The Digestive System

Upper Gastrointestinal (UGI) Tract

Gastroesophageal Reflux Disease (GERD)

• Pathophysiology:
    - Weak esophageal sphincter fails to close completely after food enters the stomach.
    - This allows backflow of gastric juices into the esophagus.
    - Throat tissue is different from stomach tissue and is unable to withstand stomach acid.
    - The condition is often developed with age, linked to habits such as straining during bowel movements increasing internal pressure against the sphincter.
    - Weightlifters holding their breath similarly experience increased internal pressure.
    - Heartburn:
      - Caused by regurgitation of chyme and gastric acid into the esophagus 30–60 minutes post meals.
      - Leads to inflammation of the esophageal mucosa and tissue erosion, resulting in Esophagitis.
      - Healing creates fibrosis (scar tissue) that is less flexible than original esophageal tissue.

• Self-medication:
    - Many use over-the-counter antacids (e.g., Tums, Rolaids).
    - Antacids provide temporary relief but do not prevent acid release, potentially leading to electrolyte imbalances due to high sodium, calcium, or magnesium content.

• Symptoms and Signs (S/S):
    - Pain intensifies when lying down or bending over.
    - Patients may sleep in a recliner or with the bed elevated to alleviate discomfort.
    - Chest pain can mimic heart attack symptoms, misleading patients into delaying emergency treatment.
    - Potential respiratory symptoms as gastric reflux may reach the larynx.

• Risk Factors:
    - Obesity
    - Pregnancy
    - Smoking
    - Hiatal hernia
    - High-fat foods
    - Alcohol consumption
    - Chocolate consumption

• Treatment (Rx):
    - Use of acid-suppressing medications (e.g., proton-pump inhibitors like omeprazole).
    - Smoking cessation and avoiding secondhand smoke (increases gastric irritation and vasoconstriction, impairing healing).
    - Eliminate caffeine and check for gluten intolerance.
    - Adopt a high-protein, low-fat diet.
    - Maintain an elevated head position while sleeping.
    - Remain upright for 2 to 3 hours post meals.
  

• Emergency Situations:
    - In the ER, patients with chest pain may receive a “cardiac cocktail” (including Mylanta and viscous lidocaine) to rule out myocardial infarction (M.I.).
    - If pain subsides after the cocktail, it's likely a GI issue rather than cardiac.
    - Lying down aggravates GERD pain, aiding in differentiation from cardiac issues.

• Surgical Interventions:
    - Severe GERD may require surgery (Nissen Fundoplication) to wrap the stomach's top around the esophagus.
    - Post-surgery, patients won't be able to vomit or belch.
    - Chronic GERD risks precancerous dysplasia (e.g., Barrett’s Esophagitis) and esophageal cancer.
    - Advise patients: “DO NOT IGNORE HEARTBURN – it can lead to throat cancer.”

Hiatal Hernia

• Pathophysiology:
    - Protrusion of the upper stomach part through the diaphragm into the thorax.
    - Causes blood flow congestion and ischemia.
    - Widening of the diaphragm's opening weakens the entry for esophagus (known as hiatus).

• Risk Factors:
    - Increased age
    - Pregnancy
    - Obesity
    - Habitual vomiting (in eating disorders)
    - Weight training
    - Smoking and alcohol consumption.

• Symptoms and Signs (S/S):
    - Rarely causes symptoms unless GERD is present (see GERD for associated symptoms).
    - Chest pain may mimic heart attack, requiring careful evaluation to rule out cardiac causes.

• Treatment (Rx):
    - Acid-suppressing medication.
    - Surgical intervention if severe enough to warrant it.

Peptic Ulcer Disease (PUD)

• Pathophysiology:
    - Involves erosion of stomach lining with Helicobacter pylori (H. pylori) present in >90% of duodenal ulcers and ~80% of stomach ulcers.
    - Stress ulcers are prevalent in hospitalized patients caused by burn trauma, head injuries, and critically ill states.
    - Treated using proton-pump inhibitors (PPIs) like intravenous pantoprazole [Protonix].

• Risk Factors for PUD:
    - Smoking and second-hand smoke
    - Alcohol (ETOH) consumption
    - NSAID utilization (aspirin, ibuprofen, naproxen).

• Symptoms and Signs (S/S):
    - Epigastric/chest pain that occurs 2 hours after eating or during the night after stomach has emptied.
    - Pain often relieved by eating.
    - Ulcers may resolve spontaneously or worsen, leading to upper gastrointestinal bleeding (UGIB) or perforation.
    - Common signs include anemia, profuse bleeding, and stomach cancer.

• Tests for PUD and UGIB:
    - CBC (Complete Blood Count)
    - Hematocrit and Hemoglobin levels
    - H. Pylori blood test
    - Occult blood smear
    - Endoscopy (EGD - Esophagogastroduodenoscopy) for visualization and possible intervention.
    - Biopsy for H. Pylori testing during EGD.

