Restrictive Pattern with Preserved FEV1/FVC Ratio
These spirometry results show a restrictive pattern (FVC 63% predicted with preserved FEV1/FVC ratio of 72%), requiring full pulmonary function testing with lung volumes and DLCO to confirm true restriction and establish the underlying cause 1, 2.
Interpretation Algorithm
Step 1: Assess FEV1/FVC Ratio
- Your ratio is 72%, which is normal (above the threshold of 70% or lower limit of normal)
- This rules out obstructive disease 3, 1
Step 2: Assess FVC
- Your FVC is 63% predicted, which is significantly reduced (below the 5th percentile threshold) 1
- Low FVC with preserved ratio = restrictive pattern
Step 3: Note the Discordant FEV1
- Your FEV1 is 82% predicted (relatively preserved)
- This creates a pattern where FVC is disproportionately reduced compared to FEV1
- The preserved FEV1 with low FVC suggests true parenchymal or chest wall restriction rather than small airway disease 2
Critical Next Steps
You must order complete pulmonary function testing including:
- Lung volumes (TLC, RV, RV/TLC) to confirm restriction (TLC <80% predicted confirms true restrictive disease)
- DLCO testing to differentiate parenchymal disease (low DLCO) from chest wall/neuromuscular causes (normal DLCO) 1, 2
Why This Matters
Spirometry alone cannot distinguish between:
- True restrictive lung disease (interstitial lung disease, pulmonary fibrosis)
- Chest wall restriction (obesity, kyphoscoliosis)
- Neuromuscular weakness
- Submaximal effort
Important Caveats
Rule Out Technical Issues First
- Ensure adequate effort and proper technique
- Look for reproducible results (within 150 mL between best two efforts)
- Review the flow-volume loop for quality
Consider Clinical Context
The differential diagnosis for this pattern includes:
- Parenchymal diseases: Interstitial lung disease, pulmonary fibrosis, sarcoidosis
- Chest wall disorders: Severe obesity (BMI >30), kyphoscoliosis, pleural disease
- Neuromuscular conditions: Myasthenia gravis, muscular dystrophy, diaphragm weakness
- Other: Previous lung resection, chronic heart failure
Special Consideration
While the 2022 ATS/ERS guidelines might classify isolated low FEV1 patterns differently 4, your case shows both low FVC and low FEV1, making this a clear restrictive pattern requiring full evaluation rather than a borderline finding.
Do not delay full PFTs - the severity of FVC reduction (63%) warrants prompt comprehensive testing to identify potentially progressive or treatable conditions 1, 2.