Malignant hyperthermia

Description

Malignant hyperthermia is an allergic reaction to certain drugs used for anesthesia. This severe reaction usually includes a dangerously high body temperature, muscle stiffness or spasms, rapid heart rate, and other symptoms. Without timely treatment of complications caused by malignant hyperthermia can be fatal.

In most cases, the gene that puts you at risk of malignant hyperthermia is an inherited disease, although it is sometimes the result of a genetic change random. Genetic testing can reveal if you have an affected gene. This genetic disorder is called susceptibility to malignant hyperthermia (MHS).

Treatments for malignant hyperthermia include medication dantrolene (Dantrium, Revonto, Ryanodex), bags of ice, and other measures to cool the temperature of the body, as well as supportive care.

Symptoms

In most cases, no signs or symptoms of susceptibility to malignant hyperthermia exist until you're exposed to certain drugs used for anesthesia.

The signs and symptoms of malignant hyperthermia may vary and can occur during anesthesia or during recovery, shortly after the surgery. These may include:

  • Severe muscle stiffness or spasms
  • Rapid and shallow breathing and problems with low oxygen levels and high carbon dioxide
  • Rapid heart rate
  • The Irregular rhythm of the heart
  • Dangerously high body temperature
  • Excessive sweating
  • Uneven, irregular, color of the skin (skin blemishes)

In rare cases, people who are at risk of malignant hyperthermia have shown signs of a reaction after an intense physical activity during excessive heat or humidity, during a viral illness, or when taking statin medication used to lower cholesterol.

If you are at risk of malignant hyperthermia, and you don't have a severe reaction during their first exposure to certain drugs of anesthesia, you are still at risk if you do not receive these drugs in the future. Other anesthetic drugs that do not trigger a reaction can be used in its place.

When to see a doctor

If someone in your family is known at risk of malignant hyperthermia, and it is necessary to have anesthesia, it is important that you inform your health care provider and a specialist of anesthesia (anesthesiologist). Other drugs can be used in its place.

Causes

Malignant hyperthermia can result when you have a susceptibility to malignant hyperthermia (MHS), a genetic disorder caused by a gene change (mutation). The affected gene increases the risk of malignant hyperthermia when exposed to certain anesthetic drugs that trigger a reaction. The affected gene is hereditary, more common, usually from a parent who also has it. Less frequently, the affected gene is not inherited and is the result of a random change in the gene.

Different genes can cause MHS . The most commonly affected is the gene RYR1 . More rarely affected genes include CACNA1S and STAC3 .

Risk factors

Your risk of suffering from the genetic disorder MHS is higher if someone in your family has.

  • You only need to inherit an altered gene from one parent to be affected by the disorder (autosomal dominant inheritance pattern). If one of your parents has the gene change that causes MHS , you have a 50% chance of having MHS too.
  • If you have other relatives with MHS , your odds of having it also is greater.

The risk of malignant hyperthermia is also higher if you or a close family member has:

  • A story of an event that is suspected to be malignant hyperthermia during anesthesia
  • A story of the breakdown of muscle tissue called rhabdomyolysis (rab-doe-my-OL-ih-sis), which may be triggered by exercise in extreme heat and humidity or when taking a statin drug
  • Certain muscle diseases and disorders caused by changes in the genes inherited

Complications

If not treated quickly, the malignant hyperthermia can result in serious complications, such as:

  • A rare disease that causes muscle cells to break down (rhabdomyolysis)
  • Kidney damage or failure
  • Problems with clotting and bleeding
  • Death

Prevention

If you have a family history of malignant hyperthermia or a relative who has problems with the anesthesia, tell your health care provider or an anesthesiologist prior to surgery or any procedure that requires anesthesia.

The assessment of their risk of malignant hyperthermia allows the anesthesiologist to avoid certain drugs of anesthesia.

Malignant hyperthermia

Diagnosis

Malignant hyperthermia is diagnosed based on signs and symptoms, follow-up during and immediately after the anesthesia, and laboratory tests to identify complications.

Susceptibility testing

The tests to find out if you are at a higher risk of malignant hyperthermia (sensitivity test) may be recommended if you have risk factors. The tests may include genetic testing or muscle biopsy of the test.

  • The genetic testing. The gene change (mutation), which makes them susceptible to malignant hyperthermia is identified by genetic testing. A blood sample is collected and sent to a laboratory for analysis. Genetic testing can identify the change in the gene that shows that you have the genetic disorder called susceptibility to malignant hyperthermia (MHS).
  • The muscle biopsy (contracture of the test). In some cases, your health care provider may recommend a muscle biopsy if you are at risk of malignant hyperthermia. During this test, a small piece of muscle tissue is surgically removed for laboratory analysis. In the laboratory, the sample is exposed to the activation of chemical products to the hyperthermia malignant to determine how the muscle contracts. Because this test should be performed in muscle tissue immediately after removing it, to travel to a specialized muscle biopsy center is necessary.

Treatment

If you or someone in your family has a susceptibility to malignant hyperthermia (MHS), or think you may be at risk of malignant hyperthermia, it is important that you inform your health care provider and the anesthesiologist prior to receiving anesthesia. Drugs that do not trigger malignant hyperthermia can be used as part of anesthesia.

Immediately the treatment of malignant hyperthermia includes:

  • The medication. A drug called dantrolene (Dantrium, Revonto, Ryanodex) is used to treat the reaction by stopping the release of calcium in the muscles. Other medications may be administered to correct problems with the balance of chemicals in the body (metabolic imbalance) and treat complications.
  • Oxygen. You may get oxygen through a face mask. In most cases, oxygen is given through a tube placed into the windpipe (trachea).
  • Body cooling. Ice packs, cooling blankets, a fan with fresh air and cooled intravenous (IV) fluids can be used to help reduce the body temperature.
  • The excess of liquids. You can also get more fluids through an intravenous line (IV).
  • Supportive care. It is possible that you need to stay in the hospital in intensive care for a day or two to monitor your temperature, blood pressure, heart rate, breathing, and response to treatment. Several laboratory tests are often performed to check the extent of muscle degradation and possible kidney damage. A stay in the hospital is usually required until the results of laboratory tests start to return to a standard range.

With treatment, malignant hyperthermia, usually resolves within a couple of days.

The follow-up care

If you have experienced malignant hyperthermia due to certain drugs of anesthesia, the exercise in the excessive heat and humidity could trigger another reaction. Talk with your health care provider about the precautions you should take.

Also, check with your health care provider to see if you should undergo genetic testing to determine if you have a genetic disorder that puts you at risk of malignant hyperthermia. Ask if the members of the family should also consider genetic testing.

If you have the genetic disorder MHS that puts you at risk of malignant hyperthermia, wear a medical alert bracelet or necklace. This allows the health care providers of their risk, especially in case of emergency when you may not be able to speak.

Symptoms and treatment of Malignant hyperthermia