GI & Nutritional Disorders – Comprehensive Study Notes
Malnutrition and Nutrition Problems
- Definitions
- Malnutrition = deficit, excess, or imbalance of essential nutrients.
- Sub-types
- Over-nutrition: intake exceeds requirements.
- Under-nutrition: nutrient/energy intake insufficient for basal needs or added stress; reserves depleted.
- Etiology categories (ASPEN taxonomy)
- Starvation-related malnutrition (Primary Protein–Calorie Malnutrition)
- Chronic starvation, little/no inflammation.
- Ex: anorexia nervosa.
- Chronic disease–related malnutrition (Secondary PCM)
- Sustained mild–moderate inflammation.
- Ex: organ failure, cancer, RA, obesity.
- Acute disease or injury–related malnutrition
- Marked inflammatory response.
- Ex: sepsis, burns, trauma, major surgery.
- Contributing factors
- Socioeconomic (food insecurity, “heat-or-eat” choices, limited support).
- Physical illnesses, hospitalisation, GI diseases.
- Impaired absorption ↓enzymes, ↓surface area, drug S/E, ↑BMR w/ fever.
- Incomplete diets (alcohol/drug use disorders, chronic illness, fad diets).
- Starvation process
- 1st 18 h: use glycogen.
- Next: skeletal protein → gluconeogenesis; later 97 % calories from fat.
- Fat stores gone ≈ 4–6 wks ⇒ visceral + body protein catabolised.
- ↓Liver fx → ↓albumin → ↓oncotic P → edema; liver fatty, shrinks.
- Death unless protein supplied.
- Clinical manifestations (mild → emaciation)
- Dry/scaly skin, brittle nails, hair loss, mouth ulcers, ↓muscle, fatigue.
- Mental changes, infection risk, anemia.
- Screening / Assessment
- The Joint Commission: nutrition screen ≤24 h of admission.
- MUST tool (BMI + wt-loss + acute-disease score)
- \text{BMI > 20}\Rightarrow0\qquad18.5{-}20\Rightarrow1\qquad<18.5\Rightarrow2
- Add wt-loss & \text{NPO}>5 d; total ≥2 = high risk.
- BMI equation BMI=\frac{\text{Wt (lb)}\times703}{\text{Ht (in)}^{2}}
- Under-wt <18.5\,kg/m^{2}; normal 18.5{-}24.9; overweight 25{-}29.9; obesity \ge30.
- Food guidance: USDA MyPlate – 5 groups visual cue.
Enteral Nutrition (EN)
- Definition: nutritionally complete formula via tube → GI tract (stomach, duodenum, jejunum) when oral unsafe/insufficient.
- Indications: anorexia, orofacial fractures, H/N cancer, neuro/psych d/o, burns, critical illness, chemo, radiation.
- Contra-indications: GI obstruction, prolonged ileus, severe V/D, high-output enterocutaneous fistula.
- Access routes
- Short-term: NG, nasoduodenal, nasojejunal.
- Long-term: gastrostomy (PEG), jejunostomy.
- Administration safety
- Confirm placement (x-ray on insertion, mark exit site, re-check q feed/8 h).
- HOB ≥30^{\circ} (continue 30–60 min post bolus).
- Monitor gastric residual per policy; consider promotility drugs.
- Complications
- Aspiration, vomiting, diarrhea, constipation, dehydration (high calorie dense formulas), refeeding syndrome (hallmark = hypophosphatemia), tube site skin irritation, accidental removal.
- Advantages vs PN: physiologic, cheaper, lower infection risk.
Parenteral Nutrition (PN)
- Definition: IV infusion of dextrose, amino acids, lipids, electrolytes, vitamins, trace elements; “TPN”.
- Indications: severe V/D, bowel obstruction, short-bowel, severe malabsorption, anorexia nervosa, complicated surgery/trauma, GI fistulae.
- Routes
- Central PN (via PICC, subclavian, IJ): long-term, hypertonic.
- Peripheral PN: short-term, lower osmolarity.
- Complications
- Refeeding syndrome (↓P, ↓K, ↓Mg, fluid retention).
- Metabolic: hyper/hypoglycemia, fatty acid deficiency, ↑TG, liver dysfunction, renal issues.
- Catheter related: infection/sepsis, air embolus, thrombosis, occlusion, hemorrhage.
Obesity
- Epidemiology
- 43\% US adults obese; highest in South/Midwest, Black & Hispanic, low-income/education.
- Pathophysiology
- Energy intake > expenditure → hypertrophy & hyperplasia of adipocytes (most visceral/subQ). >400 genes influence appetite, satiety, metabolism.
- Primary vs secondary (endocrine, CNS lesions, meds e.g., corticosteroids).
- Environmental/Psychosocial contributors: high-calorie food access, large portions, sedentariness, screen time, stress eating.
- Health risks (Fig 45-5): CVD, DM2, HTN, OSA, NAFLD/NASH, cancers, OA, psychosocial issues.
