Treatment of common GI conditions Flashcards
To be able to work up and manage a patient presenting with nausea, vomiting or diarrhea.
Weigh the patient, assess for dehydration
Assess for signs of malabsorption, malnutrition and concurrent illness
Careful history and physical exam essential
Laboratory assessment for malabsorption and nutritional parameters
Stool studies if available vs emperic treatment
Role of endoscopy if bleeding or anemia
Imaging studies
define: nausea
A vague, unpleasant or uneasy epigastric feeling
accompanied by the sensation that vomiting might occur
- typically preceded by anorexia, objectively associated with decreased gastric tone and gastric peristalsis
define: vomiting
The forceful expulsion of gastric contents through the mouth
- Typically preceded by anorexia and nausea
why and how do we vomit
1) Vagal afferent fibers carry signals from the gut mucosa to the CNS
2) Sympathetic afferents (from the GI tract, the heart, the vestibular system) synapse in the vomiting center in the medulla
3) Vomiting center collection of nuclei that coordinate act of vomiting
4) Afferents from the chemoreceptor trigger zone (CTZ) synapse in the vomiting center in the medulla as well
CTZ very sensitive to stimuli, toxins, neurotransmitters, meds
5) Afferent stimuli from higher levels in the CNS (cortex, thalamus, hypothalamus) synapse in the vomiting center as well.
6) These pathways involved in vomiting that occurs with unpleasant tastes, offensive odors, or somatic pain.
define: retching
Similar to vomiting, but occurs without expelling gastric contents
gagging
the initial motor movements involved in vomiting, mostly limited to the oral region
- non-specific
- may represent a hypersensitive pharyngeal reflex or
- the initial motor movements involved in vomiting
rugurgitation
The sudden, effortless, involuntary movement of small amounts of gastric contents into the esophagus or mouth.
- without the violence of vomiting
rumination
Food is chewed, swallowed, and then voluntarily regurgitated.
– usually psych background
what are the stages/acts of vomiting
Act 1
- The final common pathway from the vomiting center involves coordinated messages to the GI tract, diaphragm, abdominal wall muscles, palate, and oropharynx.
- The vagus and phrenic nerves are intimately involved, along with spinal nerves to the abdominal wall musculature.
- The vomiting reflex cannot occur without an intact vagus nerve.
Act 2
- Large amplitude small-bowel contractions
- Retrograde movement of bile and secretions into the stomach
- Pylorus contracts, stomach relaxes
- Abdominal wall muscles and diaphragm contract; respiration ceases
- LES relaxes, esophagus dilates
- Glottis closes, soft palate rises, mouth opens
What is the vomiting center?
- A collection of nuclei that are linked and which coordinate the complicated act of vomiting
- Not a discrete area in the brain
- When appropriately activated by afferent stimuli from the CTZ, the ANS, somatic afferents, or higher brain centers, then vomiting occurs.
what is the chemoreceptor trigger zone
- The chemoreceptor trigger zone is located in the area postrema of the floor of the 4th ventricle
- It is outside of the blood-brain barrier
- It is very sensitive to chemical stimuli, toxins, neurotransmitters, and medications
- Surgical ablation of this area prevents chemically induced vomiting (via apomorphine, a DA receptor agonist)
47yo female has just undergone cholecystectomy, on post-op check she has severe N/V
Diffdx:
- retained stone
-
47yo female has just undergone cholecystectomy, on post-op check she has severe N/V
dx?
tx?
