Comparison of two microenvironments and nurse caregiving on thermal stability of ELBW infants

This study tested a novel bioinstrumented radiant warmer (RW), designed to provide a reduced-intervention nursing caregiving environment (RINCE) on the ambient and body surface temperature stability of extremely low birth-weight (ELBW) infants (< 1,000 g) during caregiver disruptions. The RINCE was compared with a control bed consisting of a standard RW, modified with a Plexiglas hood (Rohm and Haas, Philadelphia, PA) and an external humidity source.

The sample consisted of 10 extremely low birth-weight infants. The mean gestational age was 25.7 weeks (+/- 1.4 weeks). Birth weight ranged from 570 to 880 g: mean birth weight was 730 g (+/- 95.14 g). The mean Scores for Neonatal Acute Physiology was 21.4 (+/- 6).

This clinical study used a small n sample, crossover time-series design. Infants were randomized to treatment order (control bed v RINCE) on the first day of life. A washout period between microenvironments was observed, and then each infant was placed into the other condition.

Each infant was studied for 5 hours in each treatment condition (control bed v RINCE). Abdominal skin temperatures, heel temperatures, ambient temperatures, and relative humidity (RH) were recorded by a computerized data acquisition system every 60 seconds for hours 12 to 24 of life. Caregiver interventions, microenvironment disruptions, or both were manually coded in the data set.

The mean number of minutes abdominal temperatures were less than 36.5 degrees C was not significantly different in either microenvironment (P = 0.48). The mean number of minutes that heel temperatures were less than 35.2 degrees C and central-peripheral differences were greater than 2 degrees C was significantly less in the RINCE (P < 0.04 and P < 0.0001, respectively). Although the number and duration of caregiving disruptions (P = 0.71), number of procedures (P = 0.30), and the duration of interventions (P = 0.56) were not significantly different in either environment, the ambient air temperature (P < 0.001) and RH (P < 0.001) were significantly less variable in the RINCE during and after caregiving disruptions.

This study identified the extreme inter-dependence of the ELBW infant's temperature and the ambient environment. The RINCE significantly improved ambient temperature variability, RH variability, and the infant's peripheral and delta temperature (delta T) stability, particularly during and after caregiver disruptions.