A 42-year-old male was undergoing elective hernioplasty. End tidal carbon dioxide (ETC02) was found to be increased. Abdominal wall gradually showed rigidity, along with the presence of tachycardia and tachypnea. Blood gas analysis shows an increased mixed acidosis, along with a serum lactate of 3.4 mmol/L. Which of the following has most likely resulted in the present situation?

Answer: b) Malignant hyperthermiaMALIGNANT HYPERTHERMIADrug- or stress-induced hypermetabolic syndrome.Vigorous muscle contractions, an abrupt increase in temperature, subsequent cardiovascular collapseUncontrolled release of Ca2+ from the sarcoplasmic reticulum due to defect in the ryanodine receptor (RYR1) is the initiating eventInherited as autosomal dominant fashion, with variable penetrance & expressivity.Triggers: Stress, excitement, anoxia, viral infections, lymphoma, ischemia or hypoxia.Early signs: masseter muscle contracture, muscle rigidity, metabolic acidosis, sinus tachycardia, supraventricular tachyarrhythmias, mottling or cyanosis of the skin, increased CO2 production, and hypertension.Two signs helpful in making a prehyperthermic diagnosisIncreased end-tidal CO2Masseter spasmM/C with combination of depolarizing blocking agent and anesthetic.Drugs known to trigger malignant hyperthermiaDrugs safe in malignant hyperthermia* Halothane* Methoxyflurane* Enflurane, isoflurane* Succinylcholine* Decamethonium* Gallamine* Diethyl ether,* Ethylene, Ethyl chloride* Trichloroethylene* Ketamine* Phencyclidine* Cyclopropane* Nitrous oxide* Barbiturates* Diazepam* Tubocurarine* Pancuronium, vecuronium* OpiatesManagement of Malignant HyperthermiaDiscontinue volatile anesthetic and succinylcholine.Hyperventilate with 100% O2 at high flows.Administer sodium bicarbonate, 1-2 mEq/kg intravenously.Mix dantrolene sodium with sterile distilled water and administer 2.5 mg/kg ivInstitute cooling measures (lavage, cooling blanket, cold intravenous solutions).Administer additional doses of dantrolene if needed.Treat severe hyperkalemia with dextrose, 25-50 g IV, and regular insulin, 10-20 U intravenously (adult dose).