Calculation of esophagogastric junction vector volume using three-dimensional high-resolution manometry.

Lower esophageal sphincter vector volume (V-V) was developed in the late 1980s by Bombeck, as a quantification of sphincter integrity used to select reflux patients with a defective valve who may benefit from surgery. Its calculation required motorized pull-through of an 8-lumen water perfused manometry catheter with subsequent computerized reconstruction of sphincter morphology. Recently, a three-dimensional high-resolution manometry (3D-HRM) assembly (Given Imaging, Duluth, GA, USA) has been developed with the potential to assess real-time V-V. The aim of this study was to assess the feasibility of the calculation of V-V using the 3D-HRM assembly and to compare measures of its value using real-time 3D-HRM to simulated analogous measures. Eight asymptomatic controls (4F, ages 26-49) were studied in a supine position with a solid-state 3D-HRM assembly positioned across the esophagogastric junction (EGJ). The 9-cm 3D segment comprised 12 rings of 8 radially dispersed pressure sensors, each 2.5 mm long and spaced 7.5 mm apart on center. Recordings were done during normal respiration: (i) with the 3D-HRM segment in a stationary position across the EGJ; and (ii) during a station pull-through of the 3D-HRM segment withdrawing it across the EGJ at 5-mm increments with each position held for 30 seconds. EGJ cross-sectional vector areas (CSVAs) were computed using the irregular polygon area formula: [Formula in text], and n = 8 radial sensors. V-V was computed as the sum of CSVAs at inspiration and end-expiration by three methods: real-time 3D-HRM, three-station composite, and single-sensor ring measurements. There were no statistic differences among the methods, and all methods showed significant differences between inspiration and expiration. Calculation of real-time V-V is feasible using the 3D-HRM. Moreover, the results of this study highlighted the potential primary role of the diaphragmatic hiatus in the pathophysiology of gastroesophageal reflux disease and the underrecognized but crucial role of the crural repair during the antireflux surgery.

Parameters for quantifying bolus retention with high-resolution impedance manometry.

BACKGROUND: This study aimed to develop a methodology for quantifying esophageal bolus retention using a high-resolution esophageal impedance topography (EIT) technique. METHODS: The ability of impedance to quantify bolus retention was validated by comparison with concurrent fluoroscopic imaging (barium bolus) in 10 healthy subjects. High-resolution impedance manometry (HRIM) studies without fluoroscopy were performed in another 15 healthy subjects to define normal values using saline. HRIM data from each subject were analyzed using a MATLAB program customized for calculating the esophageal impedance integral (EII) prior to the contraction wave front as EII1 and after the contraction as EII2, and presented as a ratio of EII2/EII1, which was compared to the percent of barium areas retained in the esophagus on fluoroscopy determined by a blinded reviewer. KEY RESULTS: In 93% (37/40) of barium swallows, the results from the EIT method were in agreement with fluoroscopy results with one of three patterns: (1) 25 normal bolus transit, (2) eight bolus stasis, and (3) four retrograde escape or reflux. Three swallows (8%) had slight retention identified by EIT, but no retention detected by fluoroscopy. The correlation between percent of bolus retained in the esophagus detected by fluoroscopy and percent of bolus retention (EII2/EII1) after swallows with EIT method was r = 0.96 (p < 0.001) in supine and r = 0.69 (p < 0.001) in upright position. CONCLUSIONS & INFERENCES: The EII ratio (EII2/EII1) is a surrogate for the fraction of retained bolus after a swallow and this metric may be useful in better defining esophageal function.

Quantifying esophagogastric junction contractility with a novel HRM topographic metric, the EGJ-Contractile Integral: normative values and preliminary evaluation in PPI non-responders.

BACKGROUND: Despite its obvious pathophysiological relevance, the clinical utility of measures of esophagogastric junction (EGJ) contractility is unsubstantiated. High-resolution manometry (HRM) may improve upon this with its inherent ability to integrate the magnitude of contractility over time and length of the EGJ. This study aimed to develop a novel HRM metric summarizing EGJ contractility and test its ability distinguish among subgroups of proton pump inhibitor non-responders (PPI-NRs). METHODS: 75 normal controls and 88 PPI-NRs were studied. All underwent HRM. PPI-NRs underwent pH-impedance monitoring on PPI therapy scored in terms of acid exposure, number of reflux events, and reflux-symptom correlation and grouped as meeting all criteria, some criteria, or no criteria of abnormality. Control HRM studies were used to establish normal values for candidate EGJ contractility metrics, which were then compared in their ability to differentiate among PPI-NR subgroups. KEY RESULTS: The EGJ contractile integral (EGJ-CI), a metric integrating contractility across the EGJ for three respiratory cycles, best distinguished the All Criteria PPI-NR subgroup from controls and other PPI-NR subgroups. Normal values (median, [IQR]) for this measure were 39 mmHg-cm [25-55 mmHg-cm]. The correlation between the EGJ-CI and a previously proposed metric, the lower esophageal sphincter-pressure integral, that used a fixed 10 s time frame and an atmospheric as opposed to gastric pressure reference was weak. CONCLUSIONS & INFERENCES: Among HRM metrics tested, the EGJ-CI was best in distinguishing PPI-NRs meeting all criteria of abnormality on pH-impedance testing. Future prospective studies are required to explore its utility in management of broader groups of gastroesophageal reflux disease patients.

