Isolated Pharyngeal Swallow Exists during Normal Human Feeding

Abstract

Swallowing is one of the basic activities in humans. The pharynx functions as an airway and a food channel, and a pharyngeal swallow usually occurs after bolus transport from the oral cavity. However, direct fluid infusion through a catheter into the hypopharynx produces a pharyngeal swallow without the oral stage in experimental situations. The purpose of this study was to examine whether a pharyngeal swallow, which is not accompanied by bolus transport, can occur during normal human feeding. Fifty-three healthy volunteers (25-89 years) were recorded, via videofluoroscopic examination of swallowing, during 3 different swallowing trials: command swallow of 10 ml liquid barium, chew-swallow of corned beef, and chew-swallow of a mixture of corned beef and liquid barium. Subsequently each swallow was classified as being either a consecutive pharyngeal swallow (CPS), following transport, or an isolated pharyngeal swallow (IPS), without immediately prior transport. The location of the bolus at swallow initiation was also noted. Of 307 trials, 681 swallows were identified, which included 43 IPS and 638 CPS. IPS only occurred as the first swallow of a trial, but the frequency of IPS did not differ between 28 younger (< 60 years) and 25 older (≥ 60 years) people. Of the three food types, IPS occurred more frequently with the mixed food than with liquid. These results suggest that IPS may represent an airway protective mechanism. In conclusion, IPS occurs in normal swallowing during a daily eating situation. Swallowing is more complex than a simple reflex.

Perspective chapter: Role of the Oral Healthcare Team in the Management of Obstructive Sleep Apnea

“…Finally, the laryngopharynx receives the bolus and moves it into the esophagus to continue digestion. Alternatively, air moves from either the nasal cavity to the nasopharynx or from the oral cavity to the oropharynx and enters the laryngopharynx to the trachea to continue its path on the respiratory tract (Figure 1) [2,[5][6][7].…”

Differences between drinking and eating from the viewpoint of dysphagia rehabilitation

“…The swallowing reflex starts subsequently after the bolus reaches the pharynx in the four-stage sequence model (drinking), but does not occur immediately after the bolus is transported to the middle pharynx in the process model (eating). Moreover, an isolated pharyngeal swallow (IPS) which consisted of pharyngeal and esophageal stages (two stages) without prior intraoral transport by the tongue was found in both drinking and eating [6]. IPS is considered to be a protective swallow to prevent aspiration when the bolus reaches the pharynx unexpectedly.…”

Swallowing Disorders in Cervical Facial Tumors

“…Secondary peristalsis waves are generated by esophageal distension. These are initiated by the esophageal plexus and reflexes with afferent vague fibers to the medulla oblongata [10].…”