Medical-Surgical Exam #5 Comprehensive Study Notes

Age–Related Physiologic Changes

• Normal, predictable alterations that occur with aging; recognize to differentiate from pathology.
• Thermoregulation ↓
• ↓ Subcutaneous fat & sweat-gland activity → ↑ susceptibility to hyperthermia; expect “heat intolerance.”
• Musculoskeletal
• Progressive articular cartilage wear, but rheumatoid arthritis is autoimmune, NOT inevitable with age.
• Integumentary / Hydration
• ↓ Total-body water & thirst perception → easy “dehydration.”
• GI
• Taste and smell dull, gastric emptying slows; appetite often ↓, not ↑.

Laboratory Tests & Specimen Collection

• Glycosylated hemoglobin (A1C)
• Hemoglobin becomes non-enzymatically coated with glucose; reflects average glycemia for life-span of RBC (~120 d) → “past 3 months.”
• Diagnostic categories: ≤ 5.6\% = normal; 5.7–6.4\% = pre-diabetes; ≥ 6.5\% = diabetes; therapy goal for most pts ≤ 7\%.
• 24-h urine collection
• Purpose: creatinine clearance, free cortisol, protein, etc.
• Start = DISCARD first void, note time, then collect ALL urine for next 24 h; any missed sample invalidates test; most containers pre-filled with preservative.

Autonomic Receptors & Drugs

• \beta_1 receptor stimulation → ↑ chronotropy, inotropy, dromotropy → effective response is HR ↑ (e.g., 92\;\text{beats min}^{-1} if baseline lower).

Adrenal Hormones

• Cortex → mineralocorticoids, glucocorticoids, androgens.
• Aldosterone (mineralocorticoid)
• Promotes renal Na^+ & H_2O reabsorption, K^+ & H^+ excretion → primary regulator of fluid volume/ electrolytes.
• Catecholamine surge (medulla) → fight-or-flight
• Epinephrine/norepinephrine ↑ HR & BP, shunts blood to skeletal muscle → clinical sign: “increased pulse.”

Thyroid & Parathyroid Physiology

• Thyroid
• T3 & T4 control basal metabolic rate.
• Calcitonin (parafollicular cells) → drives serum Ca^{2+} & PO_4^{3-} ↓ by inhibiting bone resorption & increasing renal excretion.
• Estrogen ↓ in older women
• Contributes to osteoporosis; injury-prevention teaching = regular weight-bearing exercise (“walk the neighborhood”).

General Characteristics of Hormones

• Secreted into blood; may travel long distances to specific receptors.
• Act through negative-feedback loops (↓ further secretion once physiologic response achieved).
• Continuous effect requires continuous secretion; most are NOT stored in target tissue.
• Mechanism: alter gene transcription/ protein synthesis to change cell activity.

Anterior Pituitary Hypofunction

• ↓ production of TSH, FSH, LH, ACTH, GH, prolactin; vasopressin is posterior.
• Consequences: hypothyroidism, infertility, adrenal insufficiency, dwarfism.

Assessment Correlations

• Excess MSH → hyperpigmented skin (“bronzing”).
• Excess PTH → ↑ bone resorption (Ca++ leaches, fractures).
• Excess ADH (SIADH) → water retention, ↓ urine output.

Hypothyroidism (often autoimmune – Hashimoto)

• Cardinal signs: lethargy, bradycardia, hypothermia, slowed speech, weight gain, constipation (NOT diarrhea).
• Nursing care
• Priority problem: impaired gas exchange r/t ↓ ventilation/ ↓ energy → focus on airway & breathing (i.e., treat bradycardia with levothyroxine, may need atropine initially if severe).
• Drug: levothyroxine—take daily on empty stomach; report chest pain/dyspnea (could signal ischemia from sudden ↑ metabolic demand). Effectiveness shown by HR returning to normal (≈ 60–100 bpm), weight stabilization, improved energy.

Hyperthyroidism / Graves’ Disease

• ↑ metabolic rate, heat intolerance, weight loss, tachycardia. Thyroid storm risk: temp +1 °F triggers emergency cooling & provider alert.
• Nutritional needs: ↑ calories, ↑ carbohydrates & proteins, ↓ fat.
• Post-thyroidectomy
• Monitor for laryngeal edema → stridor = airway obstruction → elevate HOB, apply O2, CALL RRT, prepare for intubation.
• Hypocalcemia (accidental parathyroid removal) → perioral tingling, positive Chvostek/Trousseau → check serum Ca^{2+}, give IV calcium gluconate.
• Lifelong thyroid hormone needed after total; subtotal may still need replacement.

Growth Hormone Disorders

• GH deficiency
• Short stature, osteoporosis; nursing: use lift sheet (fragile bones), dangle before standing (orthostasis).
• Acromegaly (GH excess in adults)
• Enlarged hands, face, feet, thickened skin, organomegaly; shoe size ↑.
• Transsphenoidal hypophysectomy teaching
• No tooth-brushing, bending, coughing, or straining; nasal packing 2-3 d; CSF leak precautions.
• Misconception: bone changes irreversible (can’t go back to size 8 shoes).
• Bromocriptine (dopamine agonist) education
• Start low dose with meals to ↓ GI upset & orthostatic hypotension; report chest pain/dizziness—could be coronary spasm.

