A patient with restrictive lung disease shows which of the following spirometric findings?

Explanation

## Restrictive Pattern — Spirometric Signature **Key Point:** Restrictive lung disease is characterized by **proportional reduction in FEV₁ and FVC**, resulting in a **preserved or elevated FEV₁/FVC ratio (≥80%)**, combined with **reduced total lung capacity**. ### Pathophysiology of Restriction 1. Lung parenchyma is stiff or reduced in volume (fibrosis, atelectasis, chest wall disease) 2. Both inspiration and expiration are limited equally 3. FEV₁ and FVC fall proportionally → ratio stays ≥80% 4. **TLC is reduced** (the defining feature) 5. RV is normal or reduced (no air trapping) ### Spirometric Comparison: Obstruction vs. Restriction | Parameter | Obstruction | Restriction | |-----------|-------------|-------------| | **FEV₁/FVC** | ↓ (<70%) | ≥80% (normal/high) | | **FEV₁** | ↓ | ↓ | | **FVC** | Normal or ↓ | ↓ | | **TLC** | Normal or ↑ | ↓ | | **RV** | ↑ | Normal or ↓ | | **DLCO** | Normal | ↓ (if parenchymal) | **Mnemonic:** **RESTRICT** = **Ratio Elevated, Spirometry Total Lung Capacity Reduced, Inspiratory/Expiratory equally limited, Chest wall or Tissue disease **High-Yield:** When both FEV₁ and FVC are reduced **proportionally** (ratio ≥80%), always measure TLC. If TLC is low → restriction. If TLC is normal/high → mixed or artifact. **Clinical Pearl:** In idiopathic pulmonary fibrosis (IPF), the **FEV₁/FVC ratio is paradoxically preserved or even elevated** despite severe dyspnea — a classic exam trap. [cite:Harrison 21e Ch 246]