Inter‐ and intra‐rater reproducibility of automated and integrated pressure‐flow analysis of esophageal pressure‐impedance recordings

Abstract

Background Automated impedance manometry pressure‐flow analysis (AIM analysis) determines pressure measurements relative to bolus flow and has to date shown subtle variations in esophageal motility in relation to dysphagia. In this study, we assessed intra‐ and inter‐rater reproducibility of AIM metrics derived using purpose designed software. Methods Fifty patients referred for evaluation of gastro‐esophageal reflux symptoms (33 men, age 52 ± 1.9 years) underwent combined high‐resolution impedance manometry and completed a dysphagia questionnaire. From 10 liquid and 10 viscous swallows, a subset of four swallows (two saline and two viscous) was systematically selected from each patient for manual and AIMplot analysis, which was performed twice by five observers (two experts, three non‐experts). Intra‐ and inter‐rater agreement were determined using intraclass correlation coefficients. Key Results AIMplot‐based analysis showed high intra‐rater and inter‐rater reproducibility for all metrics (mean ICCs of 0.95 and 0.94, respectively). Reproducibility of metrics derived for liquid and viscous did not differ (ICCs of 0.96 and 0.91 for liquid and viscous, respectively). In addition, metrics derived by experts had an equivalent level of reproducibility compared to non‐experts (ICCs of 0.96 and 0.94, respectively). Variables that could be derived with commercial software (ManoView™) correlated highly with variables from AIMplot‐based analysis, such as 4‐s integrated relaxation pressure (r = 0.85) and the 20‐mmHg isobaric contour defect (r = 0.92). Conclusions & Inferences Esophageal AIM analysis is highly reproducible, independent of an observer's level of experience in esophageal motility. Therefore, AIM analysis produces data that are reliable for clinical and research purposes.

Pressure-Flow Characteristics of Normal and Disordered Esophageal Motor Patterns

“…Data was then uploaded and analyzed using purposed designed software (AIMplot copyright T Omari, MATLAB version 2012a, the MathWorks Inc, Natick, MA, USA). As previously reported (Myers, 2012;Loots, 2013;Nguyen, 2013;Chen 2013;Rohof 2013), seven pressure-flow variables were derived from the automated analyses: (i) pressure at nadir impedance (PNadImp, mmHg), (ii) peak pressure (PeakP, mmHg), (iii) median intrabolus pressure (IBP, mmHg), (iv) time interval between nadir esophageal impedance and peak esophageal pressure (TNadImp-PP, sec), (v) IBP slope (IBP slope, mmHg s -1 ), (vi) the impedance ratio (NadImp/ImpPeakP Ratio) and (vii) Pressure Flow Index (PFI). The impedance ratio has been identified as a potential marker of incomplete bolus transit (Chen 2013;Rohof 2013).…”

“…As previously reported (Myers, 2012;Loots, 2013;Nguyen, 2013;Chen 2013;Rohof 2013), seven pressure-flow variables were derived from the automated analyses: (i) pressure at nadir impedance (PNadImp, mmHg), (ii) peak pressure (PeakP, mmHg), (iii) median intrabolus pressure (IBP, mmHg), (iv) time interval between nadir esophageal impedance and peak esophageal pressure (TNadImp-PP, sec), (v) IBP slope (IBP slope, mmHg s -1 ), (vi) the impedance ratio (NadImp/ImpPeakP Ratio) and (vii) Pressure Flow Index (PFI). The impedance ratio has been identified as a potential marker of incomplete bolus transit (Chen 2013;Rohof 2013). The pressure flow index (PFI) is based on an empirical formula, which was designed to amplify differences in key AIM analysis metrics seen in relation to symptoms of dysphagia (Myers 2012;Loots, 2013;Nguyen, 2013;Chen, 2013).…”

Esophageal Impedance Monitoring: Clinical Pearls and Pitfalls

“…AIM was fi rst developed to assess pharyngeal dysfunction, and it uses advanced automated soft ware to combine key manometric and impedance fi ndings to derive pressure-fl ow variables to assess bolus transport ( 64 ). AIM has subsequently been applied to esophageal body bolus transit where it has demonstrated excellent intraobserver and interobserver reproducibility among novices and experts ( 65 ). In 35 patients with nonobstructive dysphagia and 24 healthy subjects, patients with dysphagia had a higher pressure at nadir impedance (representing complete bolus clearance from the segment), a greater absolute and rate of rise of intrabolus pressure, and shorter time from nadir impedance to peak esophageal pressure.…”

Inter‐rater agreement of novel high‐resolution impedance manometry metrics: Bolus flow time and esophageal impedance integral ratio

“…3–5 A previous study evaluating inter-rater agreement of the AIM analysis pressure-flow metrics between five raters of variable analytic experience demonstrated almost perfect agreement when applied to 50 patients evaluated for gastroesophageal reflux. 12 Among the 200 upright swallows analyzed, mean ICCs of ≥0.9 for each pressure-flow metric, as well as the IRP, were reported. Although among fewer raters, the current study demonstrated similar excellent measures of inter-rater agreement between an experienced and recent trained rater with the BFT and EII ratio.…”