Introduction Many patients present to gastroenterology services with multiple upper GI symptoms. Complaints of postprandial retrosternal/epigastric discomfort with regurgitation are common and can suggest gastro-oesophageal reflux disease, gastroparesis, or both. Disentangling the differentials can be difficult on clinical history alone. The need for several tests to exclude each diagnosis has cost and time implications for clinicians and patients.

It is known that intragastric pH rises from a baseline of ~1 to a median of 4.5 during a meal, and gradually returns to fasting-state as the buffer (i.e. ingested food) leaves the stomach (Gardner et al, 2002). We aimed to establish if reflux monitoring, where intragastric pH is recorded routinely, could also detect longer periods of high pH postprandially in subjects with confirmed gastroparesis compared to those with normal gastric emptying.

Methods From our database of patients seen in our tertiary referral GI physiology unit, we identified patients with confirmed delayed gastric emptying on ¹³C-octanoic acid breath test from 2009–2015 who had also undergone 24 hour reflux monitoring off PPI (pH-only or combined pH-impedance). Another group of symptomatic patients with normal gastric emptying times on breath test, who also had reflux monitoring, were identified as controls. We interrogated reflux monitoring traces for baseline fasted pH, then measured the time taken for intragastric pH to return to baseline from the end of self-reported mealtimes. Median times for return of postprandial intragastric pH to baseline were compared between groups.

Results 80 eligible patients with gastroparesis (54 female; age range 13 to 84 years, median 42 years) were identified and compared with 20 subjects with normal gastric emptying times (12 female; age range 14 to 70 years, median 42 years). Median baseline fasting intragastric pH in both groups was 1.3. The median duration for postprandial intragastric pH to return to baseline for the gastroparesis group was 118 minutes (95% CI: 109–153 min) compared to 42.5 min for the control group (95% CI: 36–68 min). The difference between the two groups was extremely significant (two-tailed p < 0.0001).

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Abstract OC-082 Figure 1

Conclusion Intragastric pH is elevated for longer periods postprandially in patients with gastroparesis. The intragastric pH data readily captured on reflux monitoring shows promise as an alternative modality for identifying gastroparesis. To evaluate this hypothesis, a prospective study where ¹³ C-octanoic acid breath testing using standardised meals is performed with concurrent reflux monitoring is currently underway at our unit.

Disclosure of Interest J. Ooi: None Declared, G. Amarasinghe: None Declared, K. Nikaki: None Declared, S. Gabieta-Sonmez: None Declared, E. Yazaki: None Declared, D. Sifrim Grant/research support from: Reckitt Benckiser, Hull, UK; Sandhill Scientific, Colorado, USA, P. Woodland Grant/research support from: Reckitt Benckiser, Hull, UK