Persistent feeding difficulties among infants with fetal opioid exposure: mechanisms and clinical reasoning.

Aims: Infants with fetal exposure to opioids have varying pattern of feeding difficulties mainly manifesting as difficulties with aerodigestive adaptation and disruptive feeding behavior. The reasons are unclear; in a pilot study, we determined basal and adaptive pharyngo-esophageal motility in a group of infants with fetal exposure to opioids and persistent feeding difficulties impeding their discharge.

Methods

Six infants with fetal opioid exposure compared to 12 controls who underwent basal and adaptive pharyngo-esophageal manometry to characterize the basis for their symptoms. Spontaneous swallows (N = 180) and pharyngeal stimuli (N = 113)-induced swallowing responses were analyzed.

Results

Resting upper esophageal sphincter (UES) pressure was similar in both the groups, but resting lower esophageal sphincter (LES) pressure was significantly high and it relaxed slowly and inadequately in opioid-exposed infants (p < .05). Upon pharyngeal provocation, opioid-exposed infants had higher LES nadir pressure, increased duration of esophageal body contraction at proximal-, mid-, and distal-esophagus, as well as greater area under the curve with distal esophageal waveforms, compared to controls (all p < .05).

Conclusions

These pilot observations are suggestive of up-regulation of central vagal effects with heightened cholinergic excitatory responses and inadequate relaxation responses at the foregut, and may form the basis for persistent feeding difficulties in opioid-exposed infants. Abnormality with both sensory and motor aspects of vagal reflexes may be contributory.