Esophageal function testing 3.docx
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Esophageal function testing 3.docx
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Esophagealfunctiontesting3
AmJPhysiolGastrointestLiverPhysiol,Vol.280,Issue3,G457-G462,March2001
Esophagealfunctiontestingusingmultichannelintraluminalimpedance
R.Srinivasan,M.F.Vela,P.O.Katz,R.Tutuian,J.A.Castell,andD.O.
ABSTRACT
Multichannelintraluminalimpedance(MII)isanewtechniqueforevaluationofbolustransport.Weevaluatedesophagealfunctionusingbolustransporttime(BTT)andcontractionwavevelocity(CWV)ofliquid,semisolid,andsolidboluses.TenhealthysubjectsunderwentMIIswallowevaluationwithvariousbolusesofsterilewater(pH5),applesauce,threedifferentsizedmarshmallows,andicedand130°Fwater.Theeffectofbethanecholwasalsostudied.TherewasnodifferenceinBTTorCWVforallwatervolumesfrom1 to20 ml.TherewassignificantlinearincreaseofBTTwithprogressivelylargervolumesofapplesauce,andBTTofapplesaucewaslongerthanforwater.BTTwassignificantlylongerwithlargemarshmallowsvs.smallandmediumandwaslongerthanforwater.BTTforicedwaterwassimilarto130°Fwater.ApplesauceshowedasignificantlineardecreaseofCWVwithprogressivelylargervolumesandwasslowerthanwater.MarshmallowshowedsignificantlyslowerCWVwiththelargevs.small,andCWVforicewaterwassignificantlyslowerthan130°Fwater.Therefore,BTTofliquidisconstant,whereasBTTofsemisolidandsolidarevolumedependentandlongerthanliquids.CWVofsemisolidsandsolidsareslowerthanliquids.CWVofcoldliquidsisslowerthanwarmliquids.MIIcanbeusedasadiscriminatingtestofesophagealfunction.
motility;manometry;esophagealcontraction
INTRODUCTION
ESOPHAGEALFUNCTIONHASBEENstudiedusingvarioustechnologies.Currently,manometryisthegoldstandardinevaluatingesophagealmotility.However,itislimitedtoonlythecontractilepatternsoftheesophagus(18).Pressurewavesofadequateamplitudeandsequenceofcontractionsensurethatthebolusiseffectivelysweptthroughtheesophagus.However,weakercontractions(<30mmHg)arelikelytobeineffectiveforbolusmovement(4).Sincebolustransportcannotbeevaluatedbyesophagealmanometry,otherproceduresarenecessarytodeterminebolusmovementthroughtheesophagus.Scintigraphyandvideofluoroscopyarebothnoninvasiveproceduresthathavebeenusedtocomplimentesophagealmanometrybyvisualizingthetransitofthebolus.However,thesetechniquesarelimitedbyaccesstospecializedlaboratoriesandbyradiationexposure.Ultrafastcomputerizedtomographydynamicallyimagesthecomposition,distribution,andpropulsionofesophagealcontentsduringswallowing(14).Thistechnologyislimitedbytheeconomicandlogisticfactorsoftheequipmentalongwiththecomplexnatureofthemethodologyandinterpretationofresults.
Multichannelintraluminalimpedance(MII)isanewtechniquethathasbeenusedtoevaluatebolustransportandgastroesophagealreflux;however,itsroleinesophagealfunctiontestinghasnotbeenwellstudied.Inthisexperiment,weaimedtoevaluateesophagealfunctionviabolustransporttime(BTT)andcontractionwavevelocity(CWV)ofvariousboluseshavingdifferentcharacteristics:
liquid,semisolid,andsolidboluses,pH2-8,temperature35-130°F,volume1-20ml,andsize12-30mm.Also,wechallengedtheesophaguswithbethanecholtoseeifMIIcouldbeusedasadiscriminatingesophagealfunctiontest.
METHODS
TOP
ABSTRACT
INTRODUCTION
METHODS
RESULTS
DISCUSSION
REFERENCES
Subjects.Ten(5 males,5 females)healthysubjectswithameanageof34 yr(range22-51yr)hadtheimpedanceprobe(SandhillTechnologies)placedtransnasally,withthe2-cmrecordingsegmentslocatedat2, 4, 6, 8, 14, and20 cmabovetheproximalborderofloweresophagealsphincter,previouslydeterminedbymanometry.Upperesophagealsphincterlocationwasnotdetermined,andthereforeintersphincterlengthforthestudysubjectswasnotknown.However,sincethemostproximalimpedanceelectrodewasplaced20 cmabovetheloweresophagealsphincter,weareconfidentthatsubjectsaccommodatedallsixrecordingsitesonthebasisofpriorstudiesperformedbyourgroupshowingthatnormalesophageallengthis22.9 ± 0.2 cm(23.6 ± 0.3 formalesand22.4 ± 0.3 forfemales)(10a).
Allsubjectswerefastingfor6 h,werefreeofesophagealsymptoms,andwerenottakinganymedication.ThestudywasapprovedanddeemedethicalbytheGraduateHospitalInternalReviewBoard,andwrittenconsentwasobtainedfromallsubjects.
