Caecal pH is a biomarker of excessive colonic fermentation

Abstract

Aim: To ascertain whether caecal pH is different in patients with irritable bowel syndrome (IBS), whose primary symptoms are bloating and distension, to healthy controls.

Methods: Motility and pH data were reviewed from 16 patients with Rome III defined IBS and 16 healthy controls, who had undergone a wireless motility capsule (WMC) study using a standardized protocol. Motility measures were anchored around known anatomical landmarks as identified by compartmental pH changes. Sixty-minute epochs were used to quantify antral, duodenal, ileal, caecal and distal colonic contractility. The maximum and minimum pH was measured either side of the ileo-caecal junction.

Results: No differences were seen in motility parameters, compartmental transit times or maximal ileal pH between the two groups. Caecal pH was significantly lower in patients compared to controls (5.12 ± 0.05 vs 6.16 ± 0.15, P < 0.0001). The ileal:caecal Δchange was greater in patients than controls (-2.63 ± 0.08 vs -1.42 ± 0.11, P < 0.0001). There was a significant correlation between caecal pH and right colonic contractility (r = 0.54, P = 0.002).

Conclusion: Patients with bloating and distension have a lower caecal pH compared to controls. The measurement of caecal pH using the WMC provides a quantifiable biomarker of fermentation potentially identifying those patients that may preferentially benefit from antibiotic or dietary interventions.

Keywords: Bloating; Caecal pH; Caecoparesis; Colonic microbiota; Fermentation.

Figures

Figure 1

A typical wireless motility capsule trace demonstrating temperature (blue line), pH (green line) and contractility (red line) across the ileo-caecal junction. The pH drop was defined as the difference between the stable ileal pH and the caecal pH nadir. ICJ: Ileo-caecal junction.

Figure 2

Differences (mean ± SD) in ileal, caecal and ileo-caecal junction pH drop between patients and controls. Caecal pH significantly lower in patients than in controls and pH drop across the ICJ was lower in patients than in controls. bP < 0.01 vs patients group. ICJ: Ileo-caecal junction.

Figure 3

Caecal pH and caecal contractility was positively correlated (r = 0.54, P = 0.002). AUC: Area under the curve.