Background & Aims: Combined multichannel intraluminal impedance and manometry (MII-EM) assesses esophageal function by simultaneous measurement of both pressure and bolus transit. Normative data for this method have not been published. The aim of this study was to establish normative data for combined MII-EM and to correlate liquid and viscous bolus transit by impedance with esophageal contractions by manometry. Methods: Forty-three normal volunteers recruited from 4 centers (15 women, 28 men; age range, 21-72 years) underwent combined MII-EM with a catheter containing 4 impedance-measuring segments and 4 solid-state pressure transducers. Each center recruited and analyzed subjects independently, according to pre-established criteria. Each subject received 20 x 5 mL swallows, 10 liquid and 10 viscous material. Tracings were analyzed manually for bolus presence time, bolus head advance time, segmental transit times, total bolus transit time, contraction amplitude, duration, and onset velocity. Results: Ninety-seven and four-tenths percent of manometrically normal liquid and 96.1% of manometrically normal viscous swallows had complete bolus transit by impedance. Almost half (47.2%) of manometrically ineffective liquid and 34.7% of ineffective viscous swallows had complete bolus transit, whereas 91.7% of manometric simultaneous liquid swallows and 54.5% of simultaneous viscous swallows had complete bolus transit. More than 93% of normal individuals had at least 80% complete liquid or at least 70% complete viscous bolus transit. Conclusions: This study establishes normative data for combined MII-EM. Combined MII-EM may be a more sensitive tool in assessing esophageal function compared to standard manometry because impedance can distinguish different bolus transit patterns. Studies in patients with manometrically defined esophageal motility abnormalities should help clarify the functional importance of manometric ineffective and simultaneous swallows.
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