2019 Volume 49 Issue 3 Pages 107-111
COPD is an integrated disease entity which comprises pulmonary emphysema and chronic bronchitis. Pink puffer, thin, dyspneic but without cyanosis was a typical phenotype of pulmonary emphysema. Blue bloater, fat, edematous and cyanotic was a typical phenotype of chronic bronchitis. Recent clinical guideline divides COPD into emphysema type and non-emphysema type. Non-emphysema type is similar to chronic bronchitis but they are not cyanotic nor edematous as was blue bloater since the era when antibiotics became widely used. In some cases, COPD becomes symptomatic more than ten years after they quit smoking.
Pulmonary function tests show obstructive dysfunction, namely difficulty in expiration while patients often complain difficulty in inspiration. This symptom can be explained by dynamic hyper-inflation during exercise and air trapping during rest. As the diaphragm becomes flat in COPD, neck accessory muscles are used to pullup the thoracic cage for inspiration. The lung compliance (Cl) is big in COPD so the sternocleidomastoid muscle which has long stroke is effective to expand the lung. The development of sternocleidomastoid muscle, i.e., visible dimple between sternal and clavicular attachment of the muscle implies that the patient's FEV1 ＜ 1 L.
In CPFE (combined pulmonary fibrosis and emphysema), the lung size and its overall Cl is almost normal. As the diaphragmatic curvature is preserved, its excursion is preserved. This is the cause of the scalene muscles, which are wider and have bigger torque than sternocleidomastoid muscle are the dominant neck accessory muscles used in CPFE. Understanding these pathophysiology helps learning of clinical history taking and physical examination.