Oxygen consumption of hyper- and hypothermic premature infants.

Most newborn animals or human infants, when displaced from their thermal neutral environment by a sufficiently large fall or rise in environmental temperature, react by increasing their rate of 02 consumption and heat production. In certain circumstances, however, the nervous mechanisms that control heat production may be impaired, so that when an animal is exposed to a cool environment it does not respond by increasing heat production. Under these conditions classical physiological teaching suggests that there should be a direct linear relation between body temperature and heat production or 02 consumption (the van't Hoff law) such that a 100 C. rise or fall in body temperature will cause a 2-3 times increase or decrease in heat production (Qlo = 2-3). The purpose of the present paper is to examine the extent to which this expectation is fulfilled in newborn human infants. Although the changes in 02 consumption in homeothermic animals with impaired thermoregulation have usually been attributed to the consequential changes in body temperature, and although the Qlo so derived was 2-3 (Adolph, 1950; Bigelow, Lindsay, Harrison, Gordon and Greenwood, 1950; Horvath, Hutt, Spurr and Stevens, 1953; Spurr, Hutt and Horvath, 1954; Thauer, 1955; Behmann and Bontke, 1958), there are exceptions. Thus Balogh, Donhoffer, Mestyain, Pap and T6th (1952), Donhoffer, Mestyan, Obrincsaik-Pap, Pap and Toth (1953), and Donhoffer, Mestyan, Nagy and Szegvari (1957) found that the rise in 02 consumption of hyperthermic rats was not directly related to the increase in body temperature. Similarly, in hypothermia caused by hypothalamic lesions, by local heating of the hypothalamus or by various drugs which interfered with the central nervous control of thermo-regulation, the change in 02 consumption did not bear the anticipated relation to the fall in body temperature (Mestya'n, Mess, Szegvari and Donhoffer, 1958; Mestyan, et al., 1959a, b; Mestyain, Jairai, Szegvari and Farkas, 1960). Under these particular conditions there was a considerable fall or rise in body temperature without any change in heat production. A deliberate search has therefore been made for infants who spontaneously showed a low rectal temperature, and their reactions to changes of body temperature have been examined.