Certified Transport Registered Nurse Certification Practice Exam

What effect does decreased lung compliance have on CO2 levels?

1. Increases CO2 retention

2. Decreases CO2 retention

3. No effect on CO2 levels

4. Fluctuating CO2 levels

The correct answer is: Increases CO2 retention

Decreased lung compliance refers to the reduced ability of the lungs to expand and contract during the breathing process. This decreased ability can hinder effective ventilation, making it more difficult for air (and therefore oxygen) to enter and for carbon dioxide (CO2) to be expelled from the lungs. When compliance is impaired, the lungs cannot inflate properly, leading to inadequate ventilation during both inhalation and exhalation. As a result, the body struggles to eliminate CO2 efficiently, causing a buildup of this gas in the blood. This accumulation results in increased CO2 retention, which can lead to hypercapnia—a condition characterized by elevated levels of carbon dioxide in the bloodstream. In contrast, options that suggest a decrease in CO2 retention or no effect on CO2 levels overlook the physiological implications of altered lung mechanics and how they directly influence gas exchange during respiration. Thus, acknowledging that decreased lung compliance can significantly impair the body's ability to regulate CO2 excretion highlights the critical connection between lung function and metabolic stability.