ToolsCalculators
APACHE II score
ICU severity-of-disease classification and mortality estimate.
APACHE II score
Age
years
Temperature (core)
°C
Mean arterial pressure
mmHg
Heart rate
bpm
Respiratory rate
/min
FiO2 (fraction)
0.21–1.0
PaO2
mmHg
PaCO2 (for A-a gradient if FiO2 ≥0.5)
mmHg
Arterial pH
pH
Serum sodium
mmol/L
Serum potassium
mmol/