Dalani's Deck: Unit 4 - Gastrointestinal Flashcards
How much of total human body mass is the GI tract?
5%
What are the 5 main functions of the GI system?
- motility
- digestion
- absorption
- excretion
- circulation
What are the layers of the GI system from outermost to innermost including the mucosal layers from outermost to innermost?
serosa, longitudinal muscle, circular muscle layer, submucosa, mucosa: muscularias mucosae, lamina propria, epithelium
What is the serosa’s function?
smooth membrane of thin connective tissue and cells that secrete serous fluid to enclose the cavity and reduce friction between muscle movements
What is the purpose of the longitudinal muscle layer?
contracts to shorten the length of the intestinal segment
What is the purpose of the circular muscle layer?
contracts to decrease the diameter of the intestinal lumen
What innervates the GI organs up to the proximal transverse colon?
celiac plexus
What innervates the descending colon and distal GI tract?
inferior hypogastric plexus
What 4 ways can the celiac plexus be blocked?
- transcrural
- intraoperative
- endoscopic US guided
- peritoneal lavage
Where is the myenteric plexus and what does regulate?
between the smooth muscle layers and regulates the smooth muscle
What does the submucosal plexus do?
transmits information from the epithelium to the enteric and central nervous system to control absorption, secretion, and mucosal blood flow
What 3 layers make up the mucosa?
muscularis mucosa, lamina propria, and epithelium (outermost to innermost)
What does the muscularis mucosa do?
it is a thin layer of smooth muscle that functions to move the villi
What is the lamina propria?
contains the blood vessels and the nerve endings
What is the function of the GI epithelium?
GI contents are sensed, enzymes are secreted, nutrients are absorbed, and waste is secreted
What main system controls the GI tract (both names)?
the autonomic nervous system aka the extrinsic nervous system
Which extrinsic system is primarily inhibitory and decreases GI motility?
The sympathetic extrinsic system
Which extrinsic system is primarily excitatory and increases GI motility?
The parasympathetic extrinsic system
What does the enteric nervous system control?
the independent nervous system which controls motility, secretion, and blood flow
What makes up the enteric nervous system?
the myenteric plexus and the submucosal plexus
What does the myenteric plexus control?
Motility which is carried out by enteric neurons, interstitial cells of Cajal, and smooth muscle cells.
What are the interstitial cells of Cajal also called?
the ICC or GI pacemaker cells
Both the submucosal plexus and the myenteric plexus respond to __________ and ___________ stimulation.
sympathetic and parasympathetic
What is an upper gastrointestinal endoscopy (EGD)?
diagnostic or therapeutic procedure where an endoscope is placed into the esophagus, stomach, pylorus, and duodenum with or without anesthesia
What are the anesthetic challenges associated with EGD?
sharing an airway with the endoscopist; procedure is often performed outside of the main OR so we don’t always have all of our equipment
What are the anesthetic challenges associated with colonoscopy?
pts are often dehydrated due to bowel prep and NPO status
What is high resolution manometry (HRM)?
a pressure catheter measuring pressures alone the entire esophageal length generally used to diagnose motility disorders ; Does not normally require anesthesia
What does GI series with ingested barium show?
radiologic assessment of swallowing function and GI transit
What is a gastric emptying study?
where a patient fasts for at least 4 hours, then consumes a meal (usually eggs) with a radio-tracer, and the continuous or frequent imaging occurs for the next 1-2 hours to test gastric emptying
What is small intestine manometry?
a catheter measures contraction pressures and motility of the small intestine
What 3 periods do we measure contractions during with small intestine manometry?
fasting (4 hours), during a meal, post-prandial (2 hrs)
What is a lower GI series?
a barium enema to outline the intestine which allows for detection of colon and rectal anatomical abnormaliteis on radiograph
What are the 3 categories of esophageal disease?
anatomical, mechanical, neurological
What are anatomical causes of esophageal disease?
diverticula, hiatal hernia, changes associated with chronic acid reflux
How do anatomical changes cause esophageal disease?
they interrupt the normal pathway of food, which changes the pressure zones of the esophagus
What are mechanical causes of esophageal disease?
achalasia, esophageal spasms, hypertensive LES
What are neurologic causes of esophageal disease?
neurologic disorders such as stroke, vagotomy, or hormone deficiences
What are the 3 most common symptoms of esophageal disease?
dysphagia, heartburn, GERD
When do people usually develop oropharyngeal dysphagia?
after head and neck injuries
How do we classify esophageal dysphagia?
by physiology; either dysmotility or mechanical
What is esophageal dysmotility?
difficulty swallowing both liquids and solids
What is mechanical esophageal dysphagia?
difficulty swallowing only solid food
What is GERD?
effortless return of gastric contents into pharynx
What is achalasia?
neuromuscular disorder of the esophagus consisting of an outflow obstruction due to inadequate LES tone and a dilated hypomobile esophagus
What is achalasia caused by?