• Treatment (Rx):
    - Combination drug therapy comprising antibiotics to target H. pylori and acid-suppressing medications.
    - Active UGIB can be cauterized during endoscopy.

Types of Ulcers Comparison

GI Bleeding Overview

• Signs:
    - Type of blood indicates bleeding source location.
• UGIB and LGIB:
    - Can be chronic/slow with minimal symptoms or acute/life-threatening.
    - Perforated ulcer: stomach acid enters peritoneal cavity, causing severe pain and rigid abdomen, leading to shock/sepsis.
    - Occult GI bleeding: positive fecal occult blood without visible blood.
    - Overt GI bleeding: may present as hematemesis, melena, or hematochezia.
• Key Definitions:
    - Hematemesis:
      - Upper GI bleeding caused by:
        - Bright red emesis (immediate emergency).
        - Coffee-ground emesis (partial digestion of blood).
    - Melena: Black, tarry stools from partial digestion of blood in intestines.
    - Hematochezia: Bright red blood from the rectum, often due to hemorrhoids or diverticulosis rather than serious issues.

Lower Gastrointestinal Tract

Irritable Bowel Syndrome (IBS)

• Pathophysiology:
    - Classified as a functional gastrointestinal disorder; symptoms arise from GI function alterations without structural damage (unlike Ulcerative Colitis and Crohn’s Disease).
    - Historical terms included: colitis, mucous colitis, spastic colon, etc.
    - Can have physical and psychological causes.
    - Pain relief is experienced upon defecation.

• Contributing Factors:
    - Genetics, brain-gut signaling issues, bowel hypersensitivity (bowel stretching), bacterial gastroenteritis, and alterations in neurotransmitter levels.
    - Common co-occurring psychological issues include panic disorder, anxiety, depression, and PTSD; stress, particularly from past abuse, may manifest physically.

• Symptoms and Signs (S/S):
    - Abdominal pain/discomfort at least three times a month over the past 3 months (without another identifiable cause).
    - Symptoms can include changes in stool frequency/consistency, flatulence, bloating, nausea, anorexia, constipation, and diarrhea.
    - Anxiety or depression can accompany IBS.

• Treatment (Rx):
    - Dietary management focusing on FODMAP foods that exacerbate symptoms.
    - Recommendations include smaller meals, reduced fat intake, and avoidance of dairy, alcohol, caffeine, and gas-producing foods.
    - Stress management techniques and appropriate medications may be used (e.g., laxatives or antidiarrheal meds).

Inflammatory Bowel Diseases (IBD): Crohn's Disease and Ulcerative Colitis

• Definition:
    - IBD is an umbrella term for Crohn's disease (CD) and Ulcerative colitis (UC), both causing bowel inflammation.

Crohn’s Disease (CD)

• Pathophysiology:
    - Autoimmune disorder with no medical cure, causing inflammatory lesions along the GI tract, most often affecting the ascending colon and terminal ileum.
    - Affects all layers of the bowel wall, can create fistulas, necessitating watch over fluid/electrolyte balance and malabsorption of vitamins.
    - Defined by “skip lesions” and “cobblestone appearance” of intestinal lining.

• Complications:
    - Chronic inflammation, bowel wall thickening, abscesses, fistulas, perforation, and obstruction.
    - Risk of malabsorption leading to deficiencies (e.g., folic acid, calcium/vitamin D).
    - Symptoms include diarrhea, dehydration, and anal fissures.

Ulcerative Colitis (UC)

• Pathophysiology:
    - Also autoimmune, but ulcers only occur in the colon, involving the mucosal layer, leading to chronic dehydration and malnutrition.
    - May develop ulcers leading to hemorrhages/abscesses.

• Complications:
    - Intestinal obstruction, dehydration, anemia, chronic bloody diarrhea, and high risk for colorectal cancer.
    - Symptoms include weight loss, abdominal pain/cramping, and urgency to defecate.

Comparison Between Crohn’s Disease and Ulcerative Colitis

Colorectal Cancer (CRC)

• Overview:
    - Second leading cause of cancer-related deaths in the US; third most common cancer in both men and women.
    - Estimated 1 in 20 will develop colon cancer.

• Risk Factors:
    - Age (>50 years)
    - Gender (more common in men)
    - Race (higher prevalence in Black and Caucasian populations)
    - Family history (25% of colon cancer cases)
    - Personal history of Crohn's disease or ulcerative colitis.
    - Dietary factors (unhealthy fats, low fiber, etc.).
    - Rapid increase in rectal cancers among ages 40 to 50.

