Protein intake, growth and lung function of infants with chronic lung disease
Authors: Cillié E. , Jeanes Y. M. , Meek J. 
Published: May 2009

Background:  The increased survival rate of extremely preterm infants has not improved the incidence or outcome of infants diagnosed with chronic lung disease (CLD) (Riley, 2008). The relationship between optimal nutrition (particularly protein intake) and chronic lung disease has not been established. The aim of this study was to investigate the association between protein intake, growth and lung function in infants with CLD.

Methods:  A CLD database, maintained for the past 10 years, was used to select participants that had reached 1 year of corrected age. Infants who were born during 2001–2006 with a birth weight of <1500 g, and who subsequently had a diagnosis of CLD, were included. Infants with evidence of intra‐uterine growth restriction and abnormal cerebral pathology were excluded. Demographic, mean weight gain, protein intake and respiratory support data were collected retrospectively from the medical notes. Growth parameters and need for oxygen and inhalers up to 1 year of corrected age were collected from the CLD follow‐up database. SPSS, version 15 (SPSS Inc., Chicago, IL, USA) were used for Pearson's or Spearmans correlation analysis and analysis of variance or the Wilcoxon test, as appropriate.

Results:  Sixty infants were studied: 25 females and 35 males. The median (range) post‐menstrual age at birth was 26 (22–31) weeks. The most common feed was breast milk; fortified breast milk was used for 37% of the total days studied. The mean (SD) protein intake was 2.28 (0.33) g kg−1 day−1 and the mean (SD) weight gain was 11.67 (1.77) g kg−1 day−1. There was a positive correlation between protein intake and weight gain (r = 0.32, P = 0.013), which was stronger in females (r = 0.51, P = 0.009). Protein intake was significantly associated with head circumference growth in females only (r = 0.47, P = 0.038). Protein intake was inversely related to the number of days spent mechanically ventilated (r = −0.32, P = 0.015). There was no relationship between protein intake and growth at 1 year corrected age, time spent on continuous positive airway pressure, age weaned off oxygen, or the use of inhalers. There was an inverse correlation between total weeks of oxygen dependence and head circumference at 1 year (r = −0.35, P = 0.022).

Discussion:  The mean protein intake was <3 g kg−1 day−1, which is the minimum requirement for preterm infants (Tsang et al., 2005). This was associated with a sub‐optimal weight gain in our participants of <15 g kg−1 day−1 (Steward & Pridham, 2002). The study demonstrates the known association between low protein intake and poor growth with ventilator dependence (Loui et al., 2008).

Conclusions:  Low birth weight and low gestational age infants at risk of CLD should receive special attention to optimise their protein intake because sub‐optimal protein intake potentially leads to poor growth when on a neonatal intensive care unit.

References Loui, A., Tsalikaki, E., Maier, K., Walch, E., Kamarianakis, Y. & Obladen, M. (2008) Growth in high risk infants <1500 g birth weight during the first 5 weeks. Early Hum. Dev. 84, 645–650, Doi: 10.1016/j.earlhumdev.2008.04.005.

Riley, K., Roth, S., Sellwood, M. & Wyatt, J.S. (2008) Survival and neurodevelopmental morbidity at 1 year of age following extremely preterm delivery over a 20‐year period: a single centre cohort study. Acta Paediatr.97, 159–165.

Steward, D.K. & Pridham, K.F. (2002) Growth patterns of extremely low‐birth‐weight hospitalised preterm infants. JOGN Nurs31, 57–65.

Tsang, R.C., Uauy, R., Koletzko, B. & Zlotkin, S.H., eds. (2005) Nutrition of the Preterm Infant: Scientific Basis and Practical Guidelines. Cincinnati: Digital Educational Publishing.