The Voice of Reason

Acid-base disorders are commonly encountered in medicine. It is therefore important for the practitioner to know how to accurately interpret acid-base information as obtained from arterial blood gases, serum chemistries, urine electrolytes, and other sources. The below table can be used to quickly evaluate acid-base disorders.

[table caption=”Acid-Base Analysis” width=”677″ colwidth=”75|75|75|223|223″ colalign=”center|center|center|center|center”]
Primary Disorder,Initial Chemical Change,Compensatory Response,Compensatory Mechanism,Compensation
Metabolic Acidosis,↓HCO3-,↓PCO2,Hyperventilation,PCO2 = [1.5(HCO3) + 8] +/- 2 (Winter’s Formula)
Metabolic Alkalosis,↑HCO3,↑PCO2,Hypoventilation,↑PCO2 = 0.7 x ΔHCO3-
Respiratory Acidosis,↑PCO2,↑HCO3, ,
Acute, ,Intracellular Buffering (hemoglobin/intracellular proteins),Intracellular Buffering (hemoglobin/intracellular proteins),↑[HCO3-] = 1 mEq/L for every 10 mm Hg ΔPCO2
Chronic, ,Generation of new HCO3- due to increased excretion of ammonium,Generation of new HCO3- due to increased excretion of ammonium,↑[HCO3-] = 3.5 mEq/L for every 10 mm Hg ΔPCO2
Respiratory Alkalosis,↓PCO2,↓HCO3-, ,
Acute, ,Intracellular Buffering,Intracellular Buffering,↓[HCO3-] = 2 mEq/L for every 10 mm Hg ΔPCO2
Chronic, ,Intracellular Buffering,Intracellular Buffering,↓[HCO3-] = 4 mEq/L for every 10 mm Hg ΔPCO2
[/table]

See also:

[PMID]14569318[/PMID]

Filed under: EBM, Endocrinology, Primary Care Topics, Survival Guides | Tagged: abg, acid-base, acidosis, alkalosis |