Chicago Classification normative metrics in a healthy Indian cohort for a 16-channel water-perfused high-resolution esophageal manometry system.

BACKGROUND: High-resolution esophageal manometry (HREM) interpretation by the Chicago Classification (CC) derives its normal values from western volunteers using solid-state catheters. There is no normative data for the 16-channel water-perfused HREM system commonly used in India.

AIMS: To determine normal values for a 16-channel water-perfused HREM catheter in supine posture using healthy volunteers and substitute these normal values (if different from CC values) in the CC v3.0 algorithm.

METHODS: After ethics approval and informed consent, 53 volunteers (31 men) with no gastrointestinal (GI) symptoms or medications affecting GI motility underwent HREM by standard protocol. Age, gender, body mass index (BMI), and manometry parameters analyzed using Trace 1.3.3 software were collected. The median, range, and 5, 10, 75, and 95 percentiles (where applicable) were obtained for all HREM metrics. Normal value percentiles were defined as 95th (integrated relaxation pressure [IRP]), 10th-100th (distal contractile integral [DCI]), and minimum (distal latency [DL]).

RESULTS: The mean age was 30 years and the BMI was 24.2 kg m-2 . Compared to CC, our normal metrics were lower for IRP (13 mm Hg) and DCI (350-4500 mm Hg s cm). DCI >4500 and <70 (<5th percentile) were defined as hypercontractile and failed contraction, respectively. Abnormal DL (<4.5 s) and peristaltic break size (>5 cm) were similar to CC metrics. Applying these metrics, CC diagnoses changed in 15% (8/53) with downgrading of ineffective motility to fragmented peristalsis or normal, due to lower DCI cutoff used.

CONCLUSIONS: This is the first report of normative data for the 16-channel water-perfused system in supine posture. It revealed lower IRP and DCI, necessitating modification of CC cutoffs for this system.