What Is Malignant Hyperthermia and How Can You Stay Safe During Surgery?

Have you or someone you care about ever scheduled a surgery? If so, you have likely heard the word anesthesia. That is the medicine doctors use to help you sleep safely and painlessly during an operation.

Have you ever wondered if some people might have a bad reaction to these medicines? Such a reaction can sometimes threaten a person's life.

A rare and very serious condition like this is called malignant hyperthermia. This name might sound scary at first. However, if you learn the facts about it, you can help prevent dangerous problems.

What Is Malignant Hyperthermia?

Simply put, malignant hyperthermia is a genetic condition. That means it happens because of a change, or mutation, in your genes. When a person with this condition receives certain anesthesia medicines, their body reacts in a very severe way. This reaction can become a life-threatening emergency.

The good news is that even though this condition runs in families, specific treatments exist. Also, if you know you have this risk, you can take steps to stay safe.

We know that general anesthesia lets you sleep comfortably without feeling any pain during surgery. Doctors use different medicines to provide this anesthesia. However, only a few specific medicines trigger malignant hyperthermia. Most anesthesia medicines do not cause this problem at all.

Another important point is that you might carry the genetic change for malignant hyperthermia without knowing it. That is because you usually show no symptoms until you are exposed to those specific trigger medicines.

Who Has a Higher Chance of Getting It?

Let us look at who faces a higher risk of developing malignant hyperthermia.

The main risk factor is having a family history of this reaction. If a close family member, such as a parent, brother, sister, or child, has experienced malignant hyperthermia, you might also carry that risk.

Because of this, if you ever need surgery, you must tell your anesthesiologist about any family history of bad reactions to anesthesia.

What if no one in your family has ever had this reaction? Certain rare muscle diseases can still increase your risk. Some of these conditions include:

• Central core disease.
• Multiminicore disease.
• King-Denborough syndrome.
• STAC3 disorder.

Even though these medical names sound complex, knowing if you have one of these conditions helps keep you safe.

How Common Is This Condition?

How common is malignant hyperthermia in real life? Numbers can vary, but experts estimate it happens in about one out of every 100,000 adult surgeries. Among children, the rate is about one out of every 30,000 surgeries. About half of all diagnosed patients are under the age of 19.

However, scientists believe that more people might be sensitive to this condition than we realize. Many people never need the specific trigger medicines during their lifetime. Therefore, they may never find out they carry this risk.

What Are the Symptoms?

Symptoms of malignant hyperthermia can vary from person to person. They can start during surgery or shortly after while you are waking up in the recovery room.

If these symptoms start during surgery while you are asleep, you will not feel them yourself. However, your anesthesiologist and surgical team watch you very closely. They monitor every patient under anesthesia. As soon as they spot these signs, they start treatment right away.

Early Signs.

These are the first warning signs that doctors look for:

• Unexplained fast heartbeat: Your heart suddenly starts beating much faster than normal.
• High carbon dioxide levels: Your body breathes out more carbon dioxide than expected, which monitors show clearly.
• Fast breathing: You start breathing rapidly as if you are out of breath.
• Muscle stiffness: Your muscles feel hard, tense, or locked up.
• Sudden high temperature: Your body temperature begins to rise quickly.

Later Signs.

If the condition gets worse, you might show these additional symptoms:

• Extreme fever: Your body temperature climbs much higher than a normal fever.
• Dark urine: Your urine turns a very dark color, sometimes looking brownish.
• Muscle breakdown: Blood tests show that your muscle tissue is breaking down.
• Irregular heartbeat: Your heart beats in an unsafe, uneven rhythm.
• Bleeding problems: Your blood may have trouble clotting normally.
• Seizures: You might experience sudden shaking or seizures.

Why Does Malignant Hyperthermia Happen?

Let us explore why malignant hyperthermia happens inside the body.

People who are sensitive to this condition have an abnormal type of protein in their muscle cells. This happens because of a change in their genes, known as a genetic mutation.

Simply put, our DNA acts like an instruction book for our body's cells. When a part of that instruction book has missing or damaged information, genetic conditions can happen.

This genetic mutation causes no trouble in everyday life. However, if a person with this mutation is exposed to specific trigger medicines, or very rarely extreme heat or heavy exercise, their muscle cells release too much calcium.

As a result, muscles stay tightly contracted and tense. Your body's metabolism and temperature rise rapidly. In the end, muscle cells can break down, releasing large amounts of potassium into your blood. This triggers more severe symptoms and complications.

Anesthesia Medicines That Can Trigger It.

