This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Medicine
pH=7.28, PaCO2=70, Condition is consistent with: March 2005 
Select and explain. 
A. Metabolic acidosis, B. Metabolic alkalosis, C. Respiratory acidosis, D. Respiratory alkalosis
C: Respiratory acidosis
Answer: C: Respiratory acidosis 
Explanation: Ans. C: Respiratory acidosis Normal Systemic aerial pH is between 7.35-7.45 and steady state PaCO2 is 40 mm Hg. Disorders and range of values for pH and PaCO2 Metabolic acidosis-Low pH and low PaCO2 Metabolic alkalosis-High pH and high PaCO2 Respiratory acidosis-Low pH and high PaCO2 Respiratory alkalosis-High pH and low PaCO2