<prompt> 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 mmolL. Which of the following has most likely resulted in the present situation?Neuroleptic malignant syndromeMalignant hyperthermiaSerotonin syndromePheochromocytoma  <response>: 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 spasmMC 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 mEqkg intravenously.Mix dantrolene sodium with sterile distilled water and administer 2.5 mgkg 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. 