- Assessment
- BMI, waist circumference (>40'' men, >35'' women), waist-to-hip ratio, comorbidities labs (lipid, FBG, LFT, TSH).
- Management goals: modify diet, ↑exercise (\ge150 min/wk moderate), 5-10 % wt loss improves outcomes.
- Behavior therapy tools: self-monitoring logs, stimulus control, reward systems; strong motivation (appearance) predicts success.
- Pharmacology (BMI ≥30 or ≥27+comorbidity)
- Orlistat – blocks fat absorption (steatorrhea).
- Lorcaserin (5-HT agonist) – ↑satiety.
- Phentermine/topiramate; bupropion/naltrexone.
- Bariatric Surgery
- Criteria: BMI ≥40 or ≥35+comorbidity.
- Procedures: Adjustable gastric band, sleeve gastrectomy, Roux-en-Y gastric bypass, BPD w/ duodenal switch.
- Produces greatest sustained weight loss.
Upper GI Disorders
Nausea & Vomiting
- Many etiologies (GI, CNS, CV, pregnancy, drugs). Complications: dehydration, electrolyte loss (K, Na, Cl), metabolic alkalosis.
- Assess emesis characteristics (bright red ⇒ active bleed; coffee-ground ⇒ gastric bleed; fecal odor ⇒ distal obstruction; projectile ⇒ ↑ICP).
- Care: identify cause, NPO/IVF, anti-emetics tailored, aspiration precautions, semi-Fowler.
Gastro-Esophageal Reflux Disease (GERD)
- Patho: incompetence of LES ± delayed gastric emptying → reflux of corrosive gastric juices → esophagitis, strictures, Barrett’s esophagus (precancerous).
- Risk factors: ↑gastric volume post meals, obesity, tight clothes, smoking, hiatal hernia.
- Symptoms: heartburn post-prandial & supine, dysphagia, hoarseness, chest pain.
- Dx: barium swallow, EGD, pH monitoring.
- Management
- Lifestyle: upright ×3 h post meal, HOB elevated, small meals, avoid triggers (caffeine, alcohol, chocolate, peppermint, fatty/spicy), weight loss.
- Drugs: H2 blockers, PPIs.
- Surgery: Nissen fundoplication if refractory.
Hiatal Hernia
- Stomach herniates through diaphragm.
- Sliding – slides when supine; paraesophageal – beside esophagus, risk strangulation.
- Similar care to GERD; surgery if complications.
Gastritis
- Inflammation d/t mucosal barrier breakdown; acute (drugs, alcohol, stress) or chronic (H. pylori, autoimmune, toxins).
- Manifestations: anorexia, N/V, epigastric pain, fullness, melena/anemia.
- Dx: H&P, endoscopy, H. pylori tests, CBC, occult blood.
- Management: remove cause, PPIs/H2B, sucralfate, antibiotics for H. pylori, 6 small bland meals; acute usually self-limits.
Peptic Ulcer Disease (PUD)
- Ulceration in lower esophagus, stomach, duodenum from acid-pepsin.
- Risk: H. pylori (most common), NSAIDs/ASA, smoking.
- Types
- Gastric: pain 1{-}2 h post-meal, worsens with food.
- Duodenal: pain 2{-}5 h post-meal, relief with food/antacids.
- Complications: hemorrhage (melena/hematemesis), obstruction, perforation (rigid board-like abdomen, rebound tender, shock).
- Dx: EGD with biopsy, H. pylori tests, UGI/barium.
- Therapy: \text{PPI}+2 antibiotics (clarithro + amox or metro); adjunct H2B, sucralfate, misoprostol, antacids; avoid NSAIDs, smoking, alcohol.
- Complication care: NG decompression, IV antibiotics, surgery PRN.
Pharmacology Quick Reference (GI)
- H2 Receptor Blockers – cimetidine (many S/E, ↑warfarin), famotidine (Pepcid), ranitidine* withdrawn.
- PPIs – omeprazole, esomeprazole; give ≥1 h before breakfast; long-term risk C. diff, osteoporosis.
- Sucralfate – GI protectant; coats ulcer; give on empty stomach, 2 h apart from meds.
- Misoprostol – prostaglandin analog prevents NSAID ulcers; contraindicated pregnancy.
- Antacids – calcium carbonate (constipation/rebound), magnesium hydroxide (diarrhea), aluminum salts (constipation). Separate other meds ≥2 h.
- Antidiarrheals – loperamide (Imodium; no <2 y/o, high doses → arrhythmia), bismuth subsalicylate (black stool/tongue; salicylate toxicity tinnitus; avoid with ASA).
- Laxatives
- Bulk: psyllium; safe long-term; need fluids; space meds 2 h.
- Stimulant: bisacodyl.
- Osmotic: sodium phosphate (Fleet).
- Lubricant: docusate mineral oil (↓fat-vit absorption, lipid pneumonia if aspirated).
