[Ketamine].
Ketamine is an intravenous drug with special properties that make it the only agent that presently serves as anesthetic, sedative, amnesiac and analgesic. Although it is sometimes forgotten, ketamine is still considered a viable drug. Water soluble, stable and non-irritant when administered intravenously, ketamine has rapid onset after intravenous injection and provides acceptable anesthesia when administered in continuous infusion. There properties make ketamine useful for total intravenous anesthesia. Both propofol and midazolam are effective in reducing ketamine's adverse side effects. Administered in children by oral, nasal, rectal and intramuscular routes, ketamine allows for gentle anesthetic induction. It can also serve as an adjuvant in regional anesthesia to supplement analgesia. In adults ketamine is most often used for major surgery, particularly in the elderly or in high risk patients who are in shock, severely dehydrated or hemodynamically unstable, or in obstetric patients with hypovolemia or hemorrhage. It is probably the anesthetic of choice for patients with hyperreactive airways. Ketamine's strong analgesic effect at subanesthetic doses allows it to be used as an analgesic during postoperative intensive care or as an analgesic-plus-sedative for patients receiving mechanical ventilation. Interest in using ketamine at low doses for cancer and non-cancer patients with chronic pain has grown recently.