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

We examined the influence of 1) prior increase [preheating (PHT)], 2) increase throughout [heating (HT)], and 3) no increase [control (Con)] of body heat content (Hb) on neuromuscular function and manual dexterity of the hands during a 130-min exposure to −20°C (coldEx). Ten volunteers randomly underwent three passive coldEx, incorporating a 10-min moderate-exercise period at the 65th min while wearing a liquid conditioning garment (LCG) and military arctic clothing. In PHT, 50°C water was circulated in the LCG before coldEx until core temperature was increased by 0.5°C. In HT, participants regulated the inlet LCG water temperature throughout coldEx to subjective comfort, while the LCG was not operating in Con. Thermal comfort, rectal temperature, mean skin temperature, mean finger temperature (T̄fing), change in Hb (ΔHb), rate of body heat storage, Purdue pegboard test, finger tapping, handgrip, maximum voluntary contraction, and evoked twitch force of the first dorsal interosseus muscle were recorded. Results demonstrated that, unlike in HT and PHT, thermal comfort, rectal temperature, mean skin temperature, twitch force, maximum voluntary contraction, and finger tapping declined significantly in Con. In contrast, T̄fing and Purdue pegboard test remained constant only in HT. Generalized estimating equations demonstrated that ΔHb and T̄fing were associated over time with hand function, whereas no significant association was detected for rate of body heat storage. It is concluded that increasing Hb not only throughout but also before a coldEx is effective in maintaining hand function. In addition, we found that the best indicator of hand function is ΔHb followed by T̄fing.

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Relationship between body heat content and finger temperature during cold exposure

Journal of Applied Physiology ◽

10.1152/jappl.2001.90.6.2445 ◽

2001 ◽

Vol 90 (6) ◽

pp. 2445-2452 ◽

Cited By ~ 30

Author(s):

Dragan Brajkovic ◽

Michel B. Ducharme ◽

John Frim

Keyword(s):

Skin Temperature ◽

Heat Storage ◽

Heat Content ◽

The Body ◽

Finger Temperature ◽

Finger Dexterity ◽

The Relationship ◽

Finger Skin ◽

Body Heat ◽

Partitional Calorimetry

The purpose of the present experiment was to examine the relationship between rate of body heat storage (S˙), change in body heat content (ΔHb), extremity temperatures, and finger dexterity. S˙, ΔHb , finger skin temperature (Tfing), toe skin temperature, finger dexterity, and rectal temperature were measured during active torso heating while the subjects sat in a chair and were exposed to −25°C air. S˙ and ΔHb were measured using partitional calorimetry, rather than thermometry, which was used in the majority of previous studies. Eight men were exposed to four conditions in which the clothing covering the body or the level of torso heating was modified. After 3 h, Tfing was 34.9 ± 0.4, 31.2 ± 1.2, 18.3 ± 3.1, and 12.1 ± 0.5°C for the four conditions, whereas finger dexterity decreased by 0, 0, 26, and 39%, respectively. In contrast to some past studies, extremity comfort can be maintained, despite S˙ that is slightly negative. This study also found a direct linear relationship between ΔHb and Tfing and toe skin temperature at a negative ΔHb. In addition, ΔHb was a better indicator of the relative changes in extremity temperatures and finger dexterity over time than S˙.

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Thermal behavior alleviates thermal discomfort during steady-state exercise without affecting whole body heat loss

Journal of Applied Physiology ◽

10.1152/japplphysiol.00379.2019 ◽

2019 ◽

Vol 127 (4) ◽

pp. 984-994 ◽

Cited By ~ 3

Author(s):

Nicole T. Vargas ◽

Christopher L. Chapman ◽

Blair D. Johnson ◽

Rob Gathercole ◽

Matthew N. Cramer ◽

...

