Esophageal function testing 3.docx

1、Esophageal function testing 3Am J Physiol Gastrointest Liver Physiol, Vol. 280, Issue 3, G457-G462, March 2001Esophageal function testing using multichannel intraluminal impedance R. Srinivasan, M. F. Vela, P. O. Katz, R. Tutuian, J. A. Castell, and D. O.ABSTRACTMultichannel intraluminal impedance (

2、MII) is a new technique for evaluation of bolus transport. We evaluated esophageal function using bolus transport time (BTT) and contraction wave velocity (CWV) of liquid, semisolid, and solid boluses. Ten healthy subjects underwent MII swallow evaluation with various boluses of sterile water (pH 5)

3、, applesauce, three different sized marshmallows, and iced and 130F water. The effect of bethanechol was also studied. There was no difference in BTT or CWV for all water volumes from 1to 20ml. There was significant linear increase of BTT with progressively larger volumes of applesauce, and BTT of a

4、pplesauce was longer than for water. BTT was significantly longer with large marshmallows vs. small and medium and was longer than for water. BTT for iced water was similar to 130F water. Applesauce showed a significant linear decrease of CWV with progressively larger volumes and was slower than wat

5、er. Marshmallow showed significantly slower CWV with the large vs. small, and CWV for ice water was significantly slower than 130F water. Therefore, BTT of liquid is constant, whereas BTT of semisolid and solid are volume dependent and longer than liquids. CWV of semisolids and solids are slower tha

6、n liquids. CWV of cold liquids is slower than warm liquids. MII can be used as a discriminating test of esophageal function. motility; manometry; esophageal contraction INTRODUCTIONESOPHAGEAL FUNCTION HAS BEEN studied using various technologies. Currently, manometry is the gold standard in evaluatin

7、g esophageal motility. However, it is limited to only the contractile patterns of the esophagus (18). Pressure waves of adequate amplitude and sequence of contractions ensure that the bolus is effectively swept through the esophagus. However, weaker contractions (30 mmHg) are likely to be ineffectiv

8、e for bolus movement (4). Since bolus transport cannot be evaluated by esophageal manometry, other procedures are necessary to determine bolus movement through the esophagus. Scintigraphy and videofluoroscopy are both noninvasive procedures that have been used to compliment esophageal manometry by v

9、isualizing the transit of the bolus. However, these techniques are limited by access to specialized laboratories and by radiation exposure. Ultrafast computerized tomography dynamically images the composition, distribution, and propulsion of esophageal contents during swallowing (14). This technolog

10、y is limited by the economic and logistic factors of the equipment along with the complex nature of the methodology and interpretation of results. Multichannel intraluminal impedance (MII) is a new technique that has been used to evaluate bolus transport and gastroesophageal reflux; however, its rol

11、e in esophageal function testing has not been well studied. In this experiment, we aimed to evaluate esophageal function via bolus transport time (BTT) and contraction wave velocity (CWV) of various boluses having different characteristics: liquid, semisolid, and solid boluses, pH 2-8, temperature 3

12、5-130F, volume 1-20 ml, and size 12-30 mm. Also, we challenged the esophagus with bethanechol to see if MII could be used as a discriminating esophageal function test. METHODSTOP ABSTRACT INTRODUCTION METHODS RESULTS DISCUSSION REFERENCES Subjects. Ten (5males, 5females) healthy subjects with a mean

13、 age of 34yr (range 22-51 yr) had the impedance probe (Sandhill Technologies) placed transnasally, with the 2-cm recording segments located at 2,4,6,8,14,and 20cm above the proximal border of lower esophageal sphincter, previously determined by manometry. Upper esophageal sphincter location was not

14、determined, and therefore intersphincter length for the study subjects was not known. However, since the most proximal impedance electrode was placed 20cm above the lower esophageal sphincter, we are confident that subjects accommodated all six recording sites on the basis of prior studies performed

15、 by our group showing that normal esophageal length is 22.90.2cm (23.60.3for males and 22.40.3for females) (10a). All subjects were fasting for 6h, were free of esophageal symptoms, and were not taking any medication. The study was approved and deemed ethical by the Graduate Hospital Internal Review

16、 Board, and written consent was obtained from all subjects. MII. Recently, MII has been introduced as a new technique to study esophageal motility and bolus transport (16). Impedance is the average electrical resistance between two adjacent electrodes and is measured using a specialized catheter (Fi

