Understanding the Chicago Classification: From Tracings to Patients

Abstract

Current parameters of the Chicago classification include assessment of the esophageal body (contraction vigour and peristalsis), lower esophageal sphincter relaxation pressure, and intra-bolus pressure pattern. Esophageal disorders include achalasia, esophagogastric junction outflow obstruction, major disorders of peristalsis, and minor disorders of peristalsis. Sub-classification of achalasia in types I, II, and III seems to be useful to predict outcomes and choose the optimal treatment approach. The real clinical significance of other new parameters and disorders is still under investigation.

Keywords: Chicago classification; Esophageal achalasia; Esophageal motility disorders; High-resolution manometry.

Figure 1

Normal high-resolution manometry plot (left) compared to the same swallow at the conventional manometry (right).

Figure 2

Distal contractile integral (DCI). DCI value is calculated as the product of the mean amplitude of contraction in the distal esophagus (mmHg) times the duration of contraction (seconds) times the length of the distal oesophageal segment (cm) exceeding 20 mmHg for the region spanning from the transition zone to the proximal aspect of the lower esophageal sphincter.

Figure 3

Distal latency (DL) measures objectively the time frame of the wave from the beginning of the swallow (upper esophageal relaxation) to the contractile deceleration point (CDP).

Figure 4

Integrated relaxation pressure (IRP) corresponds to the mean pressure of 4 seconds of greatest post deglutitive relaxation in a 10 seconds gap, triggered at the beginning of a swallow. Note diaphragmatic contraction pressure (*) during relaxation excluded from analysis.

Figure 5

Achalasia subtypes. Type I: absence of esophageal pressurization; Type II: panesophageal pressurization; Type III: premature contractions (distal latency < 4.5 seconds).

Figure 6

Distal esophageal spasm. Premature contractions (distal latency [DL] < 4.5 seconds) in at least 20% of swallows.

Figure 7

Hypercontractile esophagus (jackhammer esophagus). Distal contractile integral (DCI) > 8000 mmHg·sec·cm in at least 20% of swallows and normal distal latency (DL).

Figure 8

Absent contractility. Aperistalsis in the setting of normal lower esophageal sphincter relaxation (integrated relaxation pressure < 10 mmHg).

Figure 9

Ineffective esophageal motility. Failed or weak peristalsis in at least ≥ 50% of swallows. DCI, distal contractile integral.

Figure 10

Fragmented peristalsis. ≥ 50% fragmented contractions with distal contractile integral (DCI) > 450 mmHg·sec·cm.