Respiratory compensation process takes 12-24 hours to become fully active. Protons are slow to diffuse across the blood brain barrier. In the case of LA this will be faster because LA is produced in the brain.
The degree of compensation can be assessed by using Winter’s Formula. It is INAPPROPRIATE to use this formula before the acidosis has existed for 12-24 hours.
PCO2 = 1.5 (HCO3) + 8 +/-2.
In steady state chronic metabolic acidoses the pCO2 almost invariably approximates the last two digits of the measured arterial pH.