Esophageal function testing 3.docx

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