Malignant hyperthermia (MH) is a quite rare disorder of skeletal muscle that causes a patient’s body to respond to general anesthesia with very fast heart rate, hypermetabolism, contractions and rigidity of muscles and in many cases fever that can be over 100 degrees followed by rhabdomyolysis, which is a severe form of myopathy, destruction of certain body chemicals and increase of amount of acid in blood (“General MH questions,” n.d.). This list in non-exhaustive, and the damage experienced by a patient can affect brain, muscles and the most important organs. The complications of the disease can include failure of heart and other organs, their bleeding, and, finally, death usually caused by cardiovascular collapse (“General MH questions,” n.d.).
MH is usually inherited from any of the parents, and there is a 50% chance of the disease being inherited. However, it is important to remember that the disease may not manifest itself in the carrier of the 80 genetic defects linked to the disease, even if the carrier receives general anesthesia (“General MH questions,” n.d.). The study has also shown that the rate of appearance of the disease is between 1 in 10,000 people to 1 in 250,000, although it may reach even 1 in 400 individuals in certain cases (Rosenberg, Pollock, Schiemann, Bulger, & Stowell, 2015). According to the epidemiological studies mentioned by the Malignant Hyperthermia Association of the United States, MH can occur in 1of 100,000 surgeries on adults and in 1 in 30,000 surgeries on children (“General MH questions,” n.d.). At the same time, since it is an inherited disease, if certain family has been living in one location during several generations, such location may have higher rates of incidence. For example, in the United States, Wisconsin, Nebraska, West Virginia and Michigan are the states with the biggest number of people having the disease (“General MH questions,” n.d.). Also, since the disease is triggered by one of many genetic changes, according to the Association, 1 in 2,000 patients has at least any genetic change that can trigger MH (“General MH questions,” n.d.).
Although this disease is usually caused by general anesthetic gases, in rare cases it can be a result of excessive exercise and hot weather (Rosenberg, Pollock, Schiemann, Bulger, & Stowell, 2015). The reason why the disease occurs lies in muscle cells containing proteins that differ from the normal ones. While they are harmless, if a person receives certain chemicals, a big amount of calcium goes to the muscles, which start intensively contracting, which increases body temperature. As a consequence, muscle cells start dying, and a lot of potassium goes into blood, causing heart problems. Another chemical, myoglobin, can cause kidney failure due to its toxicity (“General MH questions,” n.d.). Since these changes in body’s biochemical content affect many organs at once and cause huge stress to the body in general, if these problems are left without immediate treatment, the body dies.
The first most important step in treatment of the disease is the recognition of its symptoms: muscle rigidity, high temperature, contractions, tachycardia, acidosis and abnormal amount of potassium in blood (Rosenberg, Pollock, Schiemann, Bulger, & Stowell, 2015). The most widely used method for diagnosis of the disease in the laboratory setting is a test that requires injection of caffeine and halothane in a muscle and subsequent observation of the results, including muscle contraction. Unfortunately, alternative tests that exist as of 2015 are not sensitive enough to predict MH (Rosenberg, Pollock, Schiemann, Bulger, & Stowell, 2015). Another preventive step to be taken before a patient is given general anesthesia is to ask such patient about the history of the effects of general anesthesia on his relatives. First of all, if any member of the family has died or had complications from general anesthesia and was suspected to have MH, a patient should automatically be considered to have the same disease. Meanwhile, people, who previously had surgeries with general anesthesia, should still report about any incidents with their relatives, since there is no guarantee that the disease will not occur during another surgery.
Unfortunately, the disease can occur without either a patient’s or a doctor’s prior knowledge of it, and if a patient shows symptoms of the disease, while many other disease have to be excluded, the doctor needs to make quit differential diagnosis based on the symptoms and a number of tests. In any case, every anesthesiologist needs to have a plan for immediate treatment of MH for any administered anesthetic drug. Every room needs to be equipped with electrocardiographic monitor, oxygen saturation monitor, capnometer, a manual or a poster about the treatment of MH, a measure to decrease the body temperature of a patient, and refrigerated isotonic saline (“General MH questions,” n.d.). Finally, the most important drug to have is dantrolene, which is the only one that specially treats MH. After a patient is treated with this drug, he or she needs to be monitored by the healthcare professional for about 3 days because 25% of patients have a relapse (Rosenberg, Pollock, Schiemann, Bulger, & Stowell, 2015).
Finally, patients with MH still may need surgeries, and although they cannot receive general anesthesia, there are many alternatives. First of all, no drugs that trigger the disease may be used. Secondly, they can receive local and regional anesthesia, if it is applicable for their surgery. If not, a patient still needs to be sedated and anesthetized, and certain muscle relaxants should be used. Also, anesthesia can be administered into a vein. The Malignant Hyperthermia Association of the United States provides a large list of safe anesthetics, narcotics, muscle relaxants and anti-anxiety drugs that can be used safely in patients at risk of having MH.
References
General MH questions. (n.d.). Retrieved March 18, 2016, from http://www.mhaus.org/faqs/about-mh
Rosenberg, H., Pollock, N., Schiemann, A., Bulger, T., & Stowell, K. (2015). Malignant hyperthermia: A review. Orphanet Journal of Rare Diseases, 10(93). Retrieved March 18, 2016, from http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4524368/