MII.Recently,MIIhasbeenintroducedasanewtechniquetostudyesophagealmotilityandbolustransport(16).Impedanceistheaverageelectricalresistancebetweentwoadjacentelectrodesandismeasuredusingaspecializedcatheter(Fig.1)witha2.1-mmdiameterconsistingofnineelectrodesthatmakeupsixmeasuringsegments,each2 cminlength.Theintraluminalelectricalimpedancebetweenthetwoelectrodesisinverselyproportionaltotheelectricalconductivityoftheluminalcontentsandthecross-sectionalarea.Ifahighlyconductivebolusarrivesatthemeasuringsegment(i.e.,saliva),impedancewilldecrease,andtheoppositewilloccurwitharesistivebolus(i.e.,air).Also,increasingtheluminaldiameter(i.e.,arrivalofbolusintothemeasuringsegment)resultsinanimpedancedrop,whereasaluminalnarrowing(i.e.,contractionwave)causesanimpedanceincrease(16).Therefore,MIIcanevaluateesophagealmotilityalongwithassessingbolustransportthroughouttheentireesophagusinrealtimewithouttheuseofradiation.
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Fig.1. Thisschematicrepresentationshowsthelocationofthe6 measuringsegments[cmabovetheloweresophagealsphincter(LES)],whichare2 cminlength.Thecatheterconsistsof9 stainlesssteelformulatedrings,andimpedance(theoppositiontocurrentflow)iscalculatedbetween2 adjacentelectrodes.
Withtheprinciplesofimpedanceinmind,onecanunderstandthecharacteristicpatternproducedbyabolusswallow(Fig.2).Theesophagusstartsatarestingvalue(Fig.2A)thatrepresentsthecollapsedesophagealwallsonthecatheter.Whenaswallowisinitiated,airisalsoswallowed.Airseparatesfromthebolusandentersthemeasuringsegmentfirst,causinganincreaseinimpedance(Fig.2B).Afterthepassageofair,theactualboluscausesasharpdecreaseinimpedanceduetoitsconductivityanditseffectonluminaldilatation.Thebolusenters,traverses,andexitsthemeasuringsegment(Fig.2,C,D,andE,respectively).Afterthepassageofthebolus,thelumen-occludingcontraction(Fig.2F)causesanincreaseinimpedance.Ifthecontractionwavecompletelyclearsthebolusfromthesegment,areturntotheoriginalimpedancebaselineisseen(Fig.2G).Ifareturnisnotseen,onecanassumethatthebolushasnotbeensuccessfullypropagatedthroughthatsegment.Quantifyingtheintraluminalvolumewithimpedanceiscurrentlyunderinvestigation.
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Fig.2. Impedancechangesduetobolustransit.Theesophagusstartsatarestingimpedancevalue(A)thatrepresentsthecollapsedesophagealwallsonthecatheter.Whenaswallowisinitiated,airisalsoswallowed.Airseparatesfromthebolusandentersthemeasuringsegmentfirst,causinganincreaseinimpedance(B).Afterthepassageofair,theactualboluscausesasharpdecreaseinimpedanceduetoitsconductivityanditseffectonluminaldilatation.Thebolusenters,traverses,andexitsthemeasuringsegment(C,D,andE,respectively).Afterthepassageofthebolus,thelumen-occludingcontraction(F)causesanincreaseinimpedance.Ifthecontractionwavecompletelyclearsthebolusfromthesegment,areturntotheoriginalimpedancebaselineisseen(G).
TheusefulnessofMIIinthestudyofesophagealmotilityhasbeensuccessfullyverifiedincomparativestudieswithvolunteerswiththeuseofmanometryandfluoroscopy.Thecontractionwaveasseenonimpedance(Fig.2F)iscorrelatedwiththemaximalpressureproducedduringsimultaneousmanometry,andthebolusentry,transit,andexit(Fig.2,C-E)withrespecttothemeasuringsegmenthavebeencorrelatedwithsimultaneousbariumswallow(12,17).
Studydesign.Differentboluseswithvaryingconsistencies(liquid,semisolid,andsolid)andcharacteristics(pHandtemperature)wereadministeredatdifferentvolumes(1-20ml)andsizes(12-30mm)whilethesubjectwasrecumbent.Sevencategoriesofbolusweretested:
1)sterilewater,pH5, roomtemperature,2)sterilewater,pH2, roomtemperature,3)sterilewater,pH8, roomtemperature,4)sterilewater,pH5, iced,5)sterilewater,pH5, 130°F,6)applesauce(Mott's),and7)marshmallow(Jet-Puffed).SolutionsofpH2 andpH8 weremadebyadding1 NHCl(FisherScientific)or5 NNaOH(Titristar),respectively,tosterilewaterdropwiseduringtitrationwithacalibratedpHmeter(Corning215).ThepHofallsolutionswasverifiedbeforeeachsubjectstudy.Temperatureof130°Fwasmaintainedusingaconstantwaterbath(Precision181).Icedsolutionswerepreparedbyplacingtwoicecubesmadefromsterilewaterinthe100-mlsolution.Thesolutionwasallowedtocoolfor15 mintogainappropriatetemperaturebeforeuse.Icecubeswerealwayspresentinthesolution,keepingthetemperatureapproximatelyinarangeof35-45°F.
Typeofbolusadministeredwasrandomizedbyallowingthesubjecttoblindlydrawfromaboxthatcontainedpiecesofpaperwithallofthecategorynumbers.Accordingtothecategoryselected,themethodologywasdifferent.Aftercompletionofthecategory,thesubjectth
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