Gastrointestinal Flashcards
Trigeminal nerve:
Nasopharynx
Glossopharyngeal nerve:
Posterior third of the tongue and oral pharynx
Superior laryngeal nerve
base of tongue and inferior epiglottis to the vocal cords
Recurrent laryngeal nerve
vocal cords distally
Branches of the Vagus nerve
Remaining larynx and trachea
The esophagus originates at the pharynx at approximately what cervical level?
C6 and extends to the stomach
3 functional zones:
- upper esophageal sphincter
- esophageal body
- lower esophageal sphincter
Passes through a space created by the Right crus of the diaphragm
Layers of the esophageal wall:
- Outer longitudinal layer
- Inner circular muscular layer of smooth and striated muscle
- mucosal lining
- squamous epithelium
- except for distal 1-2 cm which is composed of columnar epithelium
Blood supply to esophagus:
- Interior thyroid arteries: cervical esophagus
- Aortic esophageal branches of bronchial arteries: thoracic esophagus
Intrinsic innervation of the gut (also known as the Enteric Nervous system):
2 interconnected plexuses:
- Myenteric or Auerback plexus
- Submucosal or Meissner plexus
- This system extends from the esophagus to anus.
- The enteric nervous system can operate autonomously, although the autonomic NS (PNS and SNS) can influence functions.
Extrinsic Innervation of the gut (Autonomic NS):
Sympathetic: “gastroparesis” fight or flight, slows gut.
-Acts on myenteric plexus to modulate rather than control motor activity
Parasympathetic: “Speeds up” rest and digest
-Cranial nerves IX Glossalpharyngeal, X Vagus, XI Accessory. Mostly the Vagus nerve.
Normal esophageal function:
-Both the upper and lower esophageal sphincters are closed at rest.
- Velocity of swallowing: 3-4cm/sec
- maximum pressure 150mmHg
Lower esophageal sphincter tone:
- swallowing decreases LES tone within 1.5-2.5 seconds and is maintained over the duration of the peristaltic wave (6-8 seconds)
- Normal LES tone is 20mmHg
- Vagal innervation is predominant.
Dysphagia:
Difficulty swallowing.
Barium swallow study
Upper endoscopy
Problems associated with Chronic EtOH:
- impaired esophageal peristalsis
- LES hypotonia (weak)
- Degeneration of Auerbach plexus (Intrinsic innervation)
- Mallory weis tear
Achalasia:
-Failure of the lower esophageal sphincter tone to relax during swallowing accompanied by a lack of peristalsis.
Conditions associated with Achalasia:
- DM
- Stroke
- Amyotrophic lateral sclerosis (ALS, Lou Gehrig’s dx)
- Connective tissue diseases (amyloidosis, scleroderma)
Barrett Esophagus:
- Normal squamous epithelium changes to metaplastic columnar epithelium.
- Close association with development of esophageal carcinoma.
Causes:
- Smoking
- Chronic EtOH
- Chronic exposure to acidic gastric contents (inflammation), GERD
Gastroesophageal Reflux Disease (GERD):
-Failure of the LES to function properly permitting stomach contents to reflux into the esophagus and possibly the pharynx.
Therapies:
- Proton pump inhibitors (PPI’s) -Omeprazole
- Histamine-2 (H2) blockers -famotidine
Hiatal Hernia:
- Caused by weakness in the diaphragm that allows a portion of the stomach to migrate upward into the thoracic cavity.
- 5 types
Symptoms:
- retrosternal pain of burning quality esp after meals
- assumed predisposed to developing peptic esophagitis
Surgical Tx: Nissen (anchors the stomach below the diaphragm by sewing part of the stomach up on itself)
Esophageal Diverticula:
Pouches within the esophagus.
- Zenker: upper esophagus
- Traction: mid esophagus
- Epiphrenic- near LES
Food sequestered in the pouch places patient at higher risk of aspiration.
-staged repair, usually 2 separate surgeries
Symptoms and complications of Esophageal Carcinoma:
Esophageal Malignancy:
- Advanced age
- Cachectic/Malnourished
- Suffering from age related/metastatic disease process
Possible Hx of preoperative Radiation/Chemo
- bone marrow suppression
- intrathoracic and pulmonary fibrosis
- increased friability of tissues
Anesthesia considerations for esophageal disease:
- Hx of GERD w/ active reflux symptoms = plan for aspiration prophylaxis during induction & emergence (no LMAs, ETT only)
- must be fully awake and have demonstrated conscious control of the airway prior to extubation.
- RSI: don’t mask ventilate, want to avoid pushing air into stomach.
- reglan may be helpful, however, to not give to pt with ilius.
Ivor-Lewis Repair:
Done for Esophageal CA
-Anterior abdominal incision, R thoracotomy.
Ivor-Lewis- McKeown Type repair:
Done for Esophageal CA
- R neck incision
- Excision of diseased esophagus
- anastomosis of stomach to cervical esophageal remnant.
-Can cause injury to recurrent laryngeal nerve which can impair the ability to cough and cause aspiration PNA.
Funds of the stomach:
- Thin-walled and distensible
- upper part of stomach
- primary function is storage (4 hours)
Distal Stomach:
- Thick walled for mixing of food
- Slow release of chyme (food mixed with gastric juices) through pyloric sphincter into the duodenum.
Acid release in the stomach is mediated by:
- Vagal nerve stimulation
- Gastrin release: G cell response to gastric distention
- Mistamine release
Acid secretion os parietal cells requires a hydrogen/Potassium exchange pump (ATP used)
