Therapy
Of utmost importance for the therapy is the immediate stop of the supply of the triggering substance and, if necessary, the change to another anaesthetic procedure. By administering the drug dantrolene, the disease mechanism can be interrupted. An operation already in progress should be terminated as soon as possible. The oxygen supply is increased, if necessary, hyperacidity of the body and cardiac arrhythmia can be treated with medication. Through consistent, early therapeutic action, mortality in the malignant hyperthermia crisis can be reduced to almost zero.
Prognosis
Malignant hyperthermia is a serious, potentially life-threatening anaesthetic incident. However, clinical experience in dealing with patients with MH, the possibility of using trigger-free anesthesia if a predisposition to malignant hyperthermia is suspected, determined therapeutic action and the improvement of monitoring and intensive care options have succeeded in drastically reducing the untreated high mortality rate. If patients have been suspected of having malignant hyperthermia during previous operations, this must be well documented and the patient must be informed so that he or she can inform the anesthesiologist when planning future operations.
The consequences of malignant hyperthermia (such as metabolic derailment, cardiac arrhythmia, overheating of the body) are primarily caused by the administration of so-called trigger substances (anesthetics) during an operation. Therefore, the first priority in the therapy of malignant hyperthermia is the immediate removal of the trigger substance in order to avoid further damage. Since malignant hyperthermia primarily leads to an increased release of calcium, this must be stopped as soon as possible.
If the first signs of a derailment (cardiac dysrhythmia, hyperacidity of the body) occur during an operation, immediate therapy of malignant hyperthermia with muscle relaxants (especially dantrolene) is crucial. These agents block calcium channels and thus prevent too much calcium from entering the cell. This minimizes metabolic derailment and muscle cramping.
In addition the enormous heat increase is prevented. Meanwhile it is mandatory in German operating theaters to have such a remedy within reach, since immediate administration is of crucial importance for the therapy of malignant hyperthermia. In recent years, this has led to the fact that fewer and fewer people have died of malignant hyperthermia.
Nevertheless, in cases of genetic disposition, the administration of “classic trigger substances” (anaesthetics) is avoided so that malignant hyperthermia cannot develop in the first place. It is therefore advisable, if there is a known disease in the family, to undergo a test to determine whether there is a risk during surgery. If there is a risk of malignant hyperthermia, no trigger substances are used during surgery.
Instead, agents for so-called total intravenous anesthesia (TIVA) are used. Here, for example, nitrous oxide or nondepolarizing muscle relaxants are suitable as anesthetics.The aim is to continuously inject the patient with sleeping pills such as Propofol and painkillers (e.g. opiates) during the operation. This ensures that the patient is free of pain and unconsciousness during the entire operation without having to use a trigger substance.
Thus, patients with malignant hyperthermia have no increased risk before surgery as long as they are not operated on with trigger substances as an anesthetic. Despite the immediate administration of muscle relaxants such as dantrolene, there is a (albeit reduced) derailment of the metabolism. This includes, among other things, hyperacidity of the body (acidosis) and an increased concentration of carbon dioxide (CO2) in the blood.
Since both are harmful to the body, the therapy of malignant hyperthermia uses inhalation with 100% oxygen and lets the patient breathe more with the ventilator, so that more CO2 is breathed out and at the same time more O2 is available to the body. This counteracts a lack of oxygen (hypoxia). The hyperacidity of the body is counteracted by the infection of an alkaline agent (for example sodium bicarbonate).
In order to avoid a disturbance of blood clotting, heparin is often used in addition to the therapy of malignant hyperthermia. This agent ensures that blood clotting cannot take place completely. Thus, the blood does not clump together but remains fluid.
This is particularly important to prevent thrombus formation and avoid a possible embolism. Also endangered by malignant hyperthermia, is the kidney function. The most important thing here is to avoid the crush syndrome.
In crush syndrome, renal insufficiency occurs due to an increased accumulation of myoglobin. Myoglobin is increasingly released from damaged muscles, among others. The administration of diuretics is therefore also important as a therapy for malignant hyperthermia.
During the metabolic derailment in malignant hyperthermia, there is also increased heat generation in the body. In order to minimize this, the body is cooled down slightly (for example, by using cool cloths). Since cardiac arrhythmia occurs during the operation (especially increased heartbeat), another therapeutic measure is the monitoring of heart activity and blood pressure. For this purpose, patients are often transferred to the intensive care unit.
