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Combined esophageal pH-Multiple Intraluminal Impedence
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Combined esophageal pH-Multiple Intraluminal Impedence

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  • Intragastric pH Monitoring:The evidence supporting the clinical significance and applicability of gastric pH monitoring is insufficient to recommend its routine use inclinical practice.Proximal pH Recording:available evidence does not support the routine use of proximal pH monitoring in clinical practice.
  • 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
  • A recent, multicenter study examined the impedance characteristics of 60 healthy subjects during 24-h ambulatory monitoring. Based on impedance values 5 cm above the LES, the median number of total reflux episodes per 24 h was 30, the majority of which occurred in the upright position.Approximately two-thirds of the episodes were acid and another third weakly acidic reflux. Weakly alkaline reflux was distinctly uncommon in this healthy cohort. Similar frequencies were recently reported from a multicenter European study. References:Shay S, Tutuian R, Sifrim D, et al. Twenty-four hour ambulatory simultaneous impedance and pH monitoring: A multicenter report of normal values from 60 healthy volunteers. Am J Gastroenterol 2004;99:1037–43.Zerbib F, Bruley des Barannes S, Roman S, et al. 24 hour ambulatory esophageal multichannel intraluminal impedance-pH in healthy European subjects. Gastroenterology 2005;128:A396.

Combined esophageal pH-Multiple Intraluminal Impedence Combined esophageal pH-Multiple Intraluminal Impedence Presentation Transcript

  • Combined esophageal Multiple Intraluminal Impedance-pH Samir Haffar M.D. Assistant Professor of Gastroenterology
  • pH electrode located 5 cm above LES
  • Why 5 cm above LES? • Has been standard for many years • Chosen to avoid catheter migration into 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
  • Location of LES • Manometric localization Reference method • pH step-up method Sudden rise to pH > 4 • LES locator Prior to pH • Fluoroscopic techniques Not accurate • Endoscoic technique Not accurate
  • Why pH < 4? • Defined early in development of the technology • Its choice was based on: - Marked difference from normal esophageal pH of 7 - Pepsinogen converted to pepsin at pH 4 - pH < 4 was one that tends to produce symptoms • Some believe that drops in pH that do not reach level of 4.0 still may represent reflux that these events should also be used in calculations of indices
  • 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.
  • Normal 24 hours esophageal pH monitoring Composite DeMeester score: 8.4 DeMeester normal < 14.72 (95th percentile) Bremner CG et al. Esophageal disease & testing. Taylor & Francis Group, 2005.
  • Qualitative analysis Symptom–reflux correlation • Symptom index: Positive if ≥ 50% • Symptom sensitivity index: Positive if > 10 % • Symptom association probability Positive if > 95% Determine relationship between heartburn episodes & acid reflux events, regardless if pH test is normal or abnormal
  • Symptom index Positive if 50 % or more 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 are present during each 2 minute segment • The analysis uses contingency table analysis of 4 possible outcomes for each segment: acid + symptom + acid + symptom – acid – symptom + acid – symptom –
  • 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 hours pH monitoring & medications • PPI should be stopped for 5 – 7 days • Other medications should be stopped for 1 – 3 days • Patient must not use antacids or other OTC medications for duration of the study
  • 24 hour pH esophageal monitoring On & off 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 Patient has known reflux or highly likely to have reflux pH probe in esophagus & another in stomach (NAB)
  • Percentage of total time pH < 4 Normal values • Off therapy 5 cm above LES 20 cm above LES 1 % Periods of meals or acidic beverages excluded • On therapy 5 cm above LES 20 cm above LES ? * Based on 95% CI obtained in healthy subjects treated with omeprazole 40 mg qd Kuo B et al. Am J Gastroenterol 1996 ; 91 : 1532 – 8. 4 – 5.5 % 1.6 – 4 %*
  • Combined MII-pH (MII-pH)
  • Principle of “MII” • 2 steel rings separated by isolator • Alternating-current generator to apply electrical PD • Circuit 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 Acid re-reflux
  • Liquid bolus Gastrointest Endoscopy Clin N Am 2005 ; 15 : 257 – 264. 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
  • 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.
  • Antegrade bolus movement (MII) Observed during swallowing Progression of impedance from proximal to distal Gastrointest Endoscopy Clin N Am 2005 ; 15 : 257 – 264.
  • Retrograde bolus movement (MII) Observed in reflux Progression of impedance from distal to proximal Gastrointest Endoscopy Clin N Am 2005 ; 15 : 257 – 264.
  • 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 tip • pH orifice 5 cm from the 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.
  • Recommendations for MII-pH monitoring • Endoscopy-negative patients with heartburn or regurgitation despite PPI & performed on PPI therapy • Utility of impedance in refractory reflux patients with chest pain or extraesophageal symptoms unproven • Current interpretation relies on SI, SSI or SAP • Therapeutic implications of abnormal test unproven ACG Practice Guidelines: Esophageal reflux testing. Am J Gastroenterol 2007 ; 102 : 668 – 685.
  • Advantages of 3 major types of pH testing pH Tubeless Combined MII-pH Comfort _ + _ Monitoring > 24 h _ + _ Nonacid reflux _ _ + Normal values + _ _ Proximal reflux + ? + Gastric monitoring + ? +
  • Thank You