GI System & Drugs

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GI System & Drugs
2013-07-23 22:35:14
GI Drugs parasites assessment

GI system disease processes, GI assessment, and pharmacology
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  1. Malaria
    • On the rise and becoming resistant to insecticides and drug treatment.
    • Humans infected by bite by Anapheles mosquito, which is infected by a parasite that invades liver, other tissues and RBCs
    • Sx: Cycle of malaise, chills and fever q72hr for weeks due to rupture of RBCs and parasite toxic effects
    • Tx: DOC is chloroquine (affects metabolic pathway of parasite needed for reproduction) --> Parasite is becoming resistant to this drug!!
    • --ADME: readily absorbed in GI tract, excreted very slowly
    • SE: CNC, GI, derm, vision; serious = hepatotoxicity, blindness
    • Mefloquine: newer and improved drug (not as resistant); once-weekly dosing, can be used in peds, no photosensitivity like prior drugs; serious side effects!! = psychological problems, severe anxiety, paranoia, hallucinations, unusual behaviors
  2. Amebiasis
    • infection of large intestine by protozoan parasites
    • Food and water borne transmission, ingested and parasite feeds on flora in gut
    • Types:
    • -Asymptomatic: parasite restricted to bowel lumen and person is a carrier w/ no sx
    • -Symptomatic: parasite penetrates mucosa, causing abdominal pain, diarrhea
    • -Extraintestinal: parasites migrate to other areas - liver, spleen, lungs, brain
  3. Anti-Amebiasis Agents
    • DOC is metronidazole (Flagyl): bactericidal, for invasive giardia, amebiasis, trichomonas
    • Oral and IV forms, well absorbed and distributed
    • SE: dizziness, HA < GI sx, thrombophlebitis, vaginal cadidiasis, CNS toxicity
    • D-D: interaction with anticoagulants and ETOH
  4. Toxoplasmosis (toxoplasma gondii)
    • Protozoan
    • Worldwide, often harbored in host w/o evidence of disease, ingesgted cysts found in inadequately cooked meats, commonly cat feces
    • Most common form in U.S. is subclinical (asymptomatic carrier)
    • DOC is Pyrimethamine (Daraprim): depletes folic acid in protozoa, well absorbed and distributed
    • SE: glossitis, GI sx, HA, malaise, dysrhythmias, seizures
  5. Trichomoniasis (trichomonas vaginalis)
    • Protozoan, STI (Sexually transmitted)
    • Female: yellowish frothy discharge, vaginal inflammation, "strawberry" cervix
    • Male: organism found in semen, urethra, prostatic fluid
    • DOC is metronidazole (Flagyl): both partners generally infected and need tx, good absorption orally, widely distributed
    • SE: dizziness, HA, anorexia, GI sx, furry tongue
  6. Giardiasis (giardia lamblia)
    • Most commonly diagnosed intestinal parasite (protozoan) in U.S., infection through contaminated water
    • Primary habitat in upper intestine
    • Sx: diarrhea with "rotten egg" odor, pale color, mucous-filled stool, abdominal pain, malnourishment possible
    • DOC is metronidazole (Flagyl)
  7. Scabies (Sarcoptes scabiei)
    • Ectoparasitic infection (live on surface of host)
    • Infestation of mites, female burrows under skin to lay eggs - INTENSE ITCHING
    • Common sites: writes, elbows, navel, genitalia, webs of fingers, buttocks
    • Transmission by direct contact
    • DOC is permethrim 5% cream: nerve gas type of poison - kills insects by disrupting nerve traffic and causing paralysis
  8. Pediculosis (lice)
    • Pubic (crabs): reside on skin and hair of region
    • Head: reside on scalp and lay eggs in hair
    • Body: reside on clothing, move to body to feed
    • DOC is permethrim cream (Nix, Elimite); may use Lindane (Kwell) if unresponsive to Nix; Malathion (insecticide)
    • *Nix cream made from chrysanthemums and whole house needs to be treated - resistance to this, so DOC moved to Lindane.
    • *Lindane (cream or lotion) may cause neurological problems (retardation) in children
    • *Malathion (Ovide) lotion is highly flammable and linked to chromosomal abnormalities
  9. Parasiticidal Agents & Education
    • Single application is sufficient, but must do more than just medication:
    • -permethrin: whole house needs to be treated (clorox); apply whole body now and rinse off 8 hours later - resistance to this, so going back to mayonnaise!