Diffdx:
- retained stone
- bile leak
- pain
- ?complications from surgery
tx
- zofran
- compazine
what classes of antiemetics and what are their targets
- what drugs do we have for it
M1 – muscarinic D2 – dopamine H1 – histamine 5-hydroxytryptamine (HT)-3 – serotonin Neurokinin 1 (NK1) receptor – substance P
Phenothiazines (compazine) Antihistamines (meclizine, Diphenhydramine) Anticholinergics (scopolamine) DA antagonists (metoclopramide) 5HT-3 antagonists (ondansetron) Others: marinol, lorazepam, prednisone,
what are examples of antihistamines
- why do we use it
- ADRs
examples:
- Dimenhydrinate (Dramamine) 50 mg PO q 4 hrs
- Promethazine (Phenergan) = antihistamine + phenothiazine, 12.5 to 25 mg PO/IM/IV q 4 hrs or 12.5 to 25 mg PR q 12 hrs
- Meclizine (Antivert) 25-50 mg PO q 24 hrs
- Diphenhydramine (Benadryl) 25 to 50 mg PO q 6 hrs, or 10-50 mg IV/IM
use: especially with movement-associated nausea/vomiting
ADRs: sedation
what are examples of phenothiazines
- why do we use it
- ADRs
examples:
- prochlorperazine (compazine) 5 to 10 mg PO/IM q 6 hrs or 2.5 to 10 mg IV q 4 hrs or 25 mg PR q 12 h
- promethazine (phenergan) = phenothiazine and antihistamine
use:antagonizing D2-dopamine receptors in the area postrema of the midbrain (boat rides)
ADRs:
- Extrapyramidal Reactions:
- Acute dystonia and tardive dyskinesia Prolonged usage.
- Hypotension in elderly or when drugs are used IV
what are examples of anticholinergics
- why do we use it
- ADRs
examples: scopolamine transdermal 1.5mg q72h= M1-muscarinic receptor antagonist
use: prophylaxis against motion sickness / perioperatively, chronic N/V
ADRs: Dry mouth, drowsiness, visions disturbance
what are examples of 5HT-3 antagonists
- why do we use it
- ADRs
examples:
- Ondansetron (Zofran) 4-8 mg/IV or 4-24 mg PO
- Granisetron (Kytril)
- Dolasetron (Anzemet)
use:chemotherapy-induced emesis and now widely used for other causes (post op, post endoscopy)
ADRs: QTC prolongation in high doses (16-32mg total)
Prophylactic regimen for chemotherapy combo
5-HT3 receptor antagonist
Dexamethasone
Neurokinin -1 receptor antagonist (the oral agent aprepitant and IV equivalent fosaprepitant)
68yo white male referred for upper endoscopy for a 4wk history of early satiety,nausea and vomiting. PMH notable for ETOH, s/p LLLobectomy for squamous cell cancer.
Endoscopy showing undisgested food in the stomach next to the pylorus
tx?
dx: surgical complication -
accidentally hit the vagus nerve on both sides
==> gastroparesis, decreased stomach squeezing
tx: prokinetics
what are the prokinetics
metoclorpramide erythromycin (domperidone) canada / aus (tegaserod) --> ADR: ischemic colitis (cisapride) --> ADR: cardiac arrythmia
Pathophys of metoclopramide
increased ACh release from instrinsic neurons
Pathophys of metoclopramide
ADRs?
increased ACh release from instrinsic neurons
ADRs (chronic): anxiety, depression, neuroleptic malignant syndrome, acute dystonic rxn, akathisia, Parkinsonism, tardive dyskinesia [irreversible]
Pathophys of domperidone
ADRs?
PO
- DA receptor blockade in CTZ
ADR: hyperprolactinemia
Pathophys of erythromycin
ADRs?
pathophys: macrolide antibiotic –> mimics action of motilin, induce MMC
use: upper GI bleed - to move blood through; constiipation
Uncommon antimetics
lorazepam prednisone dexamethosone dronabinol haloperidol droperidol
16yo female with 2-3mo of N/V, esp in the AM
dx?
tx?
dx: hyperemesis gravidum
tx: diety/lifestyle; pyridoxine (VitB6), (1) ondansetron; (2) domperidone
3wk old male infant presents with projectile vomiting after breast feeding
dx?
dx: pyloric stenosis
+ metabolic alkalosis
+ hypochloremic, hypokalemia, hyponatremia; volume depletion
35yo Rwandan woman from village eventually transferred to Central Hospital Univeristy of Kigali for several years of N/V. She now subsists on a mostly liquid diet and is able to maintain her weight.
