What happens if increased respiration fails to clear carbon dioxide?

When respiration increases but fails to effectively clear carbon dioxide, the result is an accumulation of carbon dioxide in the bloodstream. This excess carbon dioxide reacts with water to form carbonic acid, which subsequently dissociates into bicarbonate and hydrogen ions. The increase in hydrogen ions leads to a decrease in blood pH, making the blood more acidic. This condition is often referred to as respiratory acidosis, where the body cannot adequately eliminate carbon dioxide, resulting in an adverse shift in the body's acid-base balance.

In contrast, the other potential outcomes do not accurately reflect the physiological response associated with carbon dioxide retention. The blood does not become more alkaline, nor does pleural pressure significantly decrease or remain neutral in this context. Therefore, the transformation of the blood into an acidic state is a direct consequence of elevated carbon dioxide levels failing to be effectively expelled during increased respiration.