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Malignant hyperthermia (MH) is a rare, inherited muscle disorder aggravated by certain types of anesthesia that may cause a fast-acting, life threatening crisis. Individuals who are susceptible to MH have a mutation that results in the presence of abnormal proteins in the muscle cells of their body.
whenever vulnerable patients are exposed to certain anesthetic agents, or in extreme cases when they are exposed to high environmental heat or strenuous exercise, causes an abnormal release of calcium from the sacroplasmic reticulum (an area that stores calcium in the muscle cells). This results in a sustained muscle contraction and an abnormal increase in metabolism and heat production. General signs of an MH crisis include increased heart rate, greatly increased body metabolism, muscle rigidity, and fever that can exceed 43.3 degrees celsius or 110 degrees farenheight, with muscle breakdown, derangements of body chemicals, and elevated acid content in the blood.
MH is generally not associated with other chronic medical problems, such as hypertension, diabetes, or similar diseases. MH have occurred in patients with underlying muscle diseases. There is a definite association with central core disease (CCD), an inherited neuromuscular disorder. Both CDD and MH are caused by a genetic mutation in the skeletal muscle ryanodine receptor type 1.
Individuals with CDD have persistent mild muscle weakness that does not worsen with time. This weakness affects the muscles near the center of the body (proximal muscles, generally muscles in the upper legs and hips. Muscle weakness causes affected infants to appear flacid and can delay the development of motor skills such as sitting,
standing, and walking. In severe cases, affected infants experience profoundly weak muscle tone (hupotonia) and serious or life-threatening breathing problems. CDD is also associated with skeletal abnormalities such as abnormal curvature of the spine (scoliosis), hip dislocation, and joint deformities called contractures that restrict the movement of certain joints
Management of Malignant hyperthermia
Clinical signs and symptoms of MH appear according to the swiftness of onset. The onset may be fast, occuring immediately after anesthesia induction, or it may occur after several hours of general anesthesia or may occur in the post operative recovery period.
Spasm of the jaw muscles with rigidity of the masseter muscles, or severe fasciculation after administration may suggest the possibility of MH occurence to the anesthesia provider.
Malignant hypertension may present with a variety of signs and symptoms during an acute phase or in a more subtle way, developing over a course of several hours.
If there is a likelihood of MH, the patient should be admitted to the hospital and be under close observation for at least 24 hrs after marked jaw rigidity.
If malignant hyperthermia is suspected, notify the surgeon to discontinue the procedure ASAP
Discontinue volatile agents and sucinylcholine. If surgery must be performed, maintain general anesthesia with intra venous non-triggering anesthetics, for e.g., intravenous sedatives, narcotics, amnestic, and non-depolarizing neuromuscular blockers as needed. Hyperventilate the patient with 100% oxygen at flor of 10L/min. Administer dantrolene sodium 2.5mg/kg IV, given rapidly through a large-bore needle. Administer repeatedly until the crisis is resolved. Additionally, pack ice on the patient's head, axillae, groin, and underneath the patient. Infuse cold saline IV and initiate esophageal or rectal lavage.