New standards for neutral thermal environment of healthy very low birthweight infants in week one of life.

Abstract

SUMMARY It is generally accepted that low birthweight infants should be nursed at thermal neutral temperature-the environment in which oxygen consumption is at a minimum. Low birthweight infants do not, however, always show an increase in oxygen consumption at a temperature outside the neutral range, but react with a change in body temperature. We redefined therefore the neutral temperature for these infants as 'the ambient temperature at which the core temperature of the infant at rest is between 36&7 and 37 3°C and the core and mean skin temperatures are changing less than 0*2 and 0-3°C/hour respectively'. Using this definition, new guidelines of the neutral temperature have been made for healthy infants of 29-34 weeks' gestation. The neutral temperature during the first week of life is dependent on gestational age and postnatal age, whereas after the first week it depends on body weight and postnatal age. Using this definition and the guidelines, the appropriate environmental temperature for the individual patient can be chosen.Since the studies done by Budin in 1900,' it is known that maintaining the body temperature and therefore controlling the environmental temperature is important for the survival of low birthweight infants.Glass et al2 showed that the environmental temperature also influences growth. Although short exposures to cold stress has a facilitative effect on thermogenesis in newborns,3 it is generally accepted that these infants should be nursed in an environment that keeps heat loss at a minimum.4 The optimal ambient temperature at which the infant should be nursed is called the thermal neutral temperature and is defined as 'the range of environmental temperature within which the metabolic rate is at a minimum and within which temperature regulation is achieved by non-evaporative physical processes alone'.5Several guidelines for the neutral temperature have been published.69 These guidelines cannot, however, be used alone for setting the incubator temperature, as the temperature of the walls of the incubator,'0 humidity,' 12 and air velocity'3 are also important. Moreover, it is not known how the guidelines can be evaluated in individual patients, as it is impossible to measure metabolic rate continuously in each one. We defined the neutral 18 temperature in a more practical way and have drawn up new guidelines using this definition. Methods

Incubator weaning in preterm infants and associated practice variation

“…Incubator use for preterm infants has a long history. [5][6][7][8] Several studies have shown the effectiveness of incubator weaning at weights as low as 1500 g. [9][10][11] Glass et al's 12 article in 1968 may have set an earlier precedent for incubator weaning. A heterogeneous patient population in this small study showed increased growth at warmer incubator temperatures compared with a cooler environment.…”

“…Using an upper weight limit would have presented with the problem of potentially including SGA infants, who would be expected to wean to an open crib at a lower weight. A GA of 30 6 7 weeks was picked as an upper limit. GA is often estimated and choosing a more mature cohort presented with the possibility of including infants that were truly more mature, with corresponding larger birth weights.…”

“…All surviving infants appropriate for gestational age (AGA) from 22 to 30 6 7 weeks gestation at birth were included in the study. AGA status was determined as greater than 10th and less than 90th percentile birth weight for each gestational age (GA), as determined by Fenton's updated Fetal-Infant Growth Chart for Preterm Infants.…”

Heat Loss Prevention for Preterm Infants in the Delivery Room

“…4,5 Low birth weight infants are vulnerable to hypothermia (temperature r36.41C according to the previous definition by the AAP 6 ) since they have impaired ability to prevent heat loss 1 and decreased heat production capability. 7,8 The risk of cold stress is greatest at birth during the transition from the warm, wet, wellinsulated intrauterine environment to the cool, drafty delivery room. To reduce this risk, the Neonatal Resuscitation Program (NRP) has made the provision of warmth the first step in resuscitation of the newborn.…”

Influence of Thermal Drive on Central Sleep Apnea in the Preterm Neonate

“…18 This interactive device ensures the maintenance of a thermal condition that takes account of each neonate's particular thermoregulatory requirements. Hence, the thermal environment fulfilled the criteria for thermoneutrality given by Sauer et al 19 For the second (mild warm condition) and third sessions (mild cool condition), T inc was set to T N + 2°C and T N -2°C, respectively. This experimental sequence was chosen in order to rule out a possible effect of thermal adaptation to cool exposure, since the latter can modify thermoregulatory responses and sleep structure.…”