Variation in Cold Resistance among Small Newborn Infants

Abstract
Small newborn infants were exposed to three thermal conditions: (1) Abdominal skin controlled at 36[degree]C; (2) Ambient air controlled at 34[degree]C, (3) Ambient air controlled at 32[degree]C until there was complete equilibration of deep and surface body temperatures. The body temperatures of all infants fell in the air controlled conditions. Some infants were able to prevent a marked fall of deep body temperature by developing a relatively large gradient between core and surface and by maintaining an increase in oxygen consumption; others were unable to sustain homeothermy under these conditions. In clinical situations, air temperature is an unsatisfactory reference point for the definition of the neutral thermal state of very small newborn infants.