esophageal function testing: role of combined multichannel intraluminal impedance and manometry

15 (2005) 265–275

Esophageal Function Testing: Role of

Combined Multichannel Intraluminal

Impedance and Manometry

Radu Tutuian, MD*, Donald O. Castell, MD

Division of Gastroenterology/Hepatology, Medical University of South Carolina,

96 Jonathan Lucas Street, 210 CSB, Charleston, SC 29425, USA

The Food and Drug Administration approved multichannel intraluminal

impedance (MII) for testing intraesophageal bolus movement in July 2002.

Following this approval, combined multichannel intraluminal impedance and

manometry (MII-EM) became available to evaluate intraesophageal pressures

(EM) and bolus movement (MII) during the same swallow. Recently accumulated

clinical MII-EM data on liquid and viscous swallows have provided more

detailed insights into esophageal function.

Comparison of multichannel intraluminal impedance and manometry with

conventional manometry

Combined MII-EM systems are very similar to conventional manometry

systems, and impedance capabilities should be regarded as an add-on to con-

ventional systems. Impedance measuring segments can be mounted on catheters

that use perfusion or solid-state pressure transducers without changing the

dimension of the catheters. In the authors’ laboratory, a 9-channel MII-EM

catheter (Konigsberg Instruments, Pasadena, California) is used for esophageal

function testing (Fig. 1). This catheter is 4.6 mm in diameter (the same diameter

as conventional manometry catheters) and has five solid-state pressure trans-

ducers located at 5, 10, 15, 20, and 25 cm from the tip of the catheter and

Gastrointest Endoscopy Clin N Am

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* Corresponding author.

E-mail address: [email protected] (R. Tutuian).

Fig. 1. Nine-channel EFT probe positioned with distal transducer in the lower esophageal sphincter

(LES). The catheter contains four impedance-measuring segments (Z-1 through Z-4) and five pressure

transducers, each 5 cm apart. P1, P2, and P3 are unidirectional solid-state transducers; P4 and P5

are circumferential solid-state transducers.

tutuian & castell266

four pairs of metal rings 2 cm apart (impedance measuring segments) centered at

10, 15, 20, and 25 cm from the tip of the catheter, thus straddling the four

proximal pressure transducers. During clinical testing, the catheter is passed

transnasally into the stomach and, using stationary pull-through technique,

repositioned so the distal, circumferential pressure transducer is placed in the

lower esophageal sphincter (LES) high-pressure zone, with the combined

impedance and pressure channels at 5, 10, 15, and 20 cm above the LES.

Patients receive 10 liquid (saline) and 10 viscous (esophageal function testing

viscous; Sandhill Scientific, Highlands Ranch, Colorado) swallows, 5 mL each,

20 to 30 seconds apart. Double swallows are excluded from analysis and are

repeated when detected during acquisition. Pressure and MII data are recorded

by dedicated software (Bioview Acquisition, Sandhill Scientific) and later ana-

lyzed through a computer-based semiautomated program (Bioview Analysis,

Sandhill Scientific).

esophageal function testing: mii-em 267

Swallows are classified [1] by manometry into (1) normal peristaltic (defined

as contraction amplitude at 5 and 10 cm above the LES of at least 30 mm Hg

and onset velocity in the distal esophagus not greater than 8 cm/s), (2) simul-

taneous contractions (defined as contraction with an onset velocity greater than

8 cm/s or retrograde onset and an amplitude N 30 mm Hg at 5 and 10 cm

above the LES), and (3) ineffective contractions (defined as contraction ampli-

tude in the distal part of the esophagus less than 30 mm Hg) (Fig. 2).

Swallows are classified by MII as having (1) complete bolus transit (defined

as detection of bolus exit in all three of the distal MII channels) or (2) incom-

plete bolus transit (defined as absence of bolus exit in any of the three distal

MII channels).

Fig. 2. Manometric classification of swallows. (A) Normal peristaltic (defined as contraction

amplitude in the distal part of the esophagus of at least 30 mm Hg and onset velocity in the distal

esophagus of not more than 8 cm/s). (B) Ineffective contraction (defined as distal onset velocity

of more than 8 cm/s or retrograde onset and a contraction amplitude in the distal part of the esophagus

of at least 30 mm Hg). (C) Simultaneous contraction (defined as contraction amplitude in the distal

part of the esophagus less than 30 mm Hg).

Fig. 2 (continued).


