esophageal pH monitoring in pediatrics

1. Esophageal pH monitoring in pediatrics
Samir Haffar MD
Assistant Professor of Gastroenterology

2. pH monitoring of the esophagus
 24-hours pH monitoring
 Wireless pH monitoring
 pH-impedance monitoring (pH-MII)

3.  24-hours pH monitoring

4. 24-hours pH monitoring & medications
• Antacid discontinued 6 hours before
• Prokinetics discontinued 48 hours before
• Anti-H2 receptor discontinued 3 days before
• PPI discontinued 7 days before
Do not use antacids/OTC medications during the study
Fasting: 3 h for infants & 6 h for children over 1-year old

5. Location of pH electrode above LES
5 cm in adults and 3 cm in children

6. Why 3 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

7. Location of LES
• Manometric localization reference method
• pH step-up method sudden rise to pH > 4
• Strobel’s formula* infants up to 1 year of age
• LES locator porior to pH
• Fluoroscopic techniques not accurate
• Endoscopic technique not accurate
* length from nostrils to LES in cm = [(height × 0.252) + 5] × 0.87
Wenzl TG et al. J Pediatr Gastroenterol Nutr 2012; 55: 230-234.

8. Acid reflux: pH ˂ 4 for ˃ 5 sec
Why pH < 4?
• Defined early in development of the technology
• Marked difference from normal esophageal pH of 7
• Pepsinogen converted to pepsin at pH < 4
• pH < 4 is one that tends to produce symptoms
• However, pH that do not reach level of 4.0 still
represent reflux as demonstrated by pH-impedance

9. Device of 24-hours pH monitoring
Using buttons provided on the device
Diary: symptoms, body position (supine, standing) & eating

10. Normal 24-hours pH monitoring
Quantitative analysis
Qualitative analysis
Bremner CG et al. Esophageal disease & testing. Taylor & Francis Group, 2005.

11. Quantitative analysis
composite score
Composite score calculated by the program
Parameters Normal values
% of total time pH <4 (acid exposure time) ˂10% (˂1 y),˂5% (˃1 y)
% of upright time pH <4
% of supine time pH <4
No of reflux episodes <100 (<1 y), <70 (>1 y)
No of reflux episodes >5 min < 8 episodes
Longest reflux episode in min

12. Normal value of composite score
• Boix-Ochoa < 11.99
• DeMeester < 14.72
• Johnson-DeMeester < 22
Boix-Ochoa score is the most accurate score to be
used in pediatrics for GERD diagnosis
Boix-Ochoa J et al. J Pediatr Surg 1980;15 (1): 74-78
DeMeester TR et al. Ann Surg 1976 ; 184 :459 – 470.

13. Comparison of DeMeester to Boix-Ochoa score
• Sensibility 86%
• Specificity 98%
• Positive predictive value 99%
• Negative predictive value 73%
• Accuracy 90%
• Pearson correlation coefficient r 0.9409 – p= 0.000
Lupu VV et al. Medicine 2016;95:26(e3804).
Retrospective study of 234 children with suspected GERD

14. 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 symptoms & acid
reflux events, regardless if pH test is normal or abnormal
More reliable when at least 3 symptom events occur during test

15. Sites of 24-hours pH monitoring
• Single site 3 cm above LES
• Multiple sites 3 & 13 cm above LES
1 in esophagus & 1 in proximal stomach
1 in esophagus & 1 in hypopharynx

16. Distal & proximal esophageal pH monitoring

17. Nocturnal acid breakthrough
Gastric pH <4 for at least 1 hour during the night in patients
with persistent heartburn on standard dose PPIs twice daily
Combined gastric & esophageal 24 hr pH monitoring

18. ‘off or on therapy’ monitoring
• Off therapy (unproven GERD)
No or low-grade esophagitis on endoscopy
No prior positive pH testing
Before anti-reflux surgery
• On therapy (proven GERD)
Double-dose PPI therapy & pH-impedance monitoring
Correlation between refractory symptoms & reflux episodes
Exclude inadequate acid suppression
Exclude poor compliance

