GI Flashcards
test 4
GI tract is ___% of total body mass
5%
What are the main functions of the GI tract? (5)
-motility
-digestion
-absorption
-excretion
-circulation
What are the layers of the GI tract? outer –> inner
Serosa (most outer)
Longitudinal muscle layer
Circular muscle layer
submucosa
mucosa (most inner)
What are the layers of the mucosa layer of the GI tract? outer –> inner
What do they do?
Muscularis Mucosae (outer): move the villi
Lamina propria (middle): contains blood vessels, nerve, endings, and immune cells
Epithelium (inner): GI contents are sensed, enzymes are secreted, and nutrients are absorbed
Which two layers of the GI tract propagate gut motility? How?
Longitudinal muscle layer: contracts to shorten the length
Circular muscular layer: contracts to decrease the diameter
The GI tract is innovated by the ________ nervous system. What does this include?
autonomic
Includes:
-Extrinsic nervous system (SNS & PNS)
-Enteric nervous system: independent nervous system –> controls, motility, secretions, and blood flow
The enteric nervous system contains the _____ & ______ plexuses. Describe them
myenteric:
-Lies between smooth muscle layers
-regulates the smooth muscle
-controlled motility (by enteric neurons & cells of Cajal)
submucosal:
Transmit info from the epithelium to the enteric and central nervous system
-controls, absorption, secretion, mucosal blood flow
both respond to SNS & PNS
What does the Celiac Plexus innervate?
Proximal GI organs to the transverse colon
What does the hypogastric plexus innervate?
Descending colon & distal GI tract
What are the ways you can block the celiac plexus? (4)
-Trans-crural
-intraoperative
-endoscopic ultrasound guided
-peritoneal lavage
GI Procedures: Upper GI endoscopy
Endoscope placed thru esophagus –> stomach –> pylorus –> duodenum
challenges: sharing airway w/ endo
-done w/o ETT
-performed outside of main OR (limited equipment/supplies)
GI Procedures: Colonoscopy
Done w or w/o anesthesia
challenges: pt dehydrated from bowel prep and NPO
GI Procedures: High resolution manometry (HRM)
Pressure catheter measures pressures along entire esophageal length
Used to diagnose motility disorders
GI Procedures: Barium swallow
Assessment of swallowing function & GI transit
GI Procedures: gastric emptying study
Fast for 4+ hours –> consumes meal with radio tracer –> freq imaging done for 1-2 hours
GI Procedures: small intestine Manometry
Catheter measures contraction, pressures, and motility of the small intestine
Evaluate contractions during three period periods: fasting, during a meal, and post meal
GI Procedures: lower GI series
Barium enema, outlines the intestines and is visible on radiograph
detects colon/rectal abnormalities
What the different esophageal groups? (3) What is included in them.
Anatomical: diverticula, hiatal hernia, and changes associated with chronic acid reflux
Mechanical: achalasia, esophageal spasms, hypertensive LES
Neurologic: stroke, vagotomy, hormone deficiencies
What are the most common symptoms of esophageal disease?
Dysphagia (difficulty swallowing)
-heartburn
-GERD
What are the different types of dysphagia?
Oropharyngeal: common after head/neck surgery
Esophageal: based on physiology
-esophageal dysmotility: occurs when/ both liquids & solids
-mechanical esophageal dysphasia: occurs w/ solid food only
What are the signs of GERD?
Gastroesophageal reflux disease
effortless return of gastric contents into pharynx
Symptoms: heartburn
Nausea
“lump in throat”
Describe Achalasia
Neuromuscular disorder of the esophagus
Outflow obstruction dt in adequate LES tone and a dilated hypomobile esophagus –> food unable to move forward
Symptoms: dysphagia, regurgitation, heartburn, chest pain
Dx: esophageal manometry or esophagram
Long-term Achalasia is associated with an increased risk of ________
Esophageal cancer
What are the 3 classes of Achalasia? Describe them.
Type 1: minimal esophageal pressure; responds well to myotomy
Type 2: entire esophagus pressurized; respond well to treatment, has best outcomes
Type 3: esophageal spasms with premature contractions; has worse outcomes
What is the Tx for Achalasia?
All Tx is palliative
Meds: Nitrates, CCB <– relaxes LES
Endoscopic botox injections
Pneumatic dilation most effective non Sx Tx
Laprascopic Heller Myotomy best Sx Tx
Esophagectomy – advanced cases
What considerations should we have with all esophageal diseases?