    • -Mayonnaise and shower cap and fine tooth comb: rinse out 6-8 hours later; vinegar rinse (shampoo is more difficult); fine tooth comb after every day for 2 weeks to remove nits
  10. Helminthiasis
    • Caused by parasitic worms (helminths) 
    • May not cause clinical sx, but cause tissue injury, toxins, feed on host resources 
    • Two basic types: roundworms and flatworms (tapeworms)
    • -Flatworms: source is improperly cooked beef, pork or fish; Scolex (head) attaches to intestinal mucosa, feeds on host nutrients; larvae may travel to liver, muscle, eyes; fertilized eggs released into environment
    • -Roundworms: Pinworm (soil, cyllindrical, L intestine, causes intense itching in anus); Trichinosis (badly cooked pork or bear meat, cysts release larvae in S intestine; larvae travel around body, can cause pneumonia, HF, and encephalitis
    • Flukes: eggs found in snail feces, exclusively in rice paddies and irrigation ditches
  11. Niclosamide (Nicolicide)
    • Anti-helmintic Agents
    • For flatworms
    • Poorly absorbed from intestine so exerts its effect on the worm
    • Destroys scolex and proximal segments which are then destroyed in intestine
    • SE: stomach pain, anorexia, n/v, bad taste 
    • Cured if stool sample is negative for 3 months minimum.
  12. Mebendazole (Vermox)
    • Vermicidal and ovicidal for helminths
    • Oral absorption enhanced by fatty foods
    • SE: uncommon but GI stress, n/v/d
  13. Piperazine
    • Causes paralysis of worm muscles, lose attachment and are expelled
    • SE: GI distress, HA, dizziness, trembling, ataxia (lack of voluntary muscle movement)
  14. GI System
    • purpose: digest, absorb, eliminate
    • Primary organs: stomach, intestines
    • Accessory organs: liver, pancreas, gall bladder (often controlled by hormones of autonomic nervous system)
    • Bulk of absorption in duodenum: Fe, Ca, fats, sugars, water, proteins, vitamins, Mg, Na
    • Little in stomach, only water and alcohol
    • Jejunum: sugars, proteins
    • Ileum: bile salts, Vit B12, Cl
    • Colon: water, electrolytes
  15. Vomiting
    • forceful emptying of stomach and intestinal contents through mouth
    • Initiated by pain, distention, drugs, trauma, motion, activation of chemoreceptor trigger zone (CTZ)
    • Can be preceded by retching, tachycardia, nausea, hypersalivation
    • Hypokalemia
  16. Esophageal Atresia
    • esophagus ends in blind pouch
    • Results in polyhydraminos (too much amniotic fluid surrounding infant in sac; baby can't swallow amniotic fluid which is not absorbed into placental circultion and increases in uterus)
    • Infant unable to feed after born b/c no connection btw stomach and esophagus
  17. Tracheoesophageal Fistula
    • fistula (connection) btw esophagus and trachea
    • abdomen fills with air and becomes distended
    • Reflux of secretions into lungs 
    • Usually happen btw 4th and 6th week of embryonic development and can be repaired after baby is born.
  18. Achalasia
    • Dysphagia (difficulty swallowing) w/ loss of esophageal peristalsis and failure of lower esophageal sphincter to relax
    • Food backs up and distends esophagus.. causing spasms of esophageal muscles
    • Tx: Ca channel blockers (can stop some spasms), balloon dilation, balloon open sphincter and help it to relax, myotomy (cutting muscle to allow food to pass through)
  19. Hiatal Hernia
    • More common
    • 2 types:
    • -Sliding: 
    • -Paraesophageal: (less common) an additional squeezing out, not really affecting esophagus; can become strangled and lose bood flow, causing ischemia; dysphagia
    • protrusion of upper part of stomach comes through diaphragm into upper thoracic cavity
    • Often asymptomatic
    • Tx: surgery to reduce them; suggested more frequent, small meals; meds to reduce acid
  20. Gastroesophageal Reflux Disease (GERD)
    • Reflux of chyme from stomach into the esophagus
    • Can cause heartburn, chronic cough, asthma, dysphagia, laryngitis, abdominal pain
    • Can be worsened by increased pressure: vomiting, coughing, pregnancy, obesity, bending, lifting, lying down after eating
    • Caused by abnormal sphincter tone:
    • -causes include scarring, flapping of muscle, certain foods, and meds (estrogens, Ca channel blockers)
  21. Peptic ulcer Disease (PUD)
    • Break or ulceration in the protective mucosal lining of the lower esophagus, stomach, or duodenum (blood vessels can erode and bleed!)
