Rectal Temperature

Any physiological study of body temperature, to be of true scientific value, must deal with temperatures taken deep in the body trunk. The extraneous factors of exercise, mouth-breathing, and the effect of previously taken foods so greatly vitiate all measurements of the buccal temperature that they have little, if any, value except for demonstrating the absence of fever. It has been the custom of many clinicians to take the temperature of young children in the axilla or in the groin. These records, aside from likewise showing the presence or absence of fever, have no physiological value, for it has been found that even when these cavities are well-closed a very considerable period of time is required to raise their temperature to that approximating the interior of the body.

The rectal temperature was measured primarily to demonstrate the absence of any febrile condition, since the presence of fever would of course preclude further observations with the child in this abnormal state. Every reasonable effort was made to have these measurements meet the exactions of scientific accuracy, but as ordinary clinical mercury thermometers were used, even though well-tested, and there were changes in the personnel of the assistants from time to time, as well as possibilities of difference in the depth of insertion of the thermometer bulb, we may not look upon these observations as a refined physiological study of changes in body temperature of children.

It is to be regretted that a study of the diurnal rhythm of the rectal temperature of children of various ages could not have been included in the research, but this was impracticable. To use occasional observations of rectal temperature as a basis for determining the physiological temperature of children is open to serious question, since the well-known influences of activity, ingestion of food, and sleep make such measurements liable to gross variability. When one considers that the normal range in temperature is but 2° or 3° F:, it will be seen that if a study of the body temperature is to be made with strict scientific accuracy, a much more sensitive measurement should be used than that employed in this research. But as the measurements were all made with the child inside a chamber, lying quietly on a comfortable bed, we believe that although the method was admittedly defective, the conditions were essentially comparable and the values may legitimately be used for drawing conclusions.

The rectal temperature was usually recorded, at least with the younger children, just before and just after each respiration experiment. Several hundred observations of the body temperature of these children were thus obtained. The values for boys range from 97.1° F., the very low value for the two boys averaging 5 years of age, to a maximum of 99.52 F. in the group of six boys for 1½ years. During the first month or two of life the temperatures for boys are somewhat low, but with evidence of a tendency to rise thereafter, the maximum continuing for approximately two or three years. Subsequently the figures incline to run below rather than above 99° F., and after 10 years all values are 98.8° F. or under. Special attention has already been called to the extraordinarily low value of 97.1° F. for the two boys 5 years of age, which must not be looked upon as characteristic of that age.