GI - Oesophagus and Reflux Flashcards
Length of Oesophagus
25cm
Portions of the oesophagus
Cervical - Cricoid (C5/6) to T1
Thoracic: T1 - Oesophagus Hiatus (T10)
Abdominal: T10 - GOJ
What makes up the Upper Oesophageal Sphincter
Cricoid and thyroid cartilage, hyoid bone and 3 pharyngeal muscles
What makes up the lower oesophageal sphincter
Intrinsic: Physiological, smooth muscle. Tone is 10-15mmHg (over intragastric pressure)
Extrinsic: Crural diaphragm
Histology of Oesophagus
Epithelium: Stratified Squamous Epithelium
2 muscularis externa/ muscularis propria - circular and longitudinal
Striated muscle for upper 1/3, Smooth Muscle for lower 2/3
Innervation of oesophagus
Sympathetic: Cervical and Thoracic sympathetic Trunk. Relaxes wall and constricts BVs
Parasympathetic: Vagus nerve. Glandular Contractions, Muscles of oesophagus (peristalsis)
What Innervates the myenteric plexus?
The vagus nerve
What are the nuclei for the upper and lower oesophagus
UES and Upper Oesophagus: Nucleus ambiguus
LES and Lower Oesophagus: Dorsal motor nuclei
Blood Supply
Artery: Thyroid A, branches of gastric, inferior phrenic + splenic
Vein: Sup - IVC, azygous, hemiazygous. Inf - L gastric and short gastric anastamose to the splenic vein
Why do oesophageal varacies occur in portal hypertension
Because the left gastric and short gastric vein drain the bottom of the esophagus to the portal system
Physiology of swallowing
- Food from soft palate down pharynx
- UES relaxes, epiglottis closes over, respiration pauses
- primary peristalis pushes bolus down
- LES opens @ swallow initiation
- 2ndry peristalsis: in case of distention
Controlled by swallowing center of medulla oblongata
Oesophageal Investigations
- Endoscopy
- high resolution manometry
- pH monitor
What can can endoscopy be used for?
Can see down 2nd part duodenum
Diagnose mucosal/ structural abnormality - barrett’s oesophagus. Varices, stricture, adenocarcinoma.
Intervention
Mucosal Biopsy
high resolution manometry - how it works, what it diagnoses
- Catheter and local anesthetic
- Records pressure while you swallow
- diagnoses motility disorders - Achalasia, oesophageal spasm
pH monitor - how it works and what it does
Catheter in nose, keep pH monitor 5cm above LES and record for 24 hours
Diagnoses acid reflux - confirm pre-surgery or inf non-responsive to PPI
Red Flags for oesophageal disorders
- Unexplained weight loss
- Dysphagia
- Persistant vomiting
- GI blood loss ( haemoptysis, occult stool)
- Upper Abdominal Mass
What is GORD?
Retrograde passage of acidic gastric contents up oesophagus
Signs and Symptoms of GORD?
- Dyspepsia (Abdominal discomfort - pain, nausea)
- vomiting
- Regurgitation
- Heartburn
- Epigastric Pain
- Food Sticking
- Extraoesophageal ( wheeze, cardiac pain, pharangeal sympt)
Relieving and Exacerbating factors
Worse - lying down, after meal
Better - milk
Causes of GORD
Lowered ‘defenses’
- Hiatus Hernia
- Transient LOS relaxations
- less Sphincter Pressure (<2/3mmHg below stomach pressure)
- TIssue resistance
- decreased luminal clearance mechanisms
Increased Offenses - Duodenogastral reflux - Decreased Gastric Emptying - Increased HCL/ Pepin production Increased Abdominal Pressure
Types of Hiatus Hernia
Sliding - 20% - GOJ
Rolling - 80% - GOJ and Fundus of stomach
Complications of GORD
Oesophagitis
- Strictures
- Inflammation of squamous mucosa due to acid damage
Barett’s Oesophagus
- Metaplasia of squamous mucosa to columnar
Adenocarcinoma
- dysphagia of mucosa
Treatment of GORD
Lifestyle
(Smoking/ alcohol/ diet)
Pharmaceutical
- Antacids (Mg/ Al/ Na/ Ca)
- Alginates (NA alginate)
- mucosal agents
- H2 receptor antagonist (Cimitidine/ Ranitidine)
- PPI (Omeprazole)
- Sucralfate
- Prokinetic
Surgical
- Nillson Fundoscopy - tie stomach around oes to help sphincter pressure
- Linx procedure - metal ring to act as sphincter
- Halo - Burning of oesophageal mucosa to remove barett’s
- EMR: mechanical removal of mucosa
Mechanism of Action of Antacids and Alginates
Antacids
- Mild Reflux
- Increase pH and Reduce Pepsin and binds bile acids
-Al - constipation, Mg - diarrhoea
- Na: avoid in CHD and renal disease
Interacts with tetracyclins, digoxin, prednisolone
Alginates
- NA Alginate
- Add to antacid
- Foaming agent forms protective barrier around mucosa
Mechanism of Action of H2RA
- Cimitidine/ Rantidine
- Binds Histamine Receptor on Parietal cells and prevents histamine-mediated acid release
- Can cause constipation, diarrhoea, deranged LFT, headache and dizziness
Binds Cyctochrome C - warfarin/ phenytoin - Tachyphylaxis occurs - rapid loss of response to drug with time
Mechanism of Action of PPI
- Omeprazole
- selectivley accumulates in canniculi of parietal cells as becomes active in H+, cationic sulfamide binds irreversibly with groups on proton pump = long lasting inhibition
Usually well tolerated, but can cause diarrhoea, rash , headache, C. diff infection
Interacts with CytP450
LT, May cause atrophic gastritis (parietal cell atrophy leads to hypochlorhydria
Mechanism of Action of Prokinetics and Sucralfate
Prokinestics
- metoclopramide.
- Increases ACh release
- Increases gastric emptying and sphincter pressure
- Compli: drowsiness, diarrhoea
Sucralfate
- Complex sucrose polymer that acts as cytoprotective agent. Promotes bicarb production and acts as acid buffer
Protective Mechanisms against GORD
Intrinsic Sphincter - tone of 10-15mmHg
Extrinsic Sphincter - reflex contraction when intra-abdominal pressure increases
Intra-abdominal Oesophagus - intra-abdominal pressure helps sphinter respond to increased IAP
Angle of His/ Flap Valve - pressure increase in stomach closes cardiac sphincter
Secondary peristalsis: in response to distention
Bicarbonate in mucus