Keyword(s):

Light Intensity ◽

Thermal Behavior ◽

Skin Temperature ◽

Heat Loss ◽

Core Temperature ◽

Upper Body ◽

Whole Body ◽

Mean Skin Temperature ◽

Thermal Discomfort ◽

Body Heat

We tested the hypothesis that thermal behavior resulting in reductions in mean skin temperature alleviates thermal discomfort and mitigates the rise in core temperature during light-intensity exercise. In a 27 ± 0°C, 48 ± 6% relative humidity environment, 12 healthy subjects (6 men, 6 women) completed 60 min of recumbent cycling. In both trials, subjects wore a water-perfused suit top continually perfusing 34 ± 0°C water. In the behavior trial, subjects maintained their upper body thermally comfortable by pressing a button to perfuse cool water (2.2 ± 0.5°C) through the top for 2 min per button press. Metabolic heat production (control: 404 ± 52 W, behavior: 397 ± 65 W; P = 0.44) was similar between trials. Mean skin temperature was reduced in the behavior trial (by −2.1 ± 1.8°C, P < 0.01) because of voluntary reductions in water-perfused top temperature ( P < 0.01). Whole body ( P = 0.02) and local sweat rates were lower in the behavior trial ( P ≤ 0.05). Absolute core temperature was similar ( P ≥ 0.30); however, the change in core temperature was greater in the behavior trial after 40 min of exercise ( P ≤ 0.03). Partitional calorimetry did not reveal any differences in cumulative heat storage (control: 554 ± 229, behavior: 544 ± 283 kJ; P = 0.90). Thermal behavior alleviated whole body thermal discomfort during exercise (by −1.17 ± 0.40 arbitrary units, P < 0.01). Despite lower evaporative cooling in the behavior trial, similar heat loss was achieved by voluntarily employing convective cooling. Therefore, thermal behavior resulting in large reductions in skin temperature is effective at alleviating thermal discomfort during exercise without affecting whole body heat loss. NEW & NOTEWORTHY This study aimed to determine the effectiveness of thermal behavior in maintaining thermal comfort during exercise by allowing subjects to voluntarily cool their torso and upper limbs with 2°C water throughout a light-intensity exercise protocol. We show that voluntary cooling of the upper body alleviates thermal discomfort while maintaining heat balance through convective rather than evaporative means of heat loss.

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Finger dexterity, skin temperature, and blood flow during auxiliary heating in the cold

Journal of Applied Physiology ◽

10.1152/japplphysiol.00051.2003 ◽

2003 ◽

Vol 95 (2) ◽

pp. 758-770 ◽

Cited By ~ 34

Author(s):

Dragan Brajkovic ◽

Michel B. Ducharme

Keyword(s):

Blood Flow ◽

Skin Temperature ◽

Heat Content ◽

Finger Dexterity ◽

Significant Difference ◽

Forearm Skin ◽

The Difference ◽

Finger Skin ◽

Forearm Muscle ◽

Body Heat

The primary purpose of the present study was to compare the effectiveness of two forms of hand heating and to discuss specific trends that relate finger dexterity performance to variables such as finger skin temperature (Tfing), finger blood flow (Q̇fing), forearm skin temperature (Tfsk), forearm muscle temperature (Tfmus), mean weighted body skin temperature (T̄sk), and change in body heat content (ΔHb). These variables along with rate of body heat storage, toe skin temperature, and change in rectal temperature were measured during direct and indirect hand heating. Direct hand heating involved the use of electrically heated gloves to keep the fingers warm (heated gloves condition), whereas indirect hand heating involved warming the fingers indirectly by actively heating the torso with an electrically heated vest (heated vest condition). Seven men (age 35.6 ± 5.6 yr) were subjected to each method of hand heating while they sat in a chair for 3 h during exposure to -25°C air. Q̇fing was significantly ( P < 0.05) higher during the heated vest condition compared with the heated gloves condition (234 ± 28 and 33 ± 4 perfusion units, respectively), despite a similar Tfing (which ranged between 28 and 35°C during the 3-h exposure). Despite the difference in Q̇fing, there was no significant difference in finger dexterity performance. Therefore, finger dexterity can be maintained with direct hand heating despite a low Q̇fing. ΔHb, T̄sk, and Tfmus reached a low of -472 ± 18 kJ, 28.5 ± 0.3°C, and 29.8 ± 0.5°C, respectively, during the heated gloves condition, but the values were not low enough to affect finger dexterity.