The acoustic cough monitoring and manometric profile of cough and throat clearing.

Cough and throat clearing might be difficult to differentiate when trying to detect them acoustically or manometrically. The aim of this study was to assess the accuracy of acoustic monitoring for detecting cough and throat clearing, and to also determine whether these two symptoms present with different manometric profiles on esophageal pressure topography. Ten asymptomatic volunteers (seven females, mean age 31.1) were trained to simulate cough and throat clearing in a randomized order every 6 minutes during simultaneous acoustic monitoring and high-resolution manometry. The accuracy of automated acoustic analysis and two blinded reviewers were compared. The pattern of the events and the duration of the pressure changes were assessed using the 30 mmHg isobaric contour. There were 50 cough and 50 throat-clearing events according to the protocol. The sensitivity and specificity of automated acoustic analysis was 84% and 50% for cough, while the blinded analysis using sound revealed a sensitivity and specificity of 94% and 92%. The manometric profile of both cough and throat clearing was similar in terms of qualitative findings; however, cough was associated with a greater number of repetitive pressurizations and a more vigorous upper esophageal sphincter contraction compared with throat clearing. The acoustic analysis software has a moderate sensitivity and poor specificity to detect cough. The profile of cough and throat clearing in pressure topography revealed a similar qualitative pattern of pressurization with more vigorous pressure changes and a greater rate of repetitive pressurizations in cough.

Regional variation in distal esophagus distensibility assessed using the functional luminal imaging probe (FLIP).

BACKGROUND: This study aimed to evaluate the spatial variation in esophageal distensibility in normal subjects using a novel multichannel functional luminal imaging probe (FLIP). METHODS: Ten healthy subjects (four men, age 21-49 years) were evaluated during endoscopy with a high-resolution impedance planimetry probe (FLIP) positioned through the esophagogastric junction (EGJ) and distal 10 cm of the esophageal body. Stepwise bag distensions using 5-mL increments from 0 to 60 mL were conducted, and simultaneous measurements of cross-sectional area (CSA) and the associated intrabag pressure from each subject were analyzed using a customized MATLAB™ program. The distensibility along the esophagus was determined and compared between the EGJ and interval locations at 2-5 cm and 6-10 cm above the EGJ. KEY RESULTS: The pressure-CSA relationship was nearly linear among sites at lower pressures (0 to 7.5 mmHg) and reached a distension plateau at pressures ranging from 8 to 24 mmHg. The location of greatest distensibility was 4 cm above the EGJ. Although the CSAs of individual recording loci were not significantly different, there was a significant difference between the mean CSAs when comparing the region 2 to 5 cm proximal to EGJ with that 6 to 10 cm proximal to the EGJ. CONCLUSIONS & INFERENCES: There were significant regional differences in distensibility along the distal esophagus with lower values in the proximal part compared with more distal part. The greatest distensibility was noted to occur at about 4 cm above the EGJ in close proximity to the location of the contractile deceleration point and phrenic ampulla.

Esophagogastric Junction pressure morphology: comparison between a station pull-through and real-time 3D-HRM representation.

BACKGROUND: Esophagogastric junction (EGJ) competence is the fundamental defense against reflux making it of great clinical significance. However, characterizing EGJ competence with conventional manometric methodologies has been confounded by its anatomic and physiological complexity. Recent technological advances in miniaturization and electronics have led to the development of a novel device that may overcome these challenges. METHODS: Nine volunteer subjects were studied with a novel 3D-HRM device providing 7.5 mm axial and 45° radial pressure resolution within the EGJ. Real-time measurements were made at rest and compared to simulations of a conventional pull-through made with the same device. Moreover, 3D-HRM recordings were analyzed to differentiate contributing pressure signals within the EGJ attributable to lower esophageal sphincter (LES), diaphragm, and vasculature. KEY RESULTS: 3D-HRM recordings suggested that sphincter length assessed by a pull-through method greatly exaggerated the estimate of LES length by failing to discriminate among circumferential contractile pressure and asymmetric extrinsic pressure signals attributable to diaphragmatic and vascular structures. Real-time 3D EGJ recordings found that the dominant constituents of EGJ pressure at rest were attributable to the diaphragm. CONCLUSIONS & INFERENCES: 3D-HRM permits real-time recording of EGJ pressure morphology facilitating analysis of the EGJ constituents responsible for its function as a reflux barrier making it a promising tool in the study of GERD pathophysiology. The enhanced axial and radial recording resolution of the device should facilitate further studies to explore perturbations in the physiological constituents of EGJ pressure in health and disease.

