Alan W.
Grogono, M.D.Alan W.
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The maintenance of a stable acid base balance is a vital component of the body's homeostasis. Over one hundred diagrams, nomograms, equations, and sets of rules have been introduced to represent acid base balance. Far from solving a problem, this diversity has probably contributed to it because so many new terms and definitions have been introduced.
Many people experience difficulty understanding Acid-Base balance.
Much of this stems from unfamiliarity with the words and terminology
employed. If we have a poor understanding of the common terms, such
as neutral, pH, metabolic acidosis, base excess, etc., then it is not
surprising that we also have difficulty understanding the concepts,
patterns, and syndromes being described.
Review the Common Acid-Base Terms and
Definitions
Carbonic acid (H2CO3) is central to our
understanding and evaluation of acid-base disturbances. The
dissociation products and the ionization products are normally in
equilibrium. Understanding this relationship was the starting point
for Hendersen and, later, for his collaboration with Hasselbach.
Go to the Section on: Physiology of
Acid-Base Balance
Our understanding of acid-base balance depends on numerous underlying inventions, discoveries and theories. Blood gas analysis is frequently used; this is partly because it is now convenient, and partly because of the growth in our knowledge and understanding of acid base physiology.
The history has been summarized in a series of review-essays by two of the best known investigators in this fascinating and complex field, John Severinghaus and Poul Astrup (1985, 1986). Some of the critical events and participants that they mention are summarized in the historical summary which serves several purposes: the time required for ideas and equipment to reach their present state is evident; the names of the more prominent investigators are recorded; some of the many attempts to measure metabolic disturbances are mentioned; and the controversy which surrounded the introduction of "base excess" is described.
Interest in acid base balance stems from its physiologic
importance, from fascination in a subject which has exercised and
challenged scientific interest during the last century, and from the
requirement to set and pass examinations
Refresh your memory of the History of
Acid-Base Balance.
Some of us are primarily visual learners and obtain the greatest
benefit from visual aids (diagrams, maps, and pictures); others find
non-visual representations (equations, sounds, and words) to be more
useful. The two representations described illustrate approaches which
facilitate understanding in education and clinical practice: the
first is graphical and precise; the second relies on simple equations
and provides a good approximation to blood-gas reports :
Look at the Diagrams of In-Vivo Acid-Base
Balance. Learn the Simple Equation
representing Acid-Base Balance.
When Treating Acid-Base Disturbances, there are a number of factors to be considered, including the clinical indications for therapy. Several authors have made use of the Anion Gap to assist in determining the source of a metabolic disturbance. In some clinical situations, acid-base disturbances have to be analyzed when a patient has an abnormal temperature and the Effects of temperature have to be recognized and understood. Some of our text-books and papers now employ Kilopascals for PCO2 partial pressures. Finally, acid-base disturbances have a number of Clinical implications which should be recognized and understood.
Introduction | Definitions | Physiology | History | Diagrams | Equations | Practical | References | Author