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Anatomy, Physiology, Disorders and Overview of Diagnostic Tests of the Gastro-intestinal Tract. Tom Waterhouse. Learning Objectives. Anatomy and physiology of the GI Tract Gastro-Oesophageal Reflux Disease (GORD) Tests for diagnosis Motility disorders Diagnosis via oesophageal manometry. - PowerPoint PPT Presentation
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Anatomy, Physiology, Disorders and Overview of
Diagnostic Tests of the Gastro-intestinal Tract
Tom WaterhouseTom Waterhouse
Learning Objectives Anatomy and physiology of the GI
Tract Gastro-Oesophageal Reflux Disease
(GORD) Tests for diagnosis
Motility disorders Diagnosis via oesophageal
manometry
Anatomy and Physiology
The GI TractThe GI Tract
Cross Section
Lumen
Overview of Digestive System
Physical Digestion
Teeth - chewingTeeth - chewing Tongue - shapes bolusTongue - shapes bolus Saliva - lubricates bolusSaliva - lubricates bolus Peristalsis + SegmentationPeristalsis + Segmentation Longitudinal muscles + circular musclesLongitudinal muscles + circular muscles
Stomach also has oblique musclesStomach also has oblique muscles
Peristalsis
Segmentation
Physical digestion - locations
Mouth - mastication Mouth - mastication Oesophagus - peristalsisOesophagus - peristalsis Stomach - mastication & some Stomach - mastication & some
peristalsisperistalsis Small intestine - segmentation & some Small intestine - segmentation & some
peristalsisperistalsis Large intestine - peristalsisLarge intestine - peristalsis
Physical digestion - control valves
(Epiglottus)(Epiglottus) Upper oesophageal sphincter (UOS)Upper oesophageal sphincter (UOS) Lower oesophageal sphincter (LOS)Lower oesophageal sphincter (LOS) Pyloric sphincterPyloric sphincter (sphincter of Oddi)(sphincter of Oddi) Ileocecal valveIleocecal valve Anal SphinctersAnal Sphincters
Chemical Digestion Carbohydrate digestionCarbohydrate digestion
Salivary amylaseSalivary amylase Pancreatic amylase, lactase, sucrase, maltase etcPancreatic amylase, lactase, sucrase, maltase etc
Protein digestionProtein digestion Stomach Stomach
Denaturation by HCl, pepsinDenaturation by HCl, pepsin Small IntestineSmall Intestine
Trypsin, proteases, peptidases (pancreatic)Trypsin, proteases, peptidases (pancreatic) Bile salts (Sodium Bicarbonate) neutralise stomach acidBile salts (Sodium Bicarbonate) neutralise stomach acid
Fat DigestionFat Digestion Lipase (pancreatic)Lipase (pancreatic)
Anatomy and Physiology
The oesophagus & stomachThe oesophagus & stomach
Oesophagus Muscular tube about 25cm long.Muscular tube about 25cm long. Upper third is skeletal type muscle.Upper third is skeletal type muscle. Middle third is a mixture between Middle third is a mixture between
skeletal and smooth muscle.skeletal and smooth muscle. Lower third is smooth muscle.Lower third is smooth muscle. When empty the oesophagus collapses When empty the oesophagus collapses
into itself in longitudinal folds. These into itself in longitudinal folds. These folds flatten out when food is in transit.folds flatten out when food is in transit.
Oesophagus - 2 The lower oesophageal sphincter The lower oesophageal sphincter
separates the oesophagus from the separates the oesophagus from the stomach. stomach.
Extremely important for (in)digestion.Extremely important for (in)digestion. Stops acid coming back up from the Stops acid coming back up from the
stomach into the oesophagus and stomach into the oesophagus and causing heartburn.causing heartburn.
