Background: Currently, there are no high-resolution impedance manometry (HRIM)-based diagnostic criteria for non-obstructive dysphagia (NOD). New impedance parameters, such as the esophageal impedance integral (EII) and volume of inverted impedance (VII) ratios, have shown strong correlations with bolus transit. This study compared the EII and VII ratios as diagnostic tools for NOD.
Methods: We analyzed 36 participants (12 patients with achalasia, 12 patients with NOD [7 with normal motility and 5 with ineffective esophageal motility], and 12 asymptomatic controls) who underwent HRIM with a maximum of 5 swallows per participant. The EII and VII ratios were calculated as Z2 (post-swallow)/Z1 (pre-swallow). Bolus transit was retrospectively evaluated using transluminal impedance analysis.
Key results: Both EII and VII ratios could effectively distinguish the achalasia group from the non-achalasia groups (area under the receiver operating characteristic curve [AUROC]: 0.83 for VII vs. 0.80 for EII; p = 0.73). However, the VII ratio was significantly better in discriminating asymptomatic controls from patients with dysphagia (NOD + achalasia) (AUROC: 0.81 vs. 0.68; p = 0.01). Moreover, the VII ratio was better in discriminating asymptomatic controls from patients with NOD (AUROC: 0.68 vs. 0.51; p = 0.06). In repeated swallows, the VII ratio was consistently the lowest in controls and the highest in patients with achalasia, whereas the EII ratio did not show a consistent pattern.
Conclusions & inferences: The VII ratio was more reliable than the EII ratio for describing bolus transit and distinguishing patients with NOD from asymptomatic controls, even during repeated measures of subsequent swallows.
Keywords: esophageal impedance integral ratio; high-resolution impedance manometry; non-obstructive dysphagia; volume of inverted impedance ratio.
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