Physiological Adaptation: Practice Questions & Explanations

COPD clients chronically retain CO2 (carbon dioxide); over time, their respiratory drive may rely on hypoxic drive rather than the normal hypercapnic drive. Giving high-flow oxygen can suppress this hypoxic drive, leading to CO2 retention, hypercapnia, and CO2 narcosis (confusion, sedation, eventual respiratory failure). Goal oxygen saturation for COPD is typically 88-92% (lower than the 95%+ goal for clients without lung disease). Start with low-flow oxygen (1-2 L/min via nasal cannula) and titrate up cautiously. Monitor for signs of CO2 retention: increasing confusion, somnolence, headache, asterixis. Arterial blood gas (ABG) assessment confirms acid-base status. Other management for COPD exacerbation: bronchodilators (albuterol, ipratropium), systemic corticosteroids, antibiotics if infection suspected, non-invasive positive pressure ventilation (BiPAP) for severe distress, possible intubation in respiratory failure. The fundamental principle: 'Treat the patient, not the number' — but for COPD, don't over-oxygenate.

DVT prevention is a major postoperative concern. Virchow's triad of DVT risk: venous stasis, endothelial injury, hypercoagulability — all increased after surgery. Prevention strategies: (1) Early ambulation — get clients up walking as soon as safely possible, even on postoperative day 0; (2) Sequential compression devices (SCDs) — pneumatic sleeves on legs that intermittently compress to promote venous return — used continuously when client is in bed; (3) Pharmacologic prophylaxis — typically low-molecular-weight heparin (enoxaparin) or unfractionated heparin in lower doses, per orders; (4) Range-of-motion exercises and ankle pumps when in bed; (5) Adequate hydration; (6) Avoid prolonged sitting with legs dependent; (7) Anti-embolism stockings (TED hose) — provide gradient compression. DO NOT: massage the calves (can dislodge a clot); cross legs at the knees (impairs venous return); pillow under the knees (impairs venous return). Signs of DVT: unilateral leg swelling, warmth, erythema, calf pain, sometimes Homan's sign (no longer reliable).

Ascites is a common complication of cirrhosis caused by portal hypertension (increased pressure in the portal venous system due to liver fibrosis) combined with hypoalbuminemia (the liver can't produce enough albumin to maintain oncotic pressure). Fluid leaks into the peritoneal cavity. Signs: increased abdominal girth, weight gain, abdominal distention with shifting dullness on percussion, prominent abdominal veins (caput medusae), umbilical hernia, dyspnea if diaphragm is compromised. Management: (1) Sodium restriction (typically <2 g/day) — most important dietary intervention; (2) Diuretics — spironolactone first (potassium-sparing, addresses underlying hyperaldosteronism), often combined with furosemide; (3) Daily weight monitoring (same conditions); (4) Abdominal girth measurement; (5) Therapeutic paracentesis for symptomatic relief or refractory ascites (with albumin replacement after large-volume removal); (6) TIPS (transjugular intrahepatic portosystemic shunt) for refractory cases; (7) Liver transplant evaluation. Complications of ascites: spontaneous bacterial peritonitis (SBP — fever, abdominal pain, AMS — diagnosed by paracentesis with PMN >250), hepatorenal syndrome, umbilical hernia. Other cirrhosis complications: variceal bleeding, hepatic encephalopathy.

Acute pancreatitis is inflammation of the pancreas with severe abdominal pain (epigastric, radiating to back), nausea, vomiting, elevated amylase and lipase. Most common causes: gallstones and alcohol use. Severe cases can progress to systemic inflammatory response, ARDS, organ failure, death. Initial management: (1) NPO to rest the pancreas and reduce pancreatic enzyme secretion; (2) Aggressive IV fluid resuscitation — pancreatitis causes massive third-spacing of fluid (lactated Ringer's preferred); monitor urine output, vital signs, mental status; (3) Pain management — typically opioids (hydromorphone or morphine; some sources still avoid morphine due to theoretical concerns about sphincter of Oddi spasm, though evidence is weak); (4) Antiemetics; (5) Monitor electrolytes — hypocalcemia is common (positive Chvostek's or Trousseau's signs); also hypomagnesemia, hyperglycemia (transient or new diabetes); (6) Monitor for complications: pseudocyst, abscess, necrosis, ARDS, AKI, shock, DIC; (7) Identify and treat underlying cause; (8) Nutrition — enteral nutrition (via jejunal tube) preferred over TPN in moderate-severe cases as soon as possible; resume oral intake gradually as symptoms resolve.

