Snapshot A 36-year-old man presents to the hospital for an elective bariatric procedure. The patient followed instructions not to eat for a given amount of hours prior to the surgery. While on the surgical table, the anesthesiologist induces anesthesia with an intravenous bolus of propofol, along with a number of other agents used. 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 Intravenous (IV) anesthesia causes a rapid induction of anesthesia when the anesthetic enters the blood, a portion of it binds to plasma proteins (bound) while the rest are unbound the binding ability of the IV anesthetic is dependent on numerous factors, such as drug ionization lipid solubility after entering the venous blood and goes to the heart and into the cerebral circulation the anesthetic enters the brain at a rate that depends on arterial concentration of unbound drug lipid solubility degree of ionization the higher the arterial concentration of the unbound drug, lipid solubility, and nonionized molecules the faster the anesthetic enters the brain eventually, the anesthetic leaves the CNS (redistribution), resulting in recovery from the IV anesthetic Intravenous Anesthetic Intravenous Anesthetic Drugs Clinical Use Comments Thiopental Induction of anesthesia Short surgical procedures A short acting barbiturate that has a high lipid solubility is a potent anesthetic is a weak analgesic has a rapid redistribution; thus, it rapidly diffuses out of the brain May cause apnea laryngospasm bronchospasm Midazolam Induction of anesthesia Endoscopy Can result in temporary forms of anterograde amnesia post-operative respiratory depression Treat overdose with flumazenil Opioids To induce analgesia Fentanyl is commonly used Can result in hypotension respiratory depression muscle rigidity Etomidate Induction of anesthesia Can reduce adrenal steroid production which can result in acute adrenal crisis Ketamine Induction of a dissociative anesthetic state Ketamine is a NMDA receptor antagonist increases central sympathetic outflow, which in turn increases blood pressure cardiac output bronchodilation increases cerebral blood flow may result in hallucinations prevents opioid-induced acute tolerance Propofol Induction and/or maintenance of anesthesia Decreases blood pressure Reduced intracranial pressure Low incidence of post-operative nausea and vomiting Potentiates GABAA