Fat emulsion tolerance in very low birth weight neonates: effect on diffusion of oxygen in the lungs and on blood pH.

Forty-one very low birth weight neonates (820 to 1,510 g and 27 to 34 weeks of gestation) requiring total parenteral nutrition were randomly assigned to one of three regimens of administration of fat emulsion for a period of eight days. Groups I and II received the emulsion at a constant rate for, respectively, 24 and 16 hours, beginning with a daily dosage of 1 g/kg and increasing daily by 1 g/kg to a maximum of 4 g/kg. Group III received the emulsion at a constant rate or 4 g/kg for 24 hours. Blood pH and alveolar-arteriolar gradient of oxygen diffusion in the lungs were measured at regular intervals. The various regimens and rates of fat infusion appeared to have no deleterious effect on blood pH and alveolar-arteriolar oxygen diffusion gradient. Infusion rates as used in the study for appropriate for gestational age very low birth weight neonates appear to be safe, although caution is always warranted when dealing with tiny neonates whose pulmonary reserve is minimal. In view of data from other studies, it is suggested to infuse fat at a constant rate for 24 hours to avoid overloading the clearance mechanisms of fat particles from plasma.