What is her physical exam finding?
Dx?
Tx?
Assessment: chronic, so unlikely to be
PE: abd distension; succussion splash
Dx: Chronic ulcer, leading to duodenal stricture at GE junction, + H. pylori
Tx: Amoxicillin + metronidazole/Cipro/Clarithromycin + omeprazole
35yo Rwandan woman from village eventually transferred to Central Hospital Univeristy of Kigali for several years of N/V. She now subsists on a mostly liquid diet and is unable to maintain her weight.
Dx?
Dx: GERD –> ulcer –> gastric cancer
21yo male who is having cyclic vomiting, using lots of marijuana
GF says that he feels better after taking a shower
dx: Cannabis hyperemesis syndrome
== chronic heavy use of cannabis, recurrent episodes of severe nausea and intractable vomiting, and abd pain
temporary relief of sxs achieved by taking a hot bath or shower
resolution of problem when cannabis use is stopped
Diffdx:
- psychogenic vomitin
- cyclic vomiting syndrome
- eating disorder
Tx: stop cannabis use
21yo male who is having cyclic vomiting, using lots of marijuana
GF says that he feels better after taking a shower
dx?
diffdx?
tx?
dx: Cannabis hyperemesis syndrome
== chronic heavy use of cannabis, recurrent episodes of severe nausea and intractable vomiting, and abd pain
temporary relief of sxs achieved by taking a hot bath or shower
resolution of problem when cannabis use is stopped
Diffdx:
- psychogenic vomitin
- cyclic vomiting syndrome
- eating disorder
Tx: stop cannabis use
diarrhea: acute v. chornic
< 3 weeks = acute
> 3 weeks = chronic
what is abnormal for BMs?
In US individuals can have between 3 BM’s per day to 3 BM’s per week
Important to distinguish patient vs. physician definition
Patients may complain of “diarrhea” because of a change in
stool number
stool consistency
define: diarrhea
quantitative determination of an increase in stool weight greater than 200 grams per 24 hours
Bristol stool chart (stages)
35yo male who comes in with lots of diarrhea
- 1.5 days of boating and hiking
- had been treated for an upper respiratory tract with amoxicillin
- ate hamburgers and macaroni
Diarrhea x4-5 days
He is hypotensive
diffdx?
w/up?
Tx?
Diarrhea (acute)
- swimming: Giardia -
- Abx: Cdiff
- Hamburgers: E. coli
- Macaroni salad: Staph
most likely: gastroenteritis
w/up: Toxins
Tx:
- increased oral intake of salts + water
- avoid milk – can cause secondary lactase deficiency d/t poor lumen
- +/- antidiarrheal agents: ; can worsen if inflammatory in nature
food poisoning syndromes: C. perfringens: Salmonella: Shigella; Campylobacter: Vibrio: E coli.
C. perfringens: poorly prepared meats & poultry Salmonella: meat, poultry, eggs Shigella; vegetables, cheese, eggs Campylobacter: milk, chicken Vibrio: seafood E coli:hamburgers
you are in charge of developing asystem to provide basic medical care with the intent of improving infant and child mortality to remove villages in Northern Togo, which currently has limited access to medical care.
What 4 conditions are most important to consider (2 are GI), and how would you treat
1) Diarrhea - breastfeeding, ORT
2) Malnutrition - train to measure, nutrition tablets
3) Malaria - rapid test, ongoing fever
4) pneumonia - train to recognize fever, tachypnea
How does oral rehydration therapy work?
