The Esophagus. Группа авторов

or had significant dysphagia and/or passage disturbance on barium esophagram. The study showed that a combination of delayed bolus transit, dysphagia, and compartmentalized pressurization had the highest predictive value for identifying clinically relevant EGJOO (sensitivity, 90%; specificity, 92.5%; negative predictive value, 99.3%). Thus, we can infer that bolus transit measured using an impedance test might be a significant variable for differentiating between clinically relevant EGJOO and non‐clinically relevant EGJOO [77].

Figure 9.6 Definitions of impedance parameters. (A) Total bolus transit time (TBTT) as time elapsed between bolus entry at 20 cm above lower esophageal sphincter (LES) and bolus exit at 5 cm above LES. (B) Bolus head advance time as time elapsed between bolus entry at 20 cm above LES and bolus entry at 15, 10, and 5 cm above LES. (C) Bolus presence time (BPT) as time elapsed between bolus entry and bolus exit at each impedance measuring site (5, 10, 15, and 20 cm above LES). (D) Segmental transit time (STT) as time elapsed between bolus entry at a given level above LES and bolus exit at the next lower level.

Combined MII‐EM in belching and rumination

Impedance has shown its ability to detect the movement of gas within the esophageal lumen as a high‐impedance signal, and intraluminal impedance has allowed for better characterization of belching. Two distinct patterns of belching have been described by using intraluminal impedance: aerophagia resulting in air moving into the stomach and then being expelled (gastric belching); and a second in which air rapidly enters the esophagus and is immediately expelled without reaching the stomach (supragastric belching) [39]. Interestingly, the frequency of gastric belching is similar in patients with excessive belching and healthy volunteers. This suggests that in the majority of patients, markedly excessive belching is likely related to supragastric belching [39]. Identification of supragastric belching with intraluminal impedance has also allowed for the development of effective therapies, most notably baclofen and diaphragmatic breathing [40–42]. Intraluminal impedance monitoring can also be used to diagnose rumination syndrome by finding a large increase in gastric (“R wave”) [43], leading to reversal of the esophagogastric pressure gradient. This is associated with impedance‐detected movement of gastric contents proximally through the esophagus (Figure 9.9). Several studies have subsequently reproduced these findings by administering standard meals during HRIM studies in patients with rumination syndrome [44–47]. This high gastric pressure distinguishes ruminators from patients with gastroesophageal reflux [48]. Further, a recent study suggested that the use of HRIM could not only confirm the diagnosis of rumination syndrome but also be used successfully to give biofeedback with diaphragmatic breathing when the patient is given a solid meal to provoke symptoms [47].

Figure 9.7 Classification of swallows by multichannel intraluminal impedance (MII) criteria. (A) Complete bolus transit if bolus entry is seen at the most proximal site (20 cm above lower esophageal sphincter, LES) and bolus exit points are recorded at all three distal impedance‐measuring sites (i.e. 15, 10, and 5 cm above the LES). (B) Incomplete bolus transit if bolus exit is not identified at any one of the three distal impedance‐measuring sites.

Normal EFT values for impedance parameters were proposed based on the 95th percentile in healthy volunteers (Table 9.1). Impedance parameters define a study as normal if at least 80% of liquid and at least 70% of viscous swallows show complete MII‐detected bolus transit [5]. When using liquid testing substances, a study is considered normal manometrically if it does not contain more than 40% ineffective and 10% simultaneous/premature swallows. It has been suggested that using a viscous swallow rather than a liquid swallow will help to increase the diagnostic yield of intraluminal impedance in the assessment of esophageal bolus clearance. Chen et al. [34] studied 18 patients with dysphagia and 14 healthy controls, and the results showed that viscous bolus transit was more likely to be incomplete among those with a motility abnormality (38% vs. 70%) despite similar measurements with liquids. In another study of 129 patients with non‐obstructive dysphagia and 111 controls, the impedance‐measured viscous bolus clearance among patients with dysphagia was significantly different compared with controls (P = 0.02), whereas no difference was seen using liquid bolus clearance (P = 0.12) [35].

Table 9.1 Normative data of impedance (MII) parameters of esophageal function testing (EFT) for 10 liquid and 10 viscous swallows in 43 healthy volunteers. 95th percentile values can be considered the upper limit of normal for the given parameters.

      Source: Tutuian et al. [5] with permissions of Elsevier.

	Liquid	Viscous
	(n = 429)	(n = 425)
	Median	Percentile	Median	Percentile
		25th	75th	5–95th		25th	75th	5–95th
Bolus head advance time (s)
20–15 cm	0.2	0.1	0.3	0.0–0.7	1.0	0.6	1.5	0.2–2.5
20–10 cm	0.6	0.4	0.9	0.1–1.7	3.3	2.4	4.0	0.9–5.1
20–5 cm	1.3	0.8