AEMCA Practice Exam

In patients with COPD, what drives the urge to breathe?

1. Increased arterial CO2 levels

2. Low arterial oxygen levels detected by chemo-receptors

3. Stimulation of the diaphragm

4. Regular respiratory rhythm

The correct answer is: Low arterial oxygen levels detected by chemo-receptors

The urge to breathe in patients with Chronic Obstructive Pulmonary Disease (COPD) is primarily driven by the levels of oxygen (O2) in the blood, particularly when those levels are low. Chemoreceptors, which are sensory receptors that respond to chemical changes in the blood, play a crucial role in monitoring oxygen and carbon dioxide (CO2) levels. In COPD patients, the body often adapts to higher levels of CO2 due to impaired gas exchange. As a result, the primary drive to breathe shifts from a response to rising CO2 levels to a response to declining oxygen levels. When arterial oxygen levels drop, the peripheral chemoreceptors, mainly located in the carotid bodies, become stimulated. This stimulation increases the respiratory drive, prompting the individual to breathe more deeply or more frequently in an attempt to compensate for the low O2. This shift in respiratory drive highlights the unique physiological adaptations in patients with COPD, as their bodies become less sensitive to CO2 as a stimulus for breathing. Instead, the body relies increasingly on low oxygen levels to signal the need to take a breath. It is essential for individuals with COPD to recognize this mechanism, as managing oxygen levels is critical in their ongoing care and management of the disease.