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The gold standard for diagnosis of GERD
 

The gold standard for diagnosis of GERD

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  • Subgroups of Endoscopy-Negative reflux disease (ENRD)2 distinctive subgroups exist- Nonerosive reflux disease (NERD) Functional heartburnThese groups are separated by the presence or absence of abnormal levels of acid reflux.
  • Strong correlation in esophageal acid exposure between 2 systemsCFS under recorded acid exposure

The gold standard for diagnosis of GERD The gold standard for diagnosis of GERD Presentation Transcript

  • Gold standard for the diagnosis of GERD Samir Haffar M.D. Assistant Professor of Gastroenterology Al-Mouassat University Hospital – Damascus – Syria
  • The reflux pyramid
  • Diagnosis of GERD • History • PPI trial • UGI endoscopy (LA classification) • 24 hour pH monitoring • Bravo capsule • Combined MII & pH monitoring (MII- pH) • Bilitec (alkaline reflux)
  • 24 hours pH monitoring
  • Ideal pH electrode “No single probe meets all of these criteria” • Small • Firm enough • Rapid response time between pH 7 to pH 1 • Minimally affected by temperature • No hysteresis effect • No drift during 24 hours • Inexpensive • Simple to calibrate or disposable
  • Location of the LES • Manometric localization • pH step-up method Sudden rise to pH > 4 • LES locator Prior to pH • Fluoroscopic techniques Not accurate • Endoscopic technique Not accurate Reference method
  • Sites of 24 hour pH monitoring • Single monitoring site: 5 cm above LES • Multiple monitoring sites: 5 & 20 cm above LES • One in esophagus & one in proximal stomach (NAB*) • One or more in esophagus & another in hyopharynx * NAB: Nocturnal Acid Breakthrough
  • Typical monitoring sites of 5 & 20 cm above manometrically determined LES
  • Why 5 cm above LES ? • Has been standard for many years • Chosen to avoid catheter migration into the stomach • Moving by a 1 cm or two would not change results • Moving it 10 cm above LES miss a number of patients who are identified by the more distal location
  • Why pH < 4? • Defined early in development of the technology • Its choice based on: - Marked difference from normal esophageal pH of 7 - Pepsinogen converted to pepsin at pH 4 - pH < 4 tends to produce symptoms • Some believe that drops in pH that do not reach level of 4.0 still may represent reflux
  • Composite scoring systems Johnson & DeMeester is the most commonly used Percentage of total time pH < 4 Percentage of upright time pH < 4 Percentage of supine time pH < 4 Number of reflux episodes Number of reflux episodes >5 min Longest reflux episode DeMeester score Normal 14,72
  • Normal values of DeMeester’s score 50 healthy volunteers DeMeester TR et al. Ann Surg 1976 ; 184 :459 – 470.
  • Postprandial acid exposure Postprandial acid exposure in the esophagus Some upright reflux Major contribution from postprandial period DeMeester score: 29.3 – Normal < 14.72 (95th percentile)
  • Proximal & distal esophageal pH monitoring
  • Nocturnal acid breakthrough Intragastric pH < 4 for > 1 h overnight during PPI
  • Nocturnal acid breakthrough • Defined arbitrarily as intragastric pH < 4 for > 1 h overnight during PPI administration • Occurs even on twice-daily PPI therapy • Common enough: rule rather than exception • Not without controversy: little to do with reflux • H2RAs at bedtime + PPI bid better than PPI alone?
  • Symptom association • Symptom index ≥ 50% • Symptom sensitivity index: > 10 % • Symptom association probability calculation: 95% • Integrated acidity Simply giving impression of potential association
  • Symptom index Positive if ≥ 50 % Not take into account overall number of reflux episodes
  • Symptom sensitivity index Positive if 10 % Not take into account overall number of symptoms
  • Symptom association probability calculation Positive if 95% • Divides tracing into 2-min segments & looks at whether a symptom & acid present during each 2 min segment • Analysis uses contingency table analysis of 4 possible outcomes for each segment: acid + symptom + acid + symptom – acid – symptom + acid – symptom –
  • Integrated acidity • Integrating the pH & converting it to H+ concentration for each second of an ambulatory tracing • This index continues to be studied Has not been shown to be clinically useful
  • Overall amount of acid exposure & number of reflux episodes are the focus of many studies using ambulatory pH testing Relationship between symptoms & esophageal acid is equally (or perhaps more) important
  • 24 hour pH esophageal monitoring Off & on therapy • Off therapy Uncertainty about diagnosis of reflux Mildest grades of esophagitis: redness - friability Very short segments of BE • On therapy Patient who has failed a therapeutic trial pH probe in esophagus & another in stomach (NAB)
  • 24 hours pH monitoring off therapy • PPI should be stopped for 5 – 7 days • H2RA should be stopped 48 hours before the study • Patient must not use antacids or other OTC medications for duration of the study
  • Percentage of total time pH < 4 Normal values • Off therapy 5 cm above LES 4 – 5.5 % 20 cm above LES 1 % Periods of meals or acidic beverages excluded • On therapy 5 cm above LES 1.6 – 4 % 20 cm above LES ?
