Tricia-Manometry/Ph24hr test - Lynn

[Lynn]

Hi Tricia,

Results as follows:

The oesophageal manometry showed a lower oesophageal sphincter pressure of 15.02mmHg. The sphincter relaxed completely to all the wet swallows. Wet swallow study produced normal peristaltic contractions on 90% of the occasions, the remaining 10% being interrupted at 24cm (upper oesophagus). The mean distal amplitude was 65.57 mmHg, mean duration 3.66 seconds and peak velocity 3.98 cm/sec. Spontaneous segmental simultaneous contraction in the lower 3rd of the oesophagus was seen on one occasion. In the study period the pharyngo-upper-oesophageal sphincter co-ordination was normal. The 24 hr ambulatory ph study produced a fraction time ph <4% of 1.2 with upright fraction time ph<4% of 1.9 and none during the supine position. The DeMeester score was 7. As per the log sheet, she had 5 episodes of burning pain which corresponded to the reflux episodes. (These were after eating) as logged.

In a small proportion of patients the test can be either false negative or more likely her symptoms may be due to non-acid reflux disease. This is best detected by ambulatory impedence ph manometry. I am quite happy to repeat the ambulatory ph study if necessary to narrow dow the liklihood of the present test being false negative.

Tricia, what is non-acid reflux disease. Can you please interpret in laymans terms.

Many thanks Lynn

[tricia]

Hi Lynn Just got in from a trip , and it's 6 am, so i'll continue tomorrow. Haven't been to bed yet.

First of all your ph test was essentially normal. Your Demeester score was 7. Normal is anything below 14.72.-- so you were well within normal range. Percentage of time you refluxed was 1.2% To be positive for acid reflux disease, the percentage of time refluxed has to be higher than 5- 6 %.

You had less reflux than most normal people , however the reflux episodes you did have, correlated well with symptoms. ... So it's not in your head , or an exagerated pain sensation. I think it comes down to not having hardly any symptoms during the test.

Manometry -- mean distal amplitude was 65.57 mmHg, mean duration 3.66 seconds and peak velocity 3.98 cm/sec.---- all normal .

The rest of your manometry indicates hints of problems your doctor may not be overly concerned about, but i beleive warrents further investigtion. Not clinical spasms, but a possible cause of chest pain. i'll go into detail tomorrow because i want to explain non acid reflux... and i gotta go to bed.

Non acid reflux is defined very differently by different doctors. Non acid reflux basically means any reflux that can cause symptoms above the ph of 4 that a ph test can't detect. . It means food reflux, gas reflux , then there is what they call weakly acidic refux , weakly alkaline reflux, alkaline reflux , and liquid / gas reflux . Have i told you how complicated GERD is getting?

I'll explain it in detail tomorrow. I'm going to post a study from Medscape on people with symptoms on PPIS and non acid reflux

....and awhile back i purchaced an article on a convention the top GIS had in Europe concerning diagnosis and detection and definitions of acid, non-acid, and gas reflux. When i find it in my files, i'll post that too.

Here's the medscape study



Atypical Symptoms May Be Associated With Nonacid Reflux for Patients on PPIs




Nov. 3, 2004 (Orlando) — In a study of 125 patients with gastroesphageal reflux disease (GERD) receiving proton pump inhibitor (PPI) therapy, patients' true acid reflux was associated with typical GERD symptoms, but patients with atypical symptoms such as cough and wheezing were more likely to have nonacid reflux.

Inder Mainie, MD, from the Medical University of South Carolina in Charleston, presented the study results here at the 69th annual scientific meeting of the American College of Gastroenterology.

"About 35% of GERD patients will experience symptoms despite PPI therapy," said Dr. Mainie. "However, in order to manage these symptoms it is useful to differentiate acid reflux from nonacid reflux."

He noted that pH monitoring cannot detect nonacid reflux. Multichannel intraluminal impedance (MII-pH) can detect reflux independent of acid content. The MII-pH probe measures the presence, distribution, and clearing of refluxate at 3, 5, 7, 9, 15, and 17 cm above the LES. The reflux event is characterized as acid or nonacid based on the pH level — a pH of greater than 4 is nonacid reflux, while a pH less than 4 is acid reflux. The findings on MII-pH are then correlated with patients' self-reported symptom index scores.

The mean age of the 125 patients in the study was 43 years, and 81 were women. All patients were receiving a PPI twice daily and all had 24-hour ambulatory MII-pH monitoring.

During the study, 101 patients were symptomatic for GERD. Of those, 58 had typical symptoms such heartburn, chest pain, or regurgitation, while 43 had atypical symptoms, including hoarseness, abdominal discomfort, belch, catarrh, dysphagia, choking, globus, wheeze, and acid taste.

