What is malignant hyperthermia?

What is malignant hyperthermia?

A potentially fatal, but rare condition, malignant hyperthermia is often triggered by a severe reaction to medications (anaesthetic containing succinylcholine) administered for surgical purposes (also known as a pharmacogenetic disorder). The condition is treated as an emergency and cannot typically be foreseen. The condition can occur during a surgical procedure (in an emergency room, intensive care unit or dental office) or shortly afterwards (often within one hour of exposure to a medication substance or up to 12 hours).

Certain genes are thought to predispose a person to a severe reaction (i.e. the tendency towards a reaction is inherited) triggering the condition with signs and symptoms not apparent before anaesthetic is given.

Genetic testing can be done before a surgical procedure especially if a patient has a parent, child or sibling (sometimes aunts, uncles and grandchildren) that is known to have experienced the condition.

Due to the nature of inherited genes, the likelihood of a similar possibility in a patient with a genetic predisposition is considerably high. Testing can assess genetic mutations to determine this possibility ahead of any scheduled surgery or procedure requiring anaesthesia.

In treating malignant hyperthermia doctors and surgeons will react swiftly with medication (dantrolene or dantrium) to relax the muscles (this is given intravenously initially and then potentially in pill form for several days once stable), cooling blankets, fans, mist and ice packs to control symptoms of a dangerously high core body temperature, rapid heart rate and severe (and painful) muscle spasms.

Other signs include:

  • Flushed complexion (skin) or mottled skin
  • Profuse sweating
  • Rapid breathing
  • Fast heart rate (tachycardia)
  • Shock (very low blood pressure)
  • Muscle weakness
  • Swelling
  • Confusion
  • Dark or brown coloured urine
  • Renal failure
  • Cardiac failure

A doctor or surgeon may perform a blood test while cooling a person’s body temperature to assess levels of the muscle enzyme creatine phosphokinase (CPK) and electrolyte changes. Kidney function can also be determined using blood samples.

In the event that malignant hyperthermia occurs, doctors who recognise the signs can provide the necessary treatment quickly enough and symptoms will likely resolve safely within 12 to 24 hours. A person will be carefully monitored for a few days in the intensive care unit. Potential complications of damage caused can influence respiratory or kidney function. Some damage experienced to tissues may be permanent.

If the condition is known to have occurred in a family member, alternative anaesthetics are available for use during a procedure which may be safer. Thus, it is advisable to mention any family occurrences to a doctor, specialist, surgeon or anaesthetist before a procedure and wear a medical tag (which can be helpful during an emergency situation).

Although the condition is potentially life-threatening, treatment which is implemented quickly can ensure a successful recovery. Once diagnosed, potential future occurrence can be better prevented once the trigger (type of high-risk anaesthetic) is known.

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