Response to Sessler letter by J.R. House and M.J. Tipton

Excerpt

We would like to thank Dr. Sessler for the review of his Anaesthesiology literature, which we are sure will be of interest to the readers of the European Journal of Applied Physiology (EJAP). We think it wise to source and quote original references in the clinical literature, rather than recent reviews for the purposes of identifying the origins of a useful technique. We attempted to tell the readers of EJAP why the anaesthetics field is interested in thermoregulatory thresholds and T _sk-diff measures, which are differentials in skin temperature measured on the forearm (T _skforearm) and the finger pad (T _skfinger pad), such that T _sk-diff=T _skforearm−T _skfinger pad. However, as our experiment demonstrates, we are concerned with the much more dynamic situations that can occur during thermoregulatory studies in extreme environments. We believe it remains safe to say that the T _sk-diff method has not been validated for use in such studies. For example, the study of Rubinstein and Sessler (1990), so often cited, tested the hypothesis that "steady-state forearm-fingertip temperature gradients accurately reflect total fingertip blood flow", and examined the correlation between T _sk-diff and fingertip skin blood flow (SkBF) after 30-min periods of steady-state exposure to various conditions aimed at delivering different levels of skin blood flow. The experimental design does not allow an assessment of the relationship between vasomotor tone and T _sk-diff during the first 30 min. Indeed, a reasonable conclusion from this work could be that T _sk-diff can be used to estimate SkBF 30 min after major vasomotor adjustments may have been made, and a period of steady state has been achieved. …