Chart — Pulmonary Diseases
Obstructive vs Restrictive Patterns Chart
Two questions sort almost every set of pulmonary function tests: is air hard to get out, or hard to get in? This chart contrasts the obstructive and restrictive patterns across the spirometry and lung volume values, names the single measurement that defines each, and lists the diseases that produce them.
Written by Apex Respiratory Editorial Team
Educational use only. This material supports respiratory therapy education and exam review. It is not medical advice and is not a substitute for clinical judgment, institutional protocols, or physician orders. Always follow facility policies and current provider orders, and verify calculations independently before clinical use.
Obstructive vs Restrictive Side by Side
| Parameter | Obstructive | Restrictive |
|---|---|---|
| FEV1 | ↓↓ | ↓ or normal |
| FVC | Normal or ↓ | ↓↓ |
| FEV1/FVC ratio | ↓ below 0.70 — the hallmark | Normal or ↑ |
| TLC | Normal or ↑ — air trapping | ↓ — the hallmark |
| RV | ↑ | ↓ or normal |
| DLCO | ↓ in emphysema, normal in asthma/bronchitis | ↓ in ILD, normal in chest-wall/neuromuscular disease |
| Flow-volume loop | Scooped, concave expiratory limb | Tall, narrow, miniaturized loop |
| Examples | COPD, asthma, bronchiectasis, cystic fibrosis | Pulmonary fibrosis / ILD, chest-wall deformity, neuromuscular weakness, obesity, pleural disease |
Clinical Notes
- FEV1/FVC below 0.70 defines obstruction. The ratio is the entry point — reach for it first, then grade severity off the FEV1.
- A reduced TLC defines restriction. Restriction is a volume problem, so it is confirmed by lung volumes, not spirometry alone.
- A low FVC alone does not prove restriction. Air trapping in obstruction can drag the FVC down too. Only the TLC settles it — if the TLC is preserved, the low FVC is trapping, not true restriction.
- Mixed patterns exist. A patient can have both a reduced ratio and a reduced TLC; report what the numbers show rather than forcing one label.
Related Resources
Sources
- Kacmarek RM, Stoller JK, Heuer AJ. Egan's Fundamentals of Respiratory Care. 12th ed. Elsevier; 2021. Pulmonary function testing chapters.
- Stanojevic S, Kaminsky DA, Miller MR, et al. ERS/ATS technical standard on interpretive strategies for routine lung function tests. Eur Respir J. 2022;60(1):2101499.