Severity

• 4) What is the degree of severity? This question can be answered for an obstructive problem. However, it cannot be answered for a restrictive problem. Degree of severity for restrictive is determined by the total lung capacity.

• FEV₁ < 65-80% mild obstruction
• FEV₁ < 50-65% moderate obstruction
• FEV₁ < 50% severe obstruction

Reversibility

• 5) If a bronchodilator was administered and the test repeated, did the FEV₁ or FVC improve (see interpretation guidelines above)?