A 32-year-old Hispanic woman presents to your office with a chronic cough for 3 months. She states the cough is dry and started with a cold 3 months ago. She denies fever, chills, and night sweats. She has never been diagnosed with asthma or lung disease in the past. She does admit to having had persistent dry coughs that linger on after getting colds in the past. She is not sure what wheezing is but she has noticed a tight feeling in her chest at night with some whistling sound. On physical examination, her lungs are clear and she is moving air well. She is 5 feet tall and weighs 220 pounds, giving her a body mass index (BMI) of 43. Her peak expiratory flow (PEF) in the office is at 80% of predicted. Even though she is not wheezing her history and physical exam are highly suspicious for asthma. You prescribe a short-acting β2-agonist rescue inhaler with spacer and order pulmonary function tests (PFTs). You have your nurse provide asthma education (including proper use of an inhaler) and suggestions for weight loss.
The patient returns 1 week later and the cough is much improved. You review her PFTs (Figure 55-1) and note that she has reversible bronchospasm especially in the small airways (FEF25%-75% shows a 70% improvement with inhaled albuterol). Table 55-1 lists the meaning of typical abbreviations used with PFTs. Her lung volumes (Figure 55-1B) show hyperinflation with a high residual volume and her diffusing capacity is normal. The whole picture is consistent with asthma. An asthma action plan is created and a referral to a nutritionist is offered to help the patient with her obesity.
Pulmonary function tests in a woman with suspected asthma. A. Spirometry before and after bronchodilation with flow volumes loops and graph of forced vital capacity. The FEV1 is normal, but the FEV1/FVC ratio and FEF25-75% are reduced. Following administration of bronchodilators, there is a good response especially in the small airways as represented by FEF25-75%. B. Lung volumes are all increased (especially the residual volume), indicating overinflation and air trapping. The diffusing capacity is normal. Conclusions: Minimal airway obstruction, overinflation, and a response to bronchodilators are consistent with a diagnosis of asthma. The patient has minimal obstructive airways disease of the asthmatic type. %Chng, Percent change; %Pred, percent predicted; Pre-Bronch, prebronchodilation; Pred, predicted; Post-Bronch, postbronchodilation. See Table 55-1 for additional abbreviation explanations. (Courtesy of Richard P. Usatine, MD.)
Table 55-1 Pulmonary Function Tests: Key to Abbreviations