthy, and even athletic.

According to a 2008 study of 20 years of data related to MH injuries and deaths, reported in the North American Malignant Hyperthermia Registry, the median age of patients who experienced cardiac arrest due to MH was 20 years. Patients with a muscular build were more likely to go into cardiac arrest and die during surgery.1

For example, one recent case involved a teenage athlete undergoing elective orthopedic surgery on his ankle. The teen quickly showed signs of MH. The OR team administered dantrolene, a drug used to reverse symptoms, but it did not stop the crisis. The young man died despite the OR staff’s interventions.2

Most patients with MH show physiological signs that the surgery team could catch early enough to diagnose and provide emergency treatment. But a small number of these patients might reach a crisis point within minutes, Tobin says. Preparation is key to patient survival. “The crisis of the malignant hyperthermia syndrome is a hypermetabolic crisis, and the process must be stopped as quickly as possible,” Tobin says. “The high potassium and fever must be counteracted.”

OR staff education on malignant hyperthermia, combined with an MH cart, is what saved the life a 5-year-old girl whose tonsil surgery quickly turned into a medical crisis, says Terri Passig, BSN, CPAN, CCRN, CPAHQ, regulatory consultant with Orlando Health. Passig was working for a children’s hospital about five years ago when the little girl was given anesthesia for a tonsillectomy, adenoidectomy, and the placement of ear tubes.

“It’s a very short surgery, and the OR staff noticed problems with her carbon dioxide level going up and not responding to their intervention,” Passig says. “At first, they tried to increase her ventilation with 100% oxygen. They tried to increase the anesthetic gasses because sometimes a patient’s body is trying to fight [sleep], and the CO2 levels go up.”

But the girl did not respond to those changes. Staff decided to test her blood. Someone moved her wrist and noticed that it was slightly rigid. That was when someone said it could be MH. “Then, they gave her dantrolene, and she responded very quickly,” Passig says.

Using the MH cart, the OR staff gave the girl ice packs to lower her temperature. The cart also contained additional resources, including a refrigerator for cool IV fluid, tubes and lines, Foley catheters, irrigation fluids, and lab tubes for drawing lab specimens.

MH was first described in medical literature in the 1960s when multiple members of one family died under anesthesia. No one understood the etiology of the family’s deaths, but they assumed the deaths were related to anesthesia, Tobin explains. “In the United States, it was noted that pigs transported across the country had a significant percentage die from what appeared to be a heat-related illness,” he says. “The environmental heat stress of being transported in big tractor-trailers triggered porcine stress syndrome, a similar condition.”

That discovery gave scientists an animal model to test potential drugs in humans. By the end of the 1970s, there was a drug, dantrolene, approved to treat cases of malignant hyperthermia, according to Tobin. Dantrolene is a drug that stops the release of calcium inside the muscle cells and causes the hypermetabolic reaction to discontinue. The drug does not always stop the patient’s reaction. If he or she has a high fever or high levels of potassium, it still is possible for the patient to experience cardiac collapse.

Sometimes, surgery patients die from MH because the OR was unprepared for the crisis. There might not be dantrolene on site, or employees were not trained to recognize the earliest signs of the condition. Preventing these crises and deaths begins with staff education and training, Passig says. “We’ve started doing simulations at our hospital involving anesthesia and a simulated crisis.”

Surgery centers need to be more aware of MH and ready to act when a patient shows symptoms, Passig adds. One way they can prepare is to keep dantrolene in stock. Both Tobin and Passig note that while the drug is costly, it is necessary to protect patients’ safety.

“In hospital and outpatient surgery settings, there are defibrillators, which are expensive, but they’re there when you need them,” Passig says. “From the patient’s perspective, dantrolene is the same. They might say, ‘Are you trying to tell me that our life is not worth $3,000 if something happens to us when we’re in here?’”

Surgery centers might never use dantrolene, but better safe than sorry. “You don’t want to wait to have someone die before stocking it,” Passig offers.

Staff education is crucial to identifying MH quickly enough to save lives. One way surgery centers can improve staff’s knowledge of MH is through holding mock drills, Tobin says. “The Malignant Hyperthermia Association of the United States supports mock drill calls when someone does a MH drill and is put in contact with an expert,” he says. “You also can have an MH expert visit your facility, go over your MH preparedness, and supervise an MH-simulated event — an MH prep check.”


  1. Larach MG, Brandom BW, Allen GC, et al. Cardiac arrests and deaths associated with malignant hyperthermia in North America from 1987 to 2006: A report from the North American Malignant Hyperthermia Registry of the Malignant Hyperthermia Association of the United States. Anesthesiology 2008;108:603-611.
  2. Malignant Hyperthermia Association of the United States. Another Unusual and Disturbing Malignant Hyperthermia Death. Available at: http://bit.ly/2L0ipvh. Accessed Aug. 28, 2019.