  • Indications of esophageal pH recording* • Normal endoscopic findings & reflux symptoms refractory to PPI • Endoscopy-negative patient before surgical anti-reflux repair • Patients suspected to have abnormal reflux after surgery • Refractory reflux in pts with chest pain after cardiac evaluation • Suspected ENT manifestations after failure of 4 weeks of PPI • GERD in an adult onset nonallergic asthma *AGA Medical Position Statement. Gastroenterology 1996 ; 110 : 1981 – 1996.
  • No indications of esophageal pH recording* • Not indicated to detect or verify reflux esophagitis (this is an endoscopic dg) • Not indicated to evaluate „„alkaline reflux‟‟ *AGA Medical Position Statement. Gastroenterology 1996 ; 110 : 1981 – 1996.
  • Abnormal acid exposure time in heartburn Disease Percentage of total time pH < 4 Barrett‟s esophagus 93 % Erosive esophagitis 75 % (in one study) ENRD* NERD* Functional heartburn - SI > 50% - SI < 50% 50 % 100 % 0 % Hypersensitive esophagus Non acid reflux or motor event * ENRD Endoscpic Negative Reflux Disease * NERD Non Erosive Reflux Disease
  • Limitations of esophageal pH monitoring Is it the gold standard? • Normal 24 hr pH in 25% of patients with erosive esophagitis • Some patients with very convincing histories but negative endoscopy & normal pH test • Differences in acid exposure documented between 2 pH probes attached to each other & used simultaneously • Day-to-day variability may be seen with normal pH study in one day & abnormal in another day
  • Bravo capsule (Medtronic)
  • Bravo system (Medtronics) Esophageal Probe 25 x 6 x 5.5 mm Battery pH electrode Suction chamber Radio transmitter Delivery system Receiver 100 x 70 x 30 mm - 165 g
  • Advantages of Bravo capsule • Better tolerance by patients • Fixed position of the capsule • Prolonged monitoring under more physiologic conditions (48 hours)
  • Bravo normal values 50 asymptomatic volunteers
  • Conventional pH vs Bravo capsule Head to head comparison – 40 patients Bruley des Varannes S. Gut 2005 ; 54 ; 1682 – 1686. CPHMS Conventional pH Measurement System CFS Catheter Free System
  • Bravo capsule Causes of under-recording • Data drop-up • Short reflux event not recorded • Reflux events appear shorter
  • Bravo capsule Data drop-out Malfunctions in the electronics or the receiver Interpreted as artifact & not represented in final pH report Improved by 7 cm antenna & use of fiberglass Gastrointest Endoscopy Clin N Am 2005 ; 15 : 307 – 318.
  • Bravo capsule Short reflux events not recorded Bruley des Varannes S. Gut 2005 ; 54 ; 1682 – 1686. CPHMS Conventional pH Measurement System CFS Catheter Free System
  • Bravo capsule Reflux events appear shorter Bruley des Varannes S. Gut 2005 ; 54 ; 1682 – 1686. CPHMS Conventional pH Measurement System CFS Catheter Free System
  • Trouble shooting in Bravo capsule • Severe odynophagia & chest pain (5%) Chest radiography to exclude perforation Viscous lidocaine Endoscopic removal if symptoms continue • Capsule dislodgment • Failure to disloge Endoscopic removal similar to polypectomy
  • Bravo capsule Classic early dislodgement Easily recognized during inspection of pH tracing Sudden prolonged drop in pH represents capsule in stomach Sharp rise as capsule enters small intestine through pylorus Gastrointest Endoscopy Clin N Am 2005 ; 15 : 307 – 318.
