An Acid-Base Chart for Arterial Blood with Normal and Pathophysiological Reference Areas

Abstract

A pH-log (PCO₂) chart is described, with indications of the normal values for the acid-base status of the blood as well as the values to be expected in different types of acid-base disturbances, including acute and chronic hypercapnia, acute and chronic hypocapnia, acute and chronic base deficit, and chronic base excess. The scales allow conversion of pH to hydrogen ion concentration (10^−pH) and conversion of mm Hg to the recommended unit for pressure, kilo pascal. The chart allows estimation of the base excess or deficit of the extracellular fluid as well as the hydrogen carbonate concentration of the plasma. An example of the advantage of plotting the pH and PCO₂ values in the chart is given.

Key Words:

• Acid-base equilibrium
• acidosis
• alkalosis
• bicarbonate
• carbon dioxide
• hydrogen ion concentration