Stomach
Acidic, why?Acidic, why? Denature (unfold) proteinsDenature (unfold) proteins Pepsinogen -> PepsinPepsinogen -> Pepsin
Quiz Time
What is the link between:What is the link between:
Søren Sørensen
Acidity
What is pH?What is pH? Sorensen definition Sorensen definition
p[H] = - logp[H] = - log1010[H[H++]] IUPACIUPAC
pH = - logpH = - log1010aaH+H+
How is pH measured? Circuit with two electrodesCircuit with two electrodes Forms a cell when immersedForms a cell when immersed Nernst equation (reduction potential) Nernst equation (reduction potential)
E = EE = Eindind - E - Erefref = E = Eoo + (RT/F x ln a + (RT/F x ln aH+H+)) E = measured voltage ( mV )E = measured voltage ( mV )
E E indind = voltage of indicator electrode (mV) = voltage of indicator electrode (mV)E E refref = voltage of reference electrode (mV) = voltage of reference electrode (mV)EEoo = standard electrode potential (mV) = standard electrode potential (mV)R = gas constant ( 8.3144 J/K )R = gas constant ( 8.3144 J/K )T = absolute temperature ( K )T = absolute temperature ( K )F = Faraday's constant ( 96485.31 Coulombs )F = Faraday's constant ( 96485.31 Coulombs )
How is pH measured(2)? E = EE = Eoo + (RT/F x ln a + (RT/F x ln aH+H+)) E = EE = Eoo + (2.303 x RT/F x log + (2.303 x RT/F x log1010 a aH+H+)) But pH = -logBut pH = -log1010 a aH+H+
pH = (EpH = (Eoo-E)/(2.303*RT/F)-E)/(2.303*RT/F) EEo o is constant, RT/F is constant at constant temperature is constant, RT/F is constant at constant temperature
(25.693 mV at 25(25.693 mV at 25ooC)C) Because activity is hard to quantify, pH is defined in Because activity is hard to quantify, pH is defined in ISO 31-ISO 31-
8:1992, superceded by ISO/IEC 80000-9:2009 with 8:1992, superceded by ISO/IEC 80000-9:2009 with reference to standard solutionsreference to standard solutions
How is pH measured(3)? - Glass electrode
1.1. Glass sensing bulbGlass sensing bulb2.2. AgCl precipitate AgCl precipitate 3.3. 0.1 0.1 mol/Lmol/L HCl for pH electrodes HCl for pH electrodes 4.4. internal AgCl/Calomel electrodeinternal AgCl/Calomel electrode5.5. non-conductive body non-conductive body 6.6. reference electrode, usually same as reference electrode, usually same as
447.7. Porous (eg ceramic) junction with Porous (eg ceramic) junction with
studied solutionstudied solution
How is pH measured(4)? - Equivalent circuit
pH Electrodes Glass
Broad accurate response (gold standard) Fragile
Antimony Robust Smaller Low cost Linear between pH~1 and 10
pH Electrodes - Antimony vs Glass
Summary
Anatomy, Physiology of GI tractAnatomy, Physiology of GI tract What is acidityWhat is acidity How we measure itHow we measure it
Gastro-oesophageal Reflux Disease and 24hr Ph Studies.
Gastro-oesophageal Reflux Disease - GORD
Stomach contents ==> oesophagus via Stomach contents ==> oesophagus via LOS.LOS.
pH (Stomach contents) normally < 4 pH (Stomach contents) normally < 4 Typically pH~2.Typically pH~2.
Digestion of oesophagus!Digestion of oesophagus! 24 hour pH studies are performed to 24 hour pH studies are performed to
determine the levels of acid reflux.determine the levels of acid reflux.
GORD- Paediatric Complications/referral Criteria VomitingVomiting ApnoeaApnoea De-saturationDe-saturation Chronic coughChronic cough Recurrent chest infectionsRecurrent chest infections Failure to thrive/ gain weightFailure to thrive/ gain weight Colour changesColour changes
GORD- Adult Complications/referral Criteria VomitingVomiting RegurgitationRegurgitation HeartburnHeartburn Epigastric/ chest painEpigastric/ chest pain Barrett’s epitheliumBarrett’s epithelium
Oesophageal Ph Study - 1 This can be performed on both adults and
paediatrics. Normally lasts 24 hours. All medication that affects stomach acid is stopped
prior to the investigation. This can be up to 7 days in some instances.
Reports on the % time the ph measured drops below pH4.
Currently this tests involves the use of a naso-gastric catheter which is positioned in the oesophagus above the LOS.
Oesophageal Ph Study - 2 Catheter placement is different for adults and Catheter placement is different for adults and
paediatrics.paediatrics. Adults- catheter is placed 5cm above the Adults- catheter is placed 5cm above the
LOS.LOS. Results from manometry.Results from manometry. HPZ FormulaHPZ Formula
Paediatrics- catheter is placed 2.5cm Paediatrics- catheter is placed 2.5cm above the LOS.above the LOS.
Modified Strobel regression formula.Modified Strobel regression formula. Occasionally checked using CXR.Occasionally checked using CXR.
Oesophageal Ph Study - 3 Strobel Regression Fit (Paediatrics)
5 + 0.252 x Child’s Height(cm)=___x 0.87 HPZ formula for use in adults (Not commonly
used): Mx x 0.4 + 33
(bone at top of rib cage to Xiphi-sternum) Cx x 0.4 + 30
(chin to Xiphi-sternum) Add the above and divide by 2.
Oesophageal pH study - 4 Calibration of the probe is performed Calibration of the probe is performed
using buffer solutions at pH values of 1 using buffer solutions at pH values of 1 or 4 and 7.or 4 and 7.
