This case of a patient with "obstructive" lung disease will test your understanding of pulmonary mechanics and gas exchange in this disorder.

History

A 65 years old former garage mechanic presents with a chief complaint of increased shortness of breath and a change in the quantity and color of his sputum for the past week. The sputum is usually scant and clear. However, recently it has become yellow and continues all day. He has had trouble raising sputum in the past year. He has become progressively short of breath over the last five years. He is now dyspneic at rest. He denies asthma, childhood respiratory problems, allergies and any occupational exposures.

Physical Examination

Obvious respiratory distress with prominent use of accessory muscles.
Temperature 99.5; Blood pressure 140/90; pulse 110; respiratory rate 28.
Head/neck reveal distended neck veins throughout expiration.
Chest reveals increased A-P diameter; reduced chest wall excursion; lungs hyperresonant to percussion; diaphragms low and immobile; auscultation reveals a prolonged expiratory phase with diminished breath sounds and generalized rhonchi.
Heart reveals PMI in epigastrium; heart sounds distant with regular rhythm and no murmurs.
Extremities reveal trace pitting edema of the lower extremities.

Chest x-ray reveals hyperinflation of lungs with an increase in the retrosternal space; low, flattened diaphragms; hyperlucent lung fields with paucity of vascular markings in the periphery but prominent hila and narrow heart silhouette.

EKG reveals low voltage; right axis; peaked P waves and clockwise rotation.

Laboratory reveals WBC 8,500 with normal differential and Hgb 14.7 gm.

ABG's: