Pain relief is important — not only for humane reasons — but also for protection of the circulation and tissue perfusion which suffer as a result of the enormous secretion of catecholamines which occur. In the operating room during anesthesia we take care to combat this trend by giving adequate analgesics, and it is logical that we should attempt to take similar steps in the prehospital care phase.

One of the reasons why the provision of analgesia is so poor in practice is that the usual parenteral agents — the opiates — are accompanied by side effects which are particularly dangerous in the seriously ill or injured patient. The introduction of low dose ketamine, however, has altered this position somewhat, offering, as it does, good analgesia without significant depression of respiration or the circulation.

A major practical difficulty in providing analgesia outside hospital lies in the fact that the majority of the patients are being cared for by personnel who are not physicians. We, therefore, need an agent which can be administered by an ambulance attendant or trained rescuer. In many countries the opiates and ketamine may only be administered by a physician and therefore they are effectively ruled out for the majority of patients.

Let us look at the properties of an ideal analgesic for use outside hospital. It should be: 1) effective but safe; 2) have no undesirable side effects; 3) have a rapid onset and short duration of action; 4) be easy to administer; and 5) be capable of being used by paramedical personnel.