Pre and post calibration is performed to Pre and post calibration is performed to check for any drift during the 24 hour check for any drift during the 24 hour period of the test.period of the test.
Oesophageal Ph Study - 5 Paediatric results based on published criteria Paediatric results based on published criteria
from the RHSC (Glasgow).from the RHSC (Glasgow). Normal – below 5%.Normal – below 5%. Borderline – between 5 and 10%.Borderline – between 5 and 10%. Abnormal – over 10%.Abnormal – over 10%.
Adult resultsAdult results In the West of Scotland and elsewhere, In the West of Scotland and elsewhere,
Demeester and Johnson scores above Demeester and Johnson scores above 14.7214.72
Demonstrate Catheter
Wireless pH monitoring systems
Medtronic developed Medtronic developed an FDA approved an FDA approved wireless pH wireless pH monitoring device, the monitoring device, the Bravo pH Bravo pH Measurement SystemMeasurement System (now sold by (now sold by Given Given Imaging, Ltd., Israel)Imaging, Ltd., Israel)
Wireless pH monitoring systems
Deployment is achieved Deployment is achieved with suction that pulls with suction that pulls esophagealesophageal mucosa into mucosa into a small well on the side a small well on the side of the probe, after whichof the probe, after which
the metallic retaining bar the metallic retaining bar is triggered to pierce the is triggered to pierce the suctionedsuctioned tissue and the tissue and the placement catheter is placement catheter is withdrawn. withdrawn.
Acid Suppression Therapies Gaviscon (infant & adult).Gaviscon (infant & adult). Ranitidine (H2 receptor antagonist) (Zantac).Ranitidine (H2 receptor antagonist) (Zantac). Proton pump inhibitors.Proton pump inhibitors.
Esomeprazole (Nexium).Esomeprazole (Nexium). Omeprazole (Losec).Omeprazole (Losec). Lansopazole (Zoton).Lansopazole (Zoton). Pantoprazole (Protium).Pantoprazole (Protium).
Surgery - Nissen Fundoplication – tightening of Surgery - Nissen Fundoplication – tightening of the lower oesophageal sphincter.the lower oesophageal sphincter.
Acid Suppression Therapies cont.
Oesophageal Motility Disorders
Examples of Oesophageal Motility Disorders
DysphagiaDysphagia Oesophageal spasmOesophageal spasm AchalasiaAchalasia Hypercontractile distal oesophagusHypercontractile distal oesophagus
(nutcracker oesophagus)(nutcracker oesophagus) StrictureStricture CarcinomaCarcinoma
Dysphagia Defined asDefined as
the inability to swallow or the inability to swallow or the sensation of the obstruction of food the sensation of the obstruction of food
between mouth and stomach.between mouth and stomach. It can also be used to describe difficulty in It can also be used to describe difficulty in
swallowing and occurs from paralysis or a swallowing and occurs from paralysis or a weakness of the muscles in the soft palate. weakness of the muscles in the soft palate.
This can occur after stroke or in certain This can occur after stroke or in certain neurological disorders.neurological disorders.
Oesophageal Spasm Oesophageal spasm is characterised by Oesophageal spasm is characterised by
repetitive non-peristaltic contractions of repetitive non-peristaltic contractions of the oesophageal smooth musclesthe oesophageal smooth muscles
Contractions can either be spontaneous Contractions can either be spontaneous or triggered by swallowingor triggered by swallowing
Unknown causeUnknown cause
Achalasia the absence of oesophageal peristalsis the absence of oesophageal peristalsis
and a failure of the LOS to relax and a failure of the LOS to relax unknown cause unknown cause
may be associated with damage to may be associated with damage to the nerve fibers of the myenteric the nerve fibers of the myenteric plexus supplying the oesophagus plexus supplying the oesophagus
Hypercontractile Distal Oesophagus
Commonly referred to as nutcracker Commonly referred to as nutcracker oesophagus.oesophagus.
High distal pressures measured in the High distal pressures measured in the oesophagus above 180mmHg.oesophagus above 180mmHg.
Can mimic cardiac chest pain.Can mimic cardiac chest pain. Buscopan or glycerol trinitrate have Buscopan or glycerol trinitrate have
been used as potential treatments.been used as potential treatments.
Stricture - 1 A stricture is a stenosis (narrowing) of A stricture is a stenosis (narrowing) of
the oesophageal lumen caused by the the oesophageal lumen caused by the formation of fibrous scar tissue. formation of fibrous scar tissue.
