Pengyan Xie

Coordination of Deglutitive Glottal Function and Pharyngeal Bolus Transit During Normal Eating

BACKGROUND & AIMS Deglutitive glottal function during the preparatory phase of swallowing and its coordination with bolus transit during normal eating are important for airway protection. The aim of this study was to examine this coordination during consumption of a normal meal. METHODS Fifteen healthy volunteers were studied using a videoendoscopic and videofluoroscopic technique. RESULTS A total of 207 liquid and 470 solid bolus swallows were analyzed. In 60% of liquid and 76% of solid food swallows, the bolus was seen in the pharynx before a swallow was initiated. Entry of boluses into the pharynx was associated with brief partial adduction of the vocal cords. Solid food entered and traversed the pharynx at the midline, whereas liquid bolus was split around the larynx and rejoined in the hypopharynx. Swallowing was initiated significantly earlier when bolus made contact with the upper third of the epiglottis compared with vallecula or pyriform sinuses. CONCLUSIONS In more than half of the instances, during normal eating, food enters the pharynx during the preparatory phase before a swallow is initiated, the path of pharyngeal transit of solid bolus is different from that of liquid bolus, and the epiglottal edge appears to be the most sensitive trigger zone for swallowing.

Pharyngoglottal Closure Reflex: Characterization in Healthy Young, Elderly and Dysphagic Patients with Predeglutitive Aspiration

Background: Mechanism(s) of aspiration, a common complication of oropharyngeal dysphagia, is not completely elucidated. Since the pharyngoglottal closure reflex induces vocal cord adduction in healthy young humans, it may help prevent aspiration during premature spill of oral content. Objective: The objective of this study was to characterize this reflex in normal young and elderly humans and dysphagic patients with predeglutitive aspiration; a potential group for developing abnormalities of this reflex. Methods: We used a concurrent video endoscopic and manometric technique for recording of the vocal cords’ response to pharyngeal water stimulation. We first studied 9 young (26 ± 2 years) and 9 elderly (77 ± 14 years) healthy volunteers to characterize and determine the effect of aging on the pharyngoglottal closure reflex. Subsequently, we studied 8 patients (65 ± 16 years) with predeglutitive aspiration and 7 age-matched controls to characterize this reflex among patients with compromised airway safety during swallowing. Results: The threshold volume of water for triggering both glottal closure and reflexive pharyngeal swallow in the elderly volunteers for rapid pulse injection was significantly larger than that for the young (p < 0.05). Neither glottal closure reflex nor pharyngeal reflexive swallow could be induced in any of the dysphagic patients with volumes of injected water as large as 1 ml. In contrast, in all age-matched controls, both the pharyngoglottal reflex and reflexive pharyngeal swallow were stimulated with threshold volumes of 0.3 ± 0.07 and 0.6 ± 0.05 ml, respectively. Conclusions: Pharyngeal stimulation by water induces vocal cord adduction in humans; the pharyngoglottal closure reflex. Although preserved, a significantly larger volume of water is required to stimulate this reflex by rapid pulse injection in the elderly, suggesting some deterioration in this age group. The pharyngoglottal closure reflex induced by rapid pulse injection is absent in dysphagic patients with predeglutitive aspiration, suggesting its contribution to airway protection against aspiration.