Increased risk of aspiration
RSI or awake intubation
Describe Esophageal Spasms.
Spasms in distal esophagus dt autonomic dysfunction
Dx: on esophagram
Symptoms: mimics angina
Tx: NTG, Antidepressants, PDI
Describe Esophageal Diverticula and their types
Outpouching in the wall of the Esophagus
Pharyngoesphageal (Zenker): bad breath dt food rentention
Midesophageal: caused by old adhesions or inflamed lymph nodes
Epiphrenic: may experience achalasia
Describe Hiatal hernia
Herniation of stomach into thoracic cavity thru Esophageal hiatus in diaphragm
Symtomps: asymptomatic; associated with/ GERD
Describe Esophageal cancer
Symptoms: progressive dysphagia & weight loss
Most are adenocarcinomas – in lower Esophagus
Squamous cell carcinoma – are remainder
Tx: Esophagectomy (curative or palliative) – high risk of recurrent laryngeal nerve injury
Describe GERD & 3 mechanisms of incompetence
Incompetence of the gastro-esophageal junction –> reflux
mechanisms of incompetence
1. Transient LES relaxation –> gastric distention
2. LES hypotension (normal 29, GERD 13)
3. Autonomic dysfunction of GE junction
symptoms: heartburn, dysphagia, mucosal injury
Associated w/ Barret metaplasia & adenocarcinoma
Tx: Avoid trigger foods
Meds: antacids, H2 blockers, PPIs, Reglan
Sx: Nissen Fundoplication, Toupet, LINX
What does reflux contents include?
HCL
Pepsin
Pancreatic enzymes
bile
What Preop interventions should we have w GERD?
What factors increase intraop aspiration
Emergent Sx
Full stomach
Diff airway
Inadequate anesthesia depth
Lithotomy
Autonomic Neuropathy
Gastroparesis
DM
Pregnancy
Increased intraabdominal pressure
Sever illness
morbid obesity
Food is broken down into _____ and must be ____mm particles before entering into the _________
chyme
1-2 mm
duodenum
How does neurohormonal control modulate GI movement?
Gastrin & motilin: increase strength/freq on contractions
Gastric inhibitory peptide: inhibits contractions
Describe Pepic Ulcer Disease
Most common cause of nonvariceal upper GI bleed
associated w/ Helicobacter Pylori
symptoms: burning epigastric pain exacerbated w/ fasting (no food) & improved w/ meals
Perforations signs: severe pain dt secretions in peritoneum –> mortality dt shock >48h
Describe Gastric Outlet Obstruction
Acute or chronic
Acute: dt edema & inflammation inpyloric channel at beginning of duodenum
symptoms: vomitting, dehydration, hyperchloremic alkalosis
Tx: NTG, IVF (resolves w/i 72h)
Chronic: dt repetitive ulceration & scarring
What is the triple therapy Tx for H. Pylori?
2 abx + PPI for 14 days
Describe Zollinger Ellison Syndrome
Non B cell pancreatic tumor –> gastrin hypersecretion
(Normally gastric acid neg feedback loop to inhibit excess gastrin secretion, but that is absent)
symptoms: peptic ulcer disease, erosive esophagitis, diarrhea
Male>female
30-50yo
Tx: PPI
Sx: Resection of gastrinoma
Considerations: correction electrolytes, increase gastric pH, RSI
Describe the small intestines
Mixes nutrients with/ digestive enzymes –> reducing particle size & increasing solubility
circulates contents & exposes them to the mucosal wall to maximize absorption
Segmentation controlled by enteric NS
Motility controlled by extrinsic NS
What are reverible causes of small bowel dysmotility?
Mechanical obstruction: hernias, malignancy, adhesions, volvuluses
Bacterial overgrowth –> alteration in absorption
Ileus, electrolyte abnormalities, critical illness
What are nonreverible causes of small bowel dysmotility?
Structural: Scleroderma, connective tissue disorder, IBD
Neuropathic: pseudo-obstruction dt extrinsic NS dysfunction
Describe the large intestine
Reservoir for waste & indigestible material before elimination
Extracts remaining electrolytes & water
Exhibits giant migrating complexes movements in a healthy person 6-10x daily
What are the 2 primary symptoms of large intestine dysmotility?
altered bowel habits
intermittent cramping
What are the most common large intestine dymotility diseases?
