Mechanisms of Improving Feeding Function With Capsaicin Following Local Anesthesia in Infant Pigs

Sensory deficits are detrimental to feeding performance, whereas sensory stimulation can improve feeding. Capsaicin is one sensory intervention that improves swallowing in adult humans and alters feeding in an infant animal model. This study assessed the role of the inferior alveolar nerve (IAN) in infant feeding, and determined whether capsaicin reversed or compensated for deficits associated with IAN anesthesia.

Data were collected using simultaneous videofluoroscopy and electromyography (EMG) in an infant pig model (n = 360 swallows, 6 pigs). Variables of interest included swallow frequency, sucks per swallow, milk acquired per suck, bolus size, degree of airway compromise, excursions of the tongue and thyroid cartilage, and activity of the digastric, genioglossus, and thyrohyoid. The repeated measures data were analyzed with a three- or four-level linear mixed model and (doubly) nested subsamples.

IAN anesthetization decreased feeding efficiency as evidenced by decreased swallow frequency (p = 0.013), increased sucks per swallow (p = 0.016), decreased milk per suck (p = 0.008), and decreased bolus sizes (p = 0.036). Airway protection improved (p = 0.045) and tongue excursion was altered (p = 0.016), while digastric and genioglossus EMG were unchanged. Capsaicin application restored some, but not all variables, to baseline values, while either partially restoring or not affecting others.

The reduced efficiency following IAN anesthetization decreased instances of airway compromise, highlighting the tradeoff between feeding efficiency and airway protection. Subsequent capsaicin administration affected feeding physiology yet did not simply reverse deficits associated with impaired sensation. As such, capsaicin may be useful in treating some etiologies of dysphagia, but not others.

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