Correction factors in skin temperature measurement.

In 14 persons the skin temperature has been measured by means of thermistor thermometer. The influence of the shape of the probe and the pressure exerted on the resulting value of the skin temperature has been proved. In 10 additional men the relation of the temperature difference (deltaT) to the exerted pressure (P) was determined, the regression equations were derived for relation deltaT/P, and the correlation coefficients for recalculation of the temperatures measured by thermistor thermometer with the pressure exerted 20 g to values determined by thermovision. The skin temperature values determined by thermography were used in 24 formulas (3-16 points) for calculation of mean skin temperature. The differences of the means in determining the optimal method (16 points) were evaluated by the t-test and by the percentage expression of aggrement for criteria plus or minus 0.1, plus or minus 0.2, plus or minus 0.5, and plus or minus 0.1 degrees C. For precise laboratory work 10 points of measurement are recommended; for measurement in the field 6 points of measurement are enough. Orientational measurement can be performed very well by means of Ramanathan method (4 points).     

Evaluation of changes in selected skin parameters under the influence of extremely low temperature

The aim of the work was to evaluate changes in selected skin parameters under the influence of low temperature. The tests were conducted on a group of 20 women using whole-body cryotherapy. The average age of participants was 58.7 ± 7.54 years; the average body weight 77.84 ± 16.01 kg, the mean BMI 30.14 ± 5.81, and the average body height 160.7 ± 6.48 cm. The tested parameters included hydration, lubrication, temperature, and pH of the skin. The skin measurements were made on the first and tenth treatment days, before and after leaving the whole-body cryo-chamber. To assess the data collected before and after the experiment, the measurement taken at each time point were compared. After a series of ten treatment sessions, the greatest decrease was observed in skin hydration and skin temperature. No significant differences were noted for lubrication and skin pH. The analysis showed statistically significant differences in skin parameters between all measurement locations; the upper and lower limbs responded more significantly to cold than other parts of the body. It was also found that the facial skin was more lubricated and hydrated compared to other measuring locations. We conclude that varies skin parts respond differently to low temperature. Cryotherapy causes a significant decrease in temperature and hydration of the skin whereas differences in pH and lubrication of the skin remain insignificant.     

Relationship of skin temperature changes to the emotions accompanying music

One hundred introductory psychology students were given tasks that caused their skin temperatures to either fall or rise. Then they listened to two musical selections, one of which they rated as evoking arousing, negative emotions while the other was rated as evoking calm, positive emotions. During the first musical selection that was presented, the arousing, negative emotion music terminated skin temperature increases and perpetuated skin temperature decreases, whereas the calm, positive emotion selection terminated skin temperature decreases and perpetuated skin temperature increases. During the second musical selection, skin temperature tended to increase whichever music was played; however, the increases were significant only during the calm, positive emotion music. It was concluded that music initially affects skin temperature in ways that can be predicted from affective rating scales, although the effect of some selections may depend upon what, if any, music had been previously heard.A portion of the research reported in this paper was presented at the annual meeting of the Biofeedback Society of California, Asilomar, California, 1983.     

Relationship of skin temperature changes to the emotions accompanying music

One hundred introductory psychology students were given tasks that caused their skin temperatures to either fall or rise. Then they listened to two musical selections, one of which they rated as evoking arousing, negative emotions while the other was rated as evoking calm, positive emotions. During the first musical selection that was presented, the arousing, negative emotion music terminated skin temperature increases and perpetuated skin temperature decreases, whereas the calm, positive emotion selection terminated skin temperature decreases and perpetuated skin temperature increases. During the second musical selection, skin temperature tended to increase whichever music was played; however, the increases were significant only during the calm, positive emotion music. It was concluded that music initially affects skin temperature in ways that can be predicted from affective rating scales, although the effect of some selections may depend upon what, if any, music had been previously heard.     

No dynamic effector responses to fast changes of core temperature at constant skin temperature

Experiments in conscious goats were done to see whether heat production and respiratory evaporative heat loss show dynamic responses to changing core temperature at constant skin temperature. Core temperature was altered by external heat exchangers acting on blood temperature, while skin temperature was maintained constant by immersing the animals up to the neck in a rapidly circulating water bath. Core temperature was altered at various rates up to 0.9 degrees C/min. Step deviations of core temperature from control values were always followed by a positive time derivative of effector response, but never by a negative time derivative during sustained displacement of core temperature. Ramp experiments showed that the slopes at which heat production or heat loss rose with core temperature deviating from its control level grew smaller at higher rates of change of core temperature. It is concluded that neither heat production nor respiratory evaporative heat loss respond to the rate of change of core temperature. At constant skin temperature, thermoregulatory effector responses appear to be proportional to the degree to which core temperature deviates from its set level.     

