Base excess in the other. A secondary (compensatory) process can be readily identified because it "opposes" the observed deviation in blood pH. For example, inadequate ventilation, a respiratory problem, causes a buildup of CO, hence respiratory acidosis; the kidneys then attempt to compensate for the low pH by raising blood bicarbonate. The kidneys only partially compensate, so the patient may still have a low blood pH, i.e. acidosis. In summary, the kidneys partially compensate for respiratory acidosis by raising blood bicarbonate. A high base excess, thus metabolic alkalosis, usually involves an excess of bicarbonate. It can be caused by A base deficit
Base excess data. The term and concept of base excess were first introduced by Poul Astrup and Ole Siggaard-Andersen in 1958. Base excess can be estimated from the bicarbonate concentration ([HCO]) and pH by the equation: formula_1 with units of mEq/L. The same can be alternatively expressed as formula_2 Calculations are based on the Henderson-Hasselbalch equation: Ultimately the end result is: Base excess beyond the reference range indicates Blood pH is determined by both a metabolic component, measured by base excess, and a respiratory component, measured by PaCO (partial pressure of carbon dioxide). Often a disturbance in one triggers a partial compensation