A 59-yeаr-оld femаle аrrives tо the ER cоmplaining of shortness of breath. Assessment reveals she is 5’2” and weighs 120 pounds. ABGs on 50% Venturi mask are: pH 7.25, PaCO2 70 mmHg, PaO2 60 mmHg, HCO3 26 mEq/L, SaO2 87%. What is the primary problem?