Purging with paracetamol: report of four cases.

colder solution.Warming lignocaine may reduce the latent period as a consequence of temperature related changes in the pKa of lignocaine,9 resulting in a faster onset of neuronal blockade, inhibiting impulse con- duction before the noxious stimulus is fully appreci- ated.A similar theory has been proposed for the reduction in the pain of injection after the alkalinisation of local anaesthetic solutions.'0Indeed, it has been suggested that bicarbonate may be added to reduce the discom- fort associated with injection of local anaesthetic agents."However, unlike the relatively simple process of warming, this entails mixing the two solutions, resulting in a reduction of solubility and possibly a reduction in stability.'2Although the technique of warming lignocaine to 37°C before injection has been adopted by dental practitioners, it has unfortunately not received wide- spread acceptance by the medical profession.We strongly recommend that all practitioners should adopt this technique to minimise patients' discomfort.We thank all our volunteers, especially the officers and paramedic trainees from the Scottish Ambulance National Training Centre, Glasgow.