(343) Malignant Hyperthermia in Laparoscopic Appendectomy: A Case Report

Introduction: Malignant hyperthermia (MH) is a rare life-threatening hypermetabolic crisis that manifests when susceptible individuals are exposed to certain volatile anesthetic agents and depolarizing muscle relaxants. Its incidence has been difficult to estimate as its variable penetrance leads it to be underestimated; current literature cites that MH complicates 1:100,000 surgeries in adults. The pathophysiology stems from gene mutations primarily involving the ryanodine receptor (RYR1) which predisposes these individuals to have an uncontrolled calcium release in skeletal muscles. We present a case of malignant hyperthermia in a patient during an appendectomy.

Description: A 56-year-old man presented with right lower abdominal pain and guarding. A CT of the abdomen was consistent with acute appendicitis. General surgery planned for laparoscopic appendectomy. The patient received succinylcholine prior to intubation followed by sevoflurane for anesthesia. He developed prolonged muscle rigidity, increased end-tidal carbon dioxide (ETCO2) (98 mmHg), hyperthermia (38.5°C), diaphoresis, and hypotension. Sevoflurane was discontinued. A dantrolene bolus was given with rapid resolution of symptoms. The appendectomy was completed, and he was transferred to the ICU. Labs showed rhabdomyolysis including creatine kinase 38,076 U/L, potassium 5.5 mEq/L, and myoglobin 3,893 ng/mL. He initially had low output with pink-tinged urine but later had full renal recovery.

Discussion: MH is a rare life-threatening condition that is crucial for providers to recognize as the true incidence is unknown. Clinical signs include unexplained increase in ETCO2, hyperthermia, muscle rigidity, and arrhythmias. Lab abnormalities include respiratory and metabolic acidosis, elevated creatine kinase, potassium, and myoglobin. Treatment includes discontinuing the offending agents, hyperventilating with 100% oxygen, and administering IV Dantrolene. Other measures to consider include bicarbonate and cold isotonic crystalloids infusions. On discharge, counseling regarding the use of non-depolarizing anesthetics in future surgeries, avoiding exercise in excessive heat, and encouraging patients and family members to obtain a contracture test or a genetic test to confirm the definitive diagnosis of MH susceptibility should be provided.