Table III.

Subtypes of achalasia as defined by the Chicago Classification.

Type I	Elevated median IRP (> ULN), 100% failed peristalsis (DCI <100 mmHg s cm), premature contractions with DCI values less than 450 mmHg*s*cm satisfy criteria for failed peristalsis
Type II	Elevated median IRP (> ULN), 100% failed peristalsis, panesophageal pressurization with ≥20% of swallows. Contractions may be masked by esophageal pressurization and DCI should not be calculated
Type III	Elevated median IRP (> ULN), no normal peristalsis, premature (spastic) contractions with DCI >450 mmHg s cm with ≥20% of swallows. May be mixed with panesophageal pressurization

ULN – upper limit of normal (defined according to the HRM equipment used)