Combining the information from manometry and MII classifies swallows

into one of the six categories: (1) normal peristaltic with complete bolus transit,

(2) normal peristaltic with incomplete bolus transit, (3) simultaneous with com-

plete bolus transit, (4) simultaneous with incomplete bolus transit, (5) ineffective

with complete bolus transit, and (6) ineffective with incomplete bolus transit.

Multichannel intraluminal impedance and manometry studies in healthy

volunteers

Recently, Imam et al [2] presented a study using concurrent videoesopha-

gogram, impedance, and manometry to assess bolus transit in 13 healthy

volunteers. In this study, barium and impedance bolus transit correlated in 97%

(72/74) of swallows.

Fig. 2 (continued).


Normal values for combined MII-EM were established based on the results

of a multicenter study in 43 healthy volunteers [3]. Almost all manometric

normal peristaltic liquid (99.5%) and viscous (97.7%) swallows had complete

bolus transit. For the occasional ‘‘abnormal’’ contractions occurring in these

healthy subjects, all (100%) liquid and more than half (54.5%) of viscous simul-

taneous contractions had complete bolus transit and almost two thirds (61.9%)

of liquid and more than one third (39.1%) of viscous ineffective swallows had

complete bolus transit (Fig. 3).

During these combined MII-EM studies in normal volunteers, criteria for

normal or abnormal bolus transit were established. Normal bolus transit for

liquid was defined as the presence of 80% (8/10) or more swallows with com-

plete bolus transit. Normal bolus transit for viscous was defined as the presence

of 70% (7/10) or more swallows with complete bolus transit. Conversely,

abnormal bolus transit for liquid was defined as the presence of more than

20% (2/10) swallows and abnormal bolus transit for viscous as the presence of

more than 30% (3/10) swallows with incomplete bolus transit. These results

underscore the functional effectiveness of a normal peristaltic progression and

raise the possibility that combined MII-EM may identify which manometrically

abnormal studies are functionally defective.


Multichannel intraluminal impedance and manometry studies in patients

with esophageal motility abnormalities

The indications for combined MII-EM are similar to those for esophageal

manometry: evaluation of patients with dysphagia, noncardiac chest pain, or

heartburn/regurgitation, preoperative evaluation before antireflux surgery or

endoscopic antireflux procedures, and location of the LES before pH cathe-

ter placement.

Currently, for the interpretation of the manometric information, the authors

use criteria published by Spechler and Castell [1]. Achalasia is defined by

absent esophageal body peristalsis and, if present, poorly relaxing LES.

Scleroderma is defined based on an appropriate clinical diagnosis and confirmed

by low-amplitude contractions in the distal esophagus with or without a low LES

pressure. Distal esophageal spasm is defined as 20% or more simultaneous

contractions. Ineffective esophageal motility (IEM) is defined as 30% or more

swallows with contraction amplitude less than 30 mm Hg in either of the two

Fig. 3. Information obtained from combined MII-EM studies in patients. MII channels are in the

upper part and manometry channels in the lower part of the tracings. Swallows shown are

(A) manometric normal with complete bolus transit, manometric ineffective with complete (B) or

incomplete (C) bolus transit, and simultaneous with complete (D) or incomplete (E) bolus transit.

Fig.3(continued).



distal sites located at 5 and 10 cm above the LES. Nutcracker esophagus is

defined as normal peristalsis of the esophageal body, with an average distal

esophageal amplitude exceeding 180 mm Hg. Poorly relaxing LES is defined

as average LES residual pressure exceeding 8 mm Hg associated with normal

esophageal body contractions. Hypertensive LES is defined as LES resting

pressure exceeding 45 mm Hg, with normal esophageal body contractions.

Hypotensive LES is defined as LES resting pressure below 10 mm Hg, with

normal esophageal body contractions. Normal esophageal manometry is defined

as not more than 20% ineffective and not more than 10% simultaneous swallows

with distal esophageal amplitude b180 mm Hg and with normal LES resting

and residual pressures.

The overall diagnoses of esophageal transit abnormalities are defined as

normal liquid transit when 80% or more of liquid swallows have complete

bolus transit and normal viscous transit when 70% or more of viscous swallows

have complete bolus transit. Conversely, abnormal liquid transit is declared when

30% or more of liquid swallows have incomplete bolus transit and abnormal

viscous transit is declared when 40% or more of viscous swallows have

incomplete bolus transit.

