5.2 Respiratory Disorders & Management

Chronic Obstructive Pulmonary Disease (COPD)

COPD is progressive, largely irreversible airflow limitation confirmed by a post-bronchodilator FEV1/FVC ratio below 0.70. Its two phenotypes overlap but are tested separately:

Controlled oxygen rationale: many patients with severe COPD chronically retain CO2. Excessively high FiO2 can worsen hypercapnia through reduced hypoxic ventilatory drive, reversal of hypoxic pulmonary vasoconstriction (increased V/Q mismatch), and the Haldane effect. In acute exacerbations, titrate oxygen to an SpO2 of 88-92% — treat hypoxemia, but do not overshoot.

Pursed-lip breathing slows expiration, creates back-pressure that stents small airways open, reduces air trapping and respiratory rate, and improves tidal volume. Teach it to every COPD patient: inhale through the nose for 2 counts, exhale through pursed lips for 4. Maintenance pharmacotherapy follows GOLD principles: inhaled bronchodilators (LABA, LAMA) as the backbone, adding inhaled corticosteroids for frequent exacerbators with eosinophilia, plus smoking cessation, pulmonary rehabilitation, and influenza/pneumococcal vaccination.

Asthma

Asthma is reversible bronchospasm with airway hyperresponsiveness, inflammation, and mucus plugging. Management follows step therapy: intermittent asthma uses a short-acting beta-agonist (SABA, e.g., albuterol) alone; persistent asthma adds a daily inhaled corticosteroid (ICS) — the anti-inflammatory controller — then escalates to ICS plus a long-acting beta-agonist (LABA) and higher ICS doses as needed. LABA monotherapy without an ICS is never appropriate in asthma. Teach patients that controllers must be taken daily even when asymptomatic, to rinse the mouth after ICS use to prevent oral candidiasis, and that the SABA is for rescue only.

Peak expiratory flow (PEF) zones guide the written asthma action plan, measured against the patient's personal best:

• Green zone: 80-100% — stable, continue routine medications
• Yellow zone: 50-79% — caution; use the rescue inhaler and recheck, adjust controller per plan
• Red zone: below 50% — medical alert; use the rescue inhaler and seek emergency care immediately

Status asthmaticus is a severe exacerbation unresponsive to initial bronchodilators — a medical emergency. Warning signs include inability to speak in sentences, use of accessory muscles, a "silent chest" (airflow too limited to wheeze), and a normal or rising PaCO2 in a tiring patient. Treatment is continuous or repeated nebulized albuterol, early systemic corticosteroids, ipratropium, oxygen, and consideration of IV magnesium sulfate; prepare for possible intubation.

Pneumonia

Community-acquired pneumonia (CAP) is contracted outside healthcare settings; typical pathogens include Streptococcus pneumoniae, Haemophilus influenzae, and atypicals (Mycoplasma, Legionella). Hospital-acquired pneumonia (HAP) develops 48 hours or more after admission, and ventilator-associated pneumonia (VAP) 48 hours or more after intubation; both carry higher risk of multidrug-resistant organisms such as Pseudomonas aeruginosa and MRSA, and require broader empiric antibiotics.

The CURB-65 score estimates CAP severity and disposition — one point each for Confusion, blood Urea nitrogen above 19 mg/dL (BUN ≥20 in many U.S. references), Respiratory rate 30 or higher, low Blood pressure (systolic below 90 or diastolic 60 or below), and age 65 or older. A score of 0-1 supports outpatient treatment, 2 suggests admission, and 3 or higher warrants inpatient — often ICU — care. Nursing priorities: obtain sputum and blood cultures before antibiotics (without delaying them), support oxygenation, encourage hydration and coughing/deep breathing, and reassess response. Prevention bundles center on pneumococcal and influenza vaccination, aspiration precautions (elevate the head of bed, swallow evaluations), oral care, and smoking cessation.

Pulmonary Embolism (PE)

Virchow's triad names the three drivers of venous thromboembolism: venous stasis (immobility, surgery, heart failure), endothelial injury (trauma, central lines, prior DVT), and hypercoagulability (malignancy, estrogen therapy, pregnancy, inherited thrombophilias). Most pulmonary emboli originate as deep vein thrombi in the legs. Classic presentation: sudden dyspnea, pleuritic chest pain, tachycardia, tachypnea, hypoxemia, and sometimes hemoptysis or syncope.

