7.3 Gastrointestinal, Endocrine & Renal Disorders Management

Gastrointestinal, Endocrine & Renal Disorders Management

Clinical Core: Disorders of the gastrointestinal, endocrine, and renal systems frequently generate severe metabolic and hemodynamic instability. The professional nurse protects clients through vigilant physical assessment of the acute abdomen, meticulous glycemic and endocrine regulation, rigorous electrolyte monitoring, and precise protection of life-sustaining renal access sites.

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Gastrointestinal Disorders: PUD, Bleeding, Acute Abdomen & Stoma Care

Peptic Ulcer Disease (PUD): Gastric Versus Duodenal Ulcers

Peptic ulcer disease involves mucosal erosion of the stomach or duodenum extending through the muscularis mucosa, predominantly caused by Helicobacter pylori infection or prolonged use of NSAIDs.

• Pharmacological Eradication of H. pylori:
  • Triple Therapy (14 days): Proton Pump Inhibitor (PPI, e.g., omeprazole or pantoprazole) + Clarithromycin + Amoxicillin (or Metronidazole if penicillin-allergic).
  • Quadruple Therapy (14 days): PPI + Bismuth subsalicylate + Metronidazole + Tetracycline (chosen in areas of high clarithromycin resistance).

Gastrointestinal Bleeding: Upper Versus Lower

• Upper GI Bleed: Originates proximal to the ligament of Treitz (esophagus, stomach, duodenum). Manifests as hematemesis (bright red blood indicating active, brisk hemorrhage, or dark coffee-ground emesis indicating gastric acid conversion of hemoglobin to hematin) and melena (black, tarry, foul-smelling stool).
• Lower GI Bleed: Originates distal to the ligament of Treitz (jejunum, ileum, colon, rectum). Manifests primarily as hematochezia (bright red blood per rectum), though massive upper GI bleeding can also present with hematochezia due to rapid transit.
• Emergency Resuscitation Protocol: Establish airway patency; insert two large-bore peripheral IV catheters (16- or 18-gauge); initiate volume expansion with isotonic crystalloids (0.9% normal saline or Lactated Ringer's); draw blood for type and cross-match (packed red blood cells), complete blood count (CBC), coagulation profile, and basic metabolic panel; insert an indwelling urinary catheter to monitor hourly urine output (target $\ge 30\text{ mL/hr}$); insert a nasogastric (NG) tube for gastric lavage; and maintain continuous monitoring for hypovolemic shock (hypotension, tachycardia, pallor, diaphoresis).

Acute Abdomen: Appendicitis and Bowel Obstruction

• Acute Appendicitis: Inflammation and obstruction of the appendiceal lumen, typically by a fecalith.
  • Clinical Signs: Dull periumbilical pain that shifts over 12 to 24 hours and localizes as sharp, severe pain in the right lower quadrant at McBurney's point (located one-third the distance from the anterior superior iliac spine to the umbilicus). Hallmarks include rebound tenderness, Rovsing's sign (palpation of the left lower quadrant produces referred pain in the right lower quadrant), psoas sign (pain on right hip extension), and low-grade fever with leukocytosis ($10,000\text{ to } 18,000/\mu\text{L}$).
  • Critical Nursing Precautions: The client must remain strictly NPO. The nurse must NEVER apply heat to the abdomen (heat causes vasodilation, increases intraluminal pressure, and accelerates appendiceal perforation and widespread peritonitis). NEVER administer enemas or laxatives (stimulating peristalsis risks rupture). Administer IV fluids and analgesics as prescribed once surgical evaluation is established.
  • Red Flag for Perforation: A sudden, dramatic relief of acute abdominal pain is a critical indicator of appendiceal rupture. It is rapidly followed by high fever, severe tachycardia, board-like abdominal rigidity, and diffuse peritonitis.
• Intestinal Obstruction:
  • Mechanical Obstruction: Physical occlusion of the intestinal lumen, most commonly by postoperative fibrous adhesions, incarcerated hernias, volvulus, intussusception, or colorectal neoplasms. High-pitched, rushing, tinkling bowel sounds (borborygmi) are auscultated proximal to the obstruction, with absent sounds distally. Manifestations include severe colicky pain, visible peristaltic waves, persistent vomiting (bilious early, foul feculent emesis late in distal small bowel obstruction), profound abdominal distention, and obstipation (complete absence of stool and flatus).
  • Non-Mechanical Obstruction (Paralytic Ileus): Neurogenic failure of intestinal peristalsis without physical blockage, common following abdominal surgery, peritonitis, or severe hypokalemia. Bowel sounds are generalized, hypoactive, or completely absent; pain is diffuse, steady, and dull.
  • Nursing Interventions: Maintain strict NPO status; insert a double-lumen Salem sump nasogastric tube connected to continuous low suction for gastrointestinal decompression. The blue air vent pigtail must remain open to air and positioned above the level of the client's stomach to prevent gastric siphonage; administer IV fluid and electrolyte repletion; monitor for signs of bowel strangulation and necrosis (fever, leukocytosis, persistent localized pain).

