Early Recognition and Treatment of Malignant Hyperthermia in
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Malignant hyperthermia is a rare anesthetic event triggered by succinylcholine and/or volatile anesthetics, resulting in a hypermetabolic state with a high mortality rate of 80–90% . Dantrolene sodium is the specific treatment of MH, and the early diagnosis and prompt management with dantrolene leads to a decrease in the mortality rate to 5%
A healthy 9-year-old boy, of body weight 28 kg, was admitted with a foreign body (pin) in the left main bronchus without any signs of airway obstruction. He underwent an emergency bronchoscopy to remove the foreign body. The preanesthetic routine examination was normal. The patient had no significant medical conditions and no known medical allergies.

The patient received general anesthesia induced by propofol, 60 mg, and succinylcholine, 30 mg, given intravenously. He was ventilated with 100% oxygen and sevoflurane. After the onset of succinylcholine administration, the ENT surgeon tried to insert bronchoscope, but the child’s mouth could not be opened. The anesthesiologist returned to ventilate with 100% oxygen and gave a small additional dose of 15 mg of succinylcholine. However, the masseter muscle rigidity in the patient continued. The trend of end tidal carbon dioxide rose from 30 mmHg to 55 mmHg, body temperature to 39.5°C, heart rate to 140–160 beats/minute, and blood pressure to 130/75 mmHg.

Oxygen saturation was 100%. All of these symptoms in this patient were strong indications of malignant hyperthermia. The arterial blood gas was examined after the onset of symptoms, and the following results were found: pH 7.21, carbon dioxide partial pressure 63 mmHg (with appropriately controlled ventilation), oxygen partial pressure 245 mmHg, serum potassium 5.5 mmol/l, bicarbonate 25.2 mmol/l, BE 2.7 mmol/l, and hematocrit 33%.

The anesthesiologist discontinued sevoflurane and hyperventilated with 100% oxygen, called for backup, changed to a new anesthesia machine prepared for a malignant hyperthermia patient, and informed the ENT surgeon. Anesthesia was maintained with total intravenous anesthesia (TIVA) with propofol infusion and mask ventilation with 100% oxygen. Cold normal saline was infused intravenously, and ice packs were applied to the entire body surface. Within approximately 10 minutes after the start of symptoms, dantrolene was given as a loading bolus of 2.5 mg/kg intravenously, and then 1 mg/kg IV every 6 hours until the signs and symptoms of MH subsided.
After the first dose, the patient had an adequate clinical response, the trend of ETCO2 decreased to 38 mmHg, heart rate to 90–100 beats/minute, and blood pressure to 110/50 mmHg. All symptoms including masseter muscle rigidity, hyperthermia, and tachycardia were resolved. The ENT surgical team was informed regarding the condition of the patient. The surgical team decided to abort the endoscopic procedure. The patient was not intubated and was transferred to the pediatric intensive care unit (PICU) for further and supportive care.

After being admitted to the PICU, the patient was monitored closely for the signs of malignant hyperthermia and rhabdomyolysis. His medical condition improved, and dantrolene was discontinued on postoperative day 2. The patient came back to the operating room for a bronchoscopy to remove the foreign body on postoperative day 2. The anesthetic plan was total intravenous anesthesia (TIVA) induced with propofol, fentanyl, and atracurium and ventilation with 50% oxygen. During the operation, the patient’s condition was stable with no signs of malignant hyperthermia. The surgical procedure was performed successfully, and the pin was removed from the left main bronchus. The patient was subsequently discharged home in a stable condition on postoperative day 4.

In conclusion early recognition of symptoms and appropriate treatment are the key to successful management of MH. Anesthesia providers should be aware of the symptoms and vigilant in patients with suspected MH. Prompt management is critical. Dantrolene sodium is the gold standard of MH treatment and should be available in all anesthesia locations. Family history and genetic counselling are the vital parts of MH management.

Source: https://www.hindawi.com/journals/cria/2020/6562896/
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