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Dx-1 – A New Device for Detecting Supraesophageal Gastric Reflux (SEGR)

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Wiener, G. J. M.D., F.A.C.P.; Bankert, C. S. M.S.; Kelly, C. Ph.D.; Fisk, L. B.A.; Schmeltzer, M. R.N.; Wolf, E. H. B.S.; Tsukashima, R. B.S.

American Journal of Gastroenterology: September 2005 - Volume 100 - Issue - p S26
Supplement Abstracts Submitted for the 70th Annual Scientific Meeting of the American College of Gastroenterology: ESOPHAGUS
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Gastroenterology, Digestive Diseases, Chula Vista, CA; Medical Device, Respiratory Technology Corporation, San Diego, CA and Mathematics, San Diego State University, San Diego, CA.

Purpose: Clinical and animal data have documented deleterious effects of acid pH < 4 (AGR) and weakly acid pH 4–7 (WAGR) gastroesophageal reflux, even in small amounts, when above the UES. Despite recognition of multiple manifestations of SEGR, characterization, identification and response to therapy have evaded understanding due to lack of a suitable detection device.

Aim: Evaluate the Dx-1 minimally invasive catheter utilizing an auto-bridging ionic flow pH sensor, designed to work in the posterior oropharynx, for detection of SEGR, using standard 24hr triple sensor pH catheter(24pH) for verification.

Methods: Patients in a GI practice (GW) with chronic symptoms likely due to SEGR, off reflux meds 4–7days, underwent 24pH with 2 esophageal (E) and 1 pharyngeal (P) sensor (Sandhill PHI10-V) positioned with the LES Indicator at 5 cm > LES, 5 cm < UES and 1 cm > UES. The 1.5 mm nasopharyngeal catheter (Dx1-ResTech) was placed at the oropharynx behind the uvula, above patient's discomfort position. Tracings from all 4 synchronized pH inputs & patient diary were analyzed graphically on a single screen, excluding meals +5 min. SEGR event definition: rapid pH drops at the Dx-1 sensor, >3 S.D. from 60 sec baseline, sequential to drops in pH<4 in 24 pH sensors, then classified as AGR/WAGR. S.I. <50%:+.

Results: 8 Patients, 1M, 7F, avg. age 64 (49–75): 6 cough, 1 loss enamel, 1 sleep apnea/cough, 4 had normal 24pH. There were 14 Dx-1 SEGR events in 6 pts, one AGR (pH 3.5), and 13 (93%) WAGR (pH 4.5–6.5, avg = 5.7) Dx-1 events were near vertical, gradual return to baseline & synchronous to E pH drops (low E: 11 AGR & 3 WAGR; P: 7 AGR & 7 WAGR). These 14 SEGR events were 4.3% of # pH<4 episodes at the lower E (329). Seven P events didn't reach the Dx-1, 6 in 1 pt where P sensor possibly misplaced distal to UES. The avg pH values increased 43% from E to P, 21% from P to Dx-1. S.I.+ 83% at E, 33% at Mid E, 0 at P/6pts.

Conclusions: (A) SEGR exists in the oropharynx, detectable by Dx1. (B) There is a gradient of increasing pH from E to oropharynx, the latter rarely <4.

(C) Redefinition of significant pH events above the UES as% or >3 S.D. pH drops merits consideration; further Dx-1 studies should aid understanding SEGR.

© The American College of Gastroenterology 2005. All Rights Reserved.