NICU

Neonatal Intensive Care Unit (NICU)

Neonatal Intensive Care Unit (NICU)

Introduction

Circadian variation in neonatal deaths has been previously described through the use of birth registration data. In a study of more than 2 million births in Sweden between 1973 and 1995, Luo and Karlberg3 reported a 30% increase in early neonatal mortality rates among infants born during the night and a 70% increase in early neonatal mortality rates related to asphyxia in preterm infants born during the night compared with rates for preterm infants born during the day and that this difference had not changed between 1973 and 1995.

Tyson et al4 reported circadian variation in the quality of care and mortality rates among a small cohort of infants born at <1500 g birth weight and admitted to the neonatal intensive care unit (NICU) from 1973 to 1974, but the results were not risk-adjusted. Since then, regionalization of perinatal care and advances in perinatal and neonatal care have significantly reduced neonatal mortality rates and especially benefited preterm infants. However, there is little in the literature about whether risk-adjusted circadian variation exists in NICU deaths. Our aim was to compare the risk-adjusted early neonatal mortality rates (proportion of infants dying within 7 days of NICU admission) of infants admitted to the NICU during the daytime with those of infants admitted at night in a large cohort of preterm infants admitted to 17 NICUs in the Canadian Neonatal Network during 1996 and 1997.

We chose to examine infants by time of admission rather than time of death because the initial treatment of a sick infant after admission is often very important and because time of death usually reflects cumulative care over many days and nights. We hypothesized that preterm infants admitted to the NICU at night had a higher mortality rate than infants admitted during the daytime. The member units of the Canadian Neonatal Network account for 75% of all tertiary-level NICU beds in Canada and serve a total population of approximately 22 million people.9 In 1996, at the time of our study, Canada had a total population of nearly 30 million people, and the country had approximately 357,000 births in the fiscal year 1996/1997

Methods

Canada has a highly regionalized system of perinatal and neonatal care. [9.] and [12.] Tertiary-level NICUs serve distinct geographic regions and coordinate care with a network of primary- and secondary-level facilities. The 17 hospitals participating in this study represented all geographic regions of Canada (Table I, found online at www.us.elsevierhealth.com/jpeds). There were 662 NICU beds in the 17 hospitals, including 349 intensive care neonatal beds (range, 2-45 per hospital) and 313 intermediate-level and continuing care neonatal beds (range, 0-45 per hospital).

Medical staff at the hospitals included 96 full-time equivalent neonatologists, 76 full-time equivalent physician house staff (including clinical assistants, neonatal fellows, and pediatric residents), and 31 full-time equivalent neonatal nurse practitioners (NNPs) or clinical nurse specialists. Two NICUs did not employ physician house staff, and 6 NICUs used NNPs or clinical nurse specialists as house ...