Thirty-six of the 101 patients had acid reflux and all but one of those presented with typical symptoms. Seven of the patients with atypical symptoms had nonacid reflux. The remainder of the patients had no reflux, suggesting that symptoms were caused by other conditions.

"In our experience, as many as 75% of patients with atypical symptoms have no reflux," Dr. Mainie said.

Joel Richter, MD, professor of medicine and chairman of the department of medicine at Temple University School of Medicine in Philadelphia, Pennsylvania, said during the discussion period that the study findings "point out how unimportant nonacid reflux really is." He noted as well that the GERD symptom index used by Dr. Mainie and colleagues has been widely criticized as "flawed so I'm surprised that you are pushing a technology based on a flawed index." A better approach would be to link MII-pH findings with a more concrete clinical marker, he said.

Nonetheless, Dr. Richter said that it might be possible that MII-pH is useful in identifying patients with nonacid reflux and these patients might benefit from a nonmedical therapy.

Dr. Mainie said that his group has referred 12 patients with nonacid reflux for laparoscopic Nissen fundoplication surgery, and "those patients are doing well."

Dr. Mainie received the 2004 ACG/AstraZeneca Senior Fellow Award for his paper.

ACG 69th Annual Scientific Meeting: Abstract 20. Presented Nov. 2, 2004.

Reviewed by Gary D. Vogin, MD

http://www.medscape.com/viewarticle/493040

[Lynn]

Many thanks Tricia for answering my thread when you were so tired. You really should have had a sleep first, but it is greatly appeciated.

Blimey like you say this GERD is sooo complex.

Looking forward to hearing from you after your well earned siesta.

Lynn

[tricia]

Hi Lynn Sorry i took so long. Getting to the manometry .....

10% of peristaltic contractions were interrupted at 24cm (upper oesophagus).

Lynn , Esophageal Peristaltic contractions are muscular contractions that begin in the upper esophagus with a continuous sweep down to the lower esophagus to clear acid, food etc. 10 percent of these contractions you had pretty much stopped before they started, ..... right at the top of the esophagus ( which is an unusually place for them to stop because it's normal sometimes for the contraction to stop mid body , and the following contraction to clear things out)

They don't diagnose you officially with a major problem unless you have more failed contractions than what you had---- but because you had no symptoms , the manometry cannot paint a totally accurate picture. (100 percent of my peristaltic contractions were normal by the way)

Spontaneous segmental simultaneous contraction in the lower 3rd of the oesophagus --

If contractions within the esophagus occur at the same time and without provocation , this is called a Spontaneous simultaneous contraction. This is abnormal. But you only had one and the doctor would most likely discount it. People with diffuse esophageal spasms typically have these , and to be diagnosed with diffuse esophageal spasms , 10 percent of contractions must be simultaneous.

It shows little red flags that things may not be totally normal , but no big alarm bells . I think this is one of the reasons why the examiner suggested impedance testing. When the ph was negative, he did not say the patient's symptoms could be from non ulcer dyspepsia, IBS or something like that, he suggested non acid reflux.

As i said before, non acid reflux is a new concept since the advent of impedance testing. It means different things to different doctors. It used to mean either bile reflux or a sensitivity to normal amounts of acid. ( in the latter some doctors just don't bother with you and tell you to take an antidepressant to numb pain sensitivity) But now, to the most knowledgeable in the feild , and your examiner sounds like he was knowledgeable.......

Many now beleive that gastro-oesophageal reflux should be considered more broadly, , new definitions of reflux within the literature are required. ie That people can have real symptoms of reflux not just when the ph is below 4 , other things can cause symptoms such as esophageal motor movements, weakly acidic liquid and also gas ( Intraluminal air ) etc.The impedance test moniters these things, that the ph can't pick up.

But this is all mute because you didn't have symptoms on the ph test, and neither the ph or manometry would of been totally accurate. If it were me, ( because i know you are considering surgery) i would have another manometry and ph test ( hopefully with symptoms) --- or better yet manometry and combined impedance and ph test ( sleuth test) Take Care Lynn

[Lynn]

Hi Tricia,

Thank you is not enough. But from the bottom of my heart I thank you.

I am going to see the Professor on Monday at 10am, he is then going off to America for a week, so I am very luck to have got in with him. I will keep you advised.

I hope you are keeping well, your bloods are okay and your skin problem has lessened.

Love Lynn

[tricia]

Hi Lynn Thanks i'm doing ok. Best of luck with the professeur , it should be interesting because all of these doctors have such differing opinions . Please let me know what he says. hope he will be helpful to you.

