Greater than 45 CO2 indicates which acid-base disturbance?

Greater than 45 CO2 indicates which acid-base disturbance?

• A. Metabolic Acidosis
• B. Metabolic Alkalosis
• C. Respiratory Alkalosis
• D. Respiratory Acidosis

Answer: (D)

When the partial pressure of carbon dioxide (PaCO2) in the blood is elevated beyond about 45 mmHg, the disturbance is respiratory in origin. CO2 combines with water to form carbonic acid, which dissociates to release hydrogen ions and lower the pH. That rise in CO2 indicates the body isn’t removing CO2 effectively, usually due to hypoventilation or impaired gas exchange, causing respiratory acidosis. The body can partially compensate by retaining bicarbonate through the kidneys, especially in chronic cases, but the primary issue here is the buildup of CO2 from inadequate ventilation. Metabolic disturbances change bicarbonate or acid without needing a rise in CO2, so a CO2 level above 45 points to a respiratory acidosis rather than a metabolic one.

When the partial pressure of carbon dioxide (PaCO2) in the blood is elevated beyond about 45 mmHg, the disturbance is respiratory in origin. CO2 combines with water to form carbonic acid, which dissociates to release hydrogen ions and lower the pH. That rise in CO2 indicates the body isn’t removing CO2 effectively, usually due to hypoventilation or impaired gas exchange, causing respiratory acidosis. The body can partially compensate by retaining bicarbonate through the kidneys, especially in chronic cases, but the primary issue here is the buildup of CO2 from inadequate ventilation. Metabolic disturbances change bicarbonate or acid without needing a rise in CO2, so a CO2 level above 45 points to a respiratory acidosis rather than a metabolic one.