A man is found comatose in his room, having taken an unknown number of sleeping pills. An aerial blood sample yields the following values: pH 7.10, HCO3 - 12 meq/liter, PaCO2 66 mm Hg. This patient's acid - base status is most accurately described as:
Uncompensated metabolic acidosis Uncompensated respiratory acidosis Mixed respiratory and metabolic acidosis Respiratory acidosis with paial renal compensation