. Author manuscript; available in PMC: 2014 Mar 1.

Published in final edited form as: Gastroenterol Clin North Am. 2013 Jan 4;42(1):27–43. doi: 10.1016/j.gtc.2012.11.002

Table 2. EPT metrics used in the Chicago classification.

Abbreviation	Metric	Description	Normal
IRP	Integrated relaxation pressure	Mean EGJ pressure during the 4 s of maximal relaxation (contiguous or noncontiguous) in the 10-s window after UES relaxation	<15 mm Hg
DCI	Distal contractile integral	Amplitude × time × duration (mm Hg · s · cm) of the distal esophageal contraction >20 mm Hg from the proximal pressure through (transition zone) to the EGJ	<5000 mm Hg · s · cm
CDP	Contractile deceleration point	The inflection point along the 30–mm Hg isobaric contour where propagation velocity slows demarcating the tubular esophagus from the phrenic ampulla	—
CFV	Contractile front velocity	Slope of the tangent approximating the 30–mm Hg between the proximal pressure trough (transition zone) and the CDP	<9 cm/s
DL	Distal latency	Interval between UES relaxation and the CDP	>4.5 s

All pressures are referenced to atmospheric pressure except the IRP, which is referenced to gastric pressure.