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Pressure-flow analysis quantifies the interactions between bolus transport and pressure generation. We undertook a pilot study to assess the interrelationships between pressure-flow metrics and fluoroscopically determined bolus clearance and bolus transport across the esophagogastric junction (EGJ). We hypothesized that findings of abnormal pressure-flow metrics would correlate with impaired bolus clearance and reduced flow across the EGJ. Videofluoroscopic images, impedance, and pressure were recorded simultaneously in nine patients with dysphagia (62-82 years, seven male) tested with liquid barium boluses. A 3.6 mm diameter solid-state catheter with 25 × 1 cm pressure/12 × 2 cm impedance was utilized. Swallowed bolus clearance was assessed using a validated 7-point radiological bolus transport scale. The cumulative period of bolus flow across the EGJ was also fluoroscopically measured (EGJ flow time). Pressure only parameters included the length of breaks in the 20 mmHg iso-contour and the 4 second integrated EGJ relaxation pressure (IRP4s). Pressure-flow metrics were calculated for the distal esophagus, these were: time from nadir impedance to peak pressure (TNadImp to PeakP) to quantify bolus flow timing; pressure flow index (PFI) to integrate bolus pressurization and flow timing; and impedance ratio (IR) to assess bolus clearance. When compared with controls, patients had longer peristaltic breaks, higher IRs, and higher residual EGJ relaxation pressures (break length of 8 [2, 13] vs. 2 [0, 2] cm, P = 0.027; IR 0.5 ± 0.1 vs. 0.3 ± 0.0, P = 0.019; IRP4s 11 ± 2 vs. 6 ± 1 mmHg, P = 0.070). There was a significant positive correlation between higher bolus transport scores and longer peristaltic breaks (Spearman correlation r = 0.895, P < 0.001) and with higher IRs (r = 0.661, P < 0.05). Diminished EGJ flow times correlated with a shorter TNadImp to PeakP (r = -0.733, P < 0.05) and a higher IR (r = -0.750, P < 0.05). Longer peristaltic breaks and higher IR correlate with failed bolus clearance on videofluoroscopy. The metric TNadImp to PeakP appears to be a marker of the period of time over which the bolus flows across the EGJ., (© 2014 International Society for Diseases of the Esophagus.)

Background: The study aims were to investigate whether neural pathways involving 5-HT3 receptors mediate: (i) distension-induced upper esophageal sphincter (UES) relaxation reflex, (ii) esophageal sensitivity to acid and electrical stimuli, and (iii) viserosomatic sensitization following acid exposure., Methods: In Study I, in a double-blind crossover trial (n = 9) esophageal sensory and pain thresholds to electrical stimulation were measured in the esophagus, midsternum, and the foot, before subjects were randomized to receive either Ondansetron (8 mg i.v.) or NaCl (0.9% w/v). HCl (0.15 mol L(-1)) was then infused into distal esophagus and electrical thresholds were reassessed. Following electrical sensory threshold testing, subjects received a second esophageal infusion of HCl to evaluate esophageal sensitivity to acid. In Study II (N = 10), frequencies of distension-induced UES relaxation responses were scored before and after treatment with Ondansetron and NaCl in a double-blind crossover trial., Key Results: In Study I, ondansetron had no effect on esophageal sensitivity to HCl or acid-induced sensitization. However, blockade of 5-HT3 receptors did reduce midsternum somatic pain thresholds. Sixty minutes after esophageal acid exposure, pain thresholds were significantly lower in the ondansetron arm (mean Δ-1.36 ± 0.4 mA) when compared with NaCl (mean Δ-0.14 ± 0.58 mA) (P < 0.05). In Study II, 5-HT3 receptor blockade had no significant effect on UES relaxation reflex., Conclusions & Inferences: This study does not support the hypothesis that in health, 5-HT3 receptors play a significant role in esophago-UES distention-induced relaxation reflex and esophageal sensitivity to acid or electrical stimulation. It does provide new evidence for involvement of 5-HT3 receptors in viscerosomatic sensitization., (© 2013 Blackwell Publishing Ltd.)

Background: Inappropriate or excessive, non-swallow related, reflexive relaxation of the upper esophageal sphincter (UES) in response to esophageal distension may be the principal mechanism permitting retrograde trans-sphincteric flow during acid regurgitation. The neural pathways mediating reflexive UES relaxation in the human have received little attention. Patients with laryngitis demonstrate an increased acid reflux in the proximal esophagus. Such events, combined with an increased tendency for UES relaxation, might precipitate regurgitation into the pharynx. The aim was to determine whether the esophago-UES relaxation reflex induced by rapid esophageal distension is upregulated in patients with posterior laryngitis., Methods: In 21 healthy volunteers and 14 patients with posterior laryngitis, UES responses to rapid air insufflation were examined. UES responses were monitored with perfused manometry catheter with a oval sleeve sensor., Key Results: The probability of triggering UES relaxation in response to the rapid esophageal air distension, for all volumes of insufflation, was higher in laryngitis (45%) than in health (17%). The minimum distension volume required to elicit an UES relaxation response was significantly lower in laryngitis patients when compared with controls. Patients who demonstrated a laryngoscopic response to a trial of omeprazole, were less likely to generate a distension-induced UES contractile response (5%) than patients who did not respond (23%)., Conclusions & Inferences: The threshold for esophageal distension-induced UES relaxation is reduced in patients with laryngitis when compared with controls. This finding supports the hypothesis that in this population, a hypersensitive belch-like response may be one contributory mechanism of regurgitation when triggered by an abrupt spontaneous gastro-esophageal reflux event.

