Radiant Heat Loss versus Radiant Heat Gain in Premature Neonates under Radiant Warmers

Abstract

Premature infants nursed on open radiant warmer beds are exposed to short-wavelength infrared power density distributed evenly over the bed surface. Additionally, infants’ sides are exposed to relatively cooler nursery walls, and to the radiant warmer bed platform which may heat and reradiate to the baby. Therefore, infants may not only gain heat from the warmer (Q_{radiant warmer}) but lose or gain radiant heat to the sides as well ( ± Q_{radiant loss}). In order to quantitate these parameters, ten premature newborn infants nursed under radiant warmers servocontrolled to 36.5 °C skin temperature (weight 1.27 ± 0.24 SD kg, gestation 31 ± 3 weeks) were investigated, and partitional calorimetry previously reported. In the present study, calculation of net rate of radiant heat transfer (Q_{net radiant}) was made from these data (––2.63 ± ––1.52 kcal/kg/h), and compared to direct measurements of Q_{radiant warmer} (––2.49 ± ––0.90 kcal/kg/h). The present report further partitions net radiant heat transfer to evaluate Q_{radiant loss}: ––0.13 ± 1.82 kcal/kg/h (range-3.16 to 1.93). From these calculations mean radiant temperature of this environment was estimated (45.3 ± 4.3 °C) and compared to the radiant warmer temperature received (45.0 ± 2.9 °C). This information suggests other strategies to reduce radiant heat loss as well as convective and evaporative losses in premature neonates nursed on open radiant warmer beds.

Modelling and optimisation of the operation of a radiant warmer

“…Taking the values of the newborn's mass m and volume V presented above, as well as assuming that the neonate is, say, one day old, the metabolic heat generation rate obtained is q v = 1417.5 W m -3 , which gives Q = 2.9 W. This value is consistent with the findings presented in [7], where a newborn weighing 1.6 kg had a metabolic heat production of about 2.8 W.…”

“…Firstly, a linear correlation between the surface area of a neonate and its weight was derived based on two studies [7] and [8] performed on a group of newborns:…”

Decreasing Hypothermia During Delivery Room Stabilization of Preterm Neonates

“…Reduce air drafts by closing door, raising sides of warmer; keep all sides up and use additional blankets, with only face exposed, for transfer. 41 Keep baby' s skin covered with plastic wrap; add large blanket for transfer.…”

A Simulation Study of Gel Pillow Heat Conductance

“…17 Signs and symptoms of a cold-stressed infant may be nonspecific and difficult to recognize. [20][21][22][23][24][25][26][27][28][29] Since the gel pillow is often used in an open crib environment, nurses must be aware of the potential effects this pillow may have on an infant's body temperature. 9,18,19 Other serious consequences include arrhythmias, increased pulmonary vascular resistance, increased oxygen demand, hypoglycemia, respiratory distress, hypoxia, and acidosis.…”