Malignant Hyperthermia Requires Rapid Attention

Malignant hyperthermia (MH) is an inherited disorder related to the musculoskeletal system that puts affected individuals at risk of life-threatening adverse reactions when exposed to potent volatile inhalation anesthetics during surgery.

These anesthetics can include desflurane, isoflurane, sevoflurane, and succinylcholine.¹

MH occurs in the general population in 1 of 100,000 administered anesthetics. Some patients have been given anesthetics before without experiencing the symptoms or complications of MH, and they may experience it without warning after another surgery and exposure to anesthetic gases.¹

In individuals with MH, these anesthetic drugs can cause uncontrolled release of calcium, resulting in a rapid and continuous rise in calcium levels in the body. This may cause hyperkalemia as well as rhabdomyolysis.¹ If not treated immediately by stopping the anesthetic drug and administering reversing agents, up to 70% of cases can be fatal if not treated promptly.² Such cases may be fulminant, meaning that they can happen suddenly and without enough time for the anesthesia team, first responders, or other health care providers to react.²

Signs and symptoms of MH can include increased oxygen uptake and carbon dioxide production, hyperkalemia, and acidosis. Muscle damage can be seen as levels of calcium, phosphate, potassium, and serum creatine kinase increase. The onset of these symptoms may vary among individuals and can occur from minutes to hours into anesthesia, even in patients who have had similar anesthesia experiences before with no complications.²

Some tests exist to identify individuals at higher risk of MH. If general health and risk factors suggest that MH may occur, these individuals should be tested. Genetic testing can show the abnormal genes that make an individual susceptible to malignant hyperthermia, and a muscle biopsy can measure the level of MH risk to the muscles when exposed to chemicals.²

When treating MH, it is vital for surgery centers to be prepared to recognize it right away and treat the patient quickly. Several medications are designed for treating MH, including dantrolene, which stops the release of calcium into the muscle. Some states require surgery centers to have a full dose of dantrolene (10mg/kg) available within 10 minutes of identifying MH, and some patients may require extra dosages of dantrolene after the first dose.¹

A new formulation of dantrolene (Ryanodex, Eagle Pharmaceuticals) came to market in 2014 and is dissolved rapidly. It offers a shortened preparation time and, unlike dantrolene, may not require mannitol for fluid overload. It also achieves faster blood concentration levels.¹

When preparing for the potential of MH, a cart would need to be available in surgical centers, that includes blood and urine collection tubes, a bucket for ice, calcium chloride, dantrolene, insulin, intravenous (IV) catheters, lidocaine, nasogastric tubes, saline, sodium bicarbonate, sterile water, and syringes. For metabolic acidosis, bicarbonate may be needed.¹

Oxygen might also be needed via a face mask or through tracheal tubes. Because this syndrome causes an increase in body temperature, cooling the body could be another treatment option. For this, chilled IV fluids, cooling blankets, a fan with a cooling mist, and ice packs may help reduce the body temperature.³ Such patients may also benefit from extra fluids through the IV line. These patients may need to stay in the hospital, in an intensive care unit, or at a surgery center to monitor their blood pressure, breathing, heart rate, and temperature. Such patients may be at risk of kidney damage as well.³

With 1 in 100,000 adults and 1 in 30,000 children experiencing MH after surgery,¹ there is a need for pharmacists and other health care providers who are knowledgeable about the disorder, its symptoms, and management. Preparation for such events is essential, so that health care providers can act quickly and treat patients effectively, both following surgery and as ongoing, inpatient care.

References

1. Jones SB. Malignant hyperthermia: diagnosis and management of acute crisis. UpToDate. Updated October 24, 2019. Accessed July 7, 2021. https://www.uptodate.com/contents/malignant-hyperthermia-diagnosis-and-management-of-acute-crisis

2. Malignant hyperthermia. National Organization for Rare Disorders. Accessed July 7, 2021. https://rarediseases.org/rare-diseases/malignant-hyperthermia/

3. Malignant hyperthermia. Mayo Clinic. April 7, 2020. Accessed. July 7, 2021. https://www.mayoclinic.org/diseases-conditions/malignant-hyperthermia/diagnosis-treatment/drc-20353752