|
Introduction:
Gastrointestinal function investigations
have become an important tool in the
diagnosis of digestive diseases. Over the
past 25 yrs many techniques have been
developed to assist surgeons and physicians
in the diagnosis and treatment of patients.
Oesophageal disorders are extremely common
with most patients presenting with symptoms
of gastro-oesophageal reflux such as
heartburn, epigastric and retrosternal
discomfort, bloating and nausea. Many
patients also present with dysphagia
(difficulty swallowing), which may be
indicative of a mechanical disorder of the
lower oesophageal sphincter or a disorder of
oesophageal peristalsis. In some cases
dysphagia may be indicative of something
more sinister such as oesophageal carcinoma.
Gastro-oesophageal reflux Disease (GORD) has
increased in incidence in the past twenty
years. If left untreated, other
complications may be develop such as
Stricture and Barrett's oesophagus, which is
a pre-malignant condition.
Oesophageal motility disorders such as
Diffuse Oesophageal Spasm (DOS) and
Achalasia may cause distressing symptoms
such as dysphagia and chest pain, and these
can only be accurately diagnosed and
categorised by oesophageal physiology
studies.
Patients with angina-like chest pain,
respiratory symptoms such a wheezing and
cough, laryngeal and voice disorders and
patients with unexplained dental erosion are
also commonly referred for GI physiology
investigations to help ascertain whether the
primary cause of their symptoms is gastro –
oesophageal reflux disease.
The GI physiology unit also carries out
lower GI investigations to help colorectal
surgeons and physicians in the diagnosis of
Ano rectal disorders.
Tests carried out in a GI Physiology
Unit:
Oesophageal Manometry:
What is it?
Oesophageal manometry measures the function
of the oesophageal body and it’s associated
sphincters. Pressure profiles are documented
by use of water-perfused catheters or
directly by the use of solid-state
transducers. Oesophageal peristalsis, Lower
Oesophageal Sphincter (LOS) length, resting
pressure, relaxation and co-ordination are
assessed in addition to Upper sphincter
dynamics.
What are the indications for Oesophageal
Manometry?
-
Dysphagia:
Used in the evaluation of suspected
oesophageal motility disorders such as
Achalasia, Ineffective motility, and
diffuse oesophageal spasm and in the
evaluation of sphincter co-ordination,
relaxation upon swallowing.
-
Gastro oesophageal reflux
disease (GORD):
Oesophageal manometry is necessary to
determine the oesophageal length and
sphincter pressure, which are essential
for the correct placement of catheters
for 24 hr pH monitoring.
-
Before and after surgical
treatment for GORD to assess LOS
competence and oesophageal motility.
-
Patients with atypical
chest pain.
How is it performed?
Water perfused Manometry is the most
commonly used method in most GI physiology
units today. A typical system consists of a
pump, which perfuses sterile water through a
multi lumen catheter. The pressure ports on
the catheter are radially arranged at a 90˚
orientation and each port spaced 5cms apart.
The catheter is connected to transducers and
the pressure detected is converted to an
electrical signal via a polygraph and can be
visualized on a computer screen.
This catheter is passed through the nose of
a fasting patient and down into the stomach.
The patient is then placed in a supine
position and the catheter is withdrawn in
1cm increments. This is known as the station
pull-through technique and is used to
measure the length, resting pressure and
relaxation of the LOS.
The catheter is then positioned so that at
least three pressure ports are in the
oesophageal body and one is in the LOS so
that oesophageal motility can be measured as
wall as LOS coordination.
The patient is then given water to swallow
during the study to assess oesophageal
peristalsis.
The resting pressure and relaxation of the
Upper Oesophageal Sphincter may also be
assessed.
24 hr pH Monitoring
24 hr pH monitoring is recognised as the
‘gold-standard’ method for the measurement
of oesophageal acid exposure. It has high
sensitivity and specificity in the diagnosis
of gastro-oesophageal reflux disease (GORD)
What are the indications for 24hr pH
monitoring?
For the diagnosis of gastro oesophageal
reflux in patients who present with
heartburn, regurgitation, epigastric pain
and nausea.
-
To investigate patients
who have the above symptoms but who have
normal Endoscopic findings.
-
To investigate the
possibility of GORD as a cause of
atypical symptoms such as angina- like
chest pain, wheezing, laryngo-pharyngeal
symptoms and dental erosion.
-
To assess patients pre
and post anti reflux surgery.
-
To assess patients who
have complex oesophageal disorders.
-
To test the efficacy of
medical therapy in patients who may have
responded poorly to medication for GORD.
How is it performed?
The test involves the passing of a pH probe,
trans- nasally, so that it is positioned 5cm
above the upper border of the lower
oesophageal sphincter. A 24 hr ambulatory
recorder is then attached to the probe and
carried about the patient’s waist.
The pH probe is generally placed immediately
after manometry and the patient leaves the
hospital with the monitor and encouraged to
resume their normal daily activities.
