Description
The interpretation of acid-base data can be greatly facilitated by applying five rules: (1) use the blood gas to identify acidemia or alkalemia, (2) determine whether the underlying cause of acidemia or alkalemia is respiratory or metabolic, (3) calculate the anion gap, (4) check for the degree of compensation, and (5) assess the relationship between anions (there should be a 1:1 relationship of acid to base). Alkalemia has an underlying respiratory cause if the partial pressure of carbon dioxide (PCO2) is substantially less than 40 min Hg. It has a metabolic cause if the bicarbonate content is greater than 25 mEq/L Acidemia has a respiratory cause if the PC02 is greater than 40/min Hg. It has a metabolic cause if the bicarbonate content is less than 25 mEq/L.Calculating the acidbase ratio may reveal a metabolic alkalosis not detected by rules 1 through 4.