Reviews for Primary Care - Fall 2007 - (Page 60) GERD Symptoms on Antisecretory Therapy continued efficacious method for on therapy pH monitoring. The Bravo capsule offers the convenience mentioned previously and allows efficiency as it can be placed at the time of endoscopic evaluation (or transorally if the squamocolumnar line is known). One study has documented improved detection of symptoms by having a second day of monitoring and added sensitivity and specificity of the symptom association probability.42 In our experience discordance between day 1 and day 2 interpretation (normal day 1, abnormal day 2) is seen even when patients are on therapy, making overall interpretation somewhat complex.43 If Bravo is the only monitoring device available, the decision is easy; it should be placed at the time of endoscopy. In addition, the telemetry capsule is ideal for monitoring acid control in Barrett’s patients; it gives reliable 48-hour data and in my experience can be attached in the columnar lining at any level above the top of the gastric folds.44 The limitation of the technique is its inability to monitor patients at multiple levels Figure 6. Preliminary report of results of impedance/pH study in patients with refractory gastroesophageal reflux disease symptoms on antisecretory therapy. Data from Katz P et al32 and Mainie I et al.33 81 patients Symptoms 71 (88%) No symptoms 10 (12%) Non-acid reflux 22 (30%) Acid reflux 8 (11%) Symptoms not associated with reflux 41 (59%) Figure 5. Multichannel intraluminal impedance (MII) combined with pH monitoring. LES, lower esophageal sphincter. MII-pH catheter Impedance 17 cm 15 cm 9 cm 7 cm 5 cm 3 cm 5 cm esophageal pH LES Gastric pH in the esophagus simultaneously (technical issues and costs), to perform intragastric pH monitoring, and to detect non–acid reflux. Monitoring at multiple levels and intragastric pH monitoring is of value in limited situations. The detection of non–acid reflux requires impedance technology. Multichannel intraluminal impedance combined with pH monitoring (Figure 5) offers the opportunity to simultaneously evaluate intragastric/ intraesophageal pH, determine if non–acid reflux (impedance detected reflux with pH 4) is present, and to assess height of refluxate. The catheter is identical in diameter to a traditional transnasal pH catheter. Preliminary data from 2 laboratories, reporting on over 200 patients32,33 studied on high-dose antisecretory therapy (PPI twice daily with or without H2RA at bedtime), reveal that a potentially important number of patients had a positive association with so-called non–acid reflux, a small number continued acidrelated symptoms, and the majority had no acid or non–acid reflux correlated symptoms (Figure 6). Close to 90% demonstrate normal numbers of reflux episode, suggesting that the residual symptoms are due to hypersensitivity to physiologic amounts of reflux.32 The most common symptoms associated with non–acid reflux are regurgitation and heartburn, with few patients having non–acid reflux associated with extraesophageal symptoms (Figure 7). The technology is limited by the need for transnasal catheter (not an issue in our laboratory), and a learning curve for study interpretation. Of greatest importance is the lack of outcomes studies demonstrating the clinical importance of non–acid reflux. Uncontrolled observation from my practice suggests baclofen may be useful, particularly in the postprandial period.45 I believe agents with anticholinergic properties (such as imipramine) might be useful, either for reducing sensitivity46 or perhaps “decreasing” transient relaxations.47 Two preliminary studies report success with fundoplication in these patients; however, follow-up was short. My experience is that patients with regurgitation-associated non–acid reflux do well with surgery48,49 and are therefore surgical candidates, if continued reflux can be documented. Many of the decisions regarding whether to perform 48-hour monitoring with Bravo or impedance/pH have to be individualized. Patients who have been treated with twicedaily PPI plus H2RA at bedtime rarely have continued acid reflux, so I routinely perform impedance/pH to evaluate this group. Patients with regurgitation also are most often evaluated with impedance/pH on therapy, as 60 VOL. 1 NO. 1 2007 REVIEWS FOR PRIMARY CARE
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