  • Endoscopic removal of Bravo capsule Gastrointest Endoscopy Clin N Am 2005 ; 15 : 307 – 318.
  • Normal values of Bravo capsule Pandolfino 1 Portale 2 No of healthy subjects 44 38 % total time pH < 4 2.3 % 95th percentile 5.9 % 5.9 % 1- Pandolfino JE et al. Am J Gastroenterol 2003 ; 98 : 740 - 9. 2- Portale G et al. Gastroenterology 2003 ; 124 : A536. Further validation are required
  • Multiple Intraluminal Impedance (MII)
  • Multiple Intraluminal Impedance (MII) • Relatively new technique developed in early 1990s at Helmholtz Institute in Aachen (Germany) • Silny* provided first description of this technique that assesses intraluminal bolus movement by measuring changes in conductivity of intraluminal content * Silny J. J Gastrointest Motil 1991 ; 3 : 151 – 62.
  • Principle of “MII” • 2 steel rings separated by isolator • Alternating-current generator to apply electrical PD • Circuit can only be closed through electrical charges (ions) contained in structures surrounding the catheter Gastrointest Endoscopy Clin N Am 2005 ; 15 : 257 – 264.
  • Impedance scale Refluxate High conductivity & low impedance Air Low conductivity & high impedance Bremner CG et al. Esophageal disease & testing. Taylor & Francis Group, New York, 1st edition, 2005.
  • Advantages of MII • Content of refluxate Liquid - Gas - Mixed • Direction of bolus Anterograde - retrograde • Height of refluxate • pH characteristics Acid (combined MII-pH) Weekly acid Weekly alkaline Superimposed reflux (re-reflux)
  • Liquid bolus 1) Initial drop Liquid enters impedance-measuring segment 2) Rise Bolus cleared from this segment 3) Overshoot Decreased luminal cross-section during contraction 4) Return to baseline Atlas of investigation & management of esophageal diseases Clinical publishing , Oxford, UK, 2006.
  • Representation of MII & motility recording Impedance waveform opposite to contraction waveform Bolus exit point occurs in front of contraction wave Bremner CG et al. Esophageal disease & testing. Taylor & Francis Group, NY, 1st edition, 2005.
  • Air bolus (Belch, Air swallow) 1) Rapid rise Presence of air bolus inside esophagus 2) Rapid decrease Air bolus clears from this segment Gastrointest Endoscopy Clin N Am 2005 ; 15 : 257 - 264.
  • Mixed air – liquid Bolus 1) Rapid Rise Air in front of the bolus 2) Rapid drop Liquid component of mixed bolus 3) Rise Liquid being cleared from this segment 4) Return to baseline Gastrointest Endoscopy Clin N Am 2005 ; 15 : 257 – 264.
  • Mixed liquid – air bolus 1) Rapid drop Liquid enters impedance measuring segment 2) Rapid rise Gas reaches the segment 3) Rapid fall Gas exits the segment 4) Return to baseline Gastrointest Endoscopy Clin N Am 2005 ; 15 : 257 – 264.
  • Antegrade bolus movement (MII) Observed during swallowing Progression of impedance from proximal to distal Atlas of investigation & management of esophageal diseases Clinical publishing , Oxford, UK, 2006.
  • Retrograde bolus movement (MII) Observed in reflux Progression of impedance from distal to proximal Atlas of investigation & management of esophageal diseases Clinical publishing , Oxford, UK, 2006.
  • Combined MII • MII used clinically only in combination – With esophageal manometry (MII-EM) – With pH (MII-pH) • MII not considered as replacement for manometry & pH techniques but as complementary procedure that expands diagnostic potential of esophageal function testing & reflux monitoring
  • Combined MII-pH probe • Impedance orifices 3, 5, 7, 9, 15, & 17 cm from the catheter tip • pH orifice 5 cm from the catheter tip • MII-pH probe = pH probe Do not change patient comfort Bremner CG et al. Esophageal disease & testing. Taylor & Francis Group, NY, 1st edition, 2005.
  • “Sleuth” monitor – Sandhill “Sleuth” monitor attached to the catheter & worn around a belt during the recording period
  • GERD classification by combined MII-pH • Acid reflux Reflux with drop of pH from above 4.0 to below 4.0 • Superimposed acid reflux (Acid re-reflux) Acid reflux occurs while pH < 4.0 • Weakly acidic reflux Reflux results in esophageal pH between 4.0 & 7.0 • Weakly alkaline reflux Reflux with nadir esophageal pH does not drop < 7.0 Sifrim D et al. Gut 2004 ; 53 ; 1024 – 1031.
