Which spirometry pattern characterizes obstructive lung disease?

Which spirometry pattern characterizes obstructive lung disease?

• A. Increased TLC with decreased FEV1
• B. Decreased FEV1 with reduced FEV1/FVC ratio (<0.70); often increased TLC
• C. Normal FEV1/FVC ratio with decreased TLC
• D. Decreased FVC with preserved FEV1

Answer: (B)

Airflow limitation from obstructive disease shows up on spirometry as a drop in the amount of air you can forcefully exhale (FEV1) and, because expiration is slowed, a lower FEV1 relative to the total exhaled volume (FVC). That makes the FEV1/FVC ratio fall below the normal threshold. Additionally, air trapping can make the lungs hyperinflated, so total lung capacity (TLC) is often increased. So the characteristic pattern is decreased FEV1 with a reduced FEV1/FVC ratio (<0.70), and often increased TLC.

Airflow limitation from obstructive disease shows up on spirometry as a drop in the amount of air you can forcefully exhale (FEV1) and, because expiration is slowed, a lower FEV1 relative to the total exhaled volume (FVC). That makes the FEV1/FVC ratio fall below the normal threshold. Additionally, air trapping can make the lungs hyperinflated, so total lung capacity (TLC) is often increased. So the characteristic pattern is decreased FEV1 with a reduced FEV1/FVC ratio (<0.70), and often increased TLC.