PERITONITIS is inflammation of the peritoneum (the membrane lining the abdominal cavity and covering abdominal organs). In the post-appendectomy context, it suggests either: (1) the appendix perforated at or during surgery; (2) surgical site contamination; (3) anastomotic leak. CLINICAL PRESENTATION: CLASSIC TRIAD: Severe abdominal pain (often described as 'board-like rigidity'); Rigid, board-like abdomen (involuntary guarding — the abdominal wall muscles contract to protect underlying inflamed organs); High fever (39-40°C is typical of significant infection/inflammation); ADDITIONAL SIGNS: Rebound tenderness (pain worsens when examiner quickly releases pressure after palpation); Nausea and vomiting; Decreased or absent bowel sounds; Tachycardia and hypotension as sepsis develops. NURSING PRIORITIES: Notify provider/surgeon IMMEDIATELY — do not delay for any additional assessment; this is a potentially life-threatening surgical emergency; Position: semi-Fowler's (helps localise infection and reduces diaphragm pressure); NPO (nothing by mouth — likely return to OR); IV access and fluid resuscitation; Vital signs continuously; Labs: CBC, BMP, blood cultures, lactate; Prepare for emergent return to operating room. TREATMENT: Surgical exploration and washout; broad-spectrum antibiotics covering gram-negatives and anaerobes.

TOTAL LARYNGECTOMY creates a PERMANENT STOMA (opening) in the anterior neck as the client's ONLY airway — the trachea is no longer connected to the mouth and nose. CRITICAL CONCEPT: A standard bag-valve-mask over the face does NOT ventilate a laryngectomy patient — the mouth and nose are disconnected from the trachea; resuscitation must be done through the STOMA. AIRWAY EMERGENCY SIGNS: Decreasing SpO₂; absent or diminished breath sounds on auscultation at the stoma; audible stridor; increased respiratory effort; cyanosis; patient distress; CAUSES OF STOMA OBSTRUCTION: Mucus plug (most common — humidified air and suctioning prevent this); blood clot; stoma stenosis; equipment issues. NURSING PRIORITIES: CALL FOR HELP immediately; suction the stoma first (often clears a mucus obstruction); if suctioning doesn't relieve the obstruction, notify the provider/surgical team stat; maintain humidity (humidified air prevents mucus plugging — dry air is the enemy of laryngectomy patients); have stoma covers/bibs available; teach the patient SELF-CARE: how to suction, clean, and cover the stoma; EMERGENCY RESPONSE: BVM must be applied to the STOMA, not the face, for resuscitation; all first responders must know the patient has a laryngectomy (medic alert bracelet, 'Neck Breather' notification); some patients choose to post a note at their bedside.

HYPERPHOSPHATAEMIA in CKD occurs because damaged kidneys cannot excrete phosphate effectively. ELEVATED PHOSPHATE has serious consequences: BINDS CALCIUM — hyperphosphataemia causes hypocalcaemia by precipitation (calcium binds with phosphate and deposits in tissues rather than circulating); CALCIPHYLAXIS — calcium-phosphate deposits in blood vessels and soft tissue (vascular calcification is a major cause of cardiovascular mortality in CKD); SECONDARY HYPERPARATHYROIDISM — the parathyroid gland responds to low calcium by secreting PTH, which pulls calcium from bones (renal osteodystrophy); DIETARY PHOSPHATE RESTRICTION: Avoid: dairy products (milk, cheese, yogurt — very high phosphate); dark cola sodas (phosphoric acid added as preservative — avoid all dark colas); processed meats and fast food (phosphate preservatives); nuts and seeds; chocolate; beer and whole grains; Choose: egg whites (protein with low phosphate); fresh fruits and vegetables; white bread and white rice (lower phosphate than whole grain); PHOSPHATE BINDERS: Taken WITH every meal and snack; bind dietary phosphate in the GI tract to prevent absorption; types: calcium carbonate (Tums), calcium acetate (PhosLo), sevelamer (non-calcium, preferred when calcium is already high), lanthanum carbonate; NURSING TEACHING: Take binders WITH food (not before, not after); binders are ineffective if taken on an empty stomach; even small high-phosphate snacks require a binder dose.