ORT -increase oral intake particularly of those rich in salt (e.g. soups), potassium and carbohydrates (bread, rice, saltines)
patho: glucose + Na (grouped transport) to also drag water across to circulation
- Principles of Electrolyte Transport
- ions unable to diffuse across lipid intestinal epithelial membranes
- specialized proteins control ion movement
- passive transport via channels or carriers
- active transport via pumps
Na+/K+ ATPase pump
driving force for absorption on the basolateral membrane
-Drives sodium out of cell and into subepithelial space
SGLT-1 (sodium glucose co transporter)
-Carrier protein on the apical membrane
utilizes the gradient created by the Na+/K+ ATPase pump
-Sodium moved from lumen into cell
What are 3 other pathophysiological mechanisms that lead to diarrhea + examples (not secretory)
Osmotic diarrhea == large solutes in lumen, keeping water in gut
- ex: Go-Lightly; lactase deficiency; intestinal failure (Celiac); pancreatic exocrine insufficiency
Inflammatory == UC
Dysmotility == IBS, after gastric surgery
GI elective: IBD clinic - 20yo famel with UC, who had been medically refractory to 5-ASA meds with frequent steroid tapers, hd been well controlled on Remicade 5mg/kg q8w for the past year. she presents with 3w of non-bloody diarrhea and needs you to control her flare quickly so she can head back to college. you recommend which of the following? A. increase remicade to 10mg/kg B. check remicade levels C. Add 6-MP at 1.5 mg/kg D. add loperamide 2mg QID E. Vancomycin 0.125 mg qid F. Start Prednisone 40mg/d G. Colonoscopy
G. Colonoscopy == shows pseudomembrane
and
E. Vancomycin
6MP takes weeks to work
Dx: Those with IBD are predisposed to C. diff ==> need to check for this compulsively
45yo male presents with 2 months of diarrhea; h/o GERD
Dx: PPI –> causing microscopic colitis
(others SSRI
43 female veterinarian presents with 6 mo diarrhea. Initially profuse watery diarrhea for 10d, that slowed a bit but now is left with loose stools
w/up?
dx?
chronic evaluation:
Weigh the patient, assess for dehydration
Assess for signs of malabsorption, malnutrition and concurrent illness
Careful history and physical exam essential
Laboratory assessment for malabsorption and nutritional parameters
Stool studies if available vs emperic treatment
Role of endoscopy if bleeding or anemia
Imaging studies
dx: post-infectious IBS
treatment options for post-infectious IBS
Loperamide:
==> Patho: Interferes with peristalsis by a direct action on the circular and longitudinal muscles of the intestinal wall to slow motility. May directly inhibit fluid and electrolyte secretion and/or increase water absorption increasing the transit time of the intestinal contents reduces fecal volume, increases the bulk density and the viscosity of the feces, and decreases the loss of electrolytes and fluids from the body.
- Chemically related to opioids, but it does not exhibit analgesic or opiate-like effects, even at high doses.
- Tolerance to the antidiarrheal effect of loperamide has not been observed, and it does not appear to produce physical dependence
Lomotil (atropine-diphenoxylate): PO
- diphenoxylate: schedule C-V controlled substance; synthetic opiate agonist ~ meperidine
- atropine = to discourage deliberate abuse deliberate abuse / overdosage of diphenoxylate
Fiber
Codeine; tincture of opium
Octreotide
Bile acid binders (Colestipol)
65yo male on ortho service, POD3 for itnernal fixation of open femur fracture. Nurse calls you b/c pt complains of bloating and abd is distended. on exam, uncomfortable, he is tachycardic, 160/98 and afebrile. His abd is markedly distended with decreased bowel sounds na dtypamitic on exam. no peritoneal signs
w/up?
tx?
w/up: xray - massively distended colon == Ogilve’s (acute colonic pseudo-obstruction) without mechanical obstruction
==> may develop after surgery or severe illness
tx
- stop drugs that slow motility
- conservative therapy
- colonoscopic decompression (to prevent ischemia, perforation)
- neostigmine IV
Neostigmine ADRs
side effects: transient mild/moderate
bradycardia
problems in pts with asthma and recent MI