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Hypohydration and thermoregulation in cold air

Journal of Applied Physiology ◽

10.1152/jappl.1998.84.1.185 ◽

1998 ◽

Vol 84 (1) ◽

pp. 185-189 ◽

Cited By ~ 40

Author(s):

Catherine O’Brien ◽

Andrew J. Young ◽

Michael N. Sawka

Keyword(s):

Skin Temperature ◽

Cold Exposure ◽

Plasma Osmolality ◽

Whole Body ◽

Mean Skin Temperature ◽

Finger Temperature ◽

Cold Air ◽

Vasoconstrictor Response ◽

Weight Decrease ◽

Body Heat

O’Brien, Catherine, Andrew J. Young, and Michael N. Sawka.Hypohydration and thermoregulation in cold air. J. Appl. Physiol. 84(1): 185–189, 1998.—This study examined the effects of hypohydration on thermoregulation during cold exposure. In addition, the independent influences of hypohydration-associated hypertonicity and hypovolemia were investigated. Nine male volunteers were monitored for 30 min at 25°C, then for 120 min at 7°C, under three counterbalanced conditions: euhydration (Eu), hypertonic hypohydration (HH), and isotonic hypohydration (IH). Hypohydration was achieved 12 h before cold exposure by inducing sweating (HH) or by ingestion of furosemide (IH). Body weight decrease (4.1 ± 0.2%) caused by hypohydration was similar for HH and IH, but differences ( P < 0.05) were found between HH and IH in plasma osmolality (292 ± 1 vs. 284 ± 1 mosmol/kgH2O) and plasma volume reduction (−8 ± 2 vs. −18 ± 3%). Heat debt (349 ± 14 among) did not differ ( P > 0.05) among trials. Mean skin temperature decreased throughout cold exposure during Eu but plateaued after 90 min during HH and IH. Forearm-finger temperature gradient tended ( P = 0.06) to be greater during Eu (10.0 ± 0.7°C) than during HH or IH (8.9 ± 0.7°C). This suggests weaker vasoconstrictor tone during hypohydration than during Eu. Final mean skin temperature was higher for HH than for Eu or IH (23.5 ± 0.3, 22.6 ± 0.4, and 22.9 ± 0.3°C, respectively), and insulation was lower on HH than on IH (0.13 ± 0.01 vs. 0.15 ± 0.01°C ⋅ W−1 ⋅ m−2, respectively), but not with Eu (0.14 ± 0.01°C ⋅ W−1 ⋅ m−2). This provides some evidence that hypertonicity impairs the vasoconstrictor response to cold. Although mild hypohydration did not affect body heat balance during 2-h whole body exposure to moderate cold, hypohydration-associated hypertonicity may have subtle effects on vasoconstriction that could become important during a more severe cold exposure.

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INCREASING MEAN SKIN TEMPERATURE LINEARLY REDUCES THE VASOCONSTRICTION AND SHIVERING THRESHOLDS IN HUMANS

Anesthesiology ◽

10.1097/00000542-199409001-00251 ◽

1994 ◽

Vol 81 (SUPPLEMENT) ◽

pp. A252

Author(s):

C. Cheng ◽

T. Matsukawa ◽

A. Kurz ◽

D. I. Sessler ◽

B. Merrifield

Keyword(s):

Skin Temperature ◽

Mean Skin Temperature

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Thermoregulatory responses during competitive marathon running

Journal of Applied Physiology ◽

10.1152/jappl.1977.42.6.909 ◽

1977 ◽

Vol 42 (6) ◽

pp. 909-914 ◽

Cited By ~ 98

Author(s):

M. B. Maron ◽

J. A. Wagner ◽

S. M. Horvath

Keyword(s):

