Temperature Changes of Pulmonary Blood During Exposure to Cold

Abstract

Blood temps. of the pulmonary artery and left atrium, and rectal temps. of unanesthetized dogs in environments of 20[degree]C and -18[degree]C were measured, utilizing thermistors placed in hypodermic needles passed into the desired tissues through surgically placed director cannulae. The rectal temps. were higher than those of the pulmonary arterial blood and the left atrial blood during the time the animal was in both environments. When the animals were moved from the 20[degree]C environment to that of -18[degree]C, all temps. measured increased for approx. 5 min. after which they gradually decreased. The avg. difference in temp. between the blood in the pulmonary artery and the left atrium in the 20[degree] C environment was 0.01[degree]C, and at -18[degree]C was 0.03[degree]C (during the first 5 min. of exposure). The cooling effect of the inspiration of cold air upon the blood in the pulmonary circulation was small.