NICU Micropreemies: How do they fare?

DR. BLACKMAN is professor of pediatrics and head, division of developmental pediatrics, Kluge Children's Rehabilitation Center, Children's Medical Center, University of Virginia, Charlottesville.

Ethan was born at 25 weeks' gestation weighing 730 g. Apgar scores were 2, 5, and 6 at 1, 5, and 10 minutes, respectively. Four doses of surfactant were administered. He remained on a ventilator for three weeks and continuous positive airway pressure for an additional seven weeks.

Complications included blood culture–positive bacterial and fungal sepsis and a bilateral germinal matrix hemorrhage (Grade I) with blood in the right lateral ventricle (Grade II). He received total parenteral nutrition for three weeks, followed by enteral feedings with 27 kcal/oz formula while fluid restricted for chronic lung disease. He also underwent laser treatment for retinopathy of prematurity with good results.

Ethan's last follow-up was at chronological age 2 years, 8 months. At that time, he was generally healthy, wore glasses for strabismus correction, and received daily inhaled steroid treatments and nebulized albuterol as needed. His height, weight, and head circumference were below the third percentile, even for adjusted age. He had been evaluated for possible growth hormone treatment. His neurologic examination was normal, and his developmental skills were appropriate for his age.

Pediatricians who care for babies like Ethan are faced with some pressing questions:

The following review addresses these questions.

*The REVOLUTION in VIABILITY

When I was a medical student and pediatric resident in the mid-1970s, I witnessed the emergence of modern neonatal intensive care that followed a significant change in respirator technology. In 1974, premature infants were often ventilated with bulky Emerson or Bennett MA-1 machines, designed for adult lungs. Delivering a tiny volume of air to a 1,200-g premature infant and overcoming the huge dead space of long, large-bore tubing with these devices was a challenge we often could not meet. A scant two years later, however, the Baby Bird infant ventilator revolutionized treatment of respiratory distress syndrome and dramatically improved survival rates for premature babies.

The 1980s and 1990s brought additional significant advances, including the use of surfactant and routine antenatal steroids, that pushed the limits of viability to 24 to 25 weeks' gestation. Recent reports of the short- and long-term outcomes of these tiny infants provide the basis of judging the efficacy of neonatal intensive care for the smallest newborns, giving guidance to parents in the early decision-making period and anticipating the financial, educational, social, and other resources they might require.

*Defining TERMS

As ever-smaller premature infants have survived, the terminology we use to describe them has evolved. Now, "low birth weight" (LBW) refers to newborns weighing less than 2,500 g; "very low birth weight," (VLBW) to less than 1,500 g; and "extremely low birth weight," to less than 1,000 g. The term "micropreemie" was coined for infants less than 800 g.

Birth weights must be correlated with gestational age to determine whether the infant is appropriately sized. However, much of the neonatal follow-up literature is based on birth weight or gestational age alone, and does not separate out infants who are small for gestational age because of intrauterine growth retardation, which confers independent risk for future growth and developmental problems. This review focuses on outcomes for the micropreemie infant.