Assessment of what is going on

Assessment of acid base disorders requires knowledge of:

respiratory component - PCO2

• metabolic component:
  • standard bicarbonate
  • base excess - greater than three implies metabolic alkalosis, less than minus three implies metabolic acidosis

There is usually a correspondence between respiratory performance and the metabolic derangement, e.g. a moderate metabolic acidosis will cause moderate hyperventilation. If this correspondence breaks down then another pathology should be suspected.

Understanding what is going on may be helped by a working knowledge of the Henderson-Hasselbalch equation.