Snapshot A 25-year-old woman is on the operative table for an elective laparoscopic cholecystectomy. After administration of isoflurane and succinylcholine, the patient developed hypercarbia that is resistant to increasing the patient's minute ventilation. She also developed massester and generalized muscle rigidity. The patient is immediately treated with dantrolene and a malignant hyperthermia protocol is initiated. (Malignant hyperthermia) Introduction General anesthesia is a central nervous system (CNS) depressive state that is reversible and provides analgesia sedation and decreased anxiety amnesia and impaired consciousness relaxation of skeletal muscle prevention of reflexes can be divided into intravenous anesthesia inhaled anesthesia Inhaled anesthesia primarily used for maintenance of anesthesia leads to increased cerebral blood flow, decreased blood pressure, and decreased respiratory rate potency the index of potency is the inverse of the Minimum Alveolar Concentration (potency = 1/MAC) login to view 3 more bullets the goal of inhalation anesthesia is to maintain an optimal brain partial pressure (Pbr) the movement of the anesthetic from one body compartment to the next is based on the drug partial pressure gradient login to view 17 more bullets Examples nitrous oxide low blood solubility → low blood/gas partition coefficient → rapid induction/recovery low lipid solubility → low potency → high MAC halothane and -fluranes high blood solubility → high blood/gas partition coefficient → slow induction/recovery high lipid solubility → high potency → low MAC Medications Medications desflurane, enflurane, halothane, isoflurane, methoxyflurane, sevoflurane, and nitrous oxide Mechanism of action unknown Side effects myocardial depression (halogenated hydrocarbons are vagomimetic) respiratory depression ↑ cerebral blood flow, which in turn ↓ cerebral metabolic demand Adverse effects cardiac arrhythmias concentration-dependent hypotension malignant hyperthermia clinical presentation login to view 2 more bullets pathogenesis login to view 3 more bullets treatment login to view 1 more bullet hepatotoxicity (halothane) nephrothoxicity (methoxyflurane) increased risk of seizure (enflurane) expansion of trapped gas within a body cavity (nitrous oxide)