The clinical thermoregulatory sweat test induces maximal seating

Abstract

Although thermoregulatory sweat testing is commonly used to assess the autonomic nervous system, the power of this stimulus to induce sweating has not been studied. In 8 healthy male subjects, the authors quantitated sweat rates, core temperature, heart rate, and blood pressure during clinical thermoregulatory sweat testing, a separate exercise protocol, and with exercise added to thermal conditions. The authors found that (1) the addition of exercise to the thermal environment produced no further increase in sweat rate (3,841+/-948 versus 3,888+/-866 nl/mn - cm2); (2) maximum sweat rates closely corresponded to the theoretical maximum (6,000 nl/mn - cm2) derived from single gland studies; (3) sweat rates vary across subjects, but are similar across sites in any one individual; (4) core temperature rise is a major determinant of cardiovascular load in both thermal and exercise settings; (5) blood pressure decreased 28/11 mm Hg during thermal load, but increased 26/10 mm Hg with exercise, in agreement with current understanding of muscle and skin vascular physiology. The authors conclude that clinical thermoregulatory testing conditions produce maximum sweat rates in humans.

Abnormal sweating patterns associated with itching, burning and tingling of the skin indicate possible underlying small-fibre neuropathy

“…Normal sweat patterns were reported in the control group, with 100% sweating over the entire body surface being most common, which was distinctly different from in the diabetic group, in which 94% had sweating abnormalities. The criteria for full sweat development in normal subjects were also confirmed in a later study . Thus, the sweating abnormalities observed in our study may be compared with the already established normal patterns.…”

“…The criteria for full sweat development in normal subjects were also confirmed in a later study. 19 Thus, the sweating abnormalities observed in our study may be compared with the already established normal patterns.…”

Diagnosing Diabetic Neuropathy: Something Old, Something New

“…This is an important finding given that abnormal sweating is associated with small fiber neuropathy [ 38 ] commonly missed with bedside testing. The thermoregulatory sweat test [ 39 ] is a method of assessing location specific alterations by delivering a controlled heat stimulus to induce a generalized sweat response. The patient's response is detected by assessing a significant color change in cornstarch, sodium carbonate, or alizarin red, which are applied uniformly over the body.…”

Much strain but no gain (in sweat output, that is)

“…Hsieh, McNeeley, and Chelimsky, in "The Clinical Thermoregulatory Sweat Test Induces Maximal Sweating," have reported the results of a study designed to test the common assumption that maximal sweat rates over the whole body surface are achieved by the standard clinical thermoregulatory testing conditions [1].The intriguing and surprising conclusion of their work suggests that the addition of moderate exercise to the thermal environmental stimulus produces no further gain in sweat rate.For their study, Hsieh et al used a thermal environment of 50~ air temperature, 50% relatively humidity, and skin temperature maintained at 40~ These parameters are at, or slightly in excess of, the range of published laboratory standards. For example, the criteria for the thermoregulatory sweat test as published in modern textbooks of clinical autonomic testing specify an air temperature of between 45 ~ and 50~ a relative humidity of 35% to 40%, and a skin temperature of 39.0 ~ to 39.5~ [2].…”