How do you distinguish between respiratory or metabolic acidosis and alkalosis?
Acidosis / alkalosis depend on the blood levels of HCO3- and Partial pressure of CO2 (Pco2). Blood levels of former is regulated by kidney; therefore it is metabolic, and the latter by lungs; therefore respiratory. Normal pH of blood is 7.4. If it is less, the condition is acidosis, if higher it is alkalosis. Let’s take acidosis, if blood has low concentrations of HCO3- , it is metabolic acidosis. Or if arterial Pco2 is higher than normal, it is respiratory acidosis. Let’s assume if a person has metabolic acidosis. His respiratory system tries to compensate for acidosis by expelling more CO2 than usual; therefore lowering arterial Pco2. So we can easily find out if a person has low blood pH with a low HCO3- and a low Pco2, that it is a metabolic acidosis with respiratory compensation. I’m sure that you can work out the rest using this as a guide.
