acidemia = pH < 7.38<unk>  = pCO2 > 42
Acute<unk> : Change in pH = 0.008 X (40 - PaCO2)
Chronic<unk> : Change in pH = 0.003 X (40 - PaCO2)
Determine if another primary acid/base disturbance is occurring
Calculate AG
if HCO3 < 24 + (pCO2-40)/10 x 3(+/-1) then there is a superimposed primary metabolic<unk> 
for every 10mm increase in pCO2 >40, HCO3expected increases by 2-4mEq (2 if acute/limited time for metabolic compensation, 4 if chronic i.e. COPD)
if HCO3 > 24 + (pCO2-40)/10 x 3(+/-1) then suspect primary metabolic alkalosis
Calculate AG
if HCO3 < 24 + (pCO2-40)/10 x 3(+/-1) then there is a superimposed primary metabolic<unk> 
for every 10mm increase in pCO2 >40, HCO3expected increases by 2-4mEq (2 if acute/limited time for metabolic compensation, 4 if chronic i.e. COPD)
if HCO3 > 24 + (pCO2-40)/10 x 3(+/-1) then suspect primary metabolic alkalosis
for every 10mm increase in pCO2 >40, HCO3expected increases by 2-4mEq (2 if acute/limited time for metabolic compensation, 4 if chronic i.e. COPD)
Hypoventilation - acute vs chronic
Respiratory acidosis
COPD
Respiratory alkalosis
Drugs 
Metabolic acidosis
Chest wall disease
Metabolic alkalosis
Pleural disease