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Malignant Hyperthermia: Is Your OR Prepared?

Wed, 06/24/2009 - 5:18am

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In any surgical procedure, professionals in the OR must monitor for a number of complications to keep a patient safe. Often, risks can be identified before the procedure, and prevented through taking the proper steps before, during and after the surgery.

In any surgical procedure, professionals in the OR must monitor for a number of complications to keep a patient safe. Often, risks can be identified before the procedure, and prevented through taking the proper steps before, during and after the surgery.

However, there is a condition that cannot always be foreseen and happens only after the patient is induced under anesthesia. In this case, all the OR staff can do is be prepared to recognize the issue and be ready to handle it quickly—sometimes in as little as 15 minutes—or they may lose that surgical patient.

Malignant Hyperthermia (MH), as defined by the Malignant Hyperthermia Association of the United States (MHAUS), is a genetic disorder thought to primarily result from an alteration to a specific gene involved in the control of muscle cell function. This alteration may sometimes cause a patient to react adversely to certain “triggering” anesthetics. Any person whose parent has the disorder has a 50 percent chance of also being susceptible to MH.

According to Dianne Daugherty, Executive Director of MHAUS, what is so dangerous about MH is that unless a patient has knowledge of past family history of MH, he/she will not be aware of the potential risk, as MH-susceptible individuals do not display symptoms in normal day-to-day activities. Thus, suspicion of MH may only come about after the patient is anesthetized with the triggering anesthetics and MH symptoms start to appear. MH susceptibility can be determined through a muscle biopsy which is then put through a Caffeine Halothane Contracture Test, and DNA testing can be done, but it is not yet ready to act as a pre-screening for MH in surgical patients, the MHAUS website reports. An MH event in a surgical patient, if not recognized and treated immediately by the OR staff, can result in death.

Although uncommon, MH is a condition all OR services personnel should be aware of. According to the MHAUS website, incidence of MH ranges from 1 in 5,000 surgeries to 1 in 65,000 surgeries. Studies report 1 in every 100,000 hospital discharges are complicated by MH, with 500-600 MH cases occurring every year in the United States. MH has been observed more often in males than females, and it is unclear as to whether there is a difference between adults and children with regard to incidence.  Based on national data, the overall mortality rate for MH ranges between 4 to10 percent, with a 5 percent mortality rate when the condition occurs in the hospital. However, the mortality rate has been reported to climb to 20 percent when a patient requires transfer to the hospital from another venue when experiencing an MH event.

Recognizing an MH Event As Daugherty explains, an MH event is triggered when a susceptible patient is subjected to volatile gaseous anesthetics, such as:

  • Desflurane
  • Enflurane
  • Halothane
  • Isoflurane
  • Methoxyflurane
  • Sevoflurane

In addition, the depolarizing muscle relaxant succinylcholine is also a triggering agent.

According to the MHAUS website, most MH-susceptible patients have a mutation that results in the presence of abnormal proteins in the skeletal muscle cells of their body. An MH event is triggered when these patients are exposed to specific anesthetic agents, causing an abnormal amount of calcium release inside the muscle cell. When this happens, the muscles contract and become rigid, resulting in an abnormal increase in energy utilization (i.e., hypermetabolism) and a rise in body temperature. The muscle cells eventually run out of energy and die, and release large amounts of potassium into the bloodstream, which can lead to heart rhythm abnormalities.

The muscle pigment myoglobin is also released and can be toxic to the kidney. Without adequate treatment, these changes can cause cardiac arrest, kidney failure, blood coagulation problems, internal hemorrhage, brain injury, liver failure and can be fatal.

“Many of the internal parts and pieces are getting involved now,” Daugherty explains. “The heart is beating faster, the body temperature is rising, an accumulation of acid is occurring and the brain, kidneys, and liver may be compromised.”

According to Daugherty, an MH event can occur in a number of forms. It can happen very slowly, with initial small increases in monitored expired carbon dioxide levels and other metabolic changes. Sometimes, though, the reaction occurs very quickly—giving the OR staff only  minutes to diagnose and treat the reaction and stabilize the patient.

Be Prepared “The anesthesia care provider and the staff in the OR first need to recognize that MH is happening,” Daugherty says. “Then, they need to quickly react. Simultaneously, it is important to cool the body, administer the rescue agent, dantrolene (available as Dantrium® IV or dantrolene sodium for injection), to break the cycle and relax the muscle. Treatment for the crisis of hyperkalemia from potassium released from injured muscle cells is the most urgent priority in a fulminant MH presentation to prevent cardiovascular collapse.  Once you relax the muscle and continue other appropriate measures, things start turning around.”

While there are a number of supplies MHAUS recommends an OR have on hand in case of an MH event (click here to see a complete list), the key ingredient to saving a patient is dantrolene.

“We recommend 36 vials of dantrolene anywhere MH can occur,” Daugherty says. “If the hospital is stocking trigger anesthetics or succinylcholine, they need to have it available.”

Dantrium® IV or dantrolene sodium for injection comes in a vial as a yellowish chalky-substance. To treat MH, it must be dissolved with sterile water for injection USP (without a bacteriostatic agent) and administered intravenously.

In addition to the adequate supplies to treat MH efficiently, MHAUS also recommends the MH Emergency Therapy treatment poster be hung in the OR, and the MH hotline number be at staff’s fingertips.

“Our hotline is manned by volunteer MH experts—anesthesiologists who have proven they know all about MH,” Daugherty explains. “We have 30 experts and a coordinator who ensures three consultants are available during each two-week time period. The hotline is available 24 hours, 7 days a week, 365 days a year.”

Medical professionals can call the hotline and be connected with an MH consultant if they face MH in the OR, or, if the patient they are about to operate on is known or suspected to be susceptible to MH. The consultant will walk the medical staff through treating the MH or make sure all bases are covered in preventing an MH event.

“Patients who know their history of MH will relay the information to their anesthesiologist, who then will not use MH triggers,” Daugherty says. “The problem occurs when a patient does not know they’re MH susceptible; and could trigger while under anesthesia without warning. We are here to offer education on MH to medical professionals to increase their awareness of what can happen and give them the tools to be prepared, should it happen, because with proper recognition and preparedness, MH can be dealt with to bring your patient safely through an event.”

Increasing Awareness While the existence of MHAUS since 1981 has helped to increase awareness of MH in operating rooms in hospitals across the country, Daugherty says the organization’s job isn’t done yet.

“Questions still exist about MH,” Daugherty says. “What is MH? How do I know it’s MH? What are the questions I need to ask? As well as patients—what family history do you need to relate to your physician? What kinds of things do you need to bring to the forefront? Patients need to be an active partner with their medical professional in the planning stages of their care.”

In recent years, deaths have still occurred as a result of MH. Stephanie Kuleba, the 18-year-old from Florida died of MH while undergoing breast surgery, and Steven Nook, a 20-year-old from Wisconsin died while undergoing surgery to repair a shoulder injury.

Daugherty says it’s important for hospitals to keep protocol instructions on the walls of the OR in case an MH event should happen, and to conduct regular reviews of what MH is, how to recognize it and how to treat it. In the end, saving the patient’s life could come down to the OR’s ability to identify MH and be prepared to handle it efficiently.

“It needs to be recognized and treated quickly,” Daugherty says. “If it’s lost in the shuffle, you could lose that patient and that’s devastating all the way around. Operating room professionals need to be prepared. You, of course, hope you never see it, but if you do, be prepared for it.” 

For more information, visit www.MHAUS.org

Check out a course on Malignant Hyperthermia on Nursing CE Portal

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