I found the article i was telling you about* that i paid for from GUT concerning the GERD conference . . It explains impedance testing , bilitec, the different types of reflux involved in GERD such as non acid and gas reflux, etc. Thought it might be useful ( parts anyway ) since you will be talking to the professeur on Monday . Best wishes

[tricia]

Gastro-oesophageal reflux monitoring: review and consensus report on detection and definitions of acid, non-acid, and gas reflux


Sifrim1, D Castell2, J Dent3 and P J Kahrilas4 1 Centre for Gastroenterological Research, Faculty of Medicine, Catholic University of Leuven, Belgium
2 Director, Esophageal Disorders Program, Medical University of South Carolina, Charleston, South Carolina, USA
3 Department of Gastroenterology, Hepatology, and General Medicine, Royal Adelaide Hospital, Adelaide, Australia
4 Division of Gastroenterology, Northwestern University’s Feinberg School of Medicine, Chicago, Illinois, USA

To date, most concepts on the frequency of gastro-oesophageal reflux episodes and the efficiency of the antireflux barrier have been based on inferences derived from measurement of oesophageal pH. The development of intraluminal impedance monitoring has highlighted the fact that pH monitoring does not detect all gastro-oesophageal reflux events when little or no acid is present in the refluxate, even if special pH tracing analysis criteria are used. In November 2002, a workshop took place at which 11 specialists in the field of gastro-oesophageal reflux disease discussed and criticised all currently available techniques for measurement of reflux.

Here, a summary of their conclusions and recommendations of how to achieve the best results from the various techniques now available for reflux measurement is presented.

It was concluded that intraluminal impedance monitoring is the only recording method that can achieve high sensitivity for detection of all types of reflux episodes while pH-metry is required for characterisation of reflux acidity. However, the role of intraluminal impedance in the management of patients with gastro-oesophageal reflux disease still needs to be defined from appropriately designed clinical trials.

The impact of new techniques on the definition of different types of reflux was also discussed extensively at the workshop, and new or slightly amended definitions are proposed—namely, "acid reflux", "superimposed acid reflux", "weakly acidic reflux", and "weakly alkaline reflux".

INTRODUCTION
TOPABSTRACTSUMMARYINTRODUCTIONTECHNICAL ASPECTS OF GASTRO...REFLUX SUBCATEGORIES (TABLE 2)CONCLUSIONSREFERENCES
*
Gastro-oesophageal reflux disease (GORD) arises from increased exposure and/or sensitivity of the oesophageal mucosa to gastric contents. To date, most concepts on the frequency of gastro-oesophageal reflux episodes and the efficiency of the antireflux barrier have been based on inferences derived from measurement of oesophageal pH. However, pH monitoring does not detect all gastro-oesophageal reflux events even when special pH analysis criteria are used, particularly when little or no acid is present in the refluxate. This is the case in both adults and infants after eating, before the gastric contents have become acidified, and it also applies to reflux in patients undergoing antisecretory therapy. Not only the acidity but also the air-liquid composition of the refluxate could be relevant in the pathogenesis of GORD.

The total rate of reflux episodes is an important indicator of the competence of the antireflux barrier and is therefore relevant when evaluating the effect of therapies directed at improving the antireflux barrier function.1 Furthermore, oesophageal or extraoesophageal symptoms of GORD may be related to less acidic2–4 or gas reflux that is not detected by pH-metry.
"Oesophageal or extraoesophageal symptoms of GORD may be related to less acidic or gas reflux that is not detected by pH-metry"





Other methodologies have evolved to complement ambulatory pH monitoring for the detection and characterisation of gastro-oesophageal reflux. Intraluminal electrical impedance offers the potential to detect and monitor liquid or air movement within the oesophageal lumen,5 and Bilitec, a spectrophotometric method, can detect the presence of bilirubin in the refluxate.6 These new techniques have enabled more precise evaluation of GORD and offer the opportunity to conceive gastro-oesophageal reflux more broadly, both in terms of frequency and characteristics of the refluxate. As a consequence, new definitions of reflux and consistent terminology within the literature are required.

An international workshop that involved 11 experts working in the field of GORD was held in Oporto, Portugal, November 2002. The aims of this workshop were: (1) to review and discuss critically the performance of the various tools currently available for detection of gastro-oesophageal reflux events; and (2) to propose consensus based definitions of acid, non-acid, and gas reflux, applicable to both the adult and paediatric populations.

