Functional Lumen Imaging Probe: Difference between revisions

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{{Short description|Medical exam of the esophagus}}

{{Infobox medical intervention

| Name = Functional Lumen Imaging Probe

| Synonym = FLIP, EndoFlip

| Image =

| Caption =

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'''Functional Lumen Imaging Probe''' ('''FLIP''') is a test used to evaluate the function of the [[esophagus]], by measuring the dimensions of the esophageal lumen using [[electrical impedance|impedance]] [[planimetry]]. Typically performed with sedation during [[upper endoscopy]], FLIP is used to evaluate for [[esophageal motility disorders]], such as [[achalasia]], [[diffuse esophageal spasm]], etc.<ref name=Savarino />

==Procedure==

FLIP is most often performed immediately following upper endoscopy (EGD).<ref name=Savarino /> EGD helps to rule out a mechanical obstruction as a cause for symptoms, and also provides an estimation on the distance from the incisors to the EGJ.<ref name=Savarino />

FLIP uses impedance planimetry to measure the cross sectional area of the esophageal lumen.<ref name=Savarino /> The FLIP device consists of a balloon that encases a catheter with multiple pairs of impedance electrodes. Two catheter configurations are available, which are 8 &nbsp;cm and 16 &nbsp;cm in length. The 8 &nbsp;cm catheter includes 16 sensors spaced 0.5 &nbsp;cm apart, and is used to evaluate esophagogastric junction (EGJ) distensibility and CSA.<ref name=Savarino /> Alternatively, the 16 &nbsp;cm catheter has 16 sensors spaced 1 &nbsp;cm apart, and may be used to evaluate contractility via secondary peristalsis patterns, in addition to evaluating the esophagogastric junction (EGJ).<ref name=Savarino />

Following upper endoscopy, the balloon is inserted into the esophagus and the balloon is distended with a fluid with known properties (e.g. conductivity and volume).<ref name=Savarino /> Each electrode then measuremeasures impedance, and a single pressure sensor at the end of the device measures pressure within the balloon.<ref name=Savarino />

==Results==

The distensibility index (DI) is the most studied and most helpful result obtained with FLIP testing.<ref name=Savarino /> The normal distensibility index (DI) ranges from 3.1 to 9.0 mm2 per mmHg.<ref name=Savarino /> As the balloon is distended, the results of secondary esophageal secondary contractions may be seen via FLIP panometry.<ref name=Savarino /> Possible results may include: repetitive anterograde contractions (a normal finding), repetitive retrograde contractions (abnormal), absent contractility, and other abnormalities.<ref name=Savarino />

==Indications==

FLIP may be used for several indications to evaluate esophageal symptoms, such as dysphagia, chest pain, or regurgitation, or to assess response to treatment. FLIP is used to evaluate for esophageal motility disorders, such as [[achalasia]], [[diffuse esophageal spasm]], etc.<ref name=Savarino>{{cite journal |last1=Savarino |first1=E |last2=di Pietro |first2=M |last3=Bredenoord |first3=AJ |last4=Carlson |first4=DA |last5=Clarke |first5=JO |last6=Khan |first6=A |last7=Vela |first7=MF |last8=Yadlapati |first8=R |last9=Pohl |first9=D |last10=Pandolfino |first10=JE |last11=Roman |first11=S |last12=Gyawali |first12=CP |title=Use of the Functional Lumen Imaging Probe in Clinical Esophagology. |journal=The American Journal of Gastroenterology |date=November 2020 |volume=115 |issue=11 |pages=1786–1796 |doi=10.14309/ajg.0000000000000773 |pmid=33156096|doi-access=free |pmc=9380028 }}</ref> FLIP may be used as a complementary or alternative to esophageal manometry for evaluating esophageal outflow obstructive disorders, including achalasia. FLIP may be used as a complementary test for barium esophagram for evaluating esophageal outflow obstructive disorders. FLIP may be used to assess the effect of treatment for achalasia.{{cn|date=January 2022}}

