Skin Temperature Changes and Their Significance in the Human Newborn

Abstract

Infrared thermography has, for many years, been used to study skin surface temperature and its distribution in both healthy and sick humans. Until recently, such studies were dependent on “single shot” photographic comparisons taken after varying periods of time had elapsed in order to achieve some degree of equilibration between the subject and the environment. These limitations were partially overcome in a previous investigation of skin temperatures of infants nursed in incubators.¹ The technique used involved continuously recording thermographie pictures on 16 mm cine color film (at a frame rate of 8/sec) with a camera electronically synchronized to make it compatible with the thermographic imaging system which, at that time, was scanning at 16 fps. This was set up to avoid “roll over” and other synchronization difficulties. The infant incubator had to be modified, as infrared radiation transmission is attenuated through perspex panels. Figure 1 shows the modification. An aperture is cut in the incubator roof and a surface silvered mirror angled at 45° to reflect the thermal image of the infant to the infrared scanner. In addition, to obtain adequate magnification and thermal resolution, it was necessary to “pan” the scanner across the image of the infant. Selected frames from the eine film were then identified and photographed to produce a color transparency. By joining three transparencies of the film in this way a thermogram of the whole infant was constructed. This picture was then projected on to a white card screen and the different colored areas, representing different temperatures, were traced around, cut out and weighed (Fig 2). The process was difficult and time-consuming, and numerical results could only be obtained from a limited number of images. Sequential studies over a moderate length of time were also impracticable.