• Pathophysiology:
    - Most colorectal cancers commence as polyps on the colon/rectum lining. Some types are pre-cancerous, notably:
      1. Adenomatous polyps – may become cancerous.
      2. Hyperplastic/inflammatory polyps – usually non-cancerous.

Symptoms and Diagnosis of Colorectal Cancer

• Symptoms (S/S):
    - Changes in bowel habits (constipation, diarrhea)
    - Incomplete bowel emptying sensation
    - Rectal bleeding/cramping
    - Dark patches of blood in stool or long “pencil stools”
    - Abdominal discomfort/bloating
    - Unexplained fatigue, loss of appetite, weight loss.
    - Pelvic pain in later stages.

• Diagnostic Testing:
    - Fecal occult blood test and colonoscopy to locate and biopsy polyps.
    - Screening should begin at age 50 or sooner for high-risk patients.

• New Treatment Standard:
    - USPSTF recommends low-dose aspirin for colorectal cancer prevention.

Hepatic Pathologies

Classification of Liver Issues

1. Prehepatic: Issues before portal vein (e.g., thrombosis, cancer).
2. Intrahepatic: Problems that obstruct blood flow within the liver (e.g., alcoholic cirrhosis).
3. Post-Hepatic: Obstruction of blood flow beyond the liver (e.g., right-sided heart failure).

• Mnemonic for Liver Functions: "People Drink So Much"
    - Produces:
      - Albumin: Key plasma protein managing oncotic pressure in blood; low levels can lead to ascites and portal hypertension.
      - Bile: Transports bilirubin and cholesterol; elevated bilirubin causes jaundice.
      - Coagulation Factors: Deficiency increases bleeding risk.
      - Detoxes: Notably for ethanol and drugs.
      - Storage: Glycogen and metabolism byproducts.

Cirrhosis

• Definition: Scarred liver tissue failing to function normally.
• Causes: Predominantly chronic alcohol use, viral hepatitis, or certain medications (e.g., acetaminophen).
• Complications: Portal hypertension leading to ascites and associated symptoms; impaired coagulation.

Clinical Manifestations of Liver Disease

• Portal Hypertension:
    - Result of obstructed liver flow, causing fluid backup and engorged veins, leading to variables like splenomegaly and esophageal varices.
• Ascites: Accumulation of fluid in the abdomen due to portal hypertension and decreased albumin.

Hepatic Encephalopathy

• Definition: Liver’s failure to detoxify ammonia leads to neurological symptoms such as confusion or seizures.
• Jaundice: Excessive bilirubin accumulation leads to yellowish skin and sclera, causing intense itching.

Paracentesis Procedure

• Definition: Procedure to withdraw fluid from the abdomen for therapeutic or diagnostic purposes.

• Indications: Ascites related to conditions like cirrhosis or infections.

• Risks: May lead to hypotension and kidney damage.

• Lab Tests for Liver Function:
    - Liver Function Tests (LFTs): Elevated enzymes indicate liver damage.
    - CBC: Checks for RBC and platelet levels.
    - Ammonia Levels: Monitor for encephalopathy.
    - Bilirubin: Elevated indicates liver dysfunction.
    - PT, PTT, INR: Tests for clotting ability.
    - Occult Blood Smear: Tests for hidden blood.

Viral Hepatitis

• Types:
    1. Hepatitis A: Fecal-oral transmission; often preventable with a vaccine.
    2. Hepatitis B: Blood/body fluid transmission; vaccination series available.
    3. Hepatitis C: Blood/body fluid borne; chronic carrier state possible; no vaccine available.

Pancreatitis

• Pathophysiology: Result of injury or obstruction causing digestive enzyme leakage.
• Main Causes: Alcohol and gallstones.
• Symptoms: Severe epigastric pain, fever, leukocytosis, and steatorrhea (foamy, foul-smelling stools due to fat malabsorption).
• Initial Treatment: GI rest, often requiring fasting until the condition stabilizes.

Cholecystitis

• Etiology: Often associated with gallstones; can be acute or chronic.
• Risk Factors: Known as the "SIX F’s": fair, fat, female, fertile, forty, family history.
• Symptoms: Severe pain after fat consumption, nausea, fever, and jaundice (if obstructed).
• Treatment: Dietary changes or surgical procedures such as cholecystectomy.

Important Note on Abdominal Pain

• Do not provide oral intake to patients with abdominal pain as they may require surgery.

Bloodhound Matching Activity

• Match the Symptoms of Blood Loss:
    - A: Red blood emesis
    - B: Coffee-ground vomitus
    - C: Occult Blood
    - D: Melena
    - E: Hematochezia
• Tests for Liver Function:
    1. Test for bleeding problems.
    2. Measure liver’s function.
    3. Tests stool samples for hidden blood.
    4. Liver enzymes (ALT, AST).
    5. Blood breakdown product.
    6. Check for RBCs and platelets.