AEMCA Practice Exam

What is typically the situation in terms of V/Q mismatch for a patient with chronic bronchitis?

1. High V/Q mismatch due to enhanced ventilation

2. Normal V/Q mismatch due to optimal gas exchange

3. Low V/Q mismatch due to decreased ventilation

4. Fluctuating V/Q mismatch due to inconsistent heart rate

The correct answer is: Low V/Q mismatch due to decreased ventilation

In the case of chronic bronchitis, the underlying pathophysiology involves a long-term inflammation of the airways that leads to increased mucus production and airway obstruction. This obstruction results in decreased airflow and impaired ventilation—particularly during expiration. As a result, the ventilation-perfusion (V/Q) ratio in patients with chronic bronchitis is typically low. This means that the areas of the lung that receive blood flow (perfusion) are not adequately ventilated, leading to an imbalance. The impaired ventilation reduces the ability of these areas to participate effectively in gas exchange, which results in hypoxemia and potentially hypercapnia (increased carbon dioxide levels). In summary, the situation of low V/Q mismatch reflects the chronic airflow limitation and reduced ventilation characteristic of chronic bronchitis, which ultimately negatively affects the efficiency of gas exchange. This is in contrast to the other choices, which either suggest normal ventilation or increased ventilation that is inconsistent with the clinical scenario of chronic bronchitis.