<prompt> 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:Metabolic acidosisMetabolic alkalosisRespiratory acidosisRespiratory alkalosis  <response>: If there is acute respiratory acidosis, expected compensation is rise of HCO3 by 1 mEqL 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 