Presented at the Neonatal Society 2009 Spring Meeting.
Vasu V1, Durighel G2, Srinivasan L2, Uthaya S1, Bell JD2, Rutherford MR2, Modi N1
1 Section of Neonatal Medicine, Division of Medicine, Imperial College London, Chelsea & Westminster campus, 369 Fulham Road, London, SW10 9NH, UK
2 Division of Clinical Sciences, Imperial College London and MRC Clinical Sciences Centre Hammersmith Hospital, Du Cane Road, London, W12 0HS, UK
Background: Preterm infants have a high incidence of neurodevelopmental problems during childhood. Evidence from animal models indicates that sub-optimal early nutrition may adversely influence neurodevelopment. There are little published data exploring the impact of early nutritional intake and brain growth in preterm babies.
Aim: We are conducting a prospective observational study investigating the influence of nutrition upon magnetic resonance indices of somatic and brain development in preterm babies. Here we describe relationships between preterm nutrition and brain volume.
Methods: Research ethics permission for this study was granted by St Mary’s Hospital NHS Trust and written parental consent was obtained. We studied 19 preterm infants (GA <33 weeks) and 19 term infants using a 3 Tesla Phillips Achieva magnetic resonance scanner. T2 weighted images were acquired with the following parameters: FOV 220, slice thickness 3mm, slice gap -1.5mm, echo time 160ms, matrix 224. Intracranial volume was determined by the creation of intracranial masks using FSL (1). CSF volume was determined using the manual threshold function of ImageJ (2). Brain volume was calculated by the subtraction of CSF volume from intracranial volume. Preterm infant brain volumes were expressed as Z scores in relation to term infant brain volumes. Neonatal nutritional information was collected from birth to 34+6 weeks post menstrual age using a specifically designed neonatal nutritional data capture system (NutcrackerTM). Macronutrient nutritional data are presented as the cumulative difference between the mean of actual daily intake (MADI) and the recommended daily intake (RDI) (3) in g/kg/day. Illness severity was assessed as % ICU days in relation to total neonatal stay. Data were analysed by multivariate regression using SPSS version 16.
Results: The mean (sd) for gestational age and % ICU days were 29.0 (2.9) weeks and 15 (17). Preterm infants underwent imaging at 40.4 (3.2) weeks. Mean (sd) cumulative differences between MADI and RDI (in g/kg/day) were 1.5 (1.8) for carbohydrate, 2.6 (0.6) for fat, -0.4 (0.5) and energy 16.3 (12.5). Z scores for preterm at term and term brain volumes did not differ significantly (p=0.32). After adjustment for major confounders (post menstrual age at scan and illness severity) no relationships were found between protein intake (p= 0.94), fat intake (p=0.71), carbohydrate intake (p=0.54), and derived energy intake (p=0.85).
Conclusion: Preterm infants at term corrected age have similar brain volumes to healthy term born infants despite a cumulative deficit of protein and contrary to expectation macronutrient intake in this cohort of preterm infants was not a significant determinant of brain volume at term.
References
1. Smith SM. Human Brain Mapping 2002 17(3):143-155
2. Rasband, W.S., ImageJ, U. S. National Institutes of Health, Bethesda, Maryland, USA, http://rsb.info.nih.gov/ij/, 1997-2008.
3. Tsang RC. Nutrition of the Preterm Infant (2nd Edition). 2005