Kain

Indications

Ketamine is an anaesthetic medicine used in hospitals. It is used to start and maintain general anaesthesia, especially for short operations and procedures, for sedation and pain control during painful procedures such as dressing changes for burns, and in emergency settings where breathing support equipment may be limited. In some specialist settings it is also used in low doses for severe pain. It is a controlled drug and is given only by a doctor or trained anaesthetist.

How It Works

Ketamine blocks NMDA receptors in the brain and spinal cord, which are involved in passing pain signals and in awareness. This produces dissociative anaesthesia: the patient feels disconnected from their surroundings, has strong pain relief and does not remember the procedure, while breathing and protective airway reflexes are usually kept. It also tends to support blood pressure and widen the airways.

Dosage and Administration

Ketamine is given by a doctor or nurse as an injection into a vein or muscle, in a hospital or clinic with monitoring and resuscitation equipment. The dose is calculated by the anaesthetist according to body weight, the procedure and the patient condition. It is not for self-use.

Interactions

Other sedatives such as benzodiazepines, Opioid painkillers, alcohol and other anaesthetics increase drowsiness and may slow breathing. Theophylline and Aminophylline may increase the risk of fits. Thyroid hormone and medicines that raise blood pressure may increase the rise in blood pressure and heart rate. The anaesthetist will review all current medicines.

Contraindications

• Conditions in which a rise in blood pressure would be dangerous, such as uncontrolled high blood pressure, recent stroke, recent heart attack, aneurysm or severe heart disease.
• Severe pre-eclampsia or eclampsia.
• Known allergy to Ketamine.
• Uncontrolled overactive thyroid.

Side Effects

Common effects include raised blood pressure and heart rate, increased saliva, nausea and vomiting, double vision, jerky movements and, during recovery, vivid dreams, hallucinations, confusion or agitation (emergence reactions). These are less likely in a quiet recovery area and when a sedative is given with it. Repeated misuse can damage the bladder, causing painful, frequent urination.

Medical staff watch closely for slow or stopped breathing, spasm of the vocal cords, severe high blood pressure, irregular heartbeat and allergic reactions, and will treat them immediately. After going home, get urgent medical help for chest pain, confusion that does not settle, or difficulty breathing.

Pregnancy and Lactation

Ketamine crosses the placenta and is used in pregnancy, including for caesarean section, only when the anaesthetist judges it appropriate. Breastfeeding can usually restart once the mother is fully awake and alert; follow the advice of the medical team.

Precautions and Warnings

• Do not drive, use machines or make important decisions for at least 24 hours after anaesthesia.
• An adult should accompany you home.
• Tell the doctor about any history of psychiatric illness, raised pressure in the head or eyes, alcohol or drug use.
• It has potential for abuse and dependence and is a controlled drug.

Overdose

Overdose can cause slowed or stopped breathing and prolonged unconsciousness. It is managed in hospital with breathing support and monitoring.

Therapeutic Class

General anaesthetic, dissociative (NMDA receptor antagonist).

Storage

Store as directed on the pack, usually below 30°C and protected from light. Kept by hospitals under controlled-drug rules, out of the reach of children.