Objective: Optimal thermal management of premature infants has long been recognized as a problematic but important aspect of their care. Very-low-birth-weight infants are especially vulnerable to hypothermia immediately following birth. The purpose of this study is to determine the effectiveness of polyurethane wrapping in the delivery room for infants less than 29 weeks gestation in reducing the incidence of hypothermia on admission to the neonatal intensive care unit (NICU). We hypothesized that on admission to the NICU, there would be a reduced incidence of hypothermia (rectal temperature of less than 97.6º F) and a higher mean admission temperature when the infant’s trunk and extremeties were placed in a polyurethane bag upon delivery and removed upon admission as compared to a usual care group. In addition, we examined whether selected indicators of morbidity: duration of hospitalization, duration of oxygen treatment, and incidence of major intracranial hemorrhage were significantly different for the two groups of infants and whether the incidence of mortality was lower in the intervention infants.
Design: This study is a prospective, randomized, controlled clinical trial to determine the effectiveness of polyurethane wrapping in the delivery room. Study population consists of very-low-birth-weight premature infants, less than 29 weeks gestation, inborn, and admitted to the NICU.
Population, Sample, Setting, Years: This clinical trial began in November 2000, after approval by the Institutional Review Board, at a level three NICU in the southeastern United States. With a postulated reduction in hypothermia of 30%, power analysis was used to determine that 100 infants would provide 95% power to detect this effect. Infants meeting inclusion criteria were randomized into the study after parental consent and just prior to delivery. Infants included were less than 29 weeks gestation, by dates or ultrasound, and born in the delivery room with the NICU team present. Infants were excluded if: 1) they had congenital anomalies with open lesions (e.g. gastroschisis, meningomyelocele), 2) resuscitation was not appropriate because of extreme prematurity, or 3) there was meconium staining of amniotic fluid. Unit demographics for 1998 provided information about sampling possibilities: 51% male, 62% African American, 35% Caucasian with 67% of those admissions being less than 29 weeks gestation.
Intervention and Outcome Variables: The dependent variable was the incidence of hypothermia (temperature less than 97.6° F) on admission, obtained by taking the infant’s rectal temperature with a digital thermometer. The independent variable was the intervention (placement of the infant in a polyurethane bag). The control group received delivery room resuscitation as usual. Delivery room temperature, NICU room temperature on admission, maternal temperature near delivery, and maternal illnesses and medications prior to delivery were recorded to assess for confounding variables.
Methods: Control and treatment cards were sealed in opaque envelopes, randomly compiled, and numbered sequentially. Randomization occurred in the delivery room just prior to the infant’s birth. Usual care infants were placed on a radiant warmer and dried, wet linens were removed, and resuscitation procedures continued per Neonatal Resuscitation Program (NRP) recommendations. A sterile polyurethane bag (DeRoyal REF30-5510, sterile isolation transport bag 19” x 18”) was placed on the radiant warmer bed prior to delivery for the intervention infants. Upon delivery, the infant was placed inside the bag (while still wet with amniotic fluid) and the bag drawn in around the infant’s skin up to his/her neck, with the head protruding from the bag. The head and face were dried, after which usual NRP procedures were followed. After initial stabilization, patients in both groups were covered with warm blankets and transferred to the NICU on radiant warmers, with the power off. On arrival in the NICU, the infant was transferred to a pre-warmed admission radiant warmer. The polyurethane bag was then removed from the wrapped infants. Rectal temperatures were taken immediately on patients in both groups with a digital thermometer. The infant completed the study at discharge home, transfer to another facility or death.
Findings: This study is ongoing with 79 infants currently randomized.
This research is partially supported by NINR: T32 NR07091 Interventions to Prevent and Manage Chronic Illness.
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