Application of Newton's law to body cooling

Summary

Newton's law of cooling was used to analyze the fall in rectal temperature post mortem in 55 cases during refrigeration in a mortuary. As with solids of low thermal conductivity, there was an initial curvilinearity to the semilog plot lasting 1 to 11 hours (related to pelvic circumference) while the proper internal temperature distribution was becoming established. Thereafter there was a linear trend representing a constant percent cooling rater ₁ which lasted up to 24 hours for adults. This was followed by a less steep trend of cooling rater ₂, which was 37% less thanr ₁. This diminution in cooling rate occurred when the rectal temperature fell below 10°C and was ascribed to a reduction in the thermal diffusivity of fat.r ₁ had the highest correlation with pelvic circumference. For the nude body in still airr ₁=15.6% to 18.4% (T _r −T _a )/hour for children, 3.8% to 9.4% for adults. Wind increasedr ₁; the decrease due to clothing was questionable because of the paucity of cases.