(theoretically) by a loss of ganglionic cells of the esophageal myenteric plexus followed by absence of inhibitory neurotransmitters of the LES
Achalasia is caused by ____________ LES ____________ (the LES cant relax).
unopposed LES stimulation
What are the symptoms of achalasia?
dysphagia, regurgitaion, heartburn, chest pain
What does achalasia cause long term?
increased risk of esophageal cancer
What is used to diagnose achalasia?
esophageal manometry or esophagram
What are the 3 classes of achalasia?
1: minimal esophageal pressure, responds well to myotomy;
2: entire esophagus pressurized, responds well to treatment, has the best outcomes;
3: esophageal spasms with premature contractions; has worst outcomes
What medications treat achalasia?
nitrates and CCBs to relax LES; endoscopic botox injections
What is the most effective non-invasive treatment for achalasia?
pneumatic dilation
What is the best surgical treatment for achalasia?
Laparoscopic Hellar Myotomy
What is perioral endoscopic myotomy (POEM)?
endoscopic division of LES muscle layers
What is the biggest risk to performing POEM?
40% of patients develop pneumothorax or pneumoperitoneum
What anesthetic challenges are associated with achalasia?
high risk for aspiration; proceed with RSI or awake intubations
What procedure is considered in the most advanced disease states of achalasia?
esophagectomy
What are diffuse esophageal spasms?
spasms that usually occur in distal esophagus, likely due to autonomic dysfunction, causing pain that mimics angina
What is the diagnosis and treatment of esophageal spasms?
diagnosis: esophagram; treatment: nitroglycerin, antidepressants, PD-Is
What population most commonly experiences diffuse esophageal spasms?
elderly
What are esophageal diverticula?
out-pouchings in the wall of the esophagus
What are Zenker Diverticulum?
pharyngoesophageal diverticulum that causes bad breath due to food retention
What is midesophageal diverticulum caused by?
old adhesions or inflamed lymph nodes
What is associated with epiphrenic (supradiaphragmatic) diverticula?
achalasia
What anesthetic challenges for esophageal diverticula?
all aspiration risks; removal of particles and RSI
What is hiatal hernia?
herniation of the stomach into the thoracic cavity through the esophageal hiatus in the diaphragm
What causes hiatal hernia?
weakening in anchors of gastroesophageal junction to the diaphragm
What is the prevalence of esophageal cancer?
4-5 in 100,000 people in the US
How does esophageal cancer present?
with progressive dysphagia and weight loss
Why does esophageal cancer have a poor survival rate?
because there are abundant lymphatics in esophagus leading to lymph node metastasis
What is the majority of esophageal cancers and what are they related to?
adenocarcinomas located in the lower esophagus; related to: GERD, Barretts, Obesity
What are the rest of esophageal cancers (besides adenocarcinomas)?
squamous cell carcinoma
How is esophagectomy performed and what are the risks?
performed transthoracic, transhiatal, or minimally invasive; HIGH risk of recurrent laryngeal nerve injury of which 40% resolves spontaneously
What symptom is often associated with esophageal cancer preop and for months after treatment?
malnourishment
If patients have a history of chemo/radiation, what symptoms may be present?
pancytopenia and dehydration
Why are post-esophagectomy patients very high risk for aspiration?
they do not have an adequate LES
What is the prevalence of GERD?
occurs in 15% of adults
What are the symptoms of GERD?
heartburn, regurgitation, dysphagia
What is included in reflux contents?
HCL, pepsin, pancreatic enzymes, bile
What are the 3 mechanisms of gastroesophageal incompetence?
- transient LES relaxation, elicited by gastric distention;
- LES hypotension;
- Autonomic dysfunction of GE junction
What is normal LES pressure?
29 mmHg
What is average GERD LES pressure?
13 mmHg
What is the treatment for GERD?
avoidance of trigger foods
MEDS: antacids, H2 blockers, PPIs
SURGERY: Nissen fundoplication, Troupet, LINX
What is Nissen fundoplication?
treatment of GERD: part of the stomach is wrapped and tracked down around the esophagus like a collar to provide a one-way valve effect