For most clinical decisions, the serum bicarbonate, PaCO2, and pH are used to evaluate acid-base status. The typical clinician probably ignores the TCO2. The diagnosis of causes of acid-base disturbance is discussed later in this manual. Go to Index. The Buffer Base is the total of all the anionic buffer components in the blood such as bicarbonate, sulfates, and phosphates.
Base excess can be a negative value.
If the patient is acidotic, acid would have to be taken away to bring the pH to normal. In this case, for example, a base excess of -8 would mean that 8 mEq per liter of base would have to be added to bring the patient s blood to normal pH. Although many physicians use the difference between the patient s bicarbonate and an average bicarbonate of 24 as an indication of the patient s need for bicarbonate replacement, the base excess is a more accurate measure because it also takes into account other buffers such as phosphate and hemoglobin. It remains accurate in cases where the buffering capacity of hemoglobin is decreased due to anemia. Go to Index. Because of different protein content and the absense of hemoglobin, ECF has a different buffering capacity.