A Brief Synopsis of AFP's "Diagnosis of Chronic Obstructive Pulmonary Disease"

A brief synopsis of:  Diagnosis of Chronic Obstructive Pulmonary Disease
MARK B. STEPHENS, CDR, MC, USN, and KENNETH S. YEW, CAPT, MC, USN
Uniformed Services University of the Health Sciences, Bethesda, Maryland 
Am Fam Physician. 2008 Jul 1;78(1):87-92.
http://www.aafp.org/afp/2008/0701/p87.pdf

     COPD is a serious disease because it is preventable in many instances. It is an inflammatory disease caused mostly by smoking. It is associated with chronic bronchitis (cough and sputum production for at least 3 months in two consecutive years) and emphysema (destruction of the alveolar-capillary membrane). COPD can also be caused by alpha1-antitrypsin deficiency, environmental, and occupational pollutants. 
     The pathophysiology is that the smoking causes airway irritation, inflammation,  mucus production, decreased clearance and lung scarring. This leads to obstruction, dyspnea, and infection. Interestingly, women are more susceptible than men, due to differences in lung size and the fact that a woman's lung is more hyperresponsive to irritants. Other symptoms may be wheezing, chest tightness, weight loss, and waking up more often at night. If the patient is a smoker, determining the number of "pack-years" is helpful. Multiplying the number of packs smoked per day by the number of years smoked is the formula. 
     On the physical exam, the patient may be seen with lung hyperinflation, barrel chest, hyperresonance on percussion, or diminished breath sounds. There may also be signs of cor pulmonale,  such as JVD, hepatomegaly  peripheral edema, or a loud S2.  Other signs may be pursed breathing, increased use of accessory breathing muscles,  and increase time of expiration. 
     COPD can often be confused with asthma. They are both obstructive lung disease with similar symptoms. COPD is often seen in smokers over age 35 years old with progressive symptoms. These features are variable in asthma. The cough is productive in COPD and non productive in asthma. Asthma has a stronger family history and diurnal variation in symptoms than COPD. 
    The two measurable factors in COPD are dyspnea and spirometry. The Medical Research Council (MRC) dyspnea index can be used to assess the severity. Dyspnea is graded from one to five. A grade of one is seen if the patient becomes dyspneic only during strenuous exercise. A grade of two will be given if the patient becomes short of breath while walking up a small hill. If the patient needs to catch their breath when walking at a normal pace and walks more slowly than others, then the patient is at a grade three. A grade four is given if the patient needs to stop and catch their breath when walking 100m. A patient with level 5 dyspnea  becomes too short of breath to even leave their home or do normal ADLs.
    The two parameters in spirometry are FEV1 and FVC. To review, FEV1 is the amount of air expired in one second after a full breath. FVC is the maximum amount of air exhaled after a full breath. A diagnosis of COPD is confirmed when the FEV1/FVC ratio is less than 0.7 and the FEV1 is less than 80% of the predicted value for the persons age, sex and height.  There are different staging categories based on the spirometry findings. A smoker with good values is at stage 0 (at risk). All of the higher stages have a FEV1/FVC ratio less than 0.7 and variable FEV1.  
At stage one (mild), the FEV1 is still above 80%.
At stage two (moderate), the FEV1 is 50-80%. 
Stage three (severe) is at 30-50%.
Stage four (very severe) is below 30%.
     Other useful tests are a chest x ray to look for nodules, masses, or fibrotic changes. Pulse oximetry, CBC, ECHO and ECG may also be considered to rule out anemia, polycythemia, and pulmonary issues.