Calculation of mean skin temperature and changes in body heat content during paediatric anaesthesia.

Mean skin temperature and changes in body heat content were calculated in several different ways from measurements made in five children during operation. Mean skin temperatures were calculated from 162 sets of measurements using 15, 12, eight, seven and four skin sites with various formulae modified according to age. The results of other formulae were compared with age-adjusted, area-weighted 15-site mean skin temperature which was used as a reference. Changes in body heat content were calculated from Burton's equation in different ways and errors from different variables in the formula were evaluated. Mean skin temperature from 12 skin sites was within 0.5 degrees C of the 15-point reference method, and that from four sites within 1 degree C. The core temperature selected and the weighting coefficients used in calculating mean body temperature were more important sources of error in the determination of change in body heat content than was mean skin temperature.