SPREAD OF EXTRADURAL ANALGESIA FOLLOWING CAUDAL INJECTION IN CHILDREN

Data on the segmental spread of analgesia from three independent studies of caudal extradural blocks in children with three different local anaesthetic agents were examined with multiple regres-sion techniques to find the effects of age on dose requirements. All three studies confirmed the existence of a linear relationship between the spread of analgesia and age. As there were no signifi-cant differences between the three regression lines a common regression line was calculated. This may be used as a guideline for predicting dose requirements in the daily routine of anaesthesia. By injecting a mixture of a radio-opaque substance and 4 % lignocaine it was shown by comparison of the radiological spread of the solution and the distribution of clinical analgesia that the latter always exceeded the former by four to six segments. This may indicate the occurrence of diffusion. In 1969, Bromage published evidence of an age-dependent predictable increase of extradural dose requirement, following the lumbar approach, in children up to the age of 18 yr 6 months. However, his data for children less than 10 yr were few and did not include children younger than 4 yr. We publishe