Skin Temperature ◽

Marathon Running ◽

Heat Illness ◽

Mean Skin Temperature ◽

Total Water ◽

Water Losses ◽

Thermoregulatory Responses ◽

Marked Disparity ◽

Skin Temperatures ◽

Cool Conditions

To assess thermoregulatory responses occuring under actual marathon racing conditions, rectal (Tre) and five skin temperatures were measured in two runners approximately every 9 min of a competitive marathon run under cool conditions. Race times and total water losses were: runner 1 = 162.7 min, 3.02 kg; runner 2 = 164.6 min, 2.43 kg. Mean skin temperature was similar throughout the race in the two runners, although they exhibited a marked disparity in temperature at individual skin sites. Tre plateaued after 35--45 min (runner 1 = 40.0--40.1, runner 2 = 38.9--39.2 degrees C). While runner 2 maintained a relatively constant level for the remainder of the race, runner 1 exhibited a secondary increase in Tre. Between 113 and 119 min there was a precipitous rise in Tre from 40.9 to 41.9 degrees C. Partitional calorimetric calculations suggested that a decrease in sweating was responsible for this increment. However, runner 1's ability to maintain his high Tre and running pace for the remaining 44 min of the race and exhibit no signs of heat illness indicated thermoregulation was intact.

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The effect of hand immersion on body temperature when wearing impermeable clothing

Journal of The Royal Naval Medical Service ◽

10.1136/jrnms-77-41 ◽

1991 ◽

Vol 77 (1) ◽

pp. 41-47

Author(s):

A. J. Allsopp ◽

Kerry A. Poole

Keyword(s):

Body Temperature ◽

Skin Temperature ◽

Environmental Temperature ◽

List Type ◽

Physiological Measures ◽

Total Work ◽

Mean Skin Temperature ◽

Work Time ◽

Experimental Conditions ◽

Rest Periods

AbstractThe effects of hand immersion on body temperature have been investigated in men wearing impermeable NBC clothing. Six men worked continuously at a rate of approximately 490 J.sec−1 in an environmental temperature of 30°C. Each subject was permitted to rest for a period of 20 minutes when their aural temperature reached 37.5°C, and again on reaching 38°C, and for a third time on reaching 38.5°C (three rest periods in total). Each subject completed three experimental conditions whereby, during the rest periods they either: a.Did not immerse their hands (control).b.Immersed both hands in a water bath set at 25°c.c.Immersed both hands in water at 10°C.Physiological measures of core temperature, skin temperature and heart rate were recorded at intervals throughout the experiment.Measures of mean aural temperature and mean skin temperature were significantly (P<0.05) reduced if hands were immersed during these rest periods, compared to non immersion. As a result, the total work time of subjects was extended when in the immersed conditions by some 10–20 minutes within the confines of the protocol.It is concluded that this technique of simple hand immersion may be effective in reducing heat stress where normal routes to heat loss are compromised.

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Tissue Heat Content and Distribution during and after Cardiopulmonary Bypass at 31 [degree sign]C and 27 [degree sign]C

Anesthesiology ◽

10.1097/00000542-199806000-00015 ◽

1998 ◽

Vol 88 (6) ◽

pp. 1511-1518 ◽

Cited By ~ 46

Author(s):

Angela Rajek ◽

Rainer Lenhardt ◽

Daniel I. Sessler ◽

Andrea Kurz ◽

Gunther Laufer ◽

...

Keyword(s):