Stoma Care and Ostomies: Colostomy Versus Ileostomy

• Ileostomy: Created from the distal ileum, bypassing the entire large intestine. Effluent is continuous, liquid to semi-liquid, containing high concentrations of proteolytic digestive enzymes. The client is at extreme risk for severe dehydration, hyponatremia, hypokalemia, metabolic acidosis, and skin excoriation. Fluid intake must be maintained at $2\text{ to } 3\text{ L/day}$.
• Colostomy: Created from the colon (ascending, transverse, descending, or sigmoid). Output varies from semi-liquid (ascending/transverse) to formed, normal stool (sigmoid/descending).
• Stoma Assessment: A healthy stoma appears beefy red, moist, and shiny, protruding approximately 1 to 2 cm above the skin surface. Mild edema is expected in the immediate postoperative period. A stoma that appears pale pink indicates severe anemia. A stoma that turns dusky red, purple, blue, brown, or black indicates compromised vascular perfusion and tissue ischemia/necrosis; the nurse must notify the operating surgeon immediately.
• Appliance Management: The peristomal skin barrier wafer must be measured and cut precisely 1/8 inch (2 to 3 mm) larger than the base of the stoma. This opening protects surrounding skin from caustic enzymatic effluent while avoiding constriction of stoma vasculature. Ostomy pouches are emptied when one-third to one-half full of effluent or gas to prevent the weight from breaking the adhesive seal.

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Endocrine Disorders: Diabetes Mellitus and Thyroid Disease

Diabetes Mellitus: Diagnostic Benchmarks and Metformin Safety

Diabetes mellitus represents a spectrum of metabolic dysregulations characterized by hyperglycemia:

• Type 1 Diabetes: Autoimmune destruction of pancreatic beta cells in the islets of Langerhans, causing absolute insulin deficiency; prone to Diabetic Ketoacidosis (DKA).
• Type 2 Diabetes: Peripheral insulin resistance combined with progressive beta-cell secretory defects; prone to Hyperosmolar Hyperglycemic State (HHS).
• Diagnostic Criteria:
  • Fasting Plasma Glucose (FPG) $\ge 126\text{ mg/dL}$ ($7.0\text{ mmol/L}$) after an 8-hour fast.
  • 2-Hour Plasma Glucose $\ge 200\text{ mg/dL}$ ($11.1\text{ mmol/L}$) during a 75-g Oral Glucose Tolerance Test (OGTT).
  • Random Plasma Glucose $\ge 200\text{ mg/dL}$ in the presence of classic symptoms (polyuria, polydipsia, polyphagia, unexplained weight loss).
  • Glycated Hemoglobin ($HbA_{1c}$) $\ge 6.5\%$: Provides an objective measurement of average glycemic control over the preceding 2 to 3 months, reflecting the 120-day lifespan of erythrocytes. Standard therapeutic target for non-pregnant adults is $<7.0\%$.
• Metformin Safety Mandate: Metformin (a biguanide) decreases hepatic glucose production and enhances peripheral insulin sensitivity without stimulating insulin release or causing hypoglycemia. Contrast safety rule: Contrast-induced kidney injury can let metformin build up and cause lactic acidosis. Many hospital protocols therefore hold metformin on the day of a procedure that uses intravenous iodinated contrast and for 48 hours afterwards, restarting only when kidney function is confirmed stable. The American College of Radiology limits this mandatory hold to clients with acute kidney injury or an eGFR below 30 mL/min/1.73 m², so follow the local protocol. Routinely stopping metformin 48 hours before the scan is not required.

