A Research Program to Examine Evidenced-Based Practices in Newborn Thermoregulation.
M Schindler, C Herzner, I Berlet, S Dahlmann, F Loersch, and T Schaible, Universitätsklinikum Mannheim,
Mannheim, Germany
Lynn Lynam, GE Healthcare Perinatal, Laurel, MD, USA
Petra Heep, GE Healthcare, Rodgau, Germany
BACKGROUND: Thermoregulation is a critical component of neonatal care. Yet many of the practices
surrounding thermoregulation have not been re-tested despite the fact that the frontier of viability has markedly
changed over the last 4 decades. Maintaining a neutral thermal environment (NTE) whereby oxygen consumption
is minimized for compromised newborns is one foundation of care for this population. Environmental
temperatures impact mortality rates. There is no easy way to determine whether an infant is in his or her NTE.
Rather clinicians have extrapolated data from historical studies that have determined the correlation between O2
consumption, rectal temperature, and skin temperature. The problem with these studies is that they were
conducted on infants that did not reflect the demographics of the infant population in modern NICUs. Less than
20 years ago, the survival of infants less than 750 grams was a rare event. Now it is a common occurrence and
some of these data need to be re-examined to determine if the temperatures thought to represent NTE are still
valid and to determine if the methods of driving heater control algorithms are influenced by these demographic
differences. With this foundation as an overview, one should realize that approximately 50% of the nurseries in
the world practice a baby-control philosophy to thermoregulation while the rest practice an air-control
philosophy. Yet is the evidence base all that is should or could be? Does the data show that one approach is
better for the baby that the other?
OBJECTIVE: A multidisciplinary research group has been convened at Universitätsklinikum Mannheim. A staged
approach to investigation of thermoregulatory practices has been developed. During the first phase, the primary
goal is to evaluate and compare the thermal and physiological homeostasis of very low birthweight (VLBW)
infants during two methods of heating control (baby control versus air control conditions) during the first week of
life. Specific primary outcome measures will be the effect of heating method on skin temperature, core
temperature, heart rate, heart, respiratory rate, blood pressure, SpO2, pH, PaO2, and PaCO2.
Future stages will examine outcomes in closed versus open bed care during the first week of life, the effect
humidity (on whom should it be used, how long should it be used, and how much should be used) in
consideration of potential infection risks, and optimal methods for preserving themal balance from birth in the
delivery room and during intrahospital transport from the delivery room to the neonatal intensive care unit.
DESIGN/METHODS: During phase one, thirty preterm infants under 1500 grams will be subjected in randomized
fashion to the following conditions: Giraffe (baby control mode) versus Giraffe (air control mode). The Giraffe
bed will be set-up and pre-warmed according to manufacturer’s guidelines in closed bed/incubator/manual TMmode, using temperature recommendations from the Comfort Zone chart. An admission temperature will be
documented on the nursing observation chart. Admission procedures will be conducted in their usual manner.
Central skin temperature will be measured by a single disposable Giraffe temperature thermistor will be placed
midline, midway between the umbilicus and xiphisternum when the infant rests supine or in the paravertebral,
lower thoracic region when the baby is prone. Prone skin temperature will be measured by a single reusable YSI
neonatal thermistor placed on the left heel and connected to a Marquette temperature TRAM module. Both
thermistors will be covered with a hydrogel reflective foil disk supplied by GE Healthcare, Life Support Solutions.
The initial thermal goal will be to maintain central skin temperature at 36.5 degrees C in both groups and rectal
temperature within a range of 36.8 to 37.3 degrees C. Added humidity will be controlled at 60-80% for the 7-day
period of data collection. Variations in the level of humidity will be handled statistically as a covariate and
examined for strength of relationship before data manipulation. Rectal temperature will be monitored at least
every 4 hours.
For the purposes of phase one, several specific hypotheses are proposed:
1. An infant’s skin thermistor temperature (central) will be stable (+ 0.3 degrees C) relative to set point
(36.5 degrees C) when the infant’s thermal environment is managed by baby (patient) control mode.
2. An infant’s skin thermistor temperature (central) will be stable (36.5 degrees C + 0.3 degrees C) when
the infant’s thermal environment is managed by air (manual) control mode in incubator mode.
3. There will be no difference in the relationship between an infant’s central skin temperature (abdomen)
and peripheral skin temperature (left heel), whether the infant is nursed in baby (patient) control or air
(manual) mode.
4. There will be no difference in the relationship between infant’s skin temperature (central) and core
temperature (rectal), whether the infant is nursed in baby (patient) control or air (manual) mode. 5. There will be a relationship between infant’s skin temperature and thermograms as measured by IR
camera.
6. There will be no difference in blood gas parameters (pH, oxygen tension, and carbon dioxide tension),
whether the infant is nursed in baby (patient) control or air (manual) mode. 7. There will be no difference in physiological parameters such as heart rate, respiratory rate, oxygen
saturation, and blood pressure whether the infant is nursed in baby (patient) control or air (manual)
mode.
8. There will be a relationship between the length of environmental perturbation, infant’s skin
temperature, core temperature, physiological parameters, and blood gas parameters during invasive
procedural interventions.
RESULTS/CONCLUSIONS: To date, data on 11 babies in phase one has been completed. Upon collection of data
from 20 babies, a repeated-measures MANOVA will be performed on all data. It is anticipated the findings
derived from this multidisciplinary investigation will strengthen the evidenced-based approach to clinicians. It is
our opinion that both nurses and physicians must be fully aware of evidenced-based practices and to be
prepared to develop research protocols necessary to implement best practices.