The Wells criteria stratify pretest probability using factors such as clinical signs of DVT (3 points), PE as the most likely diagnosis (3), heart rate above 100 (1.5), immobilization or surgery within 4 weeks (1.5), prior DVT/PE (1.5), hemoptysis (1), and malignancy (1). A score above 4 makes PE likely; low scores with a negative D-dimer can safely exclude it. Definitive imaging is CT pulmonary angiography; a ventilation-perfusion (V/Q) scan is used when contrast is contraindicated.

Anticoagulation is the foundation of treatment. Unfractionated heparin (weight-based bolus and infusion, monitored by aPTT or anti-Xa) or low-molecular-weight heparin (enoxaparin 1 mg/kg every 12 hours) starts immediately when suspicion is high. Warfarin overlaps with heparin for at least 5 days and until the INR is therapeutic at 2.0-3.0 for 2 consecutive days; teach patients to keep vitamin K intake consistent. Direct oral anticoagulants (apixaban, rivaroxaban) need no routine monitoring. Thrombolytics (alteplase) are reserved for massive PE with hypotension or shock — screen hard for bleeding contraindications. An IVC filter is considered when anticoagulation is contraindicated or PE recurs despite adequate therapy. Nursing care: monitor for bleeding, maintain oxygenation, and teach anticoagulant safety.

Tuberculosis (TB)

Latent TB infection means the patient carries Mycobacterium tuberculosis without symptoms, is not contagious, and has a positive skin test or IGRA blood test with a normal chest x-ray; treatment (e.g., isoniazid plus rifapentine weekly for 3 months, or isoniazid for 6-9 months) prevents progression. Active TB disease produces productive cough over 3 weeks, fever, night sweats, weight loss, and hemoptysis; the patient is infectious via airborne droplet nuclei. Note that prior BCG vaccination can cause a false-positive tuberculin skin test but does not affect IGRA results.

Infection control: airborne precautions — a negative-pressure (airborne infection isolation) room with the door closed, a fit-tested N95 respirator for staff, and a surgical mask on the patient during transport. Diagnosis rests on sputum acid-fast bacilli (AFB) smear and culture from three morning specimens; patients typically remain in isolation until three negative smears and clinical improvement on therapy.

RIPE therapy — Rifampin, Isoniazid, Pyrazinamide, Ethambutol — treats active TB for an initial 2-month intensive phase followed by continuation therapy, usually 4 more months of rifampin and isoniazid. Teach key adverse effects: rifampin turns body fluids orange and reduces oral contraceptive efficacy; isoniazid causes hepatitis and peripheral neuropathy (give pyridoxine/vitamin B6); ethambutol can cause optic neuritis (report visual changes, red-green color blindness); pyrazinamide raises uric acid. All are hepatotoxic — baseline and periodic liver function monitoring matters, and patients must avoid alcohol. Directly observed therapy (DOT), in which a healthcare worker watches each dose being swallowed, is the standard strategy to ensure adherence and prevent drug resistance.

Pleural Effusion and Pneumothorax

A pleural effusion is fluid in the pleural space — transudative (heart failure, cirrhosis) or exudative (malignancy, infection, PE). Findings include dyspnea, decreased tactile fremitus, dull-to-flat percussion, and diminished breath sounds over the effusion. Thoracentesis relieves symptoms and provides diagnostic fluid.

A pneumothorax is air in the pleural space causing lung collapse. Spontaneous pneumothorax classically strikes tall, thin young men (primary) or patients with underlying COPD (secondary); traumatic pneumothorax follows chest injury or procedures. Findings: sudden sharp chest pain, dyspnea, absent breath sounds, hyperresonance, and decreased fremitus on the affected side. Small stable pneumothoraces may be observed or aspirated; larger or symptomatic ones need a chest tube; needle decompression followed by tube thoracostomy treats the life-threatening form.

Tension pneumothorax — the exam's favorite emergency — occurs when a one-way valve lets air in but not out, collapsing the lung and shifting the mediastinum. Hallmark signs: severe respiratory distress, absent breath sounds and hyperresonance on the affected side, tracheal deviation away from the affected side, distended neck veins, and obstructive shock (hypotension, tachycardia). This is a clinical diagnosis — do not wait for a chest x-ray. Immediate needle decompression (large-bore needle into the second intercostal space, midclavicular line, on the affected side) followed by chest tube placement is lifesaving. An open pneumothorax (sucking chest wound) is managed initially with a vented (three-sided) occlusive dressing and then a chest tube.