Interpreting Bravo® pH Studies

Interpreting Bravo®
pH Studies
A 3-Step Process
1
Interpreting Bravo pH Studies
A 3-Step Process
STEP 1 | Assess
Assess the pH Tracing
The pH tracing is a graphical representation of the data that has
been collected during the pH test. To assess the pH tracing,
review the patient history, visually inspect the data (diary and
artifacts), and develop a preliminary diagnosis.
STEP 2 | Affirm
Affirm Preliminary Diagnosis
The Reflux Tables and DeMeester Scores are used to affirm the
preliminary diagnosis. Examine each 24-hour period separately,
using the worst day for diagnosis, since the number of acid
reflux episodes can vary from day to day.
STEP 3 | Associate
Associate Symptoms
Symptom correlation is an important component of an accurate
diagnosis. Evaluate the SAP & SI Tables to determine whether
the symptoms are associated with reflux events.
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Detailed
Notes
DetailedExample
Exampleand
and
Notes
STEP 1 | Assess the pH Tracing
The pH tracing is a graphical representation of the data that have been collected during the pH test.
To assess the pH tracing, review the patient history, visually inspect the data (diary and artifacts), and
develop a preliminary diagnosis.
A.Review the Patient History and Reason for the Bravo pH Test
B. Verify Diary Entry
The software uses all of the diary information in calculations. If this information has not been entered... STOP!
Do not interpret study until the entire diary (Meals, Supine & Symptoms) has been entered.
• Verify that the Meal and Supine times have
been entered.
• Verify that the symptoms have been entered
(indicated by a line and identified above the
tracing).
• Note any artifacts (indicated by gray
sections above graph corresponding with
gaps in pH line). These will not be used in
calculations.
• Verify that capsule did not detach during
study. If detachment occurred, enter it as an
“Ignore” event in the diary – see Example of
Early Detachment on page 13.
Supine
Meals
Artifact
Heartburn
Reflux
C. Review the Tracing
•L
ook at the tracing in 12-16 hour segments. Observe acid reflux events (when red tracing line
dips below blue pH 4 line) and consider:
- Are there a large number of reflux events and/or symptoms?
- Do reflux events occur during supine or upright periods, or both?
-D
o symptoms appear to be occurring in or around reflux events? (Symptom association is
considered positive if the symptom occurs within two minutes of the reflux event. A more
detailed view of the tracing may be required.)
D. Form Preliminary Diagnosis
•F
rom this information, determine whether
you believe the patient has acid reflux or not,
based on how often and how long the tracing
shows the pH < 4, and whether this occurs
during daytime, nighttime or both.
•S
tep 2 will use the data from the study to
affirm your preliminary findings.
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Detailed Example and Notes
STEP 2 | Affirm Preliminary Diagnosis
The Reflux Table and DeMeester Scores are used to affirm the preliminary diagnosis. Examine each
24-hour period separately, using the worst day for diagnosis, since the number of acid reflux episodes
can vary from day to day.
A.Examine Reflux Tables
Percent time spent in reflux is the single parameter which has been shown to best correlate with
endoscopic damage.1 Normal is < 4.4% on the worst day.
Reflux Tables
Day I
Day II – Worst Day
Reflux Tables compile the data that have been
collected during the test, much of which is
used in the other pH report measurements.
The important parameter from the tables is
Total Fraction Time pH < 4 (%), examined for
each 24-hour period separately, using the
worst day for diagnosis.
1.Total number of reflux events
2.Number of long refluxes > 5 minutes
3.Longest reflux (HH:MM)
4.Time spent in reflux (HH:MM)
5.% Time Spent in Reflux when pH<4
B. Observe DeMeester Score2
Normal = < 14.72 – Examine each 24-hour period separately, using the worst day for diagnosis.
