Objective: We hypothesized that analysis of heart rate variability (HRV) in VLBW neonates on the first day of life (DOL #1) could prospectively identify those infants who would subsequently develop severe intraventricular hemorrhage (IVH). Design: We prospectively studied all newborns born in our nursery weighing less than 1500 gr. On the first day of life, between 12 and 24 hours of age, a single 256 second heart rate trace was recorded and a single cranial ultrasound was simultaneously obtained for each infant. A follow-up heart rate recording and cranial ultrasound were obtained at one week of age on each neonate. Exclusion criteria included dopamine infusion > 5 mcg/kg/minute and complex congenital heart disease. No recordings were obtained from neonates exposed to narcotics within the preceding four hour period. Methods: Each heart rate recording consisted of a single continuous 256 second digitally recorded trace. Power spectra of HRV for both low frequency ranges (0.05 - 0.20 Hz) and high frequency ranges (0.20 - 1.0 Hz) were calculated by Fast Fourier Transform. Only neonates who were intubated at the time of the DOL#1 heart rate recording are discussed here. Preliminary Remits; On DOL #1, neonates who were subsequently found at one week of life to have 'severe' IVH (grades 3 and 4, n=4) were found to have less low-frequency HRV than those infants with grades none, one, or two IVH (one tailed t-test, p= 0.033). These two groups were similar with respect to birthweight and FiO2 requirement at the time of study. This result may be generalizable to high frequency power as well (one tailed t-test, p=.07) as the size of our study grows. Three of the four infants with severe IVH at one week of age had no or only low-grade IVH on DOL #1. This suggests that analysis of HRV on DOL #1 may be a more sensitive indicator of subsequent development of severe IVH than a simultaneously performed cranial ultrasound. HRV analysis may be a functional index of autonomic tone and a reflection of CNS integrity with potential to predict poor outcomes in VLBW neonates.
|Original language||English (US)|
|Journal||Journal of Investigative Medicine|
|State||Published - Jan 1 1996|
ASJC Scopus subject areas
- Biochemistry, Genetics and Molecular Biology(all)