Normal temperature in various parts of the body. Temperature measurement sites
It is known that the first thermometer was invented by Galileo Galilei in the XVII century. However, it was bulky, consisted of a cylinder with a cylindrical protrusion, the open end of which was immersed in a liquid. The first mercury thermometer, manufactured by Fahrenheit in 1714, over time allowed the creation of a thermometer suitable for clinical purposes.
Announcements of the sale of clinical thermometers appeared in medical journals as early as 1800, but only 70 years later, when Wunderlich published his treatise on the clinical significance of measuring body temperature, the use of thermometers in medicine became routine. Nowadays, the measurement of body temperature is a standard study in all clinical situations and one of the most common quantitative clinical measurements in pediatrics.
There is a temperature gradient in the body, and the temperature of individual organs and muscle groups is different. As a rule, deep tissues are warmer than the surface ones and the temperature inside the body is higher than the temperature in the limbs. A formula for calculating the average body temperature is proposed: Tsrednyaya = 0.8 Tractalnaya + 0.2 Tkozhi.
For the clinical measurement of body temperature, there are several convenient superficial and deep places. Most often, the mouth and the rectum are used for this. Rectal temperature is usually 0.27–0.55 ° C higher than the oral temperature. When measuring the latter, it should be ensured that before this the patient does not drink hot or cold drinks.
The temperature in the armpit is often measured in very young children, as well as in rectal diseases. Akoillary temperature is usually 1.1-1.2 ° C lower than rectal. The temperature of blood flowing from the left ventricle is 0.27–0.55 ° C lower than the rectal temperature. The reason for this is unclear. It is assumed that under the influence of the bacterial flora, the temperature in the rectum exceeds the temperature of the rest of the body. In addition, the blood from the left ventricle can be cooled by venous blood flowing from the extremities, according to the type of countercurrent heat exchange.
In some situations, such as during a heart operation under anesthesia or hypothermia, there is a need to control body temperature by measuring it in the lower third of the esophagus or on the eardrum. It is believed that the temperature of these areas generally reflects the temperature of the aortic and carotid vessels, respectively, and therefore is somewhat lower than the rectal temperature.
The temperature of these areas reflects changes in the temperature of the “core” more quickly and accurately than rectal temperature, which is used in surgery and in (Critical situations. Dubois found that if fever is accompanied by chills, the temperature of the internal organs increases faster than rectal temperature. At the height of the chill, duodenal temperature intestine was 1.7 ° C higher than rectal, whereas before the chill the difference was only 0.17 ° C.
Measuring skin temperature is not a reliable enough method for detecting and quantifying fever. Resinger showed that a commercially available device for measuring the temperature of the forehead skin (Clinitemp) using liquid crystals encased in plastic tape was not reliable enough to detect fever. The number of false-positive results was small, but the number of false-negative results was significant.
In this series of measurements, 57% of children who had a “core” temperature of 38.3 ° C and higher, when using this device, the body temperature was within the normal range. Despite the indication in the instruction that it is necessary to check the temperature with a mercury thermometer when detecting fever, this does not solve the problem of false-negative results. Indeed, it is not surprising that a skin thermometer cannot detect a fever in most patients.
This is due both to the imperfection of the device used, and the fact that in the initial stage of fever the blood flow through the skin decreases and its temperature drops. Only later, when the temperature of the “core” and especially the muscular temperature increase significantly, an increase in body temperature affects the temperature of the skin. Even if this failure is attributed to the flaws of the device, it is still unlikely that improving its design can solve the problem, and measuring skin temperature is likely to continue to be considered an imperfect method of detecting fever.