    • Risk factors: Zollinger-Ellison syndrome (benign tumor that secretes gastrin, which eats and errodes lining)
    • -H. pylori
    • -Alcohol, smoking = inflammation of lining
    • -Chronic use of NSAIDs
    • -Advanced age
    • -steroid use
    • NOT dyspepsia (increased acid prod causing chronic discomfort - not ulceration or break of mucosa)
    • *The deeper the penetration of the erosion, the greater the chance of GI bleed and/or perforation, leading to peritonitis
  22. Heliobacter pylori
    • Gram-negative motile bacillus (rod-shaped)
    • Identified in 90% of people w/ duodenal ulcers and 70% of gastric ulcers
    • Thought to set up an inflammatory reaction
    • Transmitted by oral-fecal route
  23. Ulcers
    • Duodenal: increased acid prod, pain in upper abdomen, pain when stomach empty, pain that diminishes w/ food or antacid, heals more quickly, 5X more common and more present in younger populations
    • Gastric: decreased acid prod, r/t chronic alcohol or non-steroidal drug use, pain in upper abdomen that gets worse w/ food, heals more slowly, antacid relief pattern, more present in older adult population
  24. Pyloric Stenosis
    • Obstruction of pyloric sphincter caused by hypertrophy of the sphincter muscle 
    • Can be acquired in adults through PUD, or carcinoma or cancer causing ulceration, stiffening of sphincter muscle; mostly present in children
    • Projectile vomiting w/o apparent reason
    • In children can palpate a firm, small movable mass
  25. Abdominal Pain
    • Can be acute or chronic
    • mechanical: often due to stretching or distension
    • inflammatory: histamine and bradykinin stimulate nerve receptors to stimulate pain
    • ischemic: something is dying - blood flow is being cut off
    • parietal: localized and intense pain usually from organs (AKA somatic pain)
    • visceral: diffused pain by nerve endings
    • referred: pain at diff site than actual injury
  26. Upper GI bleeding
    • Upper GI: mouth, eso, stomach, first part of duodenum
    • Female > Male
    • Causes:
    • -drug-induced (NSAIDs, corticosteroids)
    • -esophageal: varicies (engorged veins), Mallory-Weiss tear (arterial bleed usually caused by continued retching/vomiting - a tear in eso)
    • -Stomach/duodenum: cancer, inflammation, PUD, stress-related ulcers 
    • -Ischemic ulcers: Curling's ulcers (burn pts fluid depleted, lack of blood flow & ischemia; Cushing's ulcers (related to closed-head injury - increased pressure in head, can press on vagus nerve, and when this is stimulated, this stimulates stomach to produce more acid - ulceration)
    • BUN levels are elevated when have accumulation of blood in GI tract
  27. Liver
    • Hepatic artery: 25% of CO, O2 blood
    • Most of our bloodflow to the liver comes through the portal vein; receives deoxygenated blood from intestines - rich in nutrients
    • Oxygenated blood flows through the intestines first... then to the liver!
    • FXNs:
    • -carbohydrate metabolism (glycogenesis, glycogenolysis, gluconeogenesis)
    • -protein metabolism (synthesis of clotting factors, breakdown of ammonia to urea)
    • -fat metabolism (breakdown triglycerides, synthesis of cholesterol into bile, turns fatty acids into fuel)
    • -detoxification: drugs, harmful subs, alcohol
    • -steroid metabolism: conjugates and excretes gonadal and adrenal corticosteroids hormones
    • -immune system function: Kupffer cells - breakdown RBCs, WBCs, bacteria, breakdown of hemoglobin from old RBCs to bilirubin
    • -bile synthesis: formation of bile containing bile salts (about 1L/day) - buildup of bile = jaundice
  28. Bile
    • bilirubin produced from breakdown of RBCs
    • Free bilirubin travels to liver, where it is conjugated and becomes water soluble
    • conjugated bili is excreted in urine and feces
    • Jaundice = yellow tint to body tissues from accumulation of bile (if liver does not function correctly)
  29. Cirrhosis
    • irreversible inflammatory fibrotic liver disease
    • fibrosis/scarring of liver from injury or necrosis over long period of time
    • Continual damage of hepatocytes (cells) = necrosis regeneration = formation of nodules --> bumpy liver and dysfunction occurs
    • Destruction of liver cells 
    • Regeneration of liver disorganized
    • Scar tissue, fibrotic tissue (nonfunctional) replaces liver tissue (obstructs bf, impairs fxn, asymptomatic until permanent damage)
    • Causes: chronic active hepatitis, malnutrition, toxic injury, metabolic
    • -Various types: not all are alcoholics!
