Impact of spatial resolution on results of esophageal high-resolution manometry

The Chicago classification for esophageal motility disorders was designed for a 36-channel manometry system with sensors spaced at 1 cm. However, many motility laboratories outside the USA use catheters with a lower resolution in the segments outside the esophagogastric junction. Our aim was to investigate the effect of spatial resolution on the Chicago metrics and diagnosis. In 20 healthy volunteers and 47 patients with upper gastrointestinal symptoms, high-resolution manometric studies of the esophagus were retrospectively reanalyzed using the original 1-cm spacing in the segments outside the 7-cm esophagogastric junction segment, and again after manually increasing the spacing between sensors to 2, 3, and 4 cm (above the lower esophageal sphincter region). Measurements were analyzed in random order and the investigator was blinded to the outcome of the analyses performed in another resolution of the same patient. Intra-class correlation coefficients (ICC) and Kappa values were determined. There was a very strong correlation between the 1-cm and 2-cm analysis for all Chicago metrics studied in healthy volunteers (ICCs: distal contractile integral 0.998; contractile front velocity (CFV) 0.964; distal latency 0.919; peristaltic break size 0.941). The 2-cm spacing analysis also correlated very well with the 1-cm analysis for the different Chicago diagnoses obtained in the patients (Kappa values ranging from 0.665 to 1.000). When the sensor spacing was increased to 3 and 4 cm, the correlation was reduced to moderate for the Chicago metrics, especially for break size and CFV of peristalsis. The Chicago classification for esophageal motility disorders is still valid and the same normal values can be used when catheters with a slightly lower resolution are used (i.e., 2-cm vs 1-cm spacing). For larger sensor intervals, the classification and the normal values will need to be adjusted