A 54 year-old man presents to his primary care provider with dyspnea, cough and intermittent chest tightness. His cough is worse at night, in the early morning and with exercise. He is a non-smoker with no relevant occupational exposures.
1 (L) 2.18
How would you classify the pattern of test results for this patient?
Mixed obstructive and restrictive pattern
Question 2.1 Explanation:
If you use the criteria set forth by GOLD, the actual ratio of 0.68 is below the 0.7 cutoff and the patient has an obstructive defect. If you use the other approach and determine the lower limit of normal for this particular patient, the lower limit of normal would be 0.1 below the predicted value (0.8 – 0.1 = 0.7 in this case). His actual ratio of 0.68 falls below that cut-off as well so he would also be deemed to have airflow obstruction by this criterion.
How would you rate the severity of the observed abnormality?
Very severe defect
Question 2.2 Explanation
For obstructive patterns, once the FEV
1/FVC threshold for airflow obstruction has been met, the severity is graded based on the decrement in the FEV 1.
1 > 80% predicted: mild obstruction
< FEV 1 < 80% predicted: moderate obstruction
< FEV 1 < 50% predicted: severe obstruction
1 < 30% predicted: very severe obstruction
In this case, the FEV
1 is reduced to 64% of predicted, indicating that the patient has moderate obstruction.
Does the patient have a bronchodilator response?
Question 2.3 Explanation
A bronchodilator response is defined as a 200 mL
and 12% increase in the FEV 1 or FVC following bronchodilator administration. In this case, there was an improvement of 25% (and 810 mL) in the FVC and 30% (and 650 mL) in the FEV 1 so the patient would be classified as having a bronchodilator response.
The presence of a bronchodilator response can be used to support a diagnosis of asthma in the right clinical setting since the hallmark of that disorder is
reversible airflow obstruction and the presence of a bronchodilator response demonstrates some evidence of reversibility.
Keep in mind that although some patients with COPD may not demonstrate a bronchodilator response on pulmonary function testing, bronchodilators are still the mainstay of therapy in this patient population, as they still derive symptomatic benefit from their administration. You should also be aware that bronchodilator responsiveness can vary over time so the lack of response on one occasion does not mean this is always the case.