[tricia]

REFLUX SUBCATEGORIES (TABLE 2)
TOPABSTRACTSUMMARYINTRODUCTIONTECHNICAL ASPECTS OF GASTRO...REFLUX SUBCATEGORIES (TABLE 2)CONCLUSIONSREFERENCES

ACID REFLUX
To date, studies reported in the have used different definitions for acid reflux. Acid reflux is diagnosed by pH-metry. There was strong consensus agreement among the group that acid reflux should be defined as "reflux episodes that decrease oesophageal pH across 4, or reflux that occurs when oesophageal pH is already below 4" (table 2). A caveat has to be applied to the above definition of acid reflux however as a substantial proportion of pH drops to below 4 are not due to gastro-oesophageal reflux (fluctuations of pH around 4 due to movement, respiration, or electrode drift).

It should be possible to increase the sensitivity of pH measurement by increasing the sampling frequency12 and by removing duration as a criterion of reflux.

Additionally, increasing the pH threshold from 4 to 5 almost doubles the number of reflux events detected. The specificity of pH measurement may be improved by setting a minimum interval between events (10 seconds), minimum duration of events (three seconds), minimum drop in pH (1 pH unit), minimum pH drop rate (0.5 pH units per second), or the hysteresis criterion (for example, fall to 3.8, rise to 4.2). It was also suggested that the specificity of pH measurement could be improved if the pH recovery level was increased to 5 instead of 4, as many non-reflux related fluctuations in pH occur at around pH 4.44 The use of combined pH monitoring and impedance measurement would permit detection of acid reflux episodes and would also obviate the need to use duration criteria, as the impedance criteria define whether or not reflux has occurred.



Table 2 *Recommended definitions for reflux subcategories



The occurrence of reflux episodes when the basal oesophageal pH is already below 4 was discussed in some detail. These episodes represent a special category of acid reflux and consensus was obtained that they should have a unique descriptor. This type of reflux was previously described as "re-reflux".1,45 However, this name implies that reflux occurred, it was cleared, and that the same material was then refluxed again. It was suggested that this type of acid reflux should be renamed more accurately as "superimposed acid reflux", as it represents the occurrence of a further reflux episode before the contents of the oesophagus have been cleared from the previous reflux episode (table 2). This is an important phenomenon underlying the delay in oesophageal clearance, particularly in patients with a hiatal hernia.46,47

It was agreed that even if optimal pH criteria and digitisation frequencies were used, pH-metry would have a low sensitivity and a low specificity for the recognition of "superimposed acid reflux" (fig 3). As many as 33% of superimposed acid reflux events (detected by manometry) are associated with no change in pH. Conversely, it is also known that a number of pH drops occurring when the basal oesophageal pH is below 4 (which would be classified on the basis of pH as "superimposed" reflux) are due to fluctuations in pH due to movement, respiration, or electrode drift and are not actually due to reflux. Impedance monitoring is able to detect "superimposed" reflux episodes where no change in pH occurs or when the fall in pH is <0.5 units.9

WEAKLY ACIDIC REFLUX
If an acid reflux episode is defined as a drop in pH across 4 for at least four seconds, it is likely that the number of reflux episodes will be underestimated by approximately 50% during both the interdigestive and first three postprandial hours in adults.

The terminology used to describe reflux episodes in which the nadir pH lies between 4 and 7 was discussed in some detail (table 2). In cases where the pH falls by at least 1 unit, but does not fall below 4, it was decided to accept the term "weakly acidic reflux" and to reject the old terminology of "minor or low acid reflux". The upper limit of pH 7 was chosen to define the limit of weakly acidic events, as any fall below pH 7 contains some acid. Some experts felt however that detectable pH falls usually start from pH 6.5, and so consensus agreement was not obtained on this point.
The use of combined pH monitoring and impedance measurement would permit more accurate detection of weakly acidic reflux episodes.



GAS REFLUX ---Gas reflux
Intraluminal air (which has a very low electrical conductivity) provokes a rapid (3 k/s) and pronounced rise in impedance.20 In the absence of swallowing, gastro-oesophageal reflux of gas is detected as an almost simultaneous or rapidly orally progressing rise in oesophageal impedance in at least two oesophageal impedance channels.10,20 In the upright position, intraluminal air is better detected by impedance recordings in the most proximal oesophagus.
The criteria for recognition of liquid and gas reflux events in neonates, infants, and children are essentially the same as in adults (Omari T, personal communication).19,24,25





NON ACID REFLUX
The literature contains different definitions of the term "non-acid" reflux. It has been used to refer to: (a) reflux episodes diagnosed by manometry or scintigraphy without pH drops (b) DGOR events diagnosed with Bilitec monitoring50; (c) reflux events diagnosed by impedance monitoring with no change in pH or a drop in pH (d) reflux events diagnosed by impedance monitoring with no change in pH or pH fall of less that 1 pH unit.20
It was decided that definitions should be based on the pH of the refluxate, as defined chemically. A pH of 7 should be the cut off between "weakly acidic" and "weakly alkaline reflux" (table 2, fig 6).




