"Fatal fever"... Anesthesiologists talk about malignant hyperthermia ~

In 2021, the Chinese Expert Consensus Working Group on the Prevention and Treatment of Malignant Hyperthermia published the "Chinese Expert Consensus on the Prevention and Treatment of Malignant Hyperthermia (2020 Edition)" in the Chinese Journal of Anesthesiology, which elaborated on the definition, clinical manifestations, differential diagnosis, and treatment of malignant hyperthermia, providing a basis for guiding clinical work.

Malignant hyperthermia (MH) is a clinical syndrome with autosomal dominant inheritance as the main mode of inheritance. Its typical clinical manifestations often occur after the use of volatile inhalation anesthetics. According to literature reports, the incidence of MH under general anesthesia in children (1/15000) is higher than that in adults (1/50000), and it is more common in males than in females.

As early as the 1960s, the mortality rate of MH was as high as 90%. With the continuous deepening of MH-related research, the continuous improvement of diagnosis and treatment levels, and the popularization of targeted therapeutic drugs, the mortality rate of MH has not been improved. According to incomplete statistics, the mortality rate of MH in my country is still as high as 73.5%.

Next, let us deepen our understanding of MH through a comic story.

His name is Mu Hao (MH), he is eight years old, 130 cm tall and weighs 24 kg. He lives a happy life and is a carefree child.

One day, Xiao Hao suddenly had abdominal pain and felt a lump in the right abdomen. The pain was unbearable, so his parents sent him to the hospital for treatment.

After diagnosis by his handsome doctor brother, it was confirmed that Xiaohao had an incarcerated hernia and needed surgical treatment.

Complete pre-operative examinations: blood routine, coagulation II, electrocardiogram...

The anesthesiologist explained the anesthesia method and related complications to Xiaohao and his mother. As Xiaohao's guardian, his mother signed the informed consent form.

The operation went smoothly, but when it was about to end, the anesthesiologist found that Xiao Hao's: ① end-tidal carbon dioxide suddenly increased; ② body temperature rose sharply; ③ heart rate also gradually increased.

Xiaohao's condition continued to deteriorate: ① The electrocardiogram showed ventricular tachycardia; ② The body temperature was as high as 42°C; ③ Myotonia occurred.

Based on Xiao Hao's clinical manifestations, the anesthesiologist highly suspected malignant hyperthermia...

Based on the MH clinical score, the anesthesiologist quickly made a judgment...

Multidisciplinary collaboration, time is life! Rapid implementation of multi-department rescue...

Use multiple methods of physical cooling: ice packs, ice salt water...

Within 10 minutes, infuse dantrolene sodium for injection...

After timely multidisciplinary treatment, Xiaohao's vital signs gradually stabilized. Later, after genetic testing and caffeine-halothane isolated skeletal muscle contraction test, he was diagnosed with malignant hyperthermia.

Xiao Hao was safely transferred back to the ward~

The anesthesiologist informed the ward nurse of the changes in the patient's condition during the operation and instructed that dantrolene sodium should still be infused intravenously at a rate of 0.25 mg·kg-1·h-1 for 24 hours and that changes in vital signs should continue to be monitored.

After 24 hours, Xiao Hao's condition was stable: ① core body temperature 38 ℃; ② CK continued to decrease; ③ no myoglobinuria; ④ no muscle stiffness; the nurse stopped using dantrolene sodium as ordered by the doctor.

The anesthesiologist visits the child after surgery, checks the medical records, inquires about monitoring data, temperature records, and test results, and instructs the nurse on follow-up monitoring priorities.

A week later, Mu Hao recovered and was discharged from the hospital smoothly!
After that, Mu Hao studied hard, hoping to become an anesthesiologist when he grew up, and devoted himself to the research of rare diseases...

MH has a low incidence rate, but a high mortality rate. Mu Hao developed malignant hyperthermia and received timely treatment, and he is now safe! Patient: After reading the comics, I realized how terrible malignant hyperthermia is! I want to know more. Can I ask the doctor a few more questions?

Anesthesiologist: Sure. Just ask.
Patient: What kind of people are prone to MH? Anesthesiologist: MH often occurs in patients with congenital diseases such as idiopathic scoliosis, strabismus, ptosis, umbilical hernia, inguinal hernia, etc.
Patient: What are the clinical manifestations of malignant hyperthermia? Does malignant hyperthermia occur as long as the body temperature rises? Anesthesiologist: No, the rise in body temperature is only one of the clinical manifestations of MH. Fulminant MH includes at least three of the following symptoms and signs: sustained increase in end-tidal carbon dioxide, sustained increase in body temperature (above 40°C), heart-related symptoms, acidosis, and muscle rigidity.
Patient: If MH does not occur during surgery, is it safe? Anesthesiologist: No! MH is divided into four types: the first is the explosive type, which often occurs suddenly during surgery and can recur within 24 to 36 hours of onset; the second is the masseter spasm type; the third is the delayed onset type, which occurs within 1 hour during surgery; and the fourth is the simple rhabdomyolysis type, which usually occurs 24 hours after surgery.
Patient: I had MH because of the use of volatile inhalation anesthetics. Does that mean I will be fine as long as I don't use volatile inhalation anesthetics? Anesthesiologist: The main inducing factor of MH is volatile inhalation anesthetics, but there are other influencing factors, such as high temperature environment, strenuous exercise, etc.
Patient: So how can we prevent and avoid malignant hyperthermia? Anesthesiologist: Actively inform the doctor of the anesthesia history and family history of MH; if it is not certain whether the patient has MH, laboratory screening and genetic testing are recommended; if it is confirmed that the patient is susceptible to MH, anesthetic drugs that induce MH should be avoided during surgery.
Patient: If my family members do not find the same gene mutation as mine through genetic testing, does that mean MH will not occur? Anesthesiologist: The genetic changes of human MH are relatively complex, and false negative results may occur during gene mutation analysis. Therefore, MH cannot be directly diagnosed through genetic testing at present. If the genetic test shows what you said, the caffeine-halothane isolated skeletal muscle contraction test (CHCT) is needed to confirm the diagnosis.
Patient: Will there be any adverse reactions after using dantrolene sodium? Anesthesiologist: All drugs are toxic, and all drugs have adverse reactions. The adverse reactions of dantrolene sodium include muscle weakness, hyperkalemia, digestive tract disorders and thrombophlebitis.
Patient: Oh, so malignant hyperthermia is so dangerous! But no one knows about it. This potential risk is so scary! Thank you doctor for your knowledge!

Anesthesiologist: You’re welcome, Xiaohao. Tell your family. If you get sick, remember to tell the doctor about your family medical history! I wish you a happy life and healthy growth!
Patient: Yes! Thank you, handsome doctor brother! The human body is an extremely complex and mysterious organism. People who carry the MH gene do not necessarily develop MH, but this will increase the risk of disease. Malignant hyperthermia has various clinical manifestations, and it is not easy to make a quick and accurate diagnosis. Clinicians need to combine family history and clinical manifestations, and make a comprehensive judgment through MH scoring tables, caffeine-halothane isolated skeletal muscle contraction tests, genetic testing, and other means.

At present, anesthesiologists are trying to study the rapid clinical diagnosis method of malignant hyperthermia and carry out molecular genetic research through multidisciplinary cross-collaboration. If we want to completely conquer malignant hyperthermia, scientists still need to carry out in-depth scientific research, but we firmly believe that the "true face" of MH will become clearer and clearer!