Prediction of early tolerance to enteral feeding in preterm infants by measurement of superior mesenteric artery blood flow velocity.(Statistical Data Included)

Abstract

Aims--To evaluate whether serial Doppler measurements of superior mesenteric artery (SMA) blood flow velocity after the first enteral feed could predict early tolerance to enteral feeding in preterm infants.

Methods--When clinicians decided to start enteral feeds, Doppler ultrasound blood flow velocity in the SMA was determined before and after a test feed of 0.5 ml 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 seven days. Thirty infants (group 2) took 8-30 days. There was no difference in the preprandial time averaged mean velocity (TAMY) between the groups at a median age of 3 (2-30) days. In group 1, there was a significant increase in TAMV (p[less than]0.0l), 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 has a sensitivity of 100% and a specificity of 70% for the prediction of early tolerance to enteral feeds.

Conclusions--There is a significant correlation between an increase in mean SMA blood flow velocity and early tolerance of enteral feeding. Doppler measurements of SMA blood flow velocity may be useful for deciding when to feed high risk preterm infants.

Keywords: superior mesenteric artery; blood flow velocity; enteral feeds; Doppler ultrasound

Intestinal blood flow is regulated by intrinsic and extrinsic mechanisms as well as circulating vasoactive substances. Changes in superior mesenteric artery (SMA) blood flow velocity have been shown to occur in response to feeds. [1-5] Feed composition has been shown to affect this response but the precise mechanisms controlling the postprandial increase are poorly defined.

Blood flow disturbances, reperfusion injury, infection, and early enteral feeding have been hypothesised to be associated with necrotising enterocolitis. [7] In severely growth restricted infants, absent end diastolic flow in the fetal descending aorta and umbilical artery in antenatal Doppler studies has been shown to be associated with perinatal death, necrotising enterocolitis, and haemorrhage. [8,9] Although such findings may indicate that caution should be exercised when introducing early enteral feeding, such feeding is important for the functional maturation of the gut in preterm infants. [10] For these reasons, the question of whether or not to feed a sick preterm infant remains a dilemma.

The aims of the study were to correlate changes in SMA blood flow velocity in response to a test feed with tolerance to enteral feeds and to establish whether serial Doppler measurements of SMA blood flow velocity could predict early tolerance to enteral feeding in preterm infants.

Methods

This was a prospective blinded study, carried our at King's College …