Esophageal distension during bolus transport: can it be detected by intraluminal impedance recordings?

Abstract

Introduction Esophageal multiple intraluminal impedance (MII) measurement has been in used to detect gastroesophageal reflux and bolus transport. It is not clear if MII can detect changes in luminal cross sectional area (CSA) during bolus transport. Aims Intraluminal ultrasound (US) images, MII and high resolution manometry (HRM) were recorded simultaneously to determine temporal relationship between CSA and impedance during esophageal bolus transport and to define the relationship between peak distension and nadir impedance. Methods Studies were conducted in five healthy subjects. MII, HRM and US images were recorded 6 cm above LES. Esophageal distensions were studied during swallows and injections of 0.5 N saline bolus into the esophagus. Results Temporal change in esophageal CSA correlates with changes in impedance (r value: mean ± SD = −0.80 ± 0.08, range: −0.94 to −0.66). Drop in impedance during distension occurs as a two step process; initial large drop associated with onset of CSA increase, followed by a small drop during which majority of the CSA increase occurs. Peak CSA and nadir impedance occur within 1 s of each other. Increase in swallow and injection volumes increased the CSA, had no effect on large drop but increased the small drop amplitude. We observed a significant correlation between peak CSA and nadir impedance (r = − 0.90, p<0.001) and a better correlation between peak CSA and inverse impedance (r = 0.94, p<0.001). Conclusion Further studies are needed to confirm that intraluminal impedance recordings may be used to measure luminal CSA during esophageal bolus transport.

Modulation of Upper Esophageal Sphincter (UES) Relaxation and Opening During Volume Swallowing

“…Swallows exhibiting the presence of significant quantities of swallowed air (identified by a sustained drop in admittance) were excluded from further analyses, in practice this related to a subset of 2ml volume swallows only. The Maximum UES admittance allowed estimation of the time of maximal luminal cross-sectional area/ CSA [26,27]. The time from onset of admittance increase to maximum was termed the admittance upstroke time while the time from maximal admittance to offset of admittance decrease was called the admittance downstroke time.…”

Remifentanil alters sensory neuromodulation of swallowing in healthy volunteers: quantification by a novel pressure-impedance analysis

“…The maximum admittance corresponds to the time and position where the lumen is most conductive. In normal circumstances, this identifies the axial center, or most distended part, of the intrabolus bolus domain during transport (9,16,23). Hence, pressure measured at, or timing of, maximum admittance is an accurate measure of intrabolus distension pressure and timing of maximum distension, respectively.…”

Impedance as an adjunct to manometric testing to investigate symptoms of dysphagia: What it has failed to do and what it may tell us in the future

“…The measured value of nadir impedance has been shown to be an inverse correlate of maximum luminal diameter or cross-sectional area. [63][64][65] By identifying the axial centre of the bolus, the nadir impedance can be used to determine the trajectory of the bolus in time and space as it is propelled from the pharynx to the proximal oesophagus, down to the distal oesophagus and then through into the stomach via the EGJ. It has been long recognised that pharyngeal swallow can propel boluses significant distances along the length of the oesophagus.…”