Vomiting center
-receives afferent signals from cortical nerves & peripheral nerves (vagus)-sends out efferent signals back down vagus which triggers a vomiting reflex
chemo-induced N/V (CINV) Mechanism
-chemo stimulates enterochromaffin cells to release serotonin-binds to receptors on vagal fibers-leads to Afferent stimulus via vagus up to brain which activates the central pattern generator which causes vomiting-this is a primary mechanism that chemo agents cause acute emesis
how do drugs/meds cause vomiting?
-get in bloodstream & circulate into brain-recognized as foreign-brain may induce vomiting to protect itself from "poison" (evolutionary mechanism)
Chemoreceptor trigger zone (CTZ)
-receives inputs from blood-borne drugs or hormones & communicates w/ structures in the vomiting center to initiate vomiting-opioids-dopaminergic agonists -peptides/metabolites of chemo drugs
Barrett's Esophagus
-excessive acid in lower esophagus causes esophageal tissue to take on characteristics of intestinal lining (columnar epithelium instead of squamous)-this change is an ex of metaplasia-caused by GERD-MC in white men-increases risk of esophageal cancerDx: endoscopy Tx: symptomatic -won't reverse changes-avoid unhlthy foods that require more acid for breakdown & cause delayed gastric emptying-NSAIDs block COX-signaling which may protect against esophageal cancer
Globus pharyngeus
Feels like a lump in the throat - may be sign of hiatal hernia
Categories/Classes of causes of dysphagia
MECHANICAL:-wall defects-intrinsic narrowing of esophagus -Extrinsic compression of esophagusMOTOR:-dzs of cerebral cortex & brainstem (dementia)-dzs of cranial nerves (V, VII, IX, X, XII)-Neuromuscular
Why are elderly at higher risk of dysphagia?
-decrsd function of laryngo-upper esophageal sphincter contractile reflex-decrsd salivary glands to create bolus-polypharmacy can cause dry mouth-loss of teeth-parkinson's, stroke, dementia, motor neuron dzs
xerostomia
dry mouth
DDX if dysphagia is in response to solids AND liquids
-esophageal motor/motility dysphagia-usu caused by neuro problems-scleroderma-achalasia
Achalasia
-motor problem of esophageal motility - AUTOIMMUNE-constriction of lower esophageal sphincter-liquid dysphagia-inhibitory, N.O.-producing neurons from myenteric plexus degenerate-causes impaired sm mm relaxation-can be env, viral, or Autoimmune-DX: esophagram (swallow fluoroscopy) - Bird-Beak appearance (narrowing) w/ dilation above -TX: botox, dilatation, surgery
Chalasia
Relaxation of a sphinctercommon in babies
Esophogram
-fluoroscopic (x-ray video) exam of pt while they swallow-allows you to look at mechanical process of swallowing
DDX if dysphagia is in response to solids only
-esophageal mechanical dysphagia-lower esophageal ring-carcinoma
Infectious Esophagitis & causes
-Immunosuppression!!!!-dysphagia & odynophagia-chest pain-CAUSES: candida, herpes simplex virus (HSV), & cytomegalovirus (CMV)-DX: Endoscopy & Bx
Eosinophilic Esophagitis
-MC in kids, young adults & males-50% are IgE-mediated (atopy)-Dysphagia-Heartburn-impaction-DX: may see rings or need bx-50% have eosinophilia and high IgE (not sensitive or specific)
Esophageal varices (differentiate from mallory-weiss tear)
-Emergency! - dilated submucosal veins in lower 1/3 of esophagus due to...-portal HTN (cirrhosis) - RHF or metabolic syndrome-nonalcoholic fatty liver dz-assoc w/ alcoholic gastritis-causes upper GI bleedingDx: endoscopyTx: Balloon tamponade (opens esophagus)
Different methods to treat varices
-Sclerotherapy (inject irritants into vein to make clot)-Banding (rubber bands around veins to cause clot)-Vasoconstrictors of splanchnic vessels (decrs flow into portal system) -Octreotide-Epinephrine squirt (vasoconstrict to stop bleeding)-Beta blockers (decrs CO to stop bleeding)-Blood Transfusion-Transjugular intrahepatic portosystemic shunt (TIPS)-artificial shunt btwn portal syst & systemic circulation-best tx to prevent re-bleed, but assoc w/ incrsd risk of encephalopathy
Mallory-Weiss Tear (differentiate from varices)
-bleeding from mucosal tear at gastroesophageal junction (don't bleed as much as varices)-CAUSES: severe coughing or vomiting-EtOH-Hiatal herniaDx: endoscopyTx: supportive, observation if low risk-if high risk, do sclerotherapy, epinephrine, or electrocoagulation-give PPIs
Gastroparesis
-delayed peristalsis due to pseudo-obstruction (nerves aren't working to move stuff through GI tract)-often post-surg or in diabetics-Autonomic neuropathy (vagal)-bloated, fullness-delayed gastric emptying-N/V/D or constipation
GERD Causes & Tx
-poor esophageal motility-dysfunctional lower esophageal sphincter-delayed gastric emptying (caused by fatty foods)-may be caused by hiatal hernia-obesityTX: PPIs (Omeprazole) or Histamine blockers (Zantac)
How do antihistamines (zantac) work for GERD tx?
