A 70 year old man with history of CHF presents with increased shoness of breath and leg swelling. ABG: pH 7.24, pC02 = 60 mmHg, P02 = 52, HC03 =27. Interpret:

If there is acute respiratory acidosis, expected compensation is rise of HCO3 by 1 mEq/L for every 10 mm Hg rise of pCO2. In this question change in pCO2 = 60 -40 = 20mmHg Therefore expected elevation in = 2 m Eq. Since the actual HCO3- is close to the calculated HCO3, the diagnosis is respiratory acidosis