ACTUAL AND PRESCRIBED ENERGY AND PROTEIN INTAKES FOR VERY LOW BIRTH WEIGHT INFANTS: AN OBSERVATIONAL STUDY

Abstract

Objectives: To determine (1) whether prescribed and delivered energy and protein intakes during the first two weeks of life met Ziegler’s estimated requirements for Very Low Birth Weight (VLBW) infants, (2) if actual energy during the first week of life correlated with time to regain birth weight and reach full enteral nutrition (EN) defined as 100 kcal/kg/day, (3) if growth velocity from time to reach full EN to 36 weeks’ postmenstrual age (PMA) met Ziegler’s estimated fetal growth velocity (16 g/kg/day), and (4) growth outcomes at 36 weeks’ PMA. Study design: Observational study of feeding, early nutrition and early growth of 40 VLBW infants ≤ 30 weeks GA at birth in three newborn intensive care units NICUs. Results: During the first week of life, the percentages of prescribed and delivered energy (69% [65 kcal/kg/day]) and protein (89% [3.1 g/kg/day]) were significantly less than theoretical estimated requirements. Delivered intakes were 15% less than prescribed because of numerous interruptions in delivery and medical complications. During the second week, the delivered intakes of energy (90% [86 kcal/kg/day]) and protein (102% [3.5 g/kg/day]) improved although the differences between prescribed and delivered were consistently 15%. Energy but not protein intake during the first week was significantly related to time to reach full EN. Neither energy nor protein intake significantly correlated with days to return to birth weight. The average growth velocity from the age that full EN was attained to 36 weeks’ PMA (15 g/kg/day) was significantly less than the theoretical estimated fetal growth velocity (16 g/kg/day) (p<0.03). A difference of 1 g/kg/day represents a total deficit of 42 - 54 grams over the course of a month. At 36 weeks’ PMA, 53% of the VLBW infants had extrauterine growth restriction, or EUGR (<10th percentile) on the Fenton growth grid and 34% had EUGR on the Lubchenco growth grid. Conclusions: The delivered nutrient intakes were consistently less than 15% of the prescribed intakes. Growth velocity between the age when full EN was achieved and 36 weeks’ PMA was 6.7% lower than Ziegler’s estimate. One-third to one-half of the infants have EUGR at 36 weeks’ PMA.