Insulin Pharmacokinetics and Administration Protocols

• Mixing Regular and NPH Insulin: When combining in a single syringe, inject air into NPH (cloudy), inject air into Regular (clear), withdraw Regular (clear) first, then withdraw NPH (cloudy) last ("Clear before Cloudy"). This prevents contaminating the rapid Regular vial with protamine retardant.

Thyroid Disorders: Hyperthyroidism Versus Hypothyroidism

• Thyroid Storm (Thyrotoxic Crisis): An acute, life-threatening hypermetabolic surge triggered by infection, trauma, surgery, or abrupt withdrawal of antithyroid medications. Hallmarks include extreme hyperpyrexia ($>40^{\circ}\text{C}$ [$104^{\circ}\text{F}$]), severe tachycardia ($>140\text{ bpm}$), atrial fibrillation, agitation, delirium, and shock.
  • Interventions: Administer beta-blockers (IV propranolol) to blunt peripheral adrenergic stimulation; administer thionamides (propylthiouracil [PTU] or methimazole) to halt thyroid hormone synthesis; administer oral potassium iodide solutions (Lugol's solution) at least 1 hour after PTU to block hormone release (Wolff-Chaikoff effect); administer IV glucocorticoids (dexamethasone or hydrocortisone) to block peripheral $T_4$ to $T_3$ conversion; apply hypothermia cooling blankets; and administer acetaminophen for fever. Critical Precaution: Aspirin (salicylates) is strictly contraindicated because it displaces thyroid hormones from carrier proteins (thyroid-binding globulin), worsening thyrotoxicosis.
• Myxedema Coma: End-stage, life-threatening decompensation of hypothyroidism characterized by severe hypothermia (core temp $<35^{\circ}\text{C}$ [$95^{\circ}\text{F}$]), marked bradycardia, hypotension, hypoventilation, respiratory acidosis, hyponatremia, and lethargy progressing to coma.
  • Interventions: Maintain patent airway and mechanical ventilation; administer intravenous levothyroxine; administer IV hydrocortisone (to treat coexisting adrenal insufficiency); and provide passive external rewarming with warm blankets. Critical Precaution: Avoid rapid, active external rewarming (e.g., heating lamps), which causes peripheral vasodilation, precipitating vascular collapse and refractory shock.
  • Daily Oral Levothyroxine Education: Must be taken in the morning on an empty stomach with a full glass of water, 30 to 60 minutes before breakfast. Separate from calcium, iron, or antacid supplements by at least 4 hours. Treatment is lifelong.

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Renal System Disorders: AKI, CKD & Hemodialysis Access

Acute Kidney Injury (AKI): Etiologies and Clinical Phases

AKI represents an abrupt decline in renal filtration function, clinically staged by anatomical origin:

• Prerenal AKI: Caused by renal hypoperfusion without structural parenchymal damage (hypovolemia, hemorrhage, dehydration, septic shock, congestive heart failure, renal artery stenosis). Blood Urea Nitrogen (BUN) to serum creatinine ratio exceeds $>20:1$. Resolves promptly following volume repletion.
• Intrarenal (Intrinsic) AKI: Caused by direct structural injury to the glomeruli or tubular epithelium. Most commonly Acute Tubular Necrosis (ATN) secondary to prolonged ischemia or nephrotoxic agents (aminoglycosides [gentamicin], IV radiocontrast dye, amphotericin B, NSAIDs, or myoglobinuria from rhabdomyolysis). BUN:Creatinine ratio is $10:1\text{ to } 15:1$; urinalysis demonstrates characteristic muddy brown granular casts.
• Postrenal AKI: Caused by mechanical obstruction of urinary outflow distal to the renal parenchyma (benign prostatic hyperplasia [BPH], bilateral ureteral calculi, bladder tumors, obstructed urinary catheters). Relieved by urinary catheterization, stenting, or nephrostomy.

Clinical Phases of AKI

1. Oliguric Phase: Urine output drops below $<400\text{ mL/24 hours}$. Characterized by intravascular fluid overload, hyperkalemia ($K^+ >5.0\text{ mEq/L}$, causing peaked T waves and wide QRS complexes), hyperphosphatemia, hypocalcemia, metabolic acidosis (Kussmaul breathing), elevated BUN and creatinine, and uremic encephalopathy. Lasts 1 to 3 weeks.
2. Diuretic Phase: Daily urine output increases progressively to $1\text{ to } 5\text{ L/day}$ as nephrons regain filtration capability but lack concentrating and reabsorptive capacity. The client is at profound risk for hypovolemia, dehydration, hyponatremia, and severe hypokalemia. Lasts 1 to 3 weeks.
3. Recovery Phase: Glomerular filtration rate stabilizes and normalizes; renal function continues to recover over 3 to 12 months.

Chronic Kidney Disease (CKD) and Dialysis Access

CKD is the progressive, irreversible destruction of nephrons. Staged by Glomerular Filtration Rate ($GFR$):

• Stage 1: $GFR \ge 90\text{ mL/min/1.73 m}^2$ with demonstrated structural kidney damage.
• Stage 2: $GFR \text{ 60 to 89 mL/min/1.73 m}^2$.
• Stage 3: $GFR \text{ 30 to 59 mL/min/1.73 m}^2$.
• Stage 4: $GFR \text{ 15 to 29 mL/min/1.73 m}^2$ (severe impairment; prepare for renal replacement therapy).
• Stage 5 (End-Stage Renal Disease [ESRD]): $GFR <15\text{ mL/min/1.73 m}^2$; demands maintenance dialysis or kidney transplantation.
• Pathophysiological Sequelae: Anemia develops secondary to deficient erythropoietin production by failing peritubular capillary cells; treated with erythropoietin-stimulating agents (epoetin alfa) and iron. Chronic hyperphosphatemia and hypocalcemia stimulate secondary hyperparathyroidism, causing bone demineralization (renal osteodystrophy).
• Dietary Restrictions in CKD: Sodium restriction ($<2,000\text{ mg/day}$); potassium restriction ($<2,000\text{ mg/day}$; avoid salt substitutes containing potassium chloride); phosphorus restriction ($<800\text{ to } 1,000\text{ mg/day}$); phosphate binders (calcium acetate, sevelamer) must be administered with meals to bind dietary phosphate in the gut lumen for fecal elimination; and fluid restriction calculated as 24-hour urine output plus 500 to 600 mL insensible loss.
• Hemodialysis Arteriovenous (AV) Fistula Care: Created by surgical anastomosis of an artery to a vein (e.g., radial artery to cephalic vein); requires 2 to 4 months to mature and dilate.
  • Assessment Mandates: Auscultate for a continuous, low-pitched blowing bruit over the fistula with a stethoscope every shift. Palpate for a gentle vibrating thrill with the fingertips. The absence of a thrill or bruit indicates acute thrombosis and vascular occlusion, requiring immediate surgical vascular intervention.
  • Limb Protection: NEVER take blood pressure, perform venipuncture, start IV infusions, or apply tight clothing/restraints on the extremity with an AV fistula or graft. Place prominent limb-alert signs at the bedside.