Cardiopulmonary Bypass ◽

Temperature Gradient ◽

Heat Content ◽

Peripheral Tissue ◽

Tissue Temperature ◽

Peripheral Compartment ◽

Peripheral Tissues ◽

The Core ◽

Total Body ◽

Body Heat

Background Afterdrop following cardiopulmonary bypass results from redistribution of body heat to inadequately warmed peripheral tissues. However, the distribution of heat between the thermal compartments and the extent to which core-to-peripheral redistribution contributes to post-bypass hypothermia remains unknown. Methods Patients were cooled during cardiopulmonary bypass to nasopharyngeal temperatures near 31 degrees C (n=8) or 27 degrees C (n=8) and subsequently rewarmed by the bypass heat exchanger to approximately 37.5 degrees C. A nasopharyngeal probe evaluated core (trunk and head) temperature and heat content. Peripheral compartment (arm and leg) temperature and heat content were estimated using fourth-order regressions and integration over volume from 19 intramuscular needle thermocouples, 10 skin temperatures, and "deep" foot temperature. Results In the 31 degrees C group, the average peripheral tissue temperature decreased to 31.9+/-1.4 degrees C (means+/-SD) and subsequently increased to 34+/-1.4 degrees C at the end of bypass. The core-to-peripheral tissue temperature gradient was 3.5+/-1.8 degrees C at the end of rewarming, and the afterdrop was 1.5+/-0.4 degrees C. Total body heat content decreased 231+/-93 kcal. During pump rewarming, the peripheral heat content increased to 7+/-27 kcal below precooling values, whereas the core heat content increased to 94+/-33 kcal above precooling values. Body heat content at the end of rewarming was thus 87+/-42 kcal more than at the onset of cooling. In the 27 degrees C group, the average peripheral tissue temperature decreased to a minimum of 29.8 +/-1.7 degrees C and subsequently increased to 32.8+/-2.1 degrees C at the end of bypass. The core-to-peripheral tissue temperature gradient was 4.6+/-1.9 degrees C at the end of rewarming, and the afterdrop was 2.3+/-0.9 degrees C. Total body heat content decreased 419+/-49 kcal. During pump rewarming, core heat content increased to 66+/-23 kcal above precooling values, whereas peripheral heat content remained 70+/-42 kcal below precooling values. Body heat content at the end of rewarming was thus 4+/-52 kcal less than at the onset of cooling. Conclusions Peripheral tissues failed to fully rewarm by the end of bypass in the patients in the 27 degrees C group, and the afterdrop was 2.3+/-0.9 degrees C. Peripheral tissues rewarmed better in the patients in the 31 degrees C group, and the afterdrop was only 1.5+/-0.4 degrees C.

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Effect of food intake on the ventilatory response to increasing core temperature during exercise

Applied Physiology Nutrition and Metabolism ◽

10.1139/apnm-2018-0069 ◽

2019 ◽

Vol 44 (1) ◽

pp. 22-30 ◽

Cited By ~ 2

Author(s):

Keiji Hayashi ◽

Nozomi Ito ◽

Yoko Ichikawa ◽

Yuichi Suzuki

Keyword(s):

Food Intake ◽

Body Temperature ◽

Skin Temperature ◽

Core Temperature ◽

Mean Skin Temperature ◽

Carbon Dioxide Elimination ◽

Transient Effect ◽

Mean Body Temperature ◽

Ventilatory Parameters ◽

Effect Of Food

Food intake increases metabolism and body temperature, which may in turn influence ventilatory responses. Our aim was to assess the effect of food intake on ventilatory sensitivity to rising core temperature during exercise. Nine healthy male subjects exercised on a cycle ergometer at 50% of peak oxygen uptake in sessions with and without prior food intake. Ventilatory sensitivity to rising core temperature was defined by the slopes of regression lines relating ventilatory parameters to core temperature. Mean skin temperature, mean body temperature (calculated from esophageal temperature and mean skin temperature), oxygen uptake, carbon dioxide elimination, minute ventilation, alveolar ventilation, and tidal volume (VT) were all significantly higher at baseline in sessions with food intake than without food intake. During exercise, esophageal temperature, mean skin temperature, mean body temperature, carbon dioxide elimination, and end-tidal CO2 pressure were all significantly higher in sessions with food intake than without it. By contrast, ventilatory parameters did not differ between sessions with and without food intake, with the exception of VT during the first 5 min of exercise. The ventilatory sensitivities to rising core temperature also did not differ, with the exception of an early transient effect on VT. Food intake increases body temperature before and during exercise. Other than during the first 5 min of exercise, food intake does not affect ventilatory parameters during exercise, despite elevation of both body temperature and metabolism. Thus, with the exception of an early transient effect on VT, ventilatory sensitivity to rising core temperature is not affected by food intake.

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