FLIP is recommended to further evaluate suspected [[esophagogastric junction outflow obstruction]] (EGJOO) where the manometry is normal or borderline.<ref name=Chicago2021>{{cite journal |last1=Yadlapati |first1=R |last2=Kahrilas |first2=PJ |last3=Fox |first3=MR |last4=Bredenoord |first4=AJ |last5=Prakash Gyawali |first5=C |last6=Roman |first6=S |last7=Babaei |first7=A |last8=Mittal |first8=RK |last9=Rommel |first9=N |last10=Savarino |first10=E |last11=Sifrim |first11=D |last12=Smout |first12=A |last13=Vaezi |first13=MF |last14=Zerbib |first14=F |last15=Akiyama |first15=J |last16=Bhatia |first16=S |last17=Bor |first17=S |last18=Carlson |first18=DA |last19=Chen |first19=JW |last20=Cisternas |first20=D |last21=Cock |first21=C |last22=Coss-Adame |first22=E |last23=de Bortoli |first23=N |last24=Defilippi |first24=C |last25=Fass |first25=R |last26=Ghoshal |first26=UC |last27=Gonlachanvit |first27=S |last28=Hani |first28=A |last29=Hebbard |first29=GS |last30=Wook Jung |first30=K |last31=Katz |first31=P |last32=Katzka |first32=DA |last33=Khan |first33=A |last34=Kohn |first34=GP |last35=Lazarescu |first35=A |last36=Lengliner |first36=J |last37=Mittal |first37=SK |last38=Omari |first38=T |last39=Park |first39=MI |last40=Penagini |first40=R |last41=Pohl |first41=D |last42=Richter |first42=JE |last43=Serra |first43=J |last44=Sweis |first44=R |last45=Tack |first45=J |last46=Tatum |first46=RP |last47=Tutuian |first47=R |last48=Vela |first48=MF |last49=Wong |first49=RK |last50=Wu |first50=JC |last51=Xiao |first51=Y |last52=Pandolfino |first52=JE |title=Esophageal motility disorders on high-resolution manometry: Chicago classification version 4.0^©. |journal=Neurogastroenterology and Motility |date=January 2021 |volume=33 |issue=1 |pages=e14058 |doi=10.1111/nmo.14058 |pmid=33373111|pmc=8034247 |hdl=2027.42/163962 |url=https://lirias.kuleuven.be/bitstream/123456789/667141/2/Chicago%204.0%20NMO%202020.pdf }}</ref> FLIP measurements may be used to guide intraoperative reflux surgery, or to assess the degree of fibrostenotic disease from eosinophilic esophagitis.<ref name=Savarino /><ref name=Hirano>{{cite journal |last1=Hirano |first1=I |last2=Pandolfino |first2=JE |last3=Boeckxstaens |first3=GE |title=Functional Lumen Imaging Probe for the Management of Esophageal Disorders: Expert Review From the Clinical Practice Updates Committee of the AGA Institute. |journal=Clinical Gastroenterology and Hepatology |date=March 2017 |volume=15 |issue=3 |pages=325–334 |doi=10.1016/j.cgh.2016.10.022 |pmid=28212976|pmc=5757507 }}</ref> FLIP may be used to guide endoscopic dilation of esophageal strictures.<ref name=Savarino />

While recommendations exist for its use, the evidence supporting the use of FLIP is of very low quality and further research would be useful in more clearly defining its role.<ref>{{cite journal |last1=Massey |first1=BT |title=Clinical Functional Lumen Imaging Probe Testing in Esophageal Disorders: A Need for Better Quality Evidence. |journal=The American Journal of Gastroenterology |date=November 2020 |volume=115 |issue=11 |pages=1799–1801 |doi=10.14309/ajg.0000000000000974 |pmid=33156098|s2cid=222280716 }}</ref><ref>{{cite journal |last1=Massey |first1=BT |title=Flip Technology for Assessing Esophageal Structural and Motor Disorders: a Skeptic's View. |journal=Current Gastroenterology Reports |date=10 July 2020 |volume=22 |issue=9 |pages=44 |doi=10.1007/s11894-020-00782-2 |pmid=32651682|s2cid=220462184 }}</ref>

==History==

Early development of impedance planimetry for evaluating the gastrointestinal tract began in the 1980s.<ref name=Gregersen>{{cite journal |last1=Gregersen |first1=H |last2=Lo |first2=KM |title=What Is the Future of Impedance Planimetry in Gastroenterology? |journal=Journal of Neurogastroenterology and Motility |date=30 April 2018 |volume=24 |issue=2 |pages=166–181 |doi=10.5056/jnm18013 |pmid=29605974|pmc=5885717 |doi-access=free }}</ref> FLIP was first developed with a short balloon catheter, which measures distension across the esophagogastric junction.<ref name=DeVault /> A second generation device was later released, which measures secondary peristalsis proximal to the EGJ.<ref name=DeVault>{{cite journal |last1=DeVault |first1=KR |title=Functional luminal imaging probe: an evolving technology for the diagnosis of esophageal motility disorders. |journal=Gastrointestinal Endoscopy |date=December 2019 |volume=90 |issue=6 |pages=924–925 |doi=10.1016/j.gie.2019.08.025 |pmid=31759418|doi-access=free }}</ref>