WHY DO SOME CIGARETTE SMOKERS DEVELOP CHRONIC BRONCHITIS AND OTHERS EMPHYSEMA?
As stated earlier, most patients who contract chronic obstructive lung disease have elements of both chronic bronchitis and emphysema, although one or the other may dominate in a given individual; physicians can usually determine which process predominates. Chronic bronchitis is found most commonly in patients who have inhaled tremendous amounts of cigarette smoke; the “tar” has had a direct, toxic effect on their bronchi. It’s possible that anyone inhaling comparable amounts of smoke would have similar changes. This doesn’t rule out a genetic or constitutional factor, but the end result (chronic bronchitis) does seem related to the dose of toxic material (“tar”) inhaled. Patients who develop predominant emphysema, where the lung tissue is destroyed, may have a genetic or constitutional basis. Certainly most smokers don’t develop emphysema. Evidence for a genetic tendency comes from the small percentage of emphysema patients who lack a certain enzyme called alphalantitrypsin. This en