Figure 6 Definitions of reflux are based on the pH of the refluxate. Acid reflux (A) is defined as reflux that reduces oesophageal pH to below 4 or reflux that occurs when oesophageal pH is already below 4. Superimposed acid reflux is a subcategory of acid reflux. Weakly acidic reflux (B) is defined as a pH fall of at least 1 unit where the pH does not fall below 4, and a pH of 7 is the cut off between "weakly acidic" and "non-acid reflux". Weakly alkaline reflux (C) is defined as a reflux episode during which nadir oesophageal pH does not drop below 7.




In many cases, the basal oesophageal pH is between 5 and 6 and a reflux event detected by impedance does not change the oesophageal pH. This is frequently the case in infants (fig 7). It was suggested that it would be wrong to label these types of reflux as "non-acid", as the refluxate is weakly acidic, even though it does not decrease the previous oesophageal pH.


"Based on the pH of gastric contents, the majority of reflux episodes constitute weakly acidic reflux"



BILIRUBEN REFLUX Bilirubin monitoring provides a different approach from the other methods of reflux monitoring as it is concerned with the chemical composition of the refluxate. It detects bilirubin in the refluxate, which indicates that DGOR has occurred. A bilirubin reflux event is defined as an increase in bilirubin absorbance to above 0.14, as recorded by Bilitec, and is considered to be terminated when the absorbance value returns to less than 0.14.37

[tricia]

Oesophageal reflux can now be defined both in terms of its acidity and its physical state (liquid-gas). gastro-oesophageal reflux The advantages of using impedance monitoring to differentiate between liquid and gas reflux were described above (see "Technical aspects of gastro-oesophageal reflux detection" above). "Liquid reflux" is defined by the pattern of an orally progressing drop in impedance of at least 50% in at least three adjacent distal oesophageal recording segments.

Provided that only reflux can cause such a typical aborally progressive pattern of rapid drops in impedance, a revised threshold would be acceptable. If these drops are recorded from electrode pairs in the mid and upper oesophagus, this indicates the extent of travel of liquid up the oesophagus. Gas reflux, on the other hand, results in a pattern of abrupt retrograde or simultaneous increases in impedance over any two segments, being independent of swallowing.

Mixed reflux of gas and liquid is more frequent than pure liquid reflux, both in healthy subjects and in patients with GORD.33 When gas and liquid are present in the refluxate, the impedance increase (indicative of gas) can precede the impedance drop (indicative of liquid), or vice versa. Whether the gas-liquid or liquid-gas sequence represents small amounts of liquid in a large volume of gas, small amounts of gas in a large volume of liquid, or a fine mix of liquid and gas cannot be determined without another, more sensitive, marker of gas reflux as a gold standard.


** CONCLUSIONS
TOPABSTRACTSUMMARYINTRODUCTIONTECHNICAL ASPECTS OF GASTRO...REFLUX SUBCATEGORIES (TABLE 2)CONCLUSIONSREFERENCES
*
Impedance monitoring is the only recording method that can achieve high sensitivity for detection of all types of reflux episode. Even with optimisation of methods, the sensitivity and specificity of pH monitoring will not approach that of impedance monitoring for recognition of occurrence of individual reflux episodes.

Reflux is best detected by impedance and its acidity characterised by pH-metry. A small percentage of acid reflux events may occur as slow pH drops that are not detected by impedance, suggesting that the combination of both techniques is better than pH-metry or impedance monitoring alone. Therefore, combined pH and intraluminal impedance monitoring allows detection of all reflux events and gives the best possible evaluation of the function of the antireflux barrier. Bilirubin measurement is useful to determine the presence of duodenal content in the refluxate but the current technique is limited in its ability to detect the onset or frequency of individual DGOR events.
"Reflux is best detected by impedance and its acidity characterised by pH-metry"





The different available techniques for reflux monitoring offer the opportunity to conceive gastro-oesophageal reflux more broadly, both in terms of frequency and characteristics of the refluxate. The criteria developed for their use apply to both adults and children or neonates and these techniques may be used alone or in combination, according to the clinical scenario. The decision to add impedance to pH monitoring should be determined by the primary aim of the particular investigation. For example, in diagnostic studies where patients with GORD are "off" antisecretory therapy, pH-metry alone may be sufficient in the majority of cases.

However, in adult patients with GORD and persistent symptoms despite adequate therapy, or in neonates, combined pH-impedance monitoring may prove superior. To date, the lack of automated analysis remains a significant limitation of impedance monitoring. However, algorithms for automated analysis of prolonged pH-impedance monitoring are currently under development. Clinical studies and outcome data will ultimately define the usefulness of these new techniques and definitions for reflux monitoring.