19. • SI, SSI & SAP cannot be compared with each other
• SI & SAP are predictive of response to medical/surgical therapy
Interpretation of 24-hours pH monitoring
• % of total time pH <4 <10% (<1 year) – ˂5% (>1 year)
predictive response to med/surg therapy
• No of reflux episodes <100/24 h (<1 y) – <70/24 h (>1 y)
Quantitative analysis (composite score)
Qualitative analysis (symptom-reflux association)
SI: symptom index – SSI: symptom sensibility index – SAP: symptom association probability
Patra S et al. J Trop Pediatr 2011;57:99-103.
Singendouk MMJ et al. Neurogastroenterol Motil 2016;28:1452–1459.
Normal values available for several age groups but used with caution

20. Indications of esophageal pH monitoring
• Diagnosis of acid related disorders:
NERD, hypersensitive esophagus & functional heartburn
Clarify role of acid in esophageal eosinophilia
• Correlate persistent symptoms with acid GER events
• Efficacy of acid suppression in high risk patients:
Cystic fibrosis, neurologically compromised patients
NASPGHAN: North American society of gastroenterology, hepatology & nutrition
Rosen R et al. Pediatric GERD clinical practice guidelines.
J Pediatr Gastroenterol Nutr 2018;66(3):516-554.
Insufficient evidence to support routine use of pH monitoring
for diagnosis of GERD in infants and children (NASPGHAN)

21.  Wireless pH monitoring

22. Wireless pH monitoring
Ayazi S et al. Clin Gastroenterol Hepatol 2009;7:60–7.
Recording for a minimum of 48 hours
Some studies reported recording up to 5 days

23. Rosen R et al. Pediatric GERD clinical practice guidelines.
J Pediatr Gastroenterol Nutr 2018;66(3):516-554.
Wireless pH monitoring
Advantages Disadvantages
increase diagnostic yield expensive
useful in some patients:
- developmental delay
- autism
- cystic fibrosis
- chronic cough
- exercise-induced GERD
not widely available
complications (0-15%):
- esophageal tear
- chest pain
- failure to record
- early detachment

24.  pH-impedance monitoring

25. Advantages of impedance
• Content of bolus/refluxate liquid – gas – mixed
• Direction of bolus anterograde – retrograde
• Height of refluxate
• pH characteristics acid reflux
(pH-impedance) acid re-reflux
weekly acid reflux
weekly alkaline reflux

26. Liquid bolus
high conductivity & low impedance
Gastrointest Endoscopy Clin N Am 2005 ; 15 : 257 – 264.
Single measuring site
Drop in impedance to less than 50% of baseline values

27. Air belch/air swallow
low conductivity & high impedance
Single measuring site
Rapid and pronounced rise in impedance (>3000 ohms)
ohm: unit of measure for impedance
Gastrointest Endoscopy Clin N Am 2005 ; 15 : 257 – 264.

28. Mixed air-liquid bolus
Gastrointest Endoscopy Clin N Am 2005 ; 15 : 257 – 264.
Single measuring site

29. Liquid swallow in impedance
antegrade bolus movement
Progression of impedance from proximal to distal
ohm: unit of measure for impedance
Gastrointest Endoscopy Clin N Am 2005 ; 15 : 257 – 264.

30. Liquid reflux in impedance
retrograde bolus movement
Progression of impedance from distal to proximal
ohm: unit of measure for impedance
Gastrointest Endoscopy Clin N Am 2005 ; 15 : 257 – 264.

31. Combined pH-impedance probe
age-appropriate probes
Bremner CG et al. Esophageal disease & testing.
Taylor & Francis Group, NY, 1st edition, 2005.
• pH orifice
5 cm from the tip
• Impedance orifices
3, 5, 7, 9, 15, & 17 cm from the tip
•  MII-pH probe =  pH probe
Do not change patient comfort

32. GERD classification by pH-impedance monitoring
 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.

33. Weakly acid reflux in pH-impedance monitoring
Sifrim D et al. Best Pract Research Clin Gastroenterol 2009;23:369–386.

