Abstract
Studies of tissue temperature have been made by means of fairly accurate instruments since the work of Becquerel and Breschet. 1 Interest in recording the temperature of the circulating blood in humans has been secondary to the development of scientifically accurate apparatus which has been devised on thermo-electric principles. Clark 2 developed a galvanometer deflection method of measurement. Harris and Marvin, 3 and Bradburn and Blalock 4 studied changes in the temperature of the venous blood of the hand after immersion in water at various temperatures—by means of direct measurement. Foged5, 6 reported observations on 116 patients concluding that the temperature in the ulnar vein averaged 2.6 lower than the rectal temperature. He noted, in the presence of fever, an increase in this difference and also that the temperature of the surrounding medium affected the temperature of the venous blood. Other of Foged's observations will be discussed in reference to our findings.
Our observations made on humans were recorded by means of one recording and one non-recording potentiometer (Leeds and Northrup). The readings were taken by means of a thermocouple using the metals copper and constantan at the junction. This thermocouple was contained in the tip of a No. 20 hypodermic needle and the same thermocouple was used for all readings taken in one individual. Mouth temperature was used instead of rectal—making sure that the thermocouple junction rested firmly against the under surface of the tongue. This was done because (1) the relationship between mouth and rectal temperature has been fairly well established; (2) the use of the needle made rectal readings more difficult and possibly uncomfortable; (3) it was easier to be certain that the tip of the needle rested against known tissue in the mouth; (4) changing the thermocouple or from thermocouple to mercury thermometer would introduce another possible source of error.
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