If you have a genetic risk for malignant hyperthermia, certain medicines can trigger this reaction:

Inhaled medicines:

• Halothane.
• Desflurane.
• Sevoflurane.
• Isoflurane.

Intravenous medicines:

• Succinylcholine, which is a fast-acting medicine used to relax muscles.

How Do Doctors Diagnose It?

If you do not know you are at risk and doctors use a trigger medicine during surgery, you and your doctor will only find out after the reaction begins.

During any surgery, your medical team carefully watches your vital signs. If malignant hyperthermia occurs, they spot it through sudden changes in your vital signs, such as:

• A fast heart rate with no clear cause.
• A rapid rise in body temperature.
• High carbon dioxide levels in your breath.
• Severe muscle stiffness.

Surgical teams receive special training to spot these warning signs early. This helps them act fast. The sooner they diagnose the problem, the easier it is to treat.

How to Find Out Your Risk Ahead of Time.

If your family history or other clues suggest you might have this risk, special tests can check for it:

• Caffeine halothane contracture test (CHCT): Doctors take a tiny sample of your muscle tissue and expose it in a lab to halothane and caffeine. This test shows whether your muscle tissue reacts to these agents.
• Genetic testing: Blood or saliva tests can check your DNA for mutations in genes like RYR1, STAC3, and CACNA1S. Scientists have found more than 45 different mutations linked to malignant hyperthermia.

These tests can be expensive and are only available at specialized medical centers. For example, very few labs in the United States offer the CHCT test. Because of this, if you need surgery and a close relative has had malignant hyperthermia, doctors will usually skip the trigger medicines entirely and use safe anesthesia options instead.

What Are the Treatments?

The main treatment for malignant hyperthermia is a medicine called dantrolene (brand name Dantrium).

As soon as doctors suspect malignant hyperthermia, they give you dantrolene right away. They also stop the trigger medicine right away, and the surgeon finishes the operation as fast as possible.

The medical team also treats other symptoms and complications caused by malignant hyperthermia. These treatments include:

• Cooling your body with ice packs or cold IV fluids to lower a high fever.
• Giving you extra oxygen through a face mask or breathing tube.
• Giving you heart medicines if your heartbeat becomes irregular.

Once your condition is stable, doctors will move you to the intensive care unit (ICU) for at least one day. The medical team will run blood tests and provide extra care until you recover.

Can You Prevent It?

Preventing malignant hyperthermia can be difficult unless you know you carry the genetic mutation, or unless you share your family history with your doctor before surgery. When doctors know your risk, they simply avoid using the trigger medicines in your anesthesia plan.

Sadly, many people only find out they have this risk after a reaction happens during an operation.

What Happens After Treatment? Can You Recover?

If doctors spot the signs of malignant hyperthermia early and treat it correctly, you can make a full recovery. Quick action by the anesthesia and surgical team saves lives.

However, even with fast treatment, serious complications can sometimes happen, including organ failure or death.

What Other Complications Can Happen?

Malignant hyperthermia can lead to severe health problems if not treated instantly:

• Severe muscle damage.
• Kidney failure.
• Liver failure.
• Uncontrolled bleeding.
• Cardiac arrest.
• Seizures.
• Coma.
• Death.

Is It Fatal?

Without treatment, malignant hyperthermia is almost always fatal. Even with prompt medical care, studies report that death rates range between 3% and 5%. Because of this danger, doctors take every precaution seriously.

When Should You See a Doctor?

If you are planning to have surgery, always tell your doctors about any past anesthesia problems in your family.

If a blood relative learns they carry a genetic mutation for malignant hyperthermia, you should tell your doctor right away. Make sure this important note is added to your personal medical records.

Key Things to Remember.

Malignant hyperthermia is a rare, serious reaction to certain anesthesia medicines that can threaten your life.

The best news is that doctors can treat it effectively, and you can prevent it entirely if you know your risk beforehand.

Try to learn about your family's medical history and share those details with your doctor. Because malignant hyperthermia passes down through families as a genetic trait, knowing your family history is your best defense.

If you have questions or worries about surgery and anesthesia, never hesitate to talk to your doctor. They are there to help you. Open communication between you and your medical team is the best way to stay safe.

Sources and References.

• Mayo Clinic. Malignant Hyperthermia: Symptoms and Causes. Available online.
• National Health Service (NHS). Malignant Hyperthermia Overview. Available online.
• Cleveland Clinic. Malignant Hyperthermia: Diagnosis and Treatment Guidelines. Available online.
• Malignant Hyperthermia Association of the United States (MHAUS). Clinical Guide and Patient Resources. Available online.
• National Institutes of Health (NIH) / PubMed. Genetics of Malignant Hyperthermia Susceptibility. Available online.