Certified Registered Nurse Anesthetist (CRNA) Practice Exam

What is the mechanism of cor pulmonale resulting from chronic airway obstruction?

1. Increased oxygenation of the alveoli

2. Chronic alveolar hypoventilation with an increase in pulmonary vascular resistance

3. Elevation of thoracic pressure

4. Altered pulmonary blood flow dynamics

The correct answer is: Chronic alveolar hypoventilation with an increase in pulmonary vascular resistance

Cor pulmonale, which refers to right heart failure due to lung disease, commonly results from chronic airway obstruction, such as seen in conditions like chronic obstructive pulmonary disease (COPD). The correct mechanism involves chronic alveolar hypoventilation leading to an increase in pulmonary vascular resistance. When airway obstruction occurs, it impairs airflow and gas exchange within the lungs. This results in inadequate oxygenation and an accumulation of carbon dioxide, leading to hypoventilation. Chronic elevation of carbon dioxide levels causes respiratory acidosis, which contributes to vasoconstriction of the pulmonary vasculature. As the pulmonary vessels constrict, the resistance within the pulmonary circulation increases significantly. Over time, this elevated pressure in the pulmonary arteries forces the heart's right ventricle to work harder to pump blood through the narrowed vessels, ultimately leading to its hypertrophy and eventual failure, which characterizes cor pulmonale. While an elevation of thoracic pressure can occur due to increased work of breathing in obstructive lung diseases, it is not the primary mechanism causing cor pulmonale in this context. Additionally, altered pulmonary blood flow dynamics might play a role in some situations, but it is also not a direct mechanism for the development of cor pulmonale resulting from chronic airway obstruction