Overview
This lecture covers Acute Respiratory Distress Syndrome (ARDS), focusing on its causes, pathophysiology, clinical signs, and nursing interventions for effective NCLEX exam preparation.
ARDS Basics & Lung Anatomy
- ARDS is a type of respiratory failure where alveolar-capillary membranes leak fluid into the alveoli.
- The alveoli are the lung's gas exchange units, allowing O₂ in and CO₂ out.
- Fluid-filled alveoli reduce gas exchange, leading to alveolar collapse and hypoxemia (low blood oxygen).
Causes of ARDS
- ARDS can result from indirect causes (systemic inflammation, such as sepsis, burns, multiple transfusions, pancreatitis, drug overdose).
- Direct causes include pneumonia, aspiration, inhalation injury, near-drowning, and pulmonary embolism.
- Sepsis, especially from gram-negative bacteria, is a common and serious cause.
Pathophysiology & Phases of ARDS
- Three phases: Exudative (fluid/protein leak, decreased surfactant), Proliferative (dense, non-functional lung tissue), Fibrotic (permanent lung scarring).
- Decreased surfactant causes alveolar collapse (atelectasis).
- Hallmark: refractory hypoxemia—oxygen remains low despite high O₂ therapy.
- Early: respiratory alkalosis due to rapid breathing; Late: respiratory acidosis as CO₂ increases.
Clinical Manifestations
- Early signs are subtle: normal/diminished lung sounds, mild crackles, increased respiratory rate.
- Progression: severe dyspnea, low O₂ saturation, crackles, cyanosis, confusion, increased HR, chest retractions.
- Chest X-ray: bilateral lung infiltrates ("whiteout" appearance).
- Risk of full respiratory failure and multi-organ compromise.
Nursing Interventions & Management
- Maintain airway and ensure adequate oxygenation (PaO₂ ≥ 60 mmHg, O₂ sat ≥ 90%).
- Mechanical ventilation with high PEEP keeps alveoli open and improves gas exchange.
- Monitor for complications: hypotension, decreased cardiac output, pneumothorax, subcutaneous emphysema.
- Prone positioning (patient on belly) improves ventilation/perfusion.
- Use pulmonary artery wedge pressure (<18 mmHg suggests ARDS, >18 mmHg suggests cardiac cause).
- Monitor renal output, mental status, blood pressure, and watch for pressure injuries.
- Medications: corticosteroids for inflammation, antibiotics for infection, GI drugs for ulcers, inotropic agents for cardiac output.
- Prevent ventilator-associated infections and malnutrition.
Key Terms & Definitions
- ARDS — Acute Respiratory Distress Syndrome, severe lung condition with fluid-filled alveoli.
- Alveoli — Tiny lung sacs for gas exchange.
- Hypoxemia — Low oxygen in the blood.
- PEEP — Positive end-expiratory pressure, keeps alveoli open during ventilation.
- Atelectasis — Collapse of alveoli, reducing gas exchange.
- Refractory hypoxemia — Low blood oxygen unresponsive to O₂ therapy.
- Pulmonary edema — Fluid accumulation in the lungs.
- Pulmonary artery wedge pressure — Measurement to differentiate ARDS from cardiac origin pulmonary edema.
Action Items / Next Steps
- Study the phases and hallmark symptoms of ARDS.
- Review causes and differentiate direct vs. indirect ARDS triggers.
- Practice interpreting ABG results and chest X-rays for ARDS.
- Take the recommended quiz on this condition.