Review Question - QID 100941

Chronic obstructive pulmonary disease (COPD) causes chronic hypoxemia and can cause hypercapnia. Hypoxemia induces pulmonary vasoconstriction, which increases pulmonary arterial resistance. Pulmonary hypertension and cor pulmonale may result.

Chronic bronchitis, emphysema, and bronchietasis are the three most common forms of chronic obstructive lung disease. Pulmonary function tests are characterized by an increased TLC, decreased FEV/FVC, and a decreased FEV1. COPD is mainly caused by cigarette smoking but recurrent airway infections and alpha-1-antitrypsin deficiency are also known causes. Chest X-ray of COPD show hyperinflation, flattened diaphragms and sometimes increased interstitial markings.

Szilasi et al. discuss the pathophysiology of COPD. They report that the disease is characterized by a decrease in airflow capacity and and long-term inflammation of the lung. Eventually small airway obstruction, loss of elasticity, and cell apoptosis lead to the pathologic changes seen in the disease.

Stephens et al. review the presentation, evaluation, and treatment of COPD. They state that the diagnosis of COPD is made by history, physical examination, and pulmonary function testing. FEV1 < 70 percent and is irreversible with the administration of an inhaled bronchodilator which differentiates it from another obstructive disease: asthma.

Illustration A is gross pathology of a lung showing centrilobular-type emphysema characteristic of smoking.

Answer 1: COPD patients can exhibit increased carbon dioxide content in the arterial system owing to poor ventilation. Normal carbon dioxide content is also possible in early stages of the disease.
Answer 3: pH is often decreased rather than increased in patients with COPD owing to an increase in CO2. Normal pH is also possible in early stages of the disease.
Answer 4: Cerebral vascular resistance is decreased, not increased, in COPD. This leads to increased cerebral perfusion and increased ICP.
Answer 5: In COPD, right ventricular compliance decreases as the ventricle gets stiff/hypertrophic from pulmonary arterial hypertension induced by chronic vasoconstriction due to hypoxemia in the lung.