Lower GI Disorders
Diarrhea
- Patho: ↑motility (↓absorption) or ↑secretion (infection, osmotic). Report bloody diarrhea.
- Risks: dehydration, metabolic acidosis (HCO₃⁻ loss).
- Assessment: frequency, girth, sounds, hydration, meds, food.
- Dx tests when severe/bloody: cultures, O&P, WBC, C-diff, sigmoidoscopy.
- Management: treat cause, fluid/e-lyte replace, hold solids 24 h then small meals; avoid antidiarrheals in infection.
Clostridioides difficile
- Spores persist 70 days; handwash with soap; contact isolation; clean surfaces (EPA list K).
- Tx: PO vancomycin 125 mg QID or fidaxomicin; stop other abx; metronidazole alt; recurrent: fecal microbiota transplant.
Constipation
- ↓frequency, hard stool, straining; Valsalva risk ↑ICP, cardiac strain.
- Causes: low fiber/fluids, inactivity, ignoring urge, chronic stimulant laxatives, obstruction.
- Tx: high fiber, fluids 2 L, exercise, bulk laxatives, avoid chronic stimulants; education.
Fecal impaction
- Putty mass; seepage; treat with oil retention enema → cleansing → manual removal (vagal risk).
Irritable Bowel Syndrome (IBS)
- Functional; Rome IV ≥1 day/wk ×3 mo abdominal pain + stool change.
- Subtypes: IBS-C, IBS-D, mixed, unsubtyped.
- Triggers: stress, infection, food intolerances (gluten, lactose, FODMAPs).
- Care: CBT, stress mgmt, low-FODMAP diet, exercise, antispasmodics (dicyclomine), antidepressants; IBS-D – rifaximin, alosetron; IBS-C – linaclotide, lubiprostone.
Inflammatory Bowel Disease (IBD)
Ulcerative Colitis
- Continuous superficial inflammation from rectum proximally; bloody diarrhea, LLQ pain, tenesmus.
- Complications: toxic megacolon, perforation, colorectal CA.
Crohn’s Disease
- Transmural skip lesions anywhere GI (terminal ileum common); non-bloody diarrhea, RLQ pain, weight loss, fistulas, malabsorption (B₁₂).
- Diagnostics: colonoscopy, SBFT, labs.
- Drug goals: induce/maintain remission.
- 5-ASA, corticosteroids, antimicrobials, immunomodulators (azathioprine), biologics (anti-TNF).
- Surgery
- UC: total proctocolectomy curative (ileostomy).
- Crohn: segmental resection/strictureplasty; risk short-bowel.
- Nutrition: high-calorie, high-protein, low-residue; enteral preferred during flares; avoid trigger foods, lactose, cold/high-fat.
Diverticular Disease
- Diverticulosis = sacs; diverticulitis = inflamed/perforated.
- Risks: low-fiber diet, aging, sedentary.
- S/S: LLQ pain, fever, constipation/diarrhea.
- Tx: NPO → clear → high-fiber; antibiotics; surgery if abscess/perforation.
- Prevention: fiber-rich diet, ↓fat/red meat, fluids ≥2 L, avoid straining.
Hemorrhoids & Anal Disorders
- Hemorrhoids: dilated rectal veins; internal painless bleeding, external painful; risk pregnancy, constipation.
- Conservative: high fiber/water, stool softeners, sitz baths, anesthetic creams.
- Procedures: sclerotherapy, rubber-band ligation, hemorrhoidectomy (post-op care checklist).
- Anal fissure: linear tear; severe pain; sitz baths, topical analgesia, stool softeners; maybe lateral sphincterotomy.
- Anorectal abscess: obstructed gland; pain, swelling, fever; surgical drainage, moist heat.
- Anal fistula: tract from rectum to skin/vagina; surgery (fistulotomy, LIFT).
Diagnostic & Monitoring Highlights
- EGD: NPO 8 h, consent, sedation; post – gag reflex, temp q15–30 min (perforation).
- Upper GI/Barium swallow & Lower GI/Barium enema: NPO 8 h; post – laxatives, fluids, stools white ≤72 h.
- MUST, BMI, waist metrics as earlier.
Ethical / Practical Considerations
- Non-judgmental communication about weight & nutrition; clarify need for sensitive questions.
- Ensure informed consent for invasive procedures; respect cultural dietary practices.
- Address food insecurity with community resources.
- Infection control: C-diff isolation, hand hygiene—protect patients & staff.
Quick Reference Equations & Values
- BMI=\dfrac{kg}{m^{2}}\quad\text{or}\quad BMI=\dfrac{lb\times703}{in^{2}}
- MUST scoring ≥2 = high risk.
- Waist risk: Men >40'', Women >35''.
- Exercise goal: 150 min moderate / wk or 75 min vigorous.
- EN head-of-bed \ge30^{\circ}; refeeding ↓P hallmark.