Malignant hyperthermiais caused by:

Ref: Miller Textbook of Anaesthesia. 6th editionExplanation:Malignant HyperthermiaIt is a clinical syndrome observed during GA associated with rapidly increasing temperature of >ldegree/5 minEtiologyIt is due to the abnormality of Ryanodine receptor which is a calcium releasing channel of sarcoplasmic reticulum.The abnormality leads to excessive accumulation of calcium which causes sustained contraction of the muscleRisk FactorsDuehenne Muscular DystrophyArthrogryposis multiplex congenitalOsteogenesis imperfectCongenital strabismusCentral core diseasesHistory of Neuroleptic malignant syndromeMasseter spasm with succinyl cholineCausative AgentsMuscle Relaxants: Succinyl choline - MC drug Inhalational agentsHalothane - MC agentIsofluraneDesfluraneEnfluraneSevofluraneMethoxvfluraneLocal Anesthetic: LignocaineOther drugs:Tricyclic antidepressantsMAO inhibitorsPhenothiazinesClinical featuresHyperthermiaHypoxiaCyanosisHyperkalemiaMuscle rigidityTachycardiaHypertensionCardiac ArrhythmiasRenal FailureDICPulmonary edemaCerebral edemaDeathInvestigationsSevere Metabolic acidosis (pH < 7)Increased end tidal CO2Increased CPK levelsIncreased MyoglobinTreatmentStop all anesthetics immediatelyHyperventilation with 100% 02Control Temperature by ice cooling and ice cold salineCorrect acidosis with Sodium bicarbonateCorrect electrolyte imbalance - HyperkalemiaMaintain urine outputSpecific therapyDANTROLENE - 2mg/kg every 5 minutes to a maximum of 10 mg /kg