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The effect of oral and intravenous feeding on the plasma amino acid levels of premature infants

University of British Columbia

The object of this study was to assess the adequacy of the protein solution given to premature infants receiving intravenous nutrition. Plasma aminograms from premature infants fed orally were determined and compared with aminograms from premature infants maintained on intravenous nutrition. The kilocalorie:nitrogen ratio, coupled with growth parameters, such as weight gain, body length, and head circumference were further used to evaluate nutritional adequacy. Standardized plasma aminograms were obtained using capillary blood samples from a control group of 16 infants (gestational age 31-36 weeks, mean 33½ weeks), fed SMA₂₀ (a commercial infant formula). Blood samples were taken between the 7th-l6th day after birth, 1-2 hours after the first feed of the day. The study group was comprised of 11 infants between 24-30 weeks gestation (mean 28 weeks), fed intravenously, using a synthetic crystalline L-amino acid mixture (Vamin), running continuously. Blood samples from the study group were also taken between the 7th-16th day of life at the same time of the morning as the control group. Results showed that plasma samples from the study group had lower levels of threonine, asparagine, glutamic acid, lysine, citrulline, alanine, cystine, methionine, leucine, ornithine, and arginine than the control group. Plasma phenylalanine levels were 2-3 times higher in the study group than in the control group. Plasma urea levels were lower in the intravenously fed group than in the orally fed group. It is likely that both the low plasma urea and low plasma amino acid levels indicate efficient use of the intravenously infused amino acids by infants in the study group. It is most probable that the infused amino acids are being used for protein synthesis rather than for energy purposes. Efficient use of infused amino acids is further suggested by the actual growth in length, head circumference and weight gain noted in the intravenously fed infants. Further studies are needed to explain the higher plasma levels of phenylalanine seen in infants intravenously infused with Vamin. Relatively low plasma levels of methionine and tyrosine in the intravenously fed infants seem to indicate that an increase in total protein intake may be beneficial. The total amount of phenylalanine in Vamin, in addition to relationship to the other amino acids also needs further study.

Text

2010-02-24

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http://hdl.handle.net/2429/20830

Human Nutrition

University of British Columbia

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