Ketamine is indicated as a sole anesthetic agent for diagnostic and surgical procedures that do not require skeletal muscle relaxation. Ketamine injection is particularly suitable for short procedures, although it may be used for longer procedures with repeated dosing.

Its clinical applications include:

• Debridement, painful wound dressing, and skin grafting in burn patients, as well as other minor surgical procedures.
• Neurodiagnostic procedures such as pneumoencephalography, ventriculography, myelography, and lumbar puncture.
• Diagnostic and surgical procedures involving the eye, ear, nose, and throat, including dental extractions.
• Ketamine injection is also indicated for induction of anesthesia prior to the use of other general anesthetic agents.
• Additionally, it may be used as an adjunct to low-potency anesthetics such as nitrous oxide.

Ketamine is a fast-acting, non-barbiturate general anesthetic. It produces a unique anesthetic state characterized by profound analgesia. This state is commonly referred to as “dissociative anesthesia,” which involves features such as catalepsy, catatonia, and amnesia without necessarily causing complete unconsciousness. Ketamine is often described as a unique drug because it combines hypnotic (sleep-inducing), analgesic (pain-relieving), and amnesic (memory-impairing) effects—properties that are rarely found together in a single agent. It was first introduced into clinical practice in 1970 and gained attention due to its combined pharmacological actions, making it a highly effective anesthetic option.

Onset and Duration: Because of rapid induction following the initial intravenous injection, the patient should be in a supported position during administration. The onset of action of Ketamine is rapid, an intravenous dose of 2 mg/kg of body weight usually produces surgical anesthesia within 30 seconds after injection, with the anesthetic effect usually lasting 5 to 10 minutes. If a longer effect is desired, additional increments can be administered intravenously or intramuscularly to maintain anesthesia without producing significant cumulative effects. Intramuscular doses, from experience primarily in children, in a range of 9 to 13 mg/kg usually produce surgical anesthesia within 3 to 4 minutes following injection, with the anesthetic effect usually lasting 12 to 25 minutes.

Intravenous Route: The initial dose of Ketamine administered intravenously may range from 1 mg/kg to 4.5 mg/kg. The average amount required to produce 5 to 10 minutes of surgical anesthesia has been 2 mg/kg. In adult patients an induction dose of 1 mg to 2 mg/kg intravenous Ketamine at a rate of 0.5 mg/kg/mm may be used for induction of anesthesia. In addition, diazepam in 2 mg to 5 mg doses, administered in a separate syringe over 60 seconds, may be used. In most cases, 15 mg of intravenous diazepam or less will suffice. The incidence of psychological manifestations during emergence, particularly dream-like observations and emergence delirium, may be reduced by this induction dosage program.

Rate of Administration: It is recommended that Ketamine be administered slowly (over a period of 60 seconds). More rapid administration may result in respiratory depression and enhanced pressor response.

Intramuscular Route: The initial dose of Ketamine administered intramuscularly may range from 6.5 to 13 mg/kg . A dose of 10 mg/kg will usually produce 12 to 25 minutes of surgical anesthesia.

Maintenance of anesthesia: Increments of one half to the full induction dose, either IV or IM may be repeated as needed for maintenance of anesthesia. Nystagmus, movements in response to stimulation, and vocalization may indicate lightening of anesthesia.

Recovery time may be prolonged when barbiturates and/or narcotic agents are used concurrently with ketamine. Ketamine is generally compatible with commonly used general and local anaesthetic agents, provided that adequate respiratory function is maintained.

Ketamine is contraindicated in patients where a marked increase in blood pressure would pose a significant risk, and in those with known hypersensitivity to the drug.

Cardiovascular: Ketamine often causes an increase in blood pressure and heart rate. However, hypotension, bradycardia, and arrhythmias have also been reported in some cases.

Respiratory: While respiration is usually stimulated, rapid IV administration of high doses can lead to severe respiratory depression or apnea. Laryngospasms and other airway obstructions have also been observed during ketamine anesthesia.

Eyes: Ketamine may cause diplopia (double vision) and nystagmus (involuntary eye movements). A slight increase in intraocular pressure can also occur.

Neurological: Some patients may experience increased skeletal muscle tone, leading to tonic or clonic movements that can resemble seizures.

Gastrointestinal: Mild anorexia, nausea, and vomiting may occur, though these effects are generally not severe.

The safety of ketamine during pregnancy, including for obstetric procedures (vaginal or cesarean delivery), has not been established. Therefore, its use in pregnant women is not recommended.

Ketamine should only be administered by, or under the supervision of, physicians experienced in the use of general anesthetics and skilled in airway management and respiratory support. Since pharyngeal and laryngeal reflexes typically remain active, ketamine should not be used alone for surgical or diagnostic procedures involving the pharynx, larynx, or bronchial tree. Mechanical stimulation of the pharynx should be minimized if ketamine is used as a sole anesthetic. Intravenous doses should be given slowly over approximately 60 seconds; faster administration may cause respiratory depression, apnea, or an exaggerated pressor response. For procedures involving visceral pain, ketamine should be combined with an additional agent to adequately suppress visceral pain responses.

Overdose or overly rapid administration of ketamine may lead to respiratory depression, in which case assisted or controlled ventilation should be provided. Mechanical respiratory support is preferred over the use of respiratory stimulants (analeptics). Ketamine has a wide safety margin; even accidental overdoses—up to ten times the usual dose—have been reported to result in prolonged but complete recovery.

General (Intravenous) anesthetics

Store ketamine in a cool, dry place, away from direct light. Keep out of reach of children.