With a 1°C rise, pO2 changes by which percent?

• A. pO2 decreases by 7%
• B. pCO2 increases by 7%
• C. pH increases by 0.015
• D. pO2 increases by 7%

Answer: (A)

Temperature changes alter gas solubility in blood. As temperature rises, oxygen becomes less soluble, so the amount dissolved decreases and the pO2 in blood falls. A common clinical rule of thumb is about a 7% decrease in pO2 for every 1°C increase in temperature. The other statements describe changes in pCO2 or pH, which are not the primary effect of temperature on oxygen in the blood, so they don’t fit as the main outcome. Thus, the pO2 decreasing by roughly 7% with a 1°C rise is the best answer.