In a man undergoing surgery, it was necessary to aspirate the contents of the uppergastrointestinal tract. After surgery, the following values were obtained from an arterial blood sample: pH 7.55, PCO2 52 mm Hg and HCO3 - 40 mmol/l. What is the underlying disorder?

a) Metabolic Acidosis
b) Metabolic Alkalosis
c) Respiratory Acidosis
d) Respiratory Alkalosis