  • Acid reflux (MII-pH) Gastrointest Endoscopy Clin N Am 2005 ; 15 : 361 – 371.
  • GERD classification by combined MII-pH • Acid reflux Reflux with drop of pH from above 4.0 to below 4.0 • Superimposed acid reflux (Acid re-reflux) Acid reflux occurs while pH < 4.0 • Weakly acidic reflux Reflux results in esophageal pH between 4.0 & 7.0 • Weakly alkaline reflux Reflux with nadir esophageal pH does not drop < 7.0 Sifrim D et al. Gut 2004 ; 53 ; 1024 – 1031.
  • Superimposed acid reflux (MII-pH) Gastrointest Endoscopy Clin N Am 2005 ; 15 : 361 – 371.
  • GERD classification by combined MII-pH • Acid reflux Reflux with drop of pH from above 4.0 to below 4.0 • Superimposed acid reflux (Acid re-reflux) Acid reflux occurs while pH < 4.0 • Weakly acidic reflux Reflux results in esophageal pH between 4.0 & 7.0 • Weakly alkaline reflux Reflux with nadir esophageal pH does not drop < 7.0 Sifrim D et al. Gut 2004 ; 53 ; 1024 – 1031.
  • Weakly acidic reflux (MII-pH) Gastrointest Endoscopy Clin N Am 2005 ; 15 : 361 – 371.
  • GERD classification by combined MII-pH • Acid reflux Reflux with drop of pH from above 4.0 to below 4.0 • Superimposed acid reflux (Acid re-reflux) Acid reflux occurs while pH < 4.0 • Weakly acidic reflux Reflux results in esophageal pH between 4.0 & 7.0 • Weakly alkaline reflux Reflux with nadir esophageal pH does not drop < 7.0 Sifrim D et al. Gut 2004 ; 53 ; 1024 – 1031.
  • Weakly alkaline reflux (MII-pH) Gastrointest Endoscopy Clin N Am 2005 ; 15 : 361 – 371.
  • Esophageal bilirubin monitoring (Bilitec - Medtronic)
  • Importance of DGER Best Pract Res Clin Gastroenterol 2000 ; 14 : 719 – 729.
  • Bilitec recorder
  • Principles of Bilitec • Utilizes optical properties of bilirubin Spectrophotometric absorption band at 450 nm • Detection in esophageal lumen of absorption near 450 nm suggests presence of bilirubin & therefore DGER • DGER is defined when bilirubin absorbance > 0.14 DGER is terminated when bilirubin absorbance < 0.14 Value < 0.14 due to particle & mucus in gastric content
  • Correlation between absorbance & bilirubin concentration
  • Limitations of Bilitec • Semi-quantitative means of detecting DGER Cannot detect onset or frequency of DGER • Underestimate bile reflux by 30% if pH < 3.5 Must be accompanied by 24 h esophageal pH • Require use of liquid diet to avoid false positivity • Few medical conditions (Gilbert & Dubin Johnson) may result in disproportionate secretion of bilirubin compared to other contents of bile
  • Foods that can be eaten for the Bilitec study • Bananas • Apples • Saltine crackers • Cottage cheese • Chicken breast (baked, broiled, boiled, no skin) • Rice • Cream of chicken or cream of mushroom soup
  • Esophageal pH & Bilitec study Maximal bile reflux in the esophagus during supine period Bremner CG et al. Esophageal disease & testing. Taylor & Francis Group, 2005.
  • Combined MII-pH & Bilitec Weakly alkaline reflux may or may not include duodenal contents Sifrim D et al. Gut 2004 ; 53 ; 1024 – 1031.
  • Despite its limitations, Bilitec is an important advance in assessment of DGER in clinical arena
  • Advantages of 3 major types of pH testing pH Bravo Capsule Combined MII-pH Comfort _ + _ Monitoring > 24 h _ + _ Nonacid reflux _ _ + Normal values + _ _ Proximal reflux + ? + Gastric monitoring + ? +
  • Conclusion • 24 hour pH esophageal monitoring is not the gold standard for diagnosis of GERD • Combined MII-pH of the esophagus is the best available diagnostic test for diagnosis of GERD at the present time
  • Thank You