Is there compensation?

ΔAG

ΔHCO₃

ACIDOSIS

Met or Resp ?

Resp Alkalosis

pH

ALKALOSIS

Met or Resp ?

​

Alkalosis

Acidosis

Respiratory

Acidosis

Metabolic

Acidosis

↓HC03

Metabolic

Alkalosis

↑ Hc03

Is the anion gap increased?***

AG = [Na] - ([Cl] + [HCO₃]) =12 +/- 2

correct if albumin low

(4-albumin level) x 2.5 + AG= corrected AG

If there is a metabolic acidosis

1. Expected pCO₂ = 1.5 x [HCO3] + 8 ± 2 (Winter’s)
2. If there is met alkalosis ,for every ↑1 meq/L Hc03 Expected P C02 ↑ by 0.7

If there is a mixed process ?

YES

>7.4

<7.4

• ventilation

(multiple reasons,

PNA/CNS etc.)

​

IF YES

Methanol

Uremia

DKA

Paraldehyde

Isoniazid/Iron /IIEM

Lactic acidosis

Ethanol/Ethylene glycol

Salicylates

What’s the primary

disturbance?

NO

🡹ΔΔ >2

🡻ΔΔ < 1

superimposed

metabolic alkalosis or resp acidosis

superimposed

NAGMA

No other derangement

IF NO

RTA ( will have + urine AG)

Diamox

GI loss

Hyperchloremia

acid base analysis

Does ΔHCO₃ ≈ ΔAG?

NB **** always check for AG even if PH ok as may uncover secondary metabolic acidosis

If there is respiratory acidosis

Acute : for every 10 C02 ,↑Hc03 by 1

Chronic: every 10 ↑ C02 Hc03 ↑ 4

↑ C02

↓ C02

Pain/anxiety

CNS injury

Salicylates

​

Δ AG = (calc AG-12 ΔHc03 = 24-measured Hc03

Vomiting

Diuretics

Excessive antacids

Barters (also see hypokalemia)