What is the most common cause of increased arterial blood PCO2?

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Multiple Choice

What is the most common cause of increased arterial blood PCO2?

The main idea is that arterial PCO2 is set by the balance between CO2 production and alveolar ventilation. CO2 is produced constantly by metabolism, so what determines the blood’s CO2 level is how effectively the lungs can exhale it. When you hypoventilate—breathing too slowly or too shallowly—less CO2 is removed, so it builds up in the blood and arterial PCO2 rises (hypercapnia). Hyperventilation would do the opposite, lowering PCO2. Sleep apnea can cause temporary CO2 retention during apneic episodes, but it is not the most common cause of chronically increased PCO2. Asthma can lead to CO2 retention mainly in severe, acute cases, not as the typical cause. So hypoventilation is the best explanation for an increased arterial PCO2.

The main idea is that arterial PCO2 is set by the balance between CO2 production and alveolar ventilation. CO2 is produced constantly by metabolism, so what determines the blood’s CO2 level is how effectively the lungs can exhale it. When you hypoventilate—breathing too slowly or too shallowly—less CO2 is removed, so it builds up in the blood and arterial PCO2 rises (hypercapnia). Hyperventilation would do the opposite, lowering PCO2. Sleep apnea can cause temporary CO2 retention during apneic episodes, but it is not the most common cause of chronically increased PCO2. Asthma can lead to CO2 retention mainly in severe, acute cases, not as the typical cause. So hypoventilation is the best explanation for an increased arterial PCO2.

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