Apnea, bradycardia and desaturation in preterm infants before and after feeding

The existence of a causal relationship between gastroesophageal reflux (GER) and apnea at prematurity is currently a topic of extensive debate and investigation. Early studies suggested that this might exist, but subsequent investigations led to conflicting results. Nevertheless, premature infants frequently undergo diagnostic evaluation for GER, and anti-reflux medications are frequently prescribed for this condition. A common clinical impression is that GER may be more severe and apnea may be more significant in some infants after feeding. However, although periods of prolonged airway closure have been shown during active bottle feeding, and measurable changes in pulmonary mechanics may occur during or after feeds, it remains unclear whether these physiological changes translate into increased cardiorespiratory instability after feeding.
A study has recently been conducted in the US to empirically assess the putative increase in cardiorespiratory events in preterm infants after feeds by comparing GER, apnea, bradycardia and desaturation frequencies before and after feeding.
This was a retrospective review of premature infants with a gestational age of 23 to 37 weeks at birth and a post-conceptional age of 34 to 48 weeks at the Rainbow Babies and Children's Hospital (Cleveland), who were referred for multichannel intraluminal impedance (MII), pH probe and 12-h apnea evaluation. Cardiorespiratory and GER event rates during pre- and post-feeding intervals were compared.
In total, 36 infants were evaluated. More GER events occurred after a feed than before (P=0.012). After feeds, reflux was less acidic and higher in the esophagus (P<0.05). In contrast, the rates of apnea, bradycardia and desaturations were not altered by infant feeding. Apnea of >5 s occurred at a median frequency of 0 (range 0 to 3) events per hour before a feed and 0 (0 to 2) events per hour after a feed (P=0.61).
Overall, these findings argue against the common clinical impression that cardiorespiratory events are more frequent in preterm infants after feeding. In fact, although an increase in the rate and height of GER was observed after feeds, a corresponding increase was not found in apnea, bradycardia or desaturations. The discrepancy between these findings and a clinical impression of increased cardiorespiratory events after feeding may suggest that clinicians should not interpret post-feeding events differently from those occurring at other times.
As there is no difference in the incidence of cardiorespiratory events before and after feeding, these findings suggest that routine treatment of post-feeding cardiorespiratory events with anti-reflux therapies may not be warranted.

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