    • Manifestations: Neurologic (encephalopathy), GI (anorexia, n/v, ab. pain), Reproductive (impotence, gynecomastia), Integumentary (jaundice), Hematologic (anemia, coagulation, splenomegaly), Metabolic (Hypokalemia, hyponatremia), Cardiovascular (fluid retention, peripheral edema, ascites, dysrhythmias, R-HF, portal HTN), pulmonary (dyspnea, hyperventilation, hypoxemia), renal (hepatorenal syndrome)
    • Early: insidious onset (many people don't know - slow and creeps up), altered metabolism
    • Late: hepatocellular failure, portal HTN
    • *Obstructive or hepatocellular jaundice can cause pruritis, which is billirubin when deposited in skin, can cause severe itching
  30. Portal Hypertension
    • obstruction of forward flow of portal venous sytem - backup of flow and increased pressure (usually very low!)
    • Multiple causes: thrombosis, inflammation, liver fibrosis/cirrhosis, cardiac failure
    • body responds to increased pressure by developing collateral circulation in lower esophagus, anterior abdominal wall, parietal peritoneum, rectum
    • -creates "tortuous", twisted, engorged vessels w/ weak endothelial walls (varices)
  31. Esophageal varices
    • Submucosal veins in distal esophagus
    • venous collateral circulation secondary to portal HTN seen in about 50% of pts w/ cirrhosis
    • 1/3 of pts w/ varices develop upper GI bleeding (people vomit, so go in and band vessels to cut off blood loss; bleeding is painless)
  32. Ascites
    • accumulation of fluid in peritoneal cavity
    • -Na and water retention, decreased albumin (not keeping fluid in vascular space, so decreased capillary osmotic pressure and fluid seeps into space)
    • most common cause is cirrhosis
    • Others are HF, abdominal malignancy, nephrotic syndrome, malnutrition
    • Complications: bacterial peritonitis (stagnant fluid), inguinal and femoral hernia, reflux esophagitis, elevated diaphragms, pleural effusions, respiratory distress
  33. Viral hepatitis
    • 5 types: A (fecal-oral transmission), B (3-5% are chronic, parenteral [blood - needle stick], sexual transmission), C (50% chronic, most parenteral, sexual [rare]), D (fecal-oral), E (fecal-oral)
    • Cause acute, icteric illness
    • Hepatic cell necrosis, scarring, Kupffer cell hyperplasia
    • Obstruction of bili canaliculi, cholestasis (bile can't flow from liver to duodenum, obstructive jaundice
  34. Hepatitis
    • Prodromal: 2 weeks after exposure; ends w/ jaundice
    • Icteric: 1-2 weeks after prodromal phase, lasts 2-6 weeks; actual phase of illness - dark urine, clay-colored stools, a lot of prod. and obstruction of billirubin.
    • Recovery: resolution of jaundice, 6-8 weeks after exposure
  35. Cholelithiasis
    • Gallstones
    • Risk factors: The 4 F's - female, forty, fat, fertile (females on birth control pills are at increased risk)
    • Can cause cholecystitis (inflammation of gall bladder)
  36. Exocrine Pancreas
    • "exocrine" = digestive pieces of pancreas
    • Common duct
    • Secretes into duodenum
  37. Acute pancreatitis
    • inflammation of pancreas
    • Usually mild, but can be life-threatening
    • Pathologic activation of enzymes within the pancreas causing autodigestion
    • Multiple causes: biliary tract disease (stone blocks duct opening to pancreas), Alcoholism, abdominal trauma, drugs
    • Sx: acute abd pain, sudden in onset, aggravating by eating, not relieved by vomiting, fever, dehydration
    • *S/sx may be misinterpreted as MI, PUD, gallbladder disease
  38. Appendicitis
    • acute inflammation of the appendix
    • Obstruction develops in lumen (food and particles get trapped leading to infection and inflammation
    • -edema from inflammation  = decrease bf, necrosis, tissue death
    • -gangrene and perforation can happen in 24-36 hours, so appendix must be removed and antibiotics given
  39. Intestinal obstruction
    • large or small bowel obstruction (SBO)
    • any condition that prevents the normal flow of chyme through the intestinal lumen
    • Simple (mechanical) vs. Paralytic ileus (functional - usually after surgery and related to inflammation - muscle mvmt of intestine slows down and becomes dysfunctional for a period of time) 
    • Obstruction will cause crampy/colicky pain, vomiting, distension, sweating, nausea, hypotension, diarrhea, constipation