DeMeester Score
Day I
Day II – Worst Day
The DeMeester Score is a method of adding
weights to six common pH measurement
parameters and presenting esophageal acid
exposure data as a cumulative score. The
score is then compared to data from normal
individuals. The DeMeester Score takes into
account and weights these six parameters:
1.Total percent time pH < 4.0
2.Percent time pH < 4.0 in the upright period
3.Percent time pH < 4.0 in the recumbent period
4.The total number of reflux episodes
5.The total number of reflux episodes
longer > 5 minutes
6.Longest reflux (HH:MM)
DeMeester Normal = < 14.72 – Examine each
24-hour period separately, using the worst day
for diagnosis, since the number of acid reflux
episodes can vary from day to day.
C. Affirm Preliminary Diagnosis
Assure that Percent time spent in reflux and the DeMeester Score for the worst day affirm the
preliminary tracing diagnosis. If not, review Step 1 again and look for opportunities to reconcile
the tracing with the Reflux Table and DeMeester Score.
4
Detailed Example and Notes
STEP 3 | Associate Symptoms
Symptom association is an important component of an accurate diagnosis.
Evaluate the SAP & SI Tables to determine whether the symptoms are associated with reflux events.
A.Review SI Calculations
The SI provides data on the strength of the association between symptoms and reflux events.
SI > 50% is significant and indicates that > 50% of the observed symptoms were associated with reflux.
Symptom Index (SI)2
Total
The SI is defined as the number of times
the symptom occurred when pH was < 4,
divided by the total number of times the
symptom was reported. The quotient is
multiplied by 100 to give the percentage
of symptom episodes that correlated with
reflux. (There are drawbacks to the SI, in
that it is insensitive to the number of reflux
episodes.)
B. Review SAP Calculations
The SAP calculates the probability that the observed association between reflux and symptom
occurred by chance.
SAP > 95% indicates that there is a < 5% probability that the observed symptom-to-reflux
associations occurred by chance.
Symptom Association Probability
(SAP)1
Total
The SAP test is a statistical method for
determining if there is a true correlation
between symptoms and reflux or whether
the proposed correlation is actually only
a chance occurrence. A chi-square test
is used to compare symptoms and reflux
episodes. A calculation, expressed as
a p value, is performed to determine
the probability that chance has caused
correlation between symptoms and
reflux events.
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Normal Case
Interpretation: Negative Bravo with Post-prandial Reflux
History
• Female patient with history of cough
• ENT evaluation positive for laryngitis
• Patient was unresponsive to PPI qid
• Patient had low probability for GERD
STEP 1 | Assess the pH Tracing
Meal & Supine times are entered
Symptoms are entered and/or uploaded
Meals
Heartburn
Artifacts (if any) are noted
Capsule did not detach during study
Supine
Artifact
Meals
Supine
Heartburn
Artifact
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Normal Case
STEP 2 | Affirm Preliminary Diagnosis
• Percent Time Spent in Reflux
when pH<4
•D
eMeester Score is normal (< 14.72)
on both days
Day I - Worst Day
Day II
STEP 3 | Associate Symptoms
Total
•S
AP Table has no significant
associations (values > 95%)
• SI Table has no associations
(values > 50%), so it is not shown
on report
Additional Physician Notes
• All values are normal
• Findings verify that cough are not caused by reflux
• Need to look for other cause of symptoms/other diagnosis
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Abnormal Daytime Case
Interpretation: Positive Bravo with Upright Reflux
History
• Female patient with complaints of heartburn and regurgitation
Meal & Supine times are entered
Symptoms are entered and/or uploaded
Heartburn
Artifacts (if any) are noted
Capsule did not detach during study
Supine
Regurgitation
Meals
Reflux
Regurg
8
Abnormal Daytime Case
STEP 2 | Affirm Preliminary Diagnosis
•P
ercent time spent in reflux > 4.4%
on both days
• DeMeester Score is > normal
(14.72) on both days
STEP 3 | Associate Symptoms
Day I - Worst Day
Day II
Total
• SAP Table has associations (values >
95%)
• SI Table has associations (one with
value > 50%)
Additional Physician Notes
• Further studies were done to check patient for delayed gastric emptying; studies were positive
• Patient had no history of diabetes
•A
fter Bravo study, patient began a neurotransmitter antagonist and PPIs were stopped;
improvement was noted
• Reflux was secondary to delayed gastric emptying
