Which is Safer –Drip Feeds or Bolus Feeds in Healthy Preterm Infants?

A recent provocative study (J Pediatr 2014; 165: 1255-7) takes a look at the frequency of cardiorespiratory events in healthy neonates <33 weeks gestation who needed supplemental enteral tube feeds.

It is generally accepted that continuous or “drip” feedings are less likely to provoke reflux events (and reflux-induced cardiorespiratory events) by limiting the amount of formula in the stomach at any time point.  If there is less formula, presumably there would be less stomach distention and a lower likelihood of reflux.  In addition, a continuous amount of formula would serve to buffer stomach acid.

Despite the sound theoretical underpinnings, is this really true?  In this study, the authors detected fewer cardiorespiratory events with polysomnographic monitoring in healthy premature neonates who were fed with bolus feedings rather than with drip feedings.

Study design: Each of 33 infants served as its own control.  During a 6-hour monitoring period, noninvasive polysomnographic recordings were performed.  Each infant was fed twice via an orogastric tube.  The first meal was given as a 10-minute bolus (by gravity) and the second was delivered over 3 hours. It is noted that the tube was removed after the bolus feeding (this is not routinely done in clinical practice).

Demographics: Median gestational age was 31 weeks and median postnatal age was 16 days.  Fortified human milk was given in 12, premature formula in 7, and 14 had mixed feeding.

Results (Table 2): “continuous feeding was associated with a greater number of prolonged apneas and apnea-related hypoxic episodes.”

  • Median Apnea Frequency: 4 in continuous versus 2 in bolus group (no obstructive apneas were noted)
  • Median hypoxic episodes: 3 in continuous versus 2 in bolus group.

The authors speculate that leaving the tube in place for continuous feeds could increase GER-related apnea or trigger ‘protective upper airway reflexes in response to the irritating stimulus.’

Bottomline: The assumption that continuous feedings will reduce cardiorespiratory events is not supported by this study.  The findings warrant cautious interpretation; the small sample size and specific ages of the premature infants are significant limitations.   In addition, leaving an enteral tube in place after a bolus feeding would be a better design as this is a routine practice.

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