34. pH-impedance monitoring
Advantages Disadvantages
Acid re-reflux not widely available
Weakly acid reflex (pH 4.0 – 7.0) higher cost*
Weakly alkaline reflux (pH ˃7.0) limited reference value**
Liquid & gas reflux
Higher sensitivity compared to pH-metry
* Cost of pH-impedance probe: 150 €
** Pilic D et al. German Pediatric Impedance Group. J Pediatr 2011;158:650–4.e1.

35. Indications of pH-impedance monitoring
• Differentiate NERD, hypersensitive esophagus & functional
heartburn in patients with normal endoscopy
• Clarify role of acid & non-acid reflux in etiology of
esophagitis and other signs and symptoms suggestive for GERD
• Correlate troublesome symptoms w acid & non-acid GER events
• Determine the efficacy of acid suppression therapy
Rosen R et al. Pediatric GERD clinical practice guidelines.
J Pediatr Gastroenterol Nutr 2018;66(3):516-554.
Insufficient evidence to support use of pH-MII as single technique
for diagnosis of GERD in infants and children (NASPGHAN)

36. Erosive Esophagitis
30 %
Endoscopy-Negative Reflux Disease (ENRD)
Up to 70 %
GERD
Functional Heartburn
50 %
Normal acid exposure
Normal SI & SAP
SI: symptom index – SAP: symptom association probability
Giacchino M et al. Ann Gastroenterol 2013;26:283-9.
Non-Erosive Reflux
Disease (NERD)
Hypersensitive esophagus
Normal acid exposure
Abnormal SI & SAP
to acid/non-acid reflux

37. Clinical observation
• 8-year-old boy w/o prior disease complained of heartburn
• PPI not effective
• UGI endoscopy WNL
• Esophageal biopsies Absence of EE
• Esophageal manometry WNL
• 24-hours pH-impedance Acid exposure time 4%/24 hours
SI for acid reflux normal (35%)
SAP for acid reflux normal (75%)
What is the diagnosis?
EE: eosinophilic esophagitis – SI: symptom index – SAP: symptom association
probability – WNL: within normal limit

38. Clinical observation
• 8-year-old boy w/o prior disease complained of heartburn
• PPI was not effective
• UGI endoscopy WNL
• Esophageal biopsies Absence of EE
• Esophageal manometry WNL
• 24-hours pH monitoring Acid exposure time 4%/24 hours
SI for acid reflux normal (35%)
SAP for acid reflux normal (75%)
What is the diagnosis? Functional heartburn
What is the treatment?
EE: eosinophilic esophagitis – SI: symptom index – SAP: symptom association
probability – WNL: within normal limit

39. Clinical observation
• 8-year old boy w/o prior disease complained of heartburn
• PPI was not effective
• UGI endoscopy WNL
• Esophageal biopsies Absence of EE
• Esophageal manometry WNL
• 24-hours pH monitoring Acid exposure time 4%/24 hours
SI for acid reflux normal (35%)
SAP for acid reflux normal (75%)
What is the diagnosis? Functional heartburn
What is the treatment? Trazodone or SSRI
EE: eosinophilic esophagitis – SI: symptom index – SAP: symptom association
probability – WNL: within normal limit

40. Thank You

41. Symptom Index (SI)
positive if ≥ 50 %
Not take into account overall number of reflux episodes
Number of reflux-related symptom episodes
Total number of symptom episodes
x 100

42. Symptom Sensitivity Index (SSI)
positive if 10 %
Not take into account overall number of symptoms
Number of symptom-related reflux episodes
Total number of episodes
x 100

43. • Also known as Binomial Symptom Index (BSI)
• More complex statistical calculations
Divide tracing into 2-min segments & looks at whether a
symptom & acid are present during each 2 min segment
• Take into account all relevant components:
Reflux episodes
Total numbers of symptom events
Reflux-related symptom events
Symptom Association Probability (SAP)
positive if ≥ 95%
Gyawali CP et al. Gut 2018;67(7):1351-1362.

44. Number of reflux episodes/24 hours in children
Available reference values
Singendouk MMJ et al. Neurogastroenterol Motil 2016;28:1452–1459.