ACUTE DECOMPENSATED HEART FAILURE with pulmonary oedema and SpO₂ of 88% is a respiratory emergency requiring immediate intervention. HIGH FOWLER'S POSITION (90 degrees or sitting bolt upright): MECHANISM — gravity pulls fluid from the upper lung fields downward; reduces venous return to the heart (decreasing preload); reduces the work of breathing; allows the diaphragm to descend more fully (abdominal organs don't compress the diaphragm as much when upright); EFFECT — can improve SpO₂ and reduce dyspnoea within minutes; OXYGEN: Supplemental oxygen increases the partial pressure of oxygen in the alveoli; in severe cases, non-invasive positive pressure ventilation (CPAP, BiPAP) may be needed if SpO₂ doesn't improve with supplemental oxygen; HIGH-FLOW OXYGEN target: SpO₂ above 94% in most patients; SUBSEQUENT INTERVENTIONS (ordered by priority after positioning and O₂): IV diuresis (furosemide IV — onset 15-30 min, faster than oral); nitrates (IV nitroglycerin for preload and afterload reduction); morphine (reduces preload and anxiety — use cautiously); ACEI/ARB/neprilysin inhibitor for longer-term management; URINARY CATHETER: Important for accurate output monitoring but not before addressing the immediate respiratory compromise; OUTPUT ASSESSMENT follows stabilisation of acute respiratory status; ECOG: Important but not before respiratory stabilisation.

OXYGEN THERAPY IN COPD EXACERBATION requires understanding the hypoxic drive concept — though modern evidence has refined the approach. THE HYPOXIC DRIVE: Healthy individuals drive breathing by rising CO₂ levels (central chemo-receptors); COPD patients with chronic CO₂ retention become desensitised to high CO₂; some use HYPOXIA as their primary ventilatory drive; giving high-flow oxygen to these patients can reduce their respiratory drive, causing hypoventilation and worsening respiratory failure. EVIDENCE-BASED TARGET: SpO₂ 88-92% for COPD patients with known or suspected chronic CO₂ retention (hypercapnia); titrate oxygen up to this target, not beyond; avoid high-flow oxygen unless the patient is in imminent respiratory arrest. OXYGEN DELIVERY OPTIONS: Nasal cannula 1-2 L/min (approximate FiO₂ 24-28%); Venturi mask — precise FiO₂ delivery (24%, 28%, 31%, 35%, 40%, 60%) — preferred when exact concentration matters; NOT non-rebreather mask (delivers 60-80% FiO₂ — too high for most COPD patients). NURSING PRIORITIES: ABG measurement to assess baseline PaCO₂; titrate oxygen by oximetry toward 88-92%; monitor respiratory rate and level of consciousness; prepare for non-invasive positive pressure ventilation (BiPAP) if work of breathing increases or consciousness decreases; intubation as last resort. IMPORTANT: For a COPD patient with SpO₂ of 84%, you DO give oxygen — just controlled amounts; do not withhold oxygen from a hypoxaemic patient for fear of suppressing drive; the risks of severe hypoxaemia (organ damage, death) outweigh the hypoxic drive concern.

OPIOID OVERDOSE is a life-threatening emergency with a specific antidote that must be administered rapidly. THE OPIOID OVERDOSE TRIAD: (1) Respiratory depression (rate below 12, here 6 — severely depressed); (2) Miosis (pinpoint pupils); (3) Altered/decreased consciousness. This classic triad is diagnostic of opioid overdose even before laboratory confirmation. TREATMENT: NALOXONE (NARCAN): Opioid receptor antagonist — competitively blocks and reverses opioid effects; DOSING: 0.4-2 mg IV, IM, or intranasal; onset: IV seconds, IM/SubQ 3-5 minutes, intranasal 2-3 minutes; may need REPEATED DOSES — naloxone's duration of action (30-90 minutes) is shorter than most opioids; if opioid wears off before naloxone metabolises, the patient will re-sedate; WHILE PREPARING NALOXONE: Support ventilations (bag-valve-mask at 10-12 breaths/minute); oxygen; position supine; call for resuscitation support; AFTER NALOXONE: Patient may wake up in opioid withdrawal — agitated, diaphoretic, tachycardic, may attempt to leave; do not give additional opioids; maintain airway; continuous monitoring; repeat naloxone doses as needed; FLUMAZENIL: This is the benzodiazepine antidote, not the opioid antidote — do not confuse; flumazenil has numerous contraindications and is used less often; CLINICAL CLUE: Pinpoint pupils (miosis) = opioids; mydriasis (dilated pupils) = stimulants or anticholinergics. Opioid miosis is a key distinguishing feature.