A man, age 24, is admitted to the emergency department after an acute barbiturate overdose. Results from an arterial blood gas are as follows. Evaluate the information to determine respiratory or metabolic acidosis or alkalosis, and determine if compensation has occurred. Man's values: pH 7.29, Pco2 70mEq/L, Po2 70mmHg, HCO3- 25mEq/L. Normal values: pH: 7.35-7.45, Pco2 35-45mEq/L, Po2 80-100mmHg, HCO3- 22-28mEq/L.