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Abnormal Nighttime Case
Interpretation: P
ositive Bravo with Supine Reflux
History
• Patient with a history of 4 cm hiatal hernia
• Noted low LES pressure on esophageal manometry
• EGD positive for esophagitis
• Testing was done as pre-operative evaluation prior to surgery for reflux
Meal & Supine times are entered
Symptoms are entered and/or uploaded
Meals
Artifacts (if any) are noted
Capsule did not detach during study
Supine
Cough
Reflux
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Abnormal Nighttime Case
STEP 2 | Affirm Preliminary Diagnosis
•P
ercent time spent in reflux is >
4.4% on both days
•D
eMeester Score is > normal
(14.72) on both days
STEP 3 | Associate Symptoms
Day I
Day II - Worst Day
Total
•S
AP Table shows poor correlation of
symptom (cough) which can also be
seen on the tracing
• SI Table does not have cough
association
Additional Physician Notes
• Patient proceeded to surgery
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Abnormal Combination Case
Interpretation: P
ositive Bravo for Reflux
History
• Male patient with history of short-segment Barrett’s esophagus
• History of cough (to the point of “passing out”)
• Complaints of mild heartburn – which was well controlled on PPI (bid)
• Testing was done off medication
• Testing done for evaluation prior to surgical Nissen fundoplication
Meals
Supine
Heartburn
Reflux
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Abnormal Combination Case
STEP 2 | Affirm Preliminary Diagnosis
Day I
Day II – Worst Day
• Percent Time Spent in Reflux
When pH<4
•D
eMeester Score is > normal
(14.72) on both days
STEP 3 | Associate Symptoms
Total
•S
AP Table shows no symptom
association value > 95%
•S
I Table shows heartburn is not
associated with reflux (values <
50%)
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Example of Early Detachment
Additional Physician Notes
•T
his study is an example of early detachment of the capsule prior to completion of 48
hours of recording
• The capsule remains in the stomach, as evidenced by pH levels of approximately 2.0
• During the meal period there is a rise in the pH to above 4 which is caused by buffering of
the stomach acid by the meal and saliva.
• Capsule leaves the stomach and enters the duodenum at approximately 12:00 on day three
(as evidenced by pH ~ 7.0; indicating that capsule is reading alkaline pH).
• REMEMBER: You MUST create an “Ignore” event from the point of capsule detachment
to the end of the recording. Otherwise, the pH data captured during this period will be
included in the software’s calculation
• There may still be enough data to provide an interpretation, depending on the amount of
time that data was captured before the detachment. (In this case, the capsule detached
after 30+ hours)
You MUST create an “Ignore” event from the point of capsule detachment to the end of
the recording. Otherwise, the pH data captured during this period will be included in the
software’s calculation.
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Notes
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The risks of Bravo® pH monitoring include: premature detachment, discomfort,
failure to detach, failure to attach, capsule aspiration, capsule retention, tears in the
mucosa, bleeding and perforation. Endoscopic placement may present additional
risks. Medical, endoscopic or surgical intervention may be necessary to address any of
these complications, should they occur. Because the capsule contains a small magnet,
patients should not have an MRI study within 30 days of undergoing the Bravo pH test.
Please refer to the product user manual or givenimaging.com for detailed information.
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References
1. Jamieson JR, Stein HJ, DeMeester TR, et al. Ambulatory 24-h esophageal pH monitoring: normal values, optimal thresholds,
specificity, sensitivity, and reproducibility. Am J Gastroenterol. 1992;87(9):1102-1111. 2. Hong D, Swanstrom LL, Khajanchee YS, Pereira N, Hansen PD. Postoperative objective outcomes for upright, supine, and
bipositional reflux disease following laparoscopic nissen fundoplication. Arch Surg. 2004;139(8):848.
3. Weusten BL, Roelofs JM, Akkermans LM, et al. The symptom-association probability: an improved method for symptom
analysis of 24-hour esophageal pH data. Gastroenterology. 1994;107(6):1741-1745.
4. Wiener GJ, Richter JE, Copper JB, et al. The symptom index: a clinically important parameter of ambulatory 24-hour
esophageal pH monitoring. Am J Gastroenterol. 1988;83(4):358-361.
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