Distensibility of the esophagogastric junction assessed with the functional lumen imaging probe (FLIP™) in achalasia patients.

BACKGROUND: The functional lumen imaging probe (FLIP), measures esophagogastric junction (EGJ) distensibility (cross-sectional area/luminal pressure) during volume-controlled distension. The aim of this study is to apply this tool to the assessment of the EGJ in untreated and treated achalasia patients and to compare EGJ distensibility with other diagnostic tools utilized in managing achalasia. METHODS: Findings from FLIP, high-resolution manometry (HRM), timed barium esophagram, and symptom assessment by Eckardt Score (ES) were compared in 54 achalasia patients (23 untreated, 31 treated). Twenty healthy volunteers underwent FLIP as a comparator group. The EGJ distensibility index (EGJ-DI) was defined at the 'waist' of the FLIP bag during volumetric distension, expressed in mm(2)  mmHg(-1) . The ES was used to gauge treatment outcome: good response < 3 or poor response ≥ 3. KEY RESULTS: Of the 31 treated patients, 17 had good and 14 poor treatment response. The EGJ-DI was significantly different among groups, greatest in the control subjects and least in the untreated patients; patients with good treatment response had significantly greater EGJ-DI than untreated or patients with poor response. The correlations between EGJ-DI and ES and integrated relaxation pressure on HRM were significant. CONCLUSIONS & INFERENCES: The FLIP provided a useful measure of EGJ distensibility in achalasia patients that correlated with symptom severity. The measurement of EGJ distensibility was complementary to existing tests suggesting a potentially important role in the clinical management of achalasia.

Optimizing the swallow protocol of clinical high-resolution esophageal manometry studies.

BACKGROUND: The Chicago Classification (CC) of Esophageal Motility Disorders is based on 10 water swallows performed in the supine position. The aim of the study was to assess whether upright and provocative swallows (PS) provided important information beyond that obtained from the standard supine manometric protocol. METHODS: Two independent investigators reviewed high-resolution manometry (HRM) studies of 148 patients with both supine and upright liquid swallows and additional studies from patients with PS (increased volume, viscosity, and a marshmallow) for a resultant change in CC diagnoses. Significant diagnostic changes were defined as a change from normal or borderline motor function to abnormal motor function, esophagogastric junction (EGJ) outflow obstruction, or achalasia. Discordant diagnoses were reviewed and the Kappa test was used to evaluate the agreement between diagnoses in the different protocols. KEY RESULTS: The overall agreement in diagnosis between the five supine swallows and the five upright swallows was good (k = 0.583). Changing to the upright position elicited a significant diagnostic change in 10.1% (15/148) of cases. The PS suggested an alternative diagnosis from the supine position in 14 of 75 studies (18.7%); 11 of these changed to EGJ obstruction during viscous or solid bolus challenges. CONCLUSIONS & INFERENCES: Changing position in HRM elicited a significant change in diagnosis in about 10% of studies, whereas provocative bolus challenges with viscous liquid and marshmallows increased the detection of EGJ outflow obstruction. Performing manometric evaluations in both positions with PS may increase the yield of standard HRM technique.

The effect of a sitting vs supine posture on normative esophageal pressure topography metrics and Chicago Classification diagnosis of esophageal motility disorders.

BACKGROUND: Although, the current protocol for high resolution manometry (HRM) using the Chicago Classification is based on the supine posture, some practitioners prefer a sitting posture. Our aims were to establish normative esophageal pressure topography data for the sitting position and to determine the effect of applying those norms to Chicago Classification diagnoses. METHODS: Esophageal pressure topography studies including test swallows in both a supine and sitting position of 75 healthy volunteers and 120 patients were reviewed. Integrated relaxation pressure (IRP), distal contractile integral (DCI), contractile front velocity (CFV), and distal latency were measured and compared between postures. Normative ranges were established from the healthy volunteers and the effect of applying sitting normative values to the patients was analyzed. KEY RESULTS: Normative values of IRP, DCI, and CFV all decreased significantly in the sitting posture. Applying normative sitting metrics to patient studies [27% reduction in IRP (15 to 11 mmHg), 69% reduction in DCI (8000-2500 mmHg-s-cm)] reclassified 13/120 (11%) patients as having abnormal esophagogastric junction relaxation and 26/120 (22%) as hypercontractile. Three patients with an abnormal supine IRP normalized when sitting with elimination of a vascular artifact. CONCLUSIONS & INFERENCES: Clinical HRM studies should include both a supine and sitting position to minimize misdiagnoses attributable to anatomical factors. However, until outcome studies demonstrating the significance of isolated abnormalities of IRP or DCI in the sitting position are available, the Chicago Classification of esophageal motility disorders should continue to be based on supine swallows using normative data from the supine posture.