  40. Constipation
    • difficult or infrequent defecation
    • decrease in bowel mvmts per week, hard stools, difficult evacuation
    • Can be functional (normal passage but difficult), slow transit (slowing of impaired motor activity - like from meds), pelvic floor dysfunction (muscles to expel are not functioning properly), neurogenic (spinal cord lesions)
  41. Diarrhea
    • increase in frequency of defecation and in the fluid content and volume of feces
    • 3+ stools per day
    • Acute or chronic
    • -acute: less than 2 weeks, infection, meds
    • -chronic: malabsorption, HIV
    • Osmotic: lots of water - laxatives, antacids, sugar
    • Secretory: usually by bacterial toxins 
    • Motility: impaired motility of stool 
    • Large volume: usually osmotic
    • Small volume: usually r/t inflammation to bowel disease
  42. Irritable Bowel Syndrome (IBS)
    • *Very diff from Irritable Bowel Disease (IBD)!!*
    • Idiopathic... don't know cause
    • recurrent abd pain
    • diarrhea, constipation, or both
    • abnormal GI motility
    • Visceral hypersensitivity
  43. Irritable Bowel Disease (IBD)
    • chronic, inflammatory bowel disease
    • Increases risk of colon cancer
    • combined effects of environment, genetics, mucosal immune dysregulation, alteration in microbial flora, epithelial barrier dysfunction
    • 2 Diseases:
    • 1) Ulcerative Colitis (UC): located mostly in rectum and colon; large, continuous lesion, destruction and inflammation of mucosa - bleeding and cramping; boody/painful stools [10-20/day]); periods of remission
    • 2) Crohn's disease: mouth to anus with "skip" lesions; submucosal inflammation causing diarrhea (usually non-bloody); periods of remission
  44. Diverticulosis
    • herniations or saclike outpouchings of the mucosa and submucosa
    • most common in left sigmoid colon
    • Causes: low residue diet common (low fiber diet - constipating, pushing, pressure of straining to cause aneurysms or outpouches)
    • Diverticula can become inflamed causing diverticulitis
    • *It's okay to have diverticulosis, but issue is that it can lead to diverticulitis (pouches filled with stool (fecaliths) can become infected = treat w/ antibiotics); happen in 1/3 of pts > 60 yrs
  45. Hemorroids
    • veins that prolapse into the anal canal as a result of engorgement and straining
    • Risks: age, pregnancy, low fiber diet, constipation, weight lifting, pelvic tumors (related to high pressure systems on veins)
    • Bleeding, protruding mass, anal itching, pain
    • Can remove surgically or topical creams can help veins constrict
  46. Assessment Subjective Data affecting adequate Nutrition
    • Normal eating patterns and food preference
    • -24 hr food recall-cultural/religious (i.e. restrictions)
    • -adequacy of food shopping/preparation
    • -nutritional knowledge
    • -physiological factors (swallowing)
    • -socioeconomic factors-medications
    • -developmental considerations
    • -psychological factors (eating disorders)
  47. Assessment Objective Data affecting adequate Nutrition
    • Physical observations
    • -height & weight
    • -skin fold (subcutaneous fat) and arm circumference
    • Calorie count
    • -what foods are they taking in? Are they able to withstand their current metabolic state?
    • Lab evaluation
    • -hematocrit (% of rbc in blood) & hemoglobin (body's O2 and Fe-carrying capacity)
    • -serum albumin & prealbumin: protein markers help assess nutritional status 
    • --albumin: long term (1/2 life = 18 days); < 3.5 = nutritional deficits
    • --prealbumin: half life = 2 days, gives current nutritional status
    • -serum transferrin: transferrin is a blood protein that binds with Fe = sensitive indicator of protein deficiency (more rapid than serum albumin)
    • -creatinine excretion: rate of creatinine formation proportional to total muscle mass (as muscles atrophy during malnutrition, creatinine levels ↓. Usually by 24 hr urine sample
  48. Types of Diets
    • NPO
    • Regular ~2000 calories/day (no limitations)
    • Clear liquid (transparent, when nauseous or queasy after surgery)
    • Full liquid (clear + liquid at rm temp [ice cream])
    • Soft (less energy to chew - chopped, pureed, hard to swallow)
    • Diet as tolerated
    • Restrictive (i.e. low sodium)