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Tolerance of Enteral Feedings
Prediction of Early Tolerance to Enteral Feeding in Preterm Infants by Measurement of Superior Mesenteric Artery Blood Flow Velocity. Fang S, Kempley ST, and Gamsu HR. Arch Dis Child Fetal Neonatal Ed 2001; 85: F42-F45.
This study evaluated the use of serial Doppler measurements of superior mesenteric artery (SMA) blood flow velocity to predict early tolerance to enteral feeding in preterm infants. When clinicians decided to start enteral feeds, Doppler ultrasound blood velocity in the SMA was determined before and after a test feed of 0.5 ml of milk. The number of days taken for infants to tolerate full enteral feeding (150 ml/kg/day) was recorded.
Results: Fourteen infants (group 1) achieved full enteral feeding within 7 days, and thirty infants (group 2) took 8 – 30 days. There was no difference between groups in the preprandial time-averaged mean velocity (TAMV) at a median age of 3 (2-30) days. In group 1, there was a significant increase in TAMV (p < 0.01) above the preprandial level at 45 and 60 minutes, but this did not occur in group 2. An increase in TAMV by more than 17% at 60 minutes had a sensitivity of 100% and a specificity of 70% for the prediction of early tolerance of enteral feedings.
Comment: It’s nice to see that an increase in SMA blood flow after a feeding can predict tolerance of enteral feedings, however I doubt whether this test will soon become commonplace in our NICUs. The test is impractical for most NICUs because it requires serial ultrasounds with Doppler SMA flow velocity measurements be done before and for 60 minutes after a test feeding. Another important question that remains unanswered is how to manage babies who fail this test. Should these babies be maintained on TPN until SMA blood flow response improves, or would minimal enteral (trophic) feedings speed gut maturation and feeding tolerance?