We tested the hypotheses that globus patients demonstrate oesophageal visceral hypersensitivity and aberrant viscerosomatic referral of oesophageal stimuli. Oesophageal visceral perception was assessed by oesophageal balloon distension and electrical stimulation in nine patients with globus and compared with 11 healthy controls. Oesophageal perception and pain thresholds were determined. Subjects recorded the area of thoracic viscerosomatic referral on a body map in response to each stimulus. All the patients reported their first sensation at balloon volumes between 2 and 6 mL whereas controls reported their first sensation at volumes between 3 and 14 mL (P = 0.03). All the patients reported pain at balloon volumes between 5 and 12 mL whereas controls experienced pain at volumes between 8 and 20 mL (P = 0.001). In response to electrical stimulation to the oesophagus patients and controls demonstrated comparable sensory thresholds. In response to oesophageal balloon distension seven of nine patients, but no controls, referred the sensation to the region at or above the suprasternal notch (P = 0.001). Similarly, significant differences in viscerosomatic referral pattern were observed in response to oesophageal electrical stimulation (P = 0.03). Patients with globus demonstrate oesophageal visceral hypersensitivity to mechanical distension. The differential responses to stretch and electrical stimuli may indicate that the hypersensitivity is a peripheral, rather than central, phenomenon. The aberrant referral of oesophageal sensations in response to both mechanical and electrical stimulation supports the hypothesis that referral of symptoms to the neck might be a central phenomenon.

The impedance criteria for the detection of the arrival of bolus head and clearance of bolus tail in the pharynx have not been defined, and may differ from accepted criteria used in the oesophagus. Our aim was to define the optimal impedance criteria that most accurately defined passage of the swallowed bolus moving through the pharyngo-oesophageal segment. In eight healthy volunteers, an assembly incorporating seven impedance-measuring segments was positioned across the pharyngo-oesophageal segment, and subjects swallowed liquid and semisolid radio-opaque boluses (2-20 mL) while impedance was simultaneously recorded with videofluoroscopic images. To derive the optimal criteria, in an iterative process we correlated impedance defined bolus presence with fluoroscopy (Cohen's Kappa) for a range of impedance cut-off values from 100% to 0% for both the initial fall, and recovery of impedance. Bolus presence in the pharynx, as determined by the 'standard' criteria (50% drop and recovery to 50% of baseline), correlated very modestly with videofluoroscopy (kappa approximately 0.35). The criteria that most accurately defined bolus passage varied between pharyngeal regions. Threshold (% of baseline) for bolus head entry into the region ranged from 71% to 80%. Threshold for bolus tail clearance varied from nadir to 19%. Correlation of impedance with videofluoroscopy improved to kappa approximately 0.6 with the above criteria. The impedance criteria defining bolus presence across the pharyngo-oesophageal segment differ from those adopted in the oesophagus. Pharyngeal impedance provides an accurate, non-radiological indicator of bolus transit through the pharynx.

Background The study aims were to investigate whether neural pathways involving 5-HT3 receptors mediate: (i) distension-induced upper esophageal sphincter (UES) relaxation reflex, (ii) esophageal sensitivity to acid and electrical stimuli, and (iii) viserosomatic sensitization following acid exposure. Methods In Study I, in a double-blind crossover trial ( n = 9) esophageal sensory and pain thresholds to electrical stimulation were measured in the esophagus, midsternum, and the foot, before subjects were randomized to receive either Ondansetron (8 mg i.v.) or NaCl (0.9% w/v). HCl (0.15 mol L−1) was then infused into distal esophagus and electrical thresholds were reassessed. Following electrical sensory threshold testing, subjects received a second esophageal infusion of HCl to evaluate esophageal sensitivity to acid. In Study II ( N = 10), frequencies of distension-induced UES relaxation responses were scored before and after treatment with Ondansetron and NaCl in a double-blind crossover trial. Key Results In Study I, ondansetron had no effect on esophageal sensitivity to HCl or acid-induced sensitization. However, blockade of 5-HT3 receptors did reduce midsternum somatic pain thresholds. Sixty minutes after esophageal acid exposure, pain thresholds were significantly lower in the ondansetron arm (mean Δ−1.36 ± 0.4 mA) when compared with NaCl (mean Δ−0.14 ± 0.58 mA) ( P < 0.05). In Study II, 5-HT3 receptor blockade had no significant effect on UES relaxation reflex. Conclusions & Inferences This study does not support the hypothesis that in health, 5-HT3 receptors play a significant role in esophago-UES distention-induced relaxation reflex and esophageal sensitivity to acid or electrical stimulation. It does provide new evidence for involvement of 5-HT3 receptors in viscerosomatic sensitization. [ABSTRACT FROM AUTHOR]