PetCO2 is a function of which factor?

PetCO2 is a function of which factor?

• A. Cardiac output
• B. Hemoglobin level
• C. Metabolic rate
• D. Arterial oxygen saturation

Answer: (C)

PetCO2 reflects the balance between CO2 production by metabolism and CO2 removal by alveolar ventilation. The factor that most directly changes the amount of CO2 available to be eliminated is metabolic rate, since it sets how much CO2 tissues produce. If metabolism increases while ventilation stays the same, more CO2 enters the alveoli and the end-tidal CO2 rises. Conversely, increasing ventilation or reducing metabolic CO2 production lowers the end-tidal value. The other options influence CO2 transport or oxygenation but do not determine the end-tidal CO2 as directly as how fast CO2 is produced by metabolism and how effectively ventilation removes it.

PetCO2 reflects the balance between CO2 production by metabolism and CO2 removal by alveolar ventilation. The factor that most directly changes the amount of CO2 available to be eliminated is metabolic rate, since it sets how much CO2 tissues produce. If metabolism increases while ventilation stays the same, more CO2 enters the alveoli and the end-tidal CO2 rises. Conversely, increasing ventilation or reducing metabolic CO2 production lowers the end-tidal value. The other options influence CO2 transport or oxygenation but do not determine the end-tidal CO2 as directly as how fast CO2 is produced by metabolism and how effectively ventilation removes it.