Skin temperature and cutaneous pain during warm water immersion

Abstract

Measurements of skin temperature were made during the sudden immersion of the skin of human subjects in water baths at 36–41 C and related to the reports of pain elicited during the first few seconds of immersion. Within 0.5 sec, the skin temperature rose to bath temperature and remained at this level during the 10–15 sec of immersion, pain was reported at 37–41 C occurring 1–5 sec after the start of the immersion and adapting in 2–6 sec. Calculation of the subcutaneous temperature and thermal gradients indicate maximal thermal gradients in superficial skin layers during the first 0.1–0.2 sec of immersion (60 C/mm) decreasing rapidly during the first 5 sec to 6 C/mm. Analysis of the transient pain indicated that it could be considered as the more sensitive “phasic” response of the pain ending of which the “static” unadapting response occurs at skin temperatures of 43–46 C. Several alternative explanations including subcutaneous thermal gradients, vasomotor reactions, and thermochemical changes in the nerve membrane were considered as possible explanations. The last most likely possibility requires a second-order kinetic system of three capacities with highly temperature-sensitive reaction velocities to account for both the phasic and static components of the pain. thermal pain; transient pain; thermal gradients; protein destruction rates; mathematical model; adaptation of pain Submitted on September 2, 1964