Metabolic Acidosis: Test and Diagnosis

Acid-base status

  • PH ↓
  • Bicarbonate (HCO3-) current ↓
  • Bicarbonate standard ↓
  • Blood carbon dioxide partial pressure (pCO2) – normal [decreased after partial compensation by hyperventilation [hypocapnia)].
  • Base excess (base excess) ↓

BasenexcessThe negative base deviation marks an increased need for bases.

Other possible examinations

Other possible examinations

  • Blood oxygen partial pressure (pO2) – unchanged.
  • Oxygen saturation (SpO2)
Acidoses and alkaloses
Acidosis Alkalosis
metabolic respiratory metabolic respiratory
comp. decomp. comp. decomp. comp. decomp. comp. decomp.
pH normal < 7,36 normal < 7,36 normal > 7,44 normal > 7,44
HCO3- normal to (↑) normal to (↓)
pCO2 normal to (↓) normal to (↑)
pO2

Legend

  • Comp. (= compensated)
  • Decomp. (= decompensated)
  • ↓ (= decreased), ↑ (= increased), → (= unchanged).

Compensation

The body tries to compensate for the metabolic – metabolic disorder – acidosis respiratory, that is, by increasing breathing (hyperventilation). In particularly acute cases, this leads to so-called Kussmaul respiration. This increased breathing leads to increased exhalation of CO2 from the lungs, with a simultaneous increase in blood pH. However, this compensatory mechanism is limited, so that usually there is not a sufficient decrease in pH, bicarbonate, and pCO2.