Obstructive vs Restrictive Lung Disease: Air Trapping vs Reduced Expansion — The Fundamental Classification
Every lung disease on the NCLEX maps to one of two patterns — air trapping or restricted expansion. If you can't classify the pattern, you'll misread PFT results, misinterpret breath sounds, and pick the wrong oxygen strategy. This single framework unlocks every respiratory question.
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Comparison
- ★Airway narrowing — air can't get OUT
- Asthma, COPD, CF, bronchiectasis
- ★Stiff lungs/chest — air can't get IN
- ARDS, fibrosis, scoliosis, GBS, MG
- Wheezing
- prolonged expiration
- Barrel chest
- hyperresonant percussion
- Fine crackles (fibrosis)
- shallow breaths
- Reduced expansion
- dull percussion
- ★FEV₁/FVC < 70% — FEV₁ drops most
- TLC ↑, RV ↑ (air trapped)
- FEV₁/FVC normal/↑ (≥80%)
- TLC ↓, RV ↓ (can't inflate)
- COPD: low-flow O₂
- high O₂ risks ↑ CO₂
- Position to ease air trapping
- High FiO₂
- ARDS needs PEEP for alveoli
- Support ventilation if severe
- Bronchodilators (SABA, LABA)
- ICS
- Pulmonary rehab
- smoking cessation
- Treat the underlying cause
- supplemental O₂
- Ventilatory support if severe
- Inhaler technique
- smoking cessation
- Pace exhalation
- pursed-lip breathing
- Adhere to cause-directed therapy
- Energy conservation
- report ↑ dyspnea
- Rising CO₂, somnolence (COPD)
- Silent chest / no air movement
- Falling vital capacity (GBS/MG)
- Refractory hypoxia (ARDS)
- Reversibility variable — asthma yes, COPD no
- Cor pulmonale
- chronic respiratory failure
- Fibrosis irreversible
- depends on cause
- Respiratory failure if expansion fails
Obstructive
- ★Airway narrowing — air can't get OUT
- Asthma, COPD, CF, bronchiectasis
Restrictive
- ★Stiff lungs/chest — air can't get IN
- ARDS, fibrosis, scoliosis, GBS, MG
Obstructive
- Wheezing
- prolonged expiration
- Barrel chest
- hyperresonant percussion
Restrictive
- Fine crackles (fibrosis)
- shallow breaths
- Reduced expansion
- dull percussion
Obstructive
- ★FEV₁/FVC < 70% — FEV₁ drops most
- TLC ↑, RV ↑ (air trapped)
Restrictive
- FEV₁/FVC normal/↑ (≥80%)
- TLC ↓, RV ↓ (can't inflate)
Obstructive
- COPD: low-flow O₂
- high O₂ risks ↑ CO₂
- Position to ease air trapping
Restrictive
- High FiO₂
- ARDS needs PEEP for alveoli
- Support ventilation if severe
Obstructive
- Bronchodilators (SABA, LABA)
- ICS
- Pulmonary rehab
- smoking cessation
Restrictive
- Treat the underlying cause
- supplemental O₂
- Ventilatory support if severe
Obstructive
- Inhaler technique
- smoking cessation
- Pace exhalation
- pursed-lip breathing
Restrictive
- Adhere to cause-directed therapy
- Energy conservation
- report ↑ dyspnea
Obstructive
- Rising CO₂, somnolence (COPD)
- Silent chest / no air movement
Restrictive
- Falling vital capacity (GBS/MG)
- Refractory hypoxia (ARDS)
Obstructive
- Reversibility variable — asthma yes, COPD no
- Cor pulmonale
- chronic respiratory failure
Restrictive
- Fibrosis irreversible
- depends on cause
- Respiratory failure if expansion fails
★ marks the fact that sets a column apart.
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Can't blow OUT = obstructive (low FEV1/FVC). Can't breathe IN = restrictive (low TLC, ratio preserved).
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