Physiological effects of thermoregulation in transitional ELBW infants

Problem: Extremely low birth weight (ELBW) infants are vulnerable to cold stress during the first 12 hours of life (extra-uterine transition) due to stabilization in the delivery room and NICU. Little research has examined thermoregulation in ELBW infants or the body temperature range that would lead to optimal physiological status. Purpose: The purpose of this study was to explore the physiological aspects of thermoregulation as a first step toward determining the optimal body temperature for ELBW infants during transition. The study used a multiple case design to explore the relationships between body temperature and oxygenation, heart rate, peripheral vasoconstriction, acid-base balance, and blood glucose in 10 ELBW infants over their first 12 hours in the NICU. Methodology: Infants were continuously monitored from admission to the NICU for 12 hours. Ten variables were collected using physiologic monitoring, observation and chart review. Results: Infants had a mean abdominal temperature range of 35.17; C to 36.68; C. One infant exhibited peripheral vasoconstriction 8.8% of the time, and the remaining nine had poor vasomotor control, appearing to lack the ability to vasoconstrict. The peripheral temperature was greater than the abdominal temperature for the most of the study period for 7 of 10 infants. Abdominal-peripheral temperature differences significantly increased for 9 of the 10 infants when abdominal temperature A 36.4; C. Caregiver handling of the infant was associated with an increase in the abdominal-peripheral temperature difference on graphic trends. Abdominal temperature and heart rate were significantly correlated in 7 of 10 infants. In addition, more observations in the normal heart rate range for 6 of 10 infants when abdominal temperatures were greater than 36.4;C. The abdominal temperature range in which normal heart rates for the ELBW infants in this study were maximized was 36.8;C to 37.0;C. Relevance to Nursing: These results will add to the data to guide nurses in setting control points for body temperature, inform nurses when it is necessary to augment incubator heat with additional heat sources, and help nurses guard against cold stress during stabilization procedures