The patient returns the following day and
the information gathered on the recorder is
downloaded to a specially designed computer
analysis programme. A 24 hr pH profile,
which includes frequency, duration and
pattern of reflux episodes, together with
symptom correlation is generated.
24 Hr Bile Monitoring:
Though acid is the most
commonly assessed refluxate, duodeno-gastro
oesophageal reflux may also occur which can
be injurious to the oesophageal lining.
What are the indications for 24 hr Bile
monitoring?
-
Patients who show
endoscopic evidence of reflux but have a
normal pH profile.
-
Patients who have
histological and endoscopic evidence
Barrett’s oesophagus.
-
Bilious vomiting
-
Patients who are
symptomatic post cholecystectomy
How is it performed?
Bile in the oesophageal body is measured by
the use of a fibre optic probe, which is
passed trans nasally into the oesophagus and
placed 5cms above the manometrically defined
proximal border of the LOS.
Like the 24 hr pH monitor, the Bilitec
system is ambulatory, with the patient
leaving the hospital with the monitor and
returning the following day.
After the patient returns to the hospital,
the information recorded on the monitor is
downloaded into a specially designed
computer software programme and a result is
generated.
Electrogastrography (EGG):
What is it?
EGG is a non-invasive measurement of gastric
myoelectrical activity.
Cutaneous abdominal electrodes record this
activity.
What are the indications for
Electrogastrography?
Many problems of the GI tract and those
effecting Gastric motility:
-
Peptic disease
-
Diabetic gastroparesis
-
Idiopathic gastroparesis
-
Pseudo-obstruction
-
Functional disorders such
as non-ulcer dyspepsia
-
Nausea
-
Vomiting
-
Excessive abdominal
bloating
-
Pre and post gastric
surgery.
How is it performed?
After an overnight fast, the patient is
positioned on a couch in a semi-reclined
position. The skin is then prepared with an
abrasive gel to reduce skin resistance.
An electrode gel is then rubbed into the
abraded area and EGG electrodes are placed
covering the inter body surface of the
stomach.
After a fasting period of 30 minutes the
patient is given a calorie controlled meal
and then the effect of the meal on the
myoelectrical activity of the stomach is
recorded over an hour post prandially.
It is important that the patient is
positioned in a quiet comfortable room away
from distractions, cell phones or equipment
that may emit electromagnetic noise.
Breath testing:
What is it?
Breath testing is used in the diagnosis of
many gastrointestinal disorders.
What are its applications?
-
Lactose intolerance
-
Intestinal bacterial
overgrowth
-
Intestinal transit time
-
Diagnosis of H.Pylori
infection
-
Malabsorption of sugars
-
Malabsorption of bile
salts
-
Pancreatic function
testing
-
Liver function testing.
How does it work?
The patient ingests a substrate, usually a
sugar. This sugar is metabolised by bacteria
or an enzyme present and a gas is produced
as a by-product of metabolism. This gas is
excreted via the lungs and this gas can be
analysed either quantitatively or
qualitatively by GC- mass spectrophotometry.
The patient must attend the unit fasting; a
baseline breath sample is taken followed by
ingestion of the substrate. Depending on the
protocol being followed, numerous breath
samples are taken at various time intervals
over a period of up to 2hrs .The samples are
then analysed and a graph of concentration (ppm)
vs. time (min) is plotted.
Anorectal Manometry
What is it?
Anorectal Manometry is used
for the assessment of internal and external
anal sphincter function, sphincter length
and recto-anal inhibitory reflex and
sensation.
What are its applications?
-
Faecal incontinence
-
Constipation
-
In the diagnosis of
Hirsprung’s disease
-
Mechanical injury i.e.
obstetric injury, spinal injuries
effecting S2-S4
-
Iatrogenic i.e.
Haemorrhoidectomy, Anal dilatation,
Fistula surgery, sphincterotomy
-
Neurological - pudendal
nerve damage
-
Rectal prolapse
-
Systemic disease –
Diabetes, scleroderma, MS
What does in involve?
A water perfused balloon
catheter, attached to a polygram recording
system via a set of transducers, is inserted
into the rectum.
The catheter is passed so that the perfusion
ports are positioned at seven centimetres
from the anal verge. The catheter is then
withdrawn slowly in one-centimetre
increments towards the technologist.
(Station pull through technique)
The patient is then requested to carry out a
squeeze manoeuvre as if to prevent
defecation.
The balloon is then filled with air in 10ml
increments in order to test sensation to the
presence of volume in the anal canal and to
initiate the recto anal inhibitory reflex.
What does it tell us?
The station pull-through allows for the
calculation of the length of the
high-pressure zone in the anal canal and the
maximum resting pressure.
This resting pressure is determined by the
integrity of the pelvic floor muscles in
particular the internal anal sphincter.
The squeeze manoeuvre allows for the
assessment of external anal sphincter
function and the balloon inflation assesses
sensation and the effects of rectal
distension on the relaxatory response of the
internal anal sphincter.
Other websites of interest:
(All open in new browser window)
www.giphysiology.org
www.bsg.org.uk
www.motilitysociety.org
www.isgorg.ie
|