Combined MII-EM studies in patients referred to the authors’ laboratory

suggest that different bolus transit patterns can be seen in patients with various

manometric diagnoses [4]. As expected, all patients with achalasia and

scleroderma have abnormal bolus transit, proving the principle that MII can

assess bolus transit in patients with these severe esophageal motility abnormali-

ties. On the other hand, almost all (ie, 95% or more) patients with normal

esophageal manometry, nutcracker esophagus, and isolated LES abnormalities

(ie, hypertensive, hypotensive, and poorly relaxing LES) have normal bolus

transit for liquid. In the groups of patients with IEM and distal esophageal spasm,

approximately half of the patients have normal bolus transit. Based on these

observations, it appears that esophageal motility abnormalities can be grouped

(Fig. 4) into pressure-only abnormalities (nutcracker esophagus, hypertensive

LES, hypotensive LES, and poorly relaxing LES) and pressure and transit

abnormalities (achalasia, scleroderma, IEM, distal esophageal spasm) [5].

Fig. 4. Classification of esophageal motility abnormalities using MII-EM.


Another observation from the studies in patients with esophageal motility

abnormalities is that isolated LES abnormalities impair bolus transit only when

esophageal body contractions are weak or nonperistaltic. In other words, a

potential transit defect due to elevated LES pressures (resting or residual) can be

overcome by normal- or high-amplitude peristaltic esophageal body contractions.

A more detailed evaluation of patients with IEM reveals the ability of

combined MII-EM to clarify the functional defect in this group of patients. A

recently published study in 70 IEM patients indicates that the distal esophageal

amplitude of contraction and the number of distal esophageal sites where

amplitudes less than 30 mm Hg are recorded are predictors for complete bolus

transit of individual swallows. Overall, patients with an increased number of

manometric ineffective swallows are more likely to have abnormal bolus transit

compared with those having only a few manometric ineffective swallows [6].

Imam et al [7] recently presented provocative data from patients with post–

fundoplication dysphagia. Using concurrent barium esophagogram, impedance,

and manometry measurements in five patients with dysphagia after fundoplica-

tion, the investigators identified 29 of 32 swallows with normal bolus transit to

the distal esophagus where the barium accumulated and showed retrograde

escape in 26 of 29 swallows. This phenomenon was identified on barium

esophagogram and impedance tracings and occurred despite manometric

contractions above 50 mm Hg. These preliminary data suggest that combined

MII-EM studies can detect events that would otherwise not be observed during

conventional manometry.

Outcome-based studies are needed to establish the prognostic values of com-

bined MII-EM and to establish the clinical utility of the additional information

obtained with this form of testing. These outcome studies are necessary to

evaluate whether combined MII-EM is superior to traditional manometry in

evaluating patients with nonobstructive dysphagia and in identifying patients

at risk for developing dysphagia after antireflux surgery.

References

[1] Spechler SJ, Castell DO. Classification of oesophageal motility abnormalities. Gut 2001;49:

145–51.

[2] Imam H, Baker M, Shay SS. Concurrent video-esophagogram, impedance monitoring and

manometry in the assessment of bolus transit in normal subject. Gastroenterology 2004;

126(Suppl 2):A638.

[3] Tutuian R, Vela MF, Balaji NS, et al. Esophageal function testing using combined multichan-

nel intraluminal impedance and manometry. Multicenter study of 43 healthy volunteers. Clin

Gastroenterol Hepatol 2003;1:174–82.

[4] Tutuian R, Castell DO. Combined multichannel intraluminal impedance and manometry

clarifies esophageal function abnormalities. Study in 350 patients. Am J Gastroenterol 2004;99:

1011–9.

[5] Tutuian R, Vela MF, Shay SS. Esopageal function testing and gastroesophageal reflux

testing using multichannel intraluminal impedance. In: Castell DO, Richter JE, editors. The

esophagus. 4th edition. New York7 Lippincot Williams and Wilkins; 2004. p. 155–64.


[6] Tutuian R, Castell DO. Clarification of the esophageal function defect in patients with

manometric ineffective esophageal motility. Clin Gastroenterol Hepatol 2004;2:230–6.

[7] Imam H, Baker M, Shay SS. Simultaneous barium esophagogram (Ba), impedance monitoring

(Imp) and manometry (Ba-Imp-Manometry) in patients with dysphagia due to a tight

fundoplication. Gastroenterology 2004;126(Suppl 2):A639.

esophageal function testing: role of combined multichannel intraluminal impedance and manometry

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