Diabetes Insipidus vs. SIADH

• DI (↓ ADH)
• Polyuria (up to 20 L/d), dilute urine, ↓ specific gravity (< 1.005), dehydration, hypotension, tachycardia.
• Treatment: desmopressin; therapeutic if urine ↓, SG ↑, osmolality ↑; daily weight is priority teaching (water retention sign).
• SIADH (↑ ADH)
• Water retention, hyponatremia, low serum osmolarity, ↑ urine SG.
• Care: fluid restriction (≈ 600 mL/d), daily weights, I&O, seizure precautions, hypertonic saline if severe.
• Drug: tolvaptan (vasopressin antagonist) can cause rapid hypernatremia—monitor serum sodium q4-24 h.

Adrenal Insufficiency

• Priority assessment = cardiovascular (risk of hypotension, dysrhythmia from hyper-/hypo-kalemia).

Parathyroidectomy Complication

• Carpal spasm during BP inflation (Trousseau) → hypocalcemia (e.g., Ca^{2+}=6.9\;mg\,dL^{-1}).

Metabolic Syndrome

• Cluster: abdominal obesity (waist > 40 in men, > 35 in women), hypertension, hyperglycemia, ↑ triglycerides, ↓ HDL—predisposes to type 2 DM & CVD.

Diabetes Mellitus Fundamentals

• Type 1: autoimmune β-cell destruction; absolute insulin deficiency.
• Type 2: insulin resistance ± secretory deficit; progressive; strong familial link; highest risk in American Indians/Native Americans.
• Screening criteria (ADA)
• Adults ≥45 yr or any age with BMI ≥ 25 kg/m² + risk factor (sedentary, HTN, dyslipidemia, gestational DM/baby > 9 lb, African-American, Hispanic, Asian, Native American).

Self-Monitoring & Infection Control

• Do NOT share lancets or glucometers; single-use only; wash hands before & after.

Oral/Injectable Antidiabetic Drugs

• Sulfonylurea – glipizide
• Stimulates insulin release; risk of hypoglycemia & orthostatic hypotension—teach slow position changes; avoid NSAIDs (potentiate). If dose missed, take ASAP unless close to next.
• Meglitinide – nateglinide
• Rapid/short action; give \le 30 min before each meal; skip if meal skipped.
• α-Glucosidase inhibitor – acarbose
• Delays carb absorption; must be taken WITH first bite of EACH meal.
• GLP-1 agonist – exenatide ER
• Once-weekly sub-Q; give same day each week, independent of meals.

Insulin Therapy & Technique

• Rotate sites within a zone for 1 wk, then move to new zone to limit lipodystrophy; different body regions change absorption (abd fastest).
• Lower abdomen popular, but NOT because of proximity to pancreas; client statement implying that needs correction.

Exercise Benefits

• Moderate 1-mile daily walk improves insulin sensitivity & ↓ insulin requirement; counsel for type 1.

Acute Diabetic Emergencies

• DKA
• Triad: hyperglycemia, ketosis, metabolic acidosis.
• ABG: pH < 7.35, HCO3^- < 22\;mEq\,L^{-1}, compensatory PaCO2 ↓ (Kussmaul breathing).
• Clinical: tachycardia, orthostatic hypotension, polyuria early then ↓ urine if dehydration severe, deep fast respirations.
• Treatment priorities: IVF, IV regular insulin, monitor K^+ (insulin drives K^+ into cells; if K^+<3.3, replace before insulin). Critical value: K^+ 2.5\;mEq\,L^{-1} mandates immediate action.
• Hypoglycemia (conscious)
• Rule of 15: give 15 g rapid carb (½ cup OJ), wait 15 min, recheck; if unchanged → repeat juice; glucagon IM or D50 IV if worsening or NPO.

Chronic Complications & Monitoring

• Neuropathy
• Daily foot inspection with mirror; use bath thermometer; avoid barefoot walking.
• Nephropathy
• First sign = microalbuminuria; reduce dietary protein, optimize BP/Glycemia.
• Retinopathy
• Annual dilated eye exam at diagnosis (type 2) or within 5 yr (type 1) then yearly.

Sick-Day Rules

• Never omit insulin/OADs; check BG q4 h; hydrate; consume carbs; call provider for persistent hyperglycemia, ketones, or inability to keep fluids down.

Key Numeric/Formula Reminders

• Urine specific gravity Normal 1.005–1.030
• Serum sodium Severe hyponatremia <120\;mEq\,L^{-1}
• Calcium normal 8.5–10.5\;mg\,dL^{-1}
• A1C goal (most adults) <7\%, but individualized.

Ethical & Practical Considerations

• Emphasize patient autonomy & education for self-management (insulin injections, BG checks).
• Interprofessional collaboration: dietitian for sodium/fluid restrictions, diabetes educator for device use, pharmacist for drug interactions.
• Safety: avoid sharps reuse (infection control), implement fall precautions in hypotension (DI) or orthostatic pts.