Characterization of the pharyngo-UES contractile reflex in humans

Preliminary human studies suggest the presence of an upper esophageal sphincter (UES) contractile reflex triggered by pharyngeal water stimulation. The purposes of this study were to further characterize this reflex and determine the threshold volume for its activation. We studied 10 healthy young volunteers by manometric technique before and after topical pharyngeal anesthesia. UES pressure responses to various volumes and temperatures of water injected into the pharynx were elucidated. At a threshold volume, rapid-pulse and slow continuous pharyngeal water injection resulted in significant augmentation of UES pressure in all volunteers. Threshold volume for inducing UES contraction averaged 0.1 +/- 0.01 ml for rapid-pulse injection and was significantly smaller than that for slow continuous injection (1.0 +/- 0.2 ml). UES pressure increase duration averaged 16 +/- 4 s. Augmentation of UES resting tone by injection of water with three different temperatures was similar. This augmentation was abolished after topical anesthesia. Conclusions were that stimulation of the human pharynx by injection of minute amounts of water results in a significant increase in resting UES pressure: the pharyngo-UES contractile reflex. The magnitude of pressure increase due to activation of this reflex is not volume or temperature dependent. Loss of pharyngeal sensation abolishes this reflex.Preliminary human studies suggest the presence of an upper esophageal sphincter (UES) contractile reflex triggered by pharyngeal water stimulation. The purposes of this study were to further characterize this reflex and determine the threshold volume for its activation. We studied 10 healthy young volunteers by manometric technique before and after topical pharyngeal anesthesia. UES pressure responses to various volumes and temperatures of water injected into the pharynx were elucidated. At a threshold volume, rapid-pulse and slow continuous pharyngeal water injection resulted in significant augmentation of UES pressure in all volunteers. Threshold volume for inducing UES contraction averaged 0.1 ± 0.01 ml for rapid-pulse injection and was significantly smaller than that for slow continuous injection (1.0 ± 0.2 ml). UES pressure increase duration averaged 16 ± 4 s. Augmentation of UES resting tone by injection of water with three different temperatures was similar. This augmentation was abolished after topical anesthesia. Conclusions were that stimulation of the human pharynx by injection of minute amounts of water results in a significant increase in resting UES pressure: the pharyngo-UES contractile reflex. The magnitude of pressure increase due to activation of this reflex is not volume or temperature dependent. Loss of pharyngeal sensation abolishes this reflex.

Deterioration of the Pharyngo‐UES Contractile Reflex in the Elderly

Objectives/Hypothesis Deterioration of aerodigestive tract reflexes such as the esophagoglottal and pharyngoglottal closure reflexes and pharyngeal swallow has been documented in the elderly. However, the effect of aging on the contractile response of the upper esophageal sphincter (UES) to pharyngeal water stimulation has not been studied. The aim of this study was to characterize the pharyngo‐UES reflex in the healthy elderly.

Pharyngoglottal closure reflex: identification and characterization in a feline model

Earlier studies in humans have shown that pharyngeal stimulation by water at a threshold volume induces a brief vocal cord adduction, i. e., pharyngoglottal closure reflex. The present study was undertaken to 1) develop a suitable animal model for physiological studies of this reflex and 2) delineate its neural pathway and effector organs. Studies were done in cats by concurrent videoendoscopy and manometry followed by electromyographic studies. At a threshold volume (0.3 +/- 0.06 ml), injection of water into the pharynx resulted in a brief closure of the vocal folds, closing the introitus to the trachea. Duration of this closure averaged 1.1 +/- 0.1 s. Bilateral transection of the glossopharyngeal nerve completely abolished this reflex but not swallows induced by pharyngeal water stimulation. The pharyngoglottal closure reflex is present in the cats. The glossopharyngeal nerve is the afferent pathway of this reflex, and the interarytenoid and lateral cricoarytenoid muscles are among its target organs.Earlier studies in humans have shown that pharyngeal stimulation by water at a threshold volume induces a brief vocal cord adduction, i.e., pharyngoglottal closure reflex. The present study was undertaken to 1) develop a suitable animal model for physiological studies of this reflex and 2) delineate its neural pathway and effector organs. Studies were done in cats by concurrent videoendoscopy and manometry followed by electromyographic studies. At a threshold volume (0.3 ± 0.06 ml), injection of water into the pharynx resulted in a brief closure of the vocal folds, closing the introitus to the trachea. Duration of this closure averaged 1.1 ± 0.1 s. Bilateral transection of the glossopharyngeal nerve completely abolished this reflex but not swallows induced by pharyngeal water stimulation. The pharyngoglottal closure reflex is present in the cats. The glossopharyngeal nerve is the afferent pathway of this reflex, and the interarytenoid and lateral cricoarytenoid muscles are among its target organs.

Effect of ageing on the upper and lower oesophageal sphincters

Objective To determine the effect of ageing on length and resting pressure of the upper and lower oesophageal sphincters (UOSs, LOSs). Background The effectiveness of upper and lower oesophageal sphincters (UOSs and LOSs, respectively) in the control of retrograde trans‐sphincteric flow is influenced by sphincteric pressure and length. Methods Nine young and nine elderly healthy volunteers were studied. Resting UOS and LOS pressures were measured by sleeve devices and lengths were measured by the station pull‐through technique. Results The length of the UOS high pressure zone in the elderly (2.1 ± 0.7 cm posterior; 1.9 ± 0.1 cm anterior) was significantly shorter than that of the young (2.9 ± 0.1 cm posterior; 3.1 ± 0.2 cm anterior) (P < 0.01). Resting UOS pressure in the elderly (42 ± 5 mmHg) was significantly lower than that of the young (62 ± 7 mmHg) (P < 0.05). The intersphincteric length of the oesophagus in the elderly (21 ± 0.2 cm) was similar to that of the young (21 ± 0.4 cm). Total length of the LOS high pressure zone in the young (4.0 ± 0.1 cm) was similar to that of the elderly (4.1 ± 0.1 cm). LOS resting pressure was similar between young and elderly subjects (17 ± 5 mmHg and 15 ± 3 mmHg, respectively). Conclusions Ageing affects the UOS and LOS differently. With regard to resting pressure and length, ageing weakens the UOS, but has no significant effect on the LOS.