17、g. 1) with a 2.1-mm diameter consisting of nine electrodes that make up six measuring segments, each 2cm in length. The intraluminal electrical impedance between the two electrodes is inversely proportional to the electrical conductivity of the luminal contents and the cross-sectional area. If a hig

18、hly conductive bolus arrives at the measuring segment (i.e., saliva), impedance will decrease, and the opposite will occur with a resistive bolus (i.e., air). Also, increasing the luminal diameter (i.e., arrival of bolus into the measuring segment) results in an impedance drop, whereas a luminal nar

19、rowing (i.e., contraction wave) causes an impedance increase (16). Therefore, MII can evaluate esophageal motility along with assessing bolus transport throughout the entire esophagus in real time without the use of radiation. View larger version (11K): in this window in a new window Fig. 1. This sc

20、hematic representation shows the location of the 6measuring segments cm above the lower esophageal sphincter (LES), which are 2cm in length. The catheter consists of 9stainless steel formulated rings, and impedance (the opposition to current flow) is calculated between 2adjacent electrodes. With the

21、 principles of impedance in mind, one can understand the characteristic pattern produced by a bolus swallow (Fig. 2). The esophagus starts at a resting value (Fig. 2A) that represents the collapsed esophageal walls on the catheter. When a swallow is initiated, air is also swallowed. Air separates fr

22、om the bolus and enters the measuring segment first, causing an increase in impedance (Fig. 2B). After the passage of air, the actual bolus causes a sharp decrease in impedance due to its conductivity and its effect on luminal dilatation. The bolus enters, traverses, and exits the measuring segment

23、(Fig. 2, C, D, and E, respectively). After the passage of the bolus, the lumen-occluding contraction (Fig. 2F) causes an increase in impedance. If the contraction wave completely clears the bolus from the segment, a return to the original impedance baseline is seen (Fig. 2G). If a return is not seen

24、, one can assume that the bolus has not been successfully propagated through that segment. Quantifying the intraluminal volume with impedance is currently under investigation. View larger version (5K): in this window in a new window Fig. 2. Impedance changes due to bolus transit. The esophagus start

25、s at a resting impedance value (A) that represents the collapsed esophageal walls on the catheter. When a swallow is initiated, air is also swallowed. Air separates from the bolus and enters the measuring segment first, causing an increase in impedance (B). After the passage of air, the actual bolus

26、 causes a sharp decrease in impedance due to its conductivity and its effect on luminal dilatation. The bolus enters, traverses, and exits the measuring segment (C, D, and E, respectively). After the passage of the bolus, the lumen-occluding contraction (F) causes an increase in impedance. If the co

27、ntraction wave completely clears the bolus from the segment, a return to the original impedance baseline is seen (G). The usefulness of MII in the study of esophageal motility has been successfully verified in comparative studies with volunteers with the use of manometry and fluoroscopy. The contrac

28、tion wave as seen on impedance (Fig. 2F) is correlated with the maximal pressure produced during simultaneous manometry, and the bolus entry, transit, and exit (Fig. 2, C-E) with respect to the measuring segment have been correlated with simultaneous barium swallow (12, 17). Study design. Different

29、boluses with varying consistencies (liquid, semisolid, and solid) and characteristics (pH and temperature) were administered at different volumes (1-20 ml) and sizes (12-30 mm) while the subject was recumbent. Seven categories of bolus were tested: 1) sterile water, pH 5,room temperature, 2) sterile

30、 water, pH 2,room temperature, 3) sterile water, pH 8,room temperature, 4) sterile water, pH 5,iced, 5) sterile water, pH 5,130F, 6) applesauce (Motts), and 7) marshmallow (Jet-Puffed). Solutions of pH 2and pH 8were made by adding 1N HCl (Fisher Scientific) or 5N NaOH (Titristar), respectively, to s

31、terile water dropwise during titration with a calibrated pH meter (Corning 215). The pH of all solutions was verified before each subject study. Temperature of 130F was maintained using a constant water bath (Precision 181). Iced solutions were prepared by placing two ice cubes made from sterile wat

32、er in the 100-ml solution. The solution was allowed to cool for 15min to gain appropriate temperature before use. Ice cubes were always present in the solution, keeping the temperature approximately in a range of 35-45F. Type of bolus administered was randomized by allowing the subject to blindly draw from a box that contained pieces of paper with all of the category numbers. According to the category selected, the methodology was different. After completion of the category, the subject th