[tricia]

TECHNICAL ASPECTS OF GASTRO-OESOPHAGEAL REFLUX DETECTION pH-metry
Oesophageal pH-metry consists of a continuous recording of pH in the distal oesophagus. Detection of periods of oesophageal acidification allows for a direct diagnosis of episodes of gastro-oesophageal reflux and quantification of the exposure of the distal oesophagus to acid. This technique is frequently presented as a gold standard for the diagnosis of GORD and for clinical pharmacology studies.




The basic equipment requirements are a portable data logger for data storage, a pH electrode, a computer, and software for analysis of pH data. The main characteristics expected from the data logger are a frequency of sampling of the pH signal adjustable and great enough to detect short lasting falls in pH, and the availability of several event markers to signal symptoms and other events during the recording. The pH electrode should be stable, with a fast and linear response time. The pH probe measures acidity only at the level of the pH sensor.

A pH of 4 corresponds to 0.12 mEq H+/l.9 The pH measurement gives no indication of the volume of the refluxate—that is, several litres of gastric contents with a pH 2 appears the same to the pH probe as a few millilitres of the same material. Routine clinical pH measurement is performed with one distal pH sensor and does not allow characterisation of the proximal extent of the refluxate. Experimental studies using multiple pH sensors permit evaluation of the proximal extent of acid reflux


SENSITIVITY OF PH MONITERING
The sensitivity of pH monitoring to detect individual acid reflux episodes is determined by sampling frequency, duration threshold, pH threshold,11 and the recurrence of reflux prior to pH recovery. Sampling frequency does not affect measurement of per cent time that pH is below 4 but it does affect the number of reflux events detected when the sampling frequency is too low .When greater than 1 Hz, the sampling frequency becomes optimal Short lived pH drops may represent real reflux1 or a loss of pH signal (which can be caused by air passing the pH sensor). The prevalence and clinical significance of short lived reflux events is currently unknown. For routine pH-metry, most equipment uses 0.25 Hz8 but it was agreed that when a pH data logger digitisation frequency of less than 1 Hz is used, the sensitivity of pH monitoring for recognition of reflux episodes will be impaired in proportion to the actual digitisation frequency.


Specificity of pH monitoring
False positive counting of reflux episodes may be due to acidic food ingestion or non-reflux related fluctuations in pH of approximately 4 due to body movement, respiration, or electrode drift. Suggested strategies to improve specificity included the elimination of meals from scored intervals, defining a necessary increment of pH drop, and setting a recovery time for the pH to return to a value greater than pH 4 (table 1). However, these modifications would also affect the sensitivity of the method.

Intraluminal IMPEDANCE MONITERING

The term "intraluminal impedance monitoring" should be taken to include the concurrent measurement of impedance from multiple intraluminal recording segments. This method allows detection of gastro-oesophageal reflux based on changes in resistance to electrical current flow between two electrodes, when a liquid and/or gas bolus moves between them.5
"The term "intraluminal impedance monitoring" should be taken to include the concurrent measurement of impedance from multiple intraluminal recording segments"



The impedance catheter, with mounted cylinder shaped metallic electrodes, is swallowed and positioned within the oesophageal body. The impedance (or resistance) to the current flow delivered between two electrodes depends on the electrical conductivity of the environment surrounding the electrodes (luminal content, mucosa, wall thickness) as well as the cross sectional area. When a liquid bolus with high electrical conductivity bridges two electrode rings, impedance decreases. In contrast, a gas bolus with very low electrical conductivity increases impedance.

Furthermore, opening of the lumen by a bolus passing along the measuring segment results in a drop in impedance whereas luminal closure causes impedance to increase.5 The difference in patterning of the electrical conductivity of liquid, gas, or mixed (liquid-gas) intraluminal content allows distinction among these luminal contents whereas the sequence of impedance changes in different segments allows recognition of flow in either aboral (swallow related) or oral (reflux) directions. Impedance does not measure the acidity of the intraluminal content.22
Liquid reflux

Gastro-oesophageal reflux is detected as an orally progressing drop in impedance, starting at the level of the LOS and propagating to more proximal impedance measuring segments Previous studies and an experimental validation study in using simultaneous impedance and fluoroscopy showed that liquid reflux produced an impedance drop in the oesophagus of 46.5% from baseline values, with the result that subsequent studies used drops of 50–60% in impedance to declare the presence of liquid within the oesophagus.


Most participants felt that the 50% reduction was too stringent and that the pattern of reflux was as important. Impedance is very sensitive for detection of small volumes of liquid, and similar drops in impedance are observed with boluses of 1 ml and 10 ml.30 Therefore, to date, the intraluminal impedance technique cannot estimate the volume of the refluxate.



