OXYGEN CONSUMPTION IN NORMAL NEWBORN INFANTS DURING MODERATE HYPOXIA IN WARM AND COOL ENVIRONMENTS

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The oxygen consumption of 20 normal newborn babies was measured using a closed-circuit apparatus with good time-resolution in which the environmental temperature could be closely controlled. In each baby the oxygen consumption while breathing air was compared with the value obtained a few minutes later while breathing 15% oxygen in nitrogen or vice versa. Five babies were examined in a warm environment while naked: some of these were included in the total of 18 babies who were examined in a cool environment, of these 6 were naked and 12 were clothed. In a warm environment oxygen consumption values were the same whether air or 15% oxygen was breathed. From 6 naked babies in a cool environment 10 measurements of oxygen consumption were obtained, breathing first air, then 15% oxygen. The mean value breathing air did not differ significantly from that obtained when 15% oxygen was breathed. In a further 12 babies who were in a cool environment but clothed 18 oxygen consumption measurements (air then 15% oxygen) were obtained; again there was no significant difference between the means. Sixteen additional measurements of oxygen consumption were obtained while the babies were breathing air after 15% oxygen. The mean value was not significantly different from the mean value when breathing 15% oxygen or the mean value in the preceding period breathing air. It was concluded that breathing 15% oxygen did not depress the oxygen consumption of babies either in a warm environment or a cool one; however, babies in a cool environment were subjected to only a mild degree of cold stimulus, and the metabolic response thus produced was fairly small. This work failed to confirm earlier reports that 15% oxygen did depress oxygen consumption in newborn babies in a cool environment. Possible reasons for the discrepancy are discussed.