Ketamine: a new look to an old drug

Ketamine is an NMDA receptors antagonist, with a potent anaesthetic effect. NMDA receptors are involved in nociceptive modulation, in the wind-up phenomenon, in peripheral receptive fields expansion, in primary and secondary hyperalgesia, in neuronal plasticity. Ketamine effects are well-known: it produces a state of "dissociative anaesthesia", amnesia, and, at the same time, it mantains the respiratory drive effective and supports the sistemic arterial blood pressure. Anaesthesiologists are also familiar with its side-effects, like the increase of salivar and bronchial secretions, the possible increase of intracranial and pulmonary pressures and the dysphoric effect that may produce vivid and sometimes unpleasant dreams. Reviewing scientific data and studies about the use of ketamine in children, many considerations come out: at first they considered the effects of the racemic ketamine, then they evaluated the S-enantiomer. Many surveys studied the effects (analgesia, sedation, side-effects) of different doses or different routes of administration. Other studies were designed to compare ketamine to clonidine or opioids as adjuvants in paediatric regional anaesthesia with local anesthetic drugs, in order to prolong analgesia. In our Children's Hospital, we use ketamine in the operating room, in intensive care unit and for any procedure in hospital wards. The suggested doses are: Epidural or caudal route (as an ajuvant for local anaesthetic agents, in the treatment of postoperative pain): 0.5 mg/kg. Sedative/analgesic effect (for algesic procedures): 1-2 mg/kg i.v. Continuous infusion (intensive care unit): 0.5 mg/kg/h, with a range from 20-30 microg/kg/min to 80 microg/kg/min, depending on the age of the patient.