Figure 3 Oesophageal intraluminal impedance monitoring combined with oesophageal and gastric pH measurements. Gastro-oesophageal reflux is detected as an orally progressing drop in impedance, starting at the level of the lower oesophageal sphincter and propagating to more proximal impedance measuring segments. In this tracing, three reflux episodes can be observed: (A) acid reflux (mixed liquid-gas); (B) and (C), superimposed reflux episodes (liquid).

Location of impedance electrodes
For reliable recognition of reflux episodes, it was agreed that the centre of the most distal impedance channel should be 1–2 cm above the proximal margin of the LOSThis location allows recognition of the so-called short segment reflux—that is, reflux restricted to the very distal oesophagus that does not reach 5 cm above the LOS. When there is an abnormally low baseline intraluminal impedance in the most distal oesophageal recording segment (for example, in patients with oesophagitis),32 the impedance drop recorded by this may not be sufficient to reach the defined threshold. It is possible to use the more proximal channels however and a liquid reflux episode is proven when there is an abrupt reduction in impedance in the next two adjacent recording segments. It was agreed therefore that reliable recognition of reflux episodes requires impedance recording from three adjacent 2 cm long segments in the distal oesophagus.


During gastro-oesophageal reflux, drops in impedance in the mid and upper oesophagus indicate the proximal extent of the liquid refluxate.33,34 So far there are no studies that have compared the proximal extent of reflux measured with impedance with data on this from other techniques (that is, scintigraphy or radiology).


Sensitivity of impedance monitoring
The sensitivity of impedance has been determined by comparing its ability to detect reflux with that of manometry and pH-metry. In fasting recumbent patients with severe GORD, impedance detected 95% of 408 reflux events diagnosed by combined manometry and pH-metry.9,34 Compared with manometry, impedance detected reflux in 92–99% of common cavities.9 Compared with pH-metry, 97–98% of acid reflux events were detected by impedance under both stationary and ambulatory conditions.27,28 From published evidence, it was concluded that an optimal arrangement of impedance electrodes in adults has a sensitivity of at least 90% for detection of all reflux episodes (table 1). The sensitivity of impedance for reflux recognition may be affected by the occurrence of very low baseline impedance values, such as may be observed in the presence of oesophagitis (fig 4). Preliminary studies have found that impedance changes due to acute oesophagitis are reversed when this heals.35




While the presence of oesophagitis does not preclude the recognition of reflux during visual analysis, it can make automated recognition difficult. Another cause of low basal impedance is the presence of Barrett’s columnar epithelium (table 1). There is a reasonable correlation between the length of the columnar epithelium, as measured by impedance, and endoscopy.32


Specificity of impedance monitoring
During combined impedance-pH-manometric studies, false positive impedance changes (that is, a typical impedance retrograde flow reflux pattern without any pH or manometric suggestion of reflux) were rare (table 1). One source of error is swallow related drops in impedance.34 False negative impedance (that is, pH drops without impedance change) can be observed during slow pH drifts or during reflux events that occur soon after swallowing.

[tricia]

Bilitec monitoring
Bilitec is a monitoring system that can detect duodenogastro-oesophageal reflux (DGOR) by utilising the optical properties of bilirubin (table 1).36–41 Although Bilitec does not measure concentrations of duodenal components, a good correlation has been found between bilirubin content and the concentrations of pancreatic enzymes in aspirated refluxate, suggesting that bilirubin is a good tracer for duodenal components in the gastro-oesophageal refluxate.36,37 The working principle of Bilitec is that detection in the oesophageal lumen of any absorption near 450 nm suggests the presence of bilirubin, and therefore DGOR. There was a consensus therefore that the term "oesophageal bilirubin monitoring" should be applied to the use of continuous measurement of bilirubin concentration for recognition of reflux of duodenal contents into the oesophagus.
"Bilitec is a monitoring system that can detect duodenogastro-oesophageal reflux (DGOR) by utilising the optical properties of bilirubin"



DGOR data measured by Bilitec are usually presented as "% time bilirubin absorbance is higher than 0.14"(table 1). This cut off value has been selected because studies have shown that values below this number could be due to suspended particle and mucus present in the gastric contents.36,37

Sensitivity of bilirubin measurement
The sampling rate of the Bilitec probe is only once per eight seconds. The software averages between the absorbencies calculated over two successive samples to decrease the noise of the measurements.37 This is a very low sampling frequency compared with pH monitoring and suggests that this technique is unable to detect with accuracy the time of onset of bilirubin reflux into the oesophagus. However, there are no data comparing the number of DGOR events at different sampling frequencies.

[mich]

Hi Lynn
How did you go on with the professor?
Hope you ve got some answers.
Had a few tough days.
Hope your ok
Love Michelle x

[Lynn]

Hi Tricia,

Sorry its taken me so long to get back to you. The computer has been playing up the last week, but its back on now.