Vocal cord closure pressure during volitional swallow and other voluntary tasks.

Our goal was to determine and compare vocal cord (VC) closure pressure and its associated intratracheal pressure during several physiological events such as swallowing, coughing, straining, and phonation. We studied 11 healthy subjects (age 41 ± 2 years) with no current or previous history of laryngeal or pulmonary diseases. VC closure pressure during the above-mentioned tasks was studied using a concurrent manometric and endoscopic technique. VC closure pressure during dry swallows averaged 298 ± 23 mm Hg, while intratracheal pressures exhibited a biphasic pattern ranging from ?4 ± 0.5 to +6 ± 0.8 mm Hg. Average VC closure pressure during cough was 280 ± 20 mm Hg, during straining/valsalva maneuver it averaged 330 ± 45 mm Hg, during phonation it produced an initial rapidly rising spike like pressure (222 ± 25 mm Hg) followed by a sustained minimally positive pressure during continued phonation of two tested vowel sounds (15-25 mm Hg). Between-group comparison showed that for all studied tasks, the intercordal pressures were significantly higher than those of respective intratracheal pressures (p < 0.05). The vocal cords generate closure pressures that vary depending on the performed function.

Effect of pharyngeal stimulation on the motor function of the esophagus and its sphincters.

Objectives/Hypothesis: Sensory impulses from the pharynx induce contraction of the upper esophageal sphincter CUES), relaxation of the lower esophageal sphincter (LES), and inhibition of peristalsis. To determine 1) the magnitude of UES contractile response to threshold volume of fluid that induces LES relaxation and 2) the effect of rapid pharyngeal air stimulation on LES resting pressure and its concurrent influence on the UES and progression of esophageal peristalsis. Methods: Eleven healthy volunteers (age, 31 ± 2 y) were studied by concurrent UES, esophageal‐body, and LES manometry. Results: At a threshold volume of 0.3 ± 0.05 mL, injections of water into the pharynx directed posteriorly, resulted in complete LES relaxation. Duration of these relaxations averaged 19 ± 1 seconds. In 10 of 11 subjects, these relaxations were accompanied by a simultaneous increase in UES resting tone that averaged 142% ± 27% above preinjection values. Pharyngeal stimulation by rapid air injection resulted in complete LES relaxation in ft of the 11 subjects (threshold volume, 14 ± 6 mL). Five of 8 developed a concurrent mild increase in resting UES pressure (17% ± 6% above preinjection values) (P < .05). Pharyngeal water injection inhibited the progression of the peristaltic pressure wave at all tested sites and in all subjects, but pharyngeal air injection in only 2 of the 11 studied subjects. Conclusions: The inhibitory effect of pharyngeal water injection on LES resting pressure is accompanied by a substantial contractile effect on the UES. Although stimulation of the pharynx by rapid air injection may induce LES relaxation, its inhibitory effect on esophageal peristalsis and stimulatory effect on UES pressure are negligible compared with that of water injection.

Choline acetyltransferase activity parallels the pressure gradient in the feline pharyngo-esophageal region.

Pressures generated by the pharyngeal constrictor muscles and proximal esophagus involve acetylcholine-induced muscle contractions. We hypothesized that the pharyngo-esophageal pressure gradient is related to choline acetyltransferase activity. In nine anesthetized cats, hypopharyngeal pressure and proximal esophageal pressure were recorded with a solid state transducer assembly. Enzymatic activities in the thyropharyngeus, cricopharyngeus, and proximal esophageal muscles were measured. Hypopharyngeal pressure was higher than the proximal esophagus (p < 0.01), and choline acetyltransferase activity was higher in the cricopharyngeus compared to the proximal esophagus ( p < 0.05). The pressure gradient between the hypopharynx and proximal esophagus may be influenced by the activity of choline acetyltransferase.