A
low pH of the blood or body fluid is an Acidemia. Acidosis is a
confusing term and is best avoided when referring to low pH. It
should be qualified as Metabolic Acidosis or Respiratory Acidosis
A
high pH of the blood or body fluid is an Alkalemia. Alkalosis is also
a confusing term and often used ambiguously. Clarity is given when
qualified as Metabolic Alkalosis or Respiratory Alkalosis.
An
acidosis is a process producing hydrogen ion and a lower pH.
An
alkalosis is a process consuming hydrogen ion and raises the pH.
These changes is terminology have profound implications for the concepts of acid base terminology. For instance a metabolic acidosis means that there is or has been a process producing metabolic acids. This is reflected in the level of HCO3-. This does not mean that the pH is abnormally low. That is acidemia which is different from acidosis.
The
severity of a metabolic acidosis is based on the HCO3- level and not
the pH.
The severity of a respiratory acidosis, is based on the
arterial PaCO2- and not the pH
H+
Hydrogen Ion H+
Ph Negative log of H+
pO2 Partial pressure
of Oxygen
PaO2 Partial Pressure of Oxygen in Arterial Blood
pCO2
Partial pressure of Carbon Dioxide pCO2
PaCO2 Partial Pressure
of Carbon Dioxide in Arterial Blood
HCO3− Bicarbonate ion