The Ketamine Quiz

The Medical Uses and Effects of Ketamine

• Ketamine is a dissociative anesthetic used for induction and maintenance of anesthesia, as well as for depression and pain management.
• It was derived from phencyclidine in 1962, in pursuit of a safer anesthetic with fewer hallucinogenic effects.
• At anesthetic doses, ketamine induces a state of "dissociative anesthesia", providing pain relief, sedation, and amnesia.
• The distinguishing features of ketamine anesthesia include preserved breathing and airway reflexes, stimulated heart function with increased blood pressure, and moderate bronchodilation.
• At lower, sub-anesthetic doses, ketamine is a promising agent for pain and treatment-resistant depression, but the long-term effects of repeated use are largely unknown.
• The mechanism of action involves pore blocking of the NMDA receptor, interfering with pain transmission in the spinal cord, and interacting with opioid, muscarinic, and acetylnicotinic receptors.
• Ketamine produces its effect after 1-5 minutes, inducing a state of dissociative anesthesia where the patient's eyes remain open and move from side to side, followed by emergence delirium during recovery.
• Ketamine is a potent vasodilator that increases cerebral blood flow by about 60% in normal individuals and should not be given to patients with recent head injury due to increased intracranial pressure.
• It causes mild stimulation of the cardiovascular system, increasing systolic and diastolic blood pressure, heart rate, and work overload of the heart, which can be reduced by premedication with midazolam or alpha and beta blockers.
• Rapid administration may cause the patient to stop breathing for a short period, but maintaining the airway and administering oxygen can prevent this.
• Ketamine causes bronchodilation, making it useful for anesthetic agents, but skeletal muscle tone is often increased, and eye movement may continue throughout surgery.
• Routes of drug administration include 1-2 mg/kg for I.V administration, 4-8 mg/kg for I.M administration for anesthesia, and sub-anesthetic doses for analgesia. Ketamine has several side effects, including euphoria, confusion, hallucinations, nightmares, dissociation, kidney damage, urinary problems, hypertension, increased heart rate, impaired speech, vision, and pain sensation, numbness, ataxia, and double vision.