IBD
IBS
Describe IBD
Inflammatory Bowel Disease
Contractions are suppressed dt inflammation but giant migrating complexes remain the same –> compresses infamed mucosa –> erosions & hemorrhage
Seen in Ulcerative Colitis & Crohns
Describe UC
Ulcerative Colitis
Mucosal disease or part of all/part of colon
Severe cases: hemorrhagic, edematous, ulcerated
symptoms: diarrhea, rectal bleeding, crampy abd pain, N/V, fever, wt loss
Labs: increases platelets, increased ery. sed. rate, decreased H/H, decreased albumin
Hemorrhage requiring 6u of blood in 24/48hr = sx colectomy
Toxic Megacolon: triggered by electrolyte disturbances
-colon perforation dangerous complication
Describe Crohn’s Disease
Acute/Chronic
Can affect all/part of bowel
Presistent inflammation–> fibrosis –> narrowing & stricture formation
Most common site = terminal ileum –> RUQ pain
Symptoms: wt loss, fear of eating, anorexia, diarrhea –> diarrhea decreases, chronic bowel obstruction
(1/3 pts: arthritis, dermatitis, kidney stones)
obstruction & inflammation –> loss of absorption surfaces –> malabsorption
What is Tx for IBD?
Medical: 5-Acetylsalicyclic acid (5-ASA) - main drug abx/afx
-Glucorticoids
-Abs: Rifaximin, Flagyl,, Cipro
-Purine analogues
Sx: Last resort
-Resection
-small intestine limited to <1/2 length
-more than this leads to “short bowel syndrome” requiring TPN
Most Carcinoid tumors originate in the _______. What do they secrete?
GI tract
Peptides & vasoactive substances: gastrin, insulin, somatostatin, motilin, neurotensin, tachykinins, glucagon, serotonin
Describe Carinoid syndrome
Occurs in 10% of ppl w/ carcinoid tumors
symptoms: flushing, diarrhea, HTN/HoTN, bronchoconstriction, R heart endocardial fibrosis (L heart more protected dt lungs clearing some substances)
Dx: urinary/plasma serotonin levels
CT, MRI
Tx: avoid serotonin
serotonin antagonists
somatostatin analogues
Preop: OCETROTIDE
Describe Acute Pancreatitis
Inflammatory disorder
Common causes: Gallstones & alcoholism
-also seen in immunodeficient syndrome, hyperparathyroidism, increased Ca++
symptoms: excruciating epigastric pain –radiates to back, N/V, abd distention, steatorrhea, ileus, fever, tachycardia, hypotension
Hallmark labs: increased serum amylase & lipase
Dx: contrast CT, MRI, endoscopic US
Tx: aggressive IVF, NPO to rest pancreas, enteral feeding, opioids
Sx: ERCP
Complications: 25% pts – shock, ARDS, RF, necrotic pancreatic abscess
What prevents autodigestion of pancreas?
Proteases packages in precursors form
-Protease inhibitors
-Low intra-pancreatic calcium, which decreases trypsin activity
failure of any of these mechanisms can trigger pancreatitis
Describe Upper GI bleeds
More common than lower GI bleeds
> 25% blood loss –> hypotension & tachycardia
Orthostatic hypotension = HCT <30%
Melena = bleed above cecum
Dx: EDG
Tx: Mechanical balloon tamponade last resort of uncontrolled variceal bleeding
Describe Lower GI bleeds
More commin in elderly
Causes: diverticulosis, tumors, colitis
Dx: Sigmoidoscopy, colonoscopy
Tx: presistent bleeding = angiography w/ embolic therapy
Describe an Ileus
Loss of peristalsis –> massive dilation/distention of colon
(no mechanical obstruction)
Causes: electrolyte disorder, immobility, excessive narcotics, anticholinergics
Tx: Restore electrolyte balance, hydrate, mobilize, NG suction, enemas
Meds: Neostigmine 2-2.5 mg over 5 mins –> immediate results (requires cardiac monitoring)
Untreated –> ischemia or perforation
What are anesthesia considerations for bowel diseases?
Higher anxiety = GI inhibition
Volatile agents inhibit GI function & motility
Dont use nitrous in abd Sx or when bowel is distended
Neostigmine will increase PNS activity
-Sugammadex has no affect on GI motility
Opioids that work on the mu receptor –> delays gastric emptying & glower GI transit (constipation)