block histamine from transferring protons aka releasing gastric acid
aspirin & GERD
Aspirin blocks Cox I causing increased stomach acid - exacerbates GERD
Peptic Ulcer Disease
-H. pylori & NSAIDs are 2 MC causes-leading cause of upper GI bleed-dyspepsia-epigastric pain/burning-early satiety-retrosternal pain (heartburn)Dx w/ endoscopy
H. Pylori
-spirochete -buries into mucus lining of stomach which is protective-causes cytokine release from gastric epithelial cells-causes chronic inflammation w/ neutrophil & macrophage recruitment
Ways to test (labs) for H. pylori
-Serology of IgM & IgG (high) - this won't work if pt has been treated for H. pylori in the past-Stool antigen - test of choice -Urea breath test
Urea breath test
-swallow radiolabeled urea-w/in 30 minutes, labeled CO2 in breath indicates the presence of bacterial urease in the stomach-expensive
Gastritis (esp causes)
-stomach inflammation-caused by alcohol, NSAIDs, pts in critical care, H. pylori, or portal HTN-may be pre-malignant-can be ASX or cause pain, N/V, hematemesis but is usu clinically insignificant-tx w/ PPIs
Zollinger-Ellison Syndrome - BOARDS
-rare-Gastrinoma = pocket of stomach tissue that forms in pancreas, duodenum, or lymph nodes-N/V/D-anemia-GERD sx-Incrsd serum gastrin >1000 - PATHOGNOMONIC -low pH inactivates pancreatic enzymes causing: diarrhea, steatorrhea, wt loss-associated w/ multiple endocrine neoplasia 1
Multiple Endocrine Neoplasia 1
-occurs in 25% of cases of Zollinger-Ellison -mutation in a tumor suppressor gene causing skin lesions-thyroid, adrenal, pancreas, ovaries/testes affected-refer to endocrinology
Autoimmune pernicious anemia
-make Abs against HKATPase proton pump-causes loss of HCl (Achlorhydria) then loss of parietal cells resulting in neutralized intrinsic factor -leads to incrsd gastrin production-B12 can't be absorbed-atrophic gastritis (chronic inflamm causes atrophy & fibrosis of stomach mucosa)DX: Schilling Test - give B12 shot & do urine samples to see if it was absorbed & peed out (normal) or not (pernicious anemia)
Schilling Test
-Inject non-radioactive B12 to temporarily saturate liver receptors-Give pt. oral radioactive B12 & check urine sample to see if it got peed out (meaning it was absorbed by GI tract out of stool into body)-If not in urine, body not absorbing B12 ---> pernicious anemia
MC sources of bleeding in elderly
1-Ulcers2-Varices3-No source identified in 8-14%4-Mallory-Weiss tears
primary RFs for upper GI malignancies
-smoking-EtOH-H. pylori-GERD-smoked & cured meats
Esophageal cancer
-mc adenocarcinomas-Progressive dysphagia for solids-weight lossDx: esophagram or endoscopy
Gastric Cancer (type, sx, dx)
-usually adenocarcinoma-Dyspepsia-early satiety-Wt loss & anemia -vague painDx: upper GI endoscopy