Skip to main content

Table 3 acid–base patterns observed in humans

From: Clinical review: Reunification of acid–base physiology

Disorder

HCO3- (mEq/l)

PCO2 (mmHg)

SBE (mEq/l)

Metabolic acidosis

<22

= (1.5 × HCO3-) + 8 = 40 + SBE

<-5

Metabolic alkalosis

>26

= (0.7 × HCO3-) + 21 = 40 + (0.6 × SBE)

>+5

Acute respiratory acidosis

= ([PCO2 - 40]/10) + 24

>45

= 0

Chronic respiratory acidosis

= ([PCO2 - 40]/3) + 24

>45

= 0.4 × (PCO2 - 40)

Acute respiratory alkalosis

= 24 - ([40 - PCO2]/5)

<35

= 0

Chronic respiratory alkalosis

= 24 - ([40 - PCO2]/2)

<35

= 0.4 × (PCO2 - 40)

  1. Adapted with permission from Kellum [7]. PCO2, partial carbon dioxide tension; SBE, standard base excess.
Back to article page

Critical Care

ISSN: 1364-8535