Significance of skin temperature changes in surface electromyography.

Differing results have been reported concerning the direction and quantity of the electromyogram (EMG) amplitude response to changes in tissue temperature. The EMG signals from the soleus muscle of six healthy human subjects were therefore recorded during dynamic exercise (concentric contractions) at ambient temperatures of 30 degrees C and 14 degrees C. The mean skin temperature (Tsk) above the muscle investigated was 32.9 degrees C and 21.7 degrees C, respectively. The core temperature, estimated by rectal temperature, was unchanged. The cooling of the superficial tissues caused approximately a doubling of the EMG amplitude. For the probability level 0.9 in the amplitude probability distribution function, the average signal level increased from 73 microV to 135 microV (P = 0.02). The average mean power frequency of the EMG signal was reduced from 142 Hz to 83 Hz (P = 0.004). The amplitude increase was not due to shivering but other possible explanations are presented. As the changes in Tsk investigated were within the range which may occur normally during the working hours, it was concluded that Tsk should be carefully controlled in vocational EMG studies.     

Measurement of torso skin temperature under clothing

The influence of clothing on skin temperature distributions of the torso was investigated during and after cold exposure. Volunteers were cooled for one hour at 5 degrees C while wearing clothing designed to have insulation which was intended to be relatively uniformly distributed. Three different thicknesses of clothing were used. Following thermistor measurements of skin temperatures during the cold exposures, clothing was quickly removed from the upper parts of the body to enable thermographic investigations of the temperature distributions of the front of the bare torso. The evolution of temperature distributions were then studied at different ambient temperatures (5 degrees C and 20 degrees C) as a function of the thickness of the insulation which had previously been worn. The patterns of the temperature distributions, and the range and standard deviation of torso temperatures were all found to be relatively constant in spite of the different thicknesses of clothing worn or in the time-variant mean torso temperatures which resulted. The front torso sites normally used for the determination of mean skin temperatures were found to be on portions of the torso which were cooler than the surrounding regions. It was concluded that a site midway between the umbilicus and a nipple yields a more accurate estimate of mean torso temperature in the conditions of the present study.     

Electrical skin resistance and rectal temperature changes in resting human subjects exposed to heat

1. 1.|Fourteen male volunteers were examined under passive heating.

2. 2.|Electrical skin resistance (ESR) and rectal temperature (T_re) were measured during the whole period of exposure.

3. 3.|It was found that:

• —|ESR decreases rapidly with increasing air temperature. Assuming an exponential curve yields a mean time constant of 14 min.

• —|There is a correlation between the individual ESR time constants and T_re increases (r = 0.695, P < 0.005).

• —|Additional changes of ESR were noted in 8 subjects at a constant air temperature of 42°C.

4. 4.|It is concluded that ESR may be a useful indicator of the sweating response of the human thermoregulatory system during exogenous heat load.

Errors in calculating cardiac output due to administration of perfluorochemicals

Intravenous administration of perfluorochemicals (PFC) will alter the density (rho)B, the gravimetric specific heat (c)B, and the volumetric specific heat (rho c)B of blood. Changes in hematocrit also influence (rho c)B. The calibration constant employed in the determination of cardiac output (CO) by thermal dilution depends inversely on (rho c)B. We estimate the effect of addition of PFC and changes in hematocrit on (rho c)B. Consider blood to be a mixture of red cells, emulsified PFC particles, and plasma. This leads to the equation: (rho c)cB = 0.96 - 0.11Hct - 0.48Fct. Here Hct and Fct are the fractional volume concentrations of red blood cells and PFC, and (rho c)cB is the calculated specific heat based on the actual composition of blood. CO can be corrected for changes in (rho c)B by the equation: (CO)c = [(rho c)sB/(rho c)cB](CO)o. Here (CO)o is the observed cardiac output, (rho c)sB is the standard specific heat of blood used in the calculation of (CO)o, and (CO)c is the corrected cardiac output. We have observed laboratory situations where the correction factors have been as high as 10%.