Malignant hyperthermia-like syndrome in acute chlorfenapyr poisoning – A case report

Background: Chlorfenapyr is a pesticide that interferes with mitochondrial oxidative phosphorylation, resulting in the disruption of ATP production and cellular death. We present a fatal case of chlorfenapyr poisoning presented with malignant hyperthermia- like syndrome after intubation. Case presentation: A 49-year-old male presented with fatigue and diaphoresis four days after ingesting emamectin chlorfenapyr. IV hydration was given, and two sessions of hemoperfusion were performed. He was intubated for airway protection on Day 3 because of drowsiness. Immediately after intubation, he developed tachycardia and hyperthermia (temperature 41 °C), followed by cardiac arrest. During resuscitation, we noted he had severe diaphoresis and generalized muscle rigidity. Peri-arrest ABG showed abrupt onset of severe type 2 respiratory failure, lactate acidosis, and hyperkalemia. The clinical manifestation and ABG result lead to the possible diagnosis of malignant hyperthermia. The resuscitation was unsuccessful, and the patient eventually passed away. Propofol might be the culprit drug in this case as it is known to affect mitochondrial metabolism via uncoupling oxidative phosphorylation. Conclusion: We suggest monitoring for signs and symptoms of malignant hyperthermia in chlorfenapyr poisoning, especially after intubation. Propofol should be avoided or used with caution during induction for intubation. Further research on the possible antidote and usage of early RRT in ED is needed.