Difference between acidemia and acidosis
Acid emia describes the concentration of hydrogen ions ([H + ]) in plasma; thus it includes all conditions where [H + ] in plasma is higher than the values observed in normal subjects (40 ± 2 nmol/L, or a pH less than 7.38). Acid emia has two general causes, and this leads to the concept of acid osis . An acid osis is any process by which there is increased [H + ] and a decrease in the concentration and/or the content of bicarbonate (HCO 3 − ) in the extracellular fluid (ECF) compartment. As noted previously, there are two general processes whereby [H + ] is increased in plasma. First, there may be a high carbon dioxide tension in arterial blood (i.e., the PaCO 2 —called a respiratory acidosis) or, second, a high [H + ] in plasma from a low bicarbonate (called metabolic acidosis). Notably, an acidosis does not necessarily mean there is an acidemia. This is because there may be multiple processes—of metabolic or respiratory origin—that cause [H + ] in plasma to fall despite there being an identified metabolic acidosis.