Standards message here
Calculate the serum bicarbonate from the serum pH and pCO2.
The calculations above are based on the Henderson-Hasselbalch equation:
|pH = pK + log||[HCO3-]|
Replacing pK = 6.1, and [CO2] = 0.03 * pCO2, and removing the logarithms to get
HCO3 = 0.03 * pCO2 * 10 (pH - 6.1)
In conjunction with the Siggaard-Anderson equation:
B.E. = 0.9287 (HCO3 - 24.4 + 14.83 (pH - 7.4))
B.E. = 0.9287 * HCO3 + 13.77 * pH - 124.58
The end result is:
B.E. = 0.02786 * pCO2 * 10 (pH - 6.1) + 13.77 * pH - 124.58
See further the great online tutorial on Acid-Base Balance by Dr. Alan W. Grogono, MB, BS, MD, FRCA. Retired Professor and former Chair, Department of Anesthesiology, Tulane University School of Medicine.
Siggaard-Andersen O. An acid-base chart for arterial blood with normal and pathophysiological reference areas. Scan J Clin Lab Invest. 27:239-245, 1971.
Revised: January 3, 2001