Grateful thanks for all that information.

The Professor was great. I went in sat down with a cup of coffee, and he asked me to start at the beginning, he just sat and listened (what a difference). We talked and talked for well over 90 minutes. Basically, he is against the operation because he said the results of all my tests point to a leaky valve, and he felt I was not at the operation stage. I told him about my fears of the endoscopy results, he said not to worry here, the tester was very experienced and there was no evidence of B.E. I told him my Doctor did not want me to take 40mg Losec a day she said it was too high a dose. He said you need to take whatever amount of a PPI gives you relief, as people make different amounts of acid anyway, so someone might need to take double what the next person needs for relief. 90% of acid I thought was eliminated by a good dose of a PPI and he said there will always be ample amounts of acid in the stomach unless you take 9 or 10 PPI's. He thought my condition was probably not helped by being overweight when it started, and even though I have now lost 4 stone I have been stressing and this will not be helping the situation, because when you stress you naturally produce more acid.

Blimey Tricia I have just written a load of rubbish. My Husband came in with me and when we came out we discussed it all and some of the things the Professor said I couldn't remember. My mind was full of information. The upshot of it all is is that I feel so much better about it all. I have to live with it and handle it, both diet and meds. Since Monday I have felt great, its not going to kill me, I have to deal with it and in 18 months I am having another endoscopy, just to keep on top of the job. Perhaps some of it has been psychological, I don't know, all I do know is that when I walked out of his office I felt as if a massive weight had been lifted off my shoulders, and I should start to get on with my life and stop dwelling on it all, just deal with it. There was tons of stuff I asked him. I just can't remember it all. If you want to ask me some questions - did you ask him this or that, it will trigger my memory and I will tell you. I know I sound a bit vague, but it is difficult to write it all down. I will visit the boards a couple of times a week, I can't believe feeling this good is going to last and I still feel that this forum is my saviour, particularly you Tricia, maybe I would have started to feel better anyway, with the knowledge I have gained from you with coping with this GORD, the great thing for me is that I don't have to have the op. The Professor never once played GORD down he said it was a condition that needed managing, but it could be well managed.

I hope this feeling of euphoria lasts, if it doesn't I know I have the forum and hopefully yourself and friends I have met here and a lovely Professor to see if it all gets out of hand again.

How are you now Tricia your blood problem and your skin and hows your dog doing.

With love and gratitude - Lynn

Tricia - I have just replied to two posts regarding use of PPI's on the forum. Its driving me mad when Doctors and Consultants are telling their patients that there is no difference in the different PPI's. Do you think it is okay me telling people my problems with the PPI's, i'm not very clued up on it all like you Tricia and I don't want to give false information, but I feel so much for these people, I have been there as you know and how alwful it has been for me. As you know I was told from Oct 2004 you should be able to take any PPI, they are all basically the same. Please be honest with me Tricia, I won't be offended. But I just feel so mad about all this rubbish information the medical profession is handing out regarding PPI's.

[tricia]

Hi Lynn Glad you got on with the professeur . I agree with everything he said, and i certainly wouldn't jump into an operation right away.

I understand what you mean by a massive weight being lifted off of your shoulders . I felt the same way. You are right on with the PPIS and i get disgusted when doctors tell people that they are all the same because they aren't.

Here in Canada there was a lawsuit with the insurance companies because they were forcing people to take the cheaper drug prilosec ,which wasn't working. Three pharmacology experts testified that the PPIS are not all the same and different ones work better than others, depending on the person. And it was ruled by a judge , they are in fact different.

I know protonix didn't do a darn for me, and that was the first PPI i ever tried --

The dog is doing ok, still no scratching at all. I am glad i didn't let the vet put her on those drugs. I guess we have to watch vets as close as we watch doctors.

My bloodwork isn't back yet and still having problems with my face. I cancelled my appointment with the dermatologist again because i have a suntan and i don't want a lecture on the dangers of the sun. I am just going to try a few things on my own for now , including the things you suggested.

So glad you are feeling much better Lynn , it does help if you don't worry , i found that one out myself. Best wishes to you

[Lynn]

Hi Tricia,

So very glad your dog is doing well. Hope through trial and error you can get your skin problem sorted. Hope the blood results come back okay. Talk about life begins at 40, my health started to take a nose dive at 40. Thinking positive now, feeling much better.

Its ironic Tricia re the law suit in Canada, when Prilosec was the least effective PPI, its the only one I can take (Losec its called in the UK). The medical profession need a dose of GERD to see for themselves the difference in the PPI's.

Will keep in touch.

Love and Take Care Lynn