This can result from the inflammation This can result from the inflammation caused by acid reflux from the stomach. caused by acid reflux from the stomach. About 50% of oesophageal strictures About 50% of oesophageal strictures are associated with Barrett’s epithelium. are associated with Barrett’s epithelium.
Stricture –2 Barrett’s Epithelium
This occurs in reflux oesophagitis and is This occurs in reflux oesophagitis and is a columnar epithelium, which replaces a columnar epithelium, which replaces the normal squamous epithelium in the the normal squamous epithelium in the mucosa of the lower third of the mucosa of the lower third of the oesophagus.oesophagus.
Barrett’s epithelium carries a significant Barrett’s epithelium carries a significant risk of malignant transformation into risk of malignant transformation into adenocarinoma.adenocarinoma.
Barrett’s Epithelium
Carcinoma A carcinoma is a malignant tumour A carcinoma is a malignant tumour
consisting of epithelial cells. consisting of epithelial cells. 70% of oesophageal cancers are 70% of oesophageal cancers are
squamous cell carcinoma. squamous cell carcinoma. Nearly all the rest are adenocarinomas Nearly all the rest are adenocarinomas
using occurring from Barrett’s using occurring from Barrett’s epithelium.epithelium.
GORD Summary Motility disordersMotility disorders
DysphagiaDysphagia Oesophageal spasmOesophageal spasm AchalasiaAchalasia Hypercontractile distal oesophagusHypercontractile distal oesophagus
Tissue changesTissue changes StrictureStricture
Barrett’s OesophagusBarrett’s Oesophagus CarcinomaCarcinoma
Oesophageal Manometry
Oesophageal Manometry -1 This investigation uses a catheter which has a This investigation uses a catheter which has a
minimum of 4 pressure transducersminimum of 4 pressure transducers The investigation is used to determine:The investigation is used to determine:
The length of the LOS (by drawing catheter through The length of the LOS (by drawing catheter through LOS)LOS)
The pressure it exerts when asked to do nothingThe pressure it exerts when asked to do nothing Where the LOS is in relation to the nares of the Where the LOS is in relation to the nares of the
nose. This is used in the placement of the pH nose. This is used in the placement of the pH cathetercatheter
The function of the oesophagus during swallowing The function of the oesophagus during swallowing sequencessequences
Oesophageal Manometry -2
Can be used in the diagnosis of a Can be used in the diagnosis of a number of motility disorders.number of motility disorders.
Investigation performed on patients who Investigation performed on patients who are being considered for surgical are being considered for surgical interventions which can involve the interventions which can involve the manipulation of the LOS.manipulation of the LOS.
Water Perfused System Typically 4 to 8 thin Typically 4 to 8 thin
plastic tubes with plastic tubes with outward facing holes.outward facing holes.
Spaced along the length Spaced along the length of catheter.of catheter.
Perfused with water as Perfused with water as the non-compressible the non-compressible medium.medium.
Volume in the tube is Volume in the tube is monitored by a water monitored by a water displacement transducer.displacement transducer.
Advantages & Disadvantages of Water Perfused System
AdvantagesAdvantages Greater flexibility in configuration of cathetersGreater flexibility in configuration of catheters Lower ownership costsLower ownership costs Disposable catheters and transducersDisposable catheters and transducers
DisadvantagesDisadvantages Stationary studies onlyStationary studies only Slow response rate – less suitable for upper Slow response rate – less suitable for upper
oesophageal sphincter measurementsoesophageal sphincter measurements Water perfusion system requiredWater perfusion system required
Intra-luminal Micro-transducers
Linear and non-linear arrangement of Linear and non-linear arrangement of between 4 and 8 solid state strain between 4 and 8 solid state strain gauge transducers spaced radially gauge transducers spaced radially along the catheter.along the catheter.
Direct measurement of intra-luminal Direct measurement of intra-luminal pressure.pressure.
Advantages and Disadvantages of Solid State Catheters
Advantages. Fast response rates – upper oesophageal
sphincter measurements possible. Suitable for ambulatory recordings. Easy to use and calibrate.
Disadvantages. Fragile. Overall ownership costs higher.
Catheter Calibration Water Perfused manometry systems
Apply a relative hydrostatic pressure equivalent to 50cm of water relative to a pre-determined zero point.
Solid state catheters Insert catheter into a small tube with an air seal at
one end and a manometry gauge at the other. Apply a positive pressure of between 50 and 100mmHg equivalent depending on software configuration.
High resolution Manometry
Sensor at least every cmSensor at least every cm micro-manometric water-perfused micro-manometric water-perfused
assemblies with 21–32 channels assemblies with 21–32 channels solid-state - up to 36 pressure sensors solid-state - up to 36 pressure sensors
Manometry overview
UsesUses Types of system availableTypes of system available CalibrationCalibration