Malignant hyperthermia is a rare, life-threatening rise in body temperature that occurs in susceptible people who are given certain muscle-relaxing drugs plus an anesthetic gas for surgery.
Malignant hyperthermia can occur when the anesthesia is given or during or soon after surgery.
Muscle cells become overactive, causing sustained muscle contractions that produce heat and raise body temperature extremely high.
Symptoms include muscle rigidity, rapid heart rate, and rapid breathing
Doctors diagnose malignant hyperthermia based on symptoms in people who have just had surgery.
Treatment is rapid cooling.
(See also Overview of Heat Disorders.)
Malignant hyperthermia may cause imbalances in body salts (electrolytes) and blood clotting. Excessive blood clotting (disseminated intravascular coagulation) causes organ damage, followed by excessive bleeding when the body runs out of clotting factors.
Malignant hyperthermia can also cause significant muscle damage. Damaged muscles release the protein myoglobin, which turns the urine brown or bloody. This condition (myoglobinuria) can lead to acute kidney injury or even kidney failure. Death may occur.
Symptoms of Malignant Hyperthermia
Malignant hyperthermia may develop during anesthesia or shortly after surgery. Often, the first signs are rapid breathing, a fast heart rate, and muscle rigidity, especially in the jaw. Temperature usually becomes extremely high (usually over 104° [40° C] and sometimes higher than 109° F [43° C]). Abnormal heart rhythms, nausea, and vomiting may occur. Urine may appear brown or bloody.
Diagnosis of Malignant Hyperthermia
Typical symptoms developing after anesthesia is given
Doctors suspect malignant hyperthermia when typical symptoms and signs occur within a few minutes to a few hours after anesthesia is given.
Blood is tested to detect organ damage and to exclude other possible causes. Urine is tested for myoglobinuria.
Genetic testing can also be done. However, because many gene abnormalities may be involved, genetic testing does not detect all (or even most) susceptible people and is not always available.
Treatment of Malignant Hyperthermia
Rapid cooling of the body
Abnormal blood clotting and symptoms related to organ malfunction may also need treatment. As with neuroleptic malignant syndrome
Many people with malignant hyperthermia die even when they receive early and intensive treatment.
Prevention of Malignant Hyperthermia
Doctors try to prevent malignant hyperthermia in people who are high risk, which includes those with
Previous episodes of malignant hyperthermia
Positive genetic markers
Family members who have had problems with anesthesia
In these instances, doctors use local or regional anesthesia when possible. When general anesthesia must be used, doctors select those anesthetics that are least likely to cause a reaction.
