Respiratory Acidosis is characterized by which of the following?

• A. Regulation of pH
• B. pH measure
• C. Excess acid from poor perfusion
• D. Elevated CO2

Answer: (D)

Respiratory acidosis is defined by an inability to eliminate CO2, so arterial CO2 rises. This increase in CO2 shifts the equation toward more carbonic acid, lowering the blood pH. The essential signal here is elevated CO2, which directly reflects the respiratory failure in ventillation or gas exchange.

Other statements describe general pH regulation, or are about what you measure (pH) or about a different cause of acidosis. A high CO2 tells you the problem is respiratory in origin, whereas metabolic acidosis would be driven by excess non-CO2 acids such as lactic acid from poor perfusion. In chronic cases, the kidneys try to compensate by retaining bicarbonate, but CO2 levels remain elevated as the primary driver.