Table 1

Observational acid–base patterns

Disorder
HCO3- (mmol/l)
pCO2 (mmHg)
SBE (mmol/I)

Metabolic acidosis
<22
= (1.5 × HCO3-) + 8
<-5


= 40 + SBE

Metabolic alkalosis
>26
= (0.7 × HCO3-) + 21
>+5


= 40 + (0.6 × SBE)

Acute respiratory acidosis
= [(pCO2 – 40)/10] + 24
>45
= 0
Chronic respiratory acidosis
= [(pCO2 – 40)/3] + 24
>45
= 0.4 × (pCO2 – 40)
Acute respiratory alkalosis
= [(40 – pCO2)/5] + 24
<35
= 0
Chronic respiratory alkalosis
= [(40 – pCO2)/2] + 24
<35
= 0.4 × (pCO2 – 40)

Compiled from various sources. The changes in SBE were taken fromSchlichtig et al [7]. pCO2, partialcarbon dioxide tension; SBE, standard base excess.

Kellum Critical Care 2000 4:6   doi:10.1186/cc644