Anesthetic drugs that trigger Malignant Hypehermia include ether, halothane, enflurane, isoflurane, desflurane, sevoflurane, anddepolarizing muscle relaxants, succinylcholine being the only anesthetic drug currently used. Desflurane and sevoflurane appear to be less potent triggers than halothane and produce a more gradual onset of MH. The onset may be explosive if succinylcholine is used. Mild hypothermia and the preadministration of barbiturates, tranquilizers, propofol, or nondepolarizing neuromuscular blockers delay or prevent the onset of MH The two classic clinical manifestations of fulminant MH syndrome may sta with one of the following two scenarios:1. Rigidity after induction with succinylcholine but successful intubation, followed rapidly by the symptomslisted after scenario 22. Normal response to induction of anesthesia and uneventful anesthetic course until the onset of the following symptoms:* Unexplained sinus tachycardia or ventricular arrhythmias (or both)* Tachypnea, if spontaneous ventilation is present* Unexplained decrease in oxygen (O2) saturation (because of a decrease in venous O2 saturation)* Increase in end-tidal paial pressure of CO2 (Pco2) with adequate ventilation and, in most cases, unchanged ventilation* Unexpected metabolic and respiratory acidosis* Central venous desaturation* Increase in body temperature above 38.8deg C with no obvious cause. TREATMENTAcute management for MH can be summarized as follows:1. Discontinue all anesthetic agents and hyperventilate with 100% O2 with a fresh flow to at least 10 L/min. With increased aerobic metabolism, normal ventilation must increase. However, CO2 production is also increased because of neutralization of fixed acid by bicarbonate; hyperventilation removes this additional CO2.2. Reconstitute dantrolene in sterile water (not saline), and administer rapidly (2.5 mg/kg intravenously to a total dose of 10 mg/kg IV) every 5 to 10 minutes until the initial symptoms subside.3. Administer bicarbonate (1 to 4 mEq/kg IV) to correct the metabolic acidosis with frequent monitoring of blood gases and pH.4. Control fever by administering iced fluids, cooling the body surface, cooling body cavities with sterile iced fluids, and, if necessary, using a heat exchanger with a pump oxygenator. Cooling should be halted when the temperature approaches 38deg C to prevent inadveent hypothermia.5. Monitor urinary output, and establish diuresis if urine output is inadequate. Administer bicarbonate to alkalinize urine to protect the kidney from myoglobinuria induced renal failure.6. Blood gases, electrolytes, CK, temperature, arrhythmia, muscle tone, and urinary output guide fuher therapy. Hyperkalemia should be treated with bicarbonate, glucose, and insulin. Effective doses of dantrolene to reverse MH are the most effective way to lower serum potassium levels. In severe cases, calcium chloride or calcium gluconate may be used.7. Analyze coagulation studies (e.g., international normalized ratio , platelet count, prothrombin time, fibrinogen, fibrin split degradation products). Safe anesthetics consist of nitrous oxide, barbiturates, etomidate, propofol, opiates, tranquilizers, and nondepolarizing neuromuscular blocking drugs. Volatile anesthetics and succinylcholine must be avoided at all times, even in the presence of dantrolene. Ref: Miller's anesthesia 8th edition Ref: Morgan & Mikhail's clinical anesthesiology 6e