How does chronic lung disease primarily affect the hypoxic drive?

• A. It abolishes the drive completely
• B. It activates the drive in the presence of normal oxygen levels
• C. It alters the sensitivity to oxygen levels
• D. It has no effect on hypoxic drive

Answer: (C)

Chronic lung disease primarily affects the hypoxic drive by altering the sensitivity to oxygen levels. In healthy individuals, the primary drive for breathing is the level of carbon dioxide in the blood. However, in people with chronic lung disease, such as chronic obstructive pulmonary disease (COPD), the body may become accustomed to higher levels of carbon dioxide and lower levels of oxygen over time.

As a result, the normal chemoreceptor response to changes in oxygen levels is altered. The peripheral chemoreceptors become less sensitive to hypoxia (low oxygen levels), meaning it takes a greater drop in oxygen levels to trigger the respiratory drive effectively. This adaptation can lead to a reliance more on carbon dioxide levels for the drive to breathe rather than the oxygen levels, potentially complicating treatment strategies such as supplemental oxygen use.

While some individuals may still respond to significant hypoxia, the general alteration in sensitivity affects how they respond to both oxygen and carbon dioxide levels in their blood. This is why understanding the changes in hypoxic drive due to chronic lung conditions is crucial when treating patients with such diseases.