Dissociative anaesthesia

Ketamine produces dissociative anaesthesia meaning 'detached from their surroundings'. Patients' eyes will often be open and they may have reflex movements.

Tolerance

Patients can become tolerant of ketamine. With frequent repeat anaesthetics bigger doses are needed, this tolerance usually wears off over 3 days.

Analgesia

Ketamine is a good analgesic, i.e. painkiller. This is useful in surgery and, in low doses ketamine, can also be used as a painkiller postoperatively.

Hallucinations

Ketamine produces hallucinations. These can be distressing when the patient wakes up. They are reduced by giving IV benzodiazepines at induction. Ketamine should be avoided if possible in patients who have a history of schizophrenia or other delusional disorders.

Nystagmus

Ketamine causes nystagmus. This means the eyes make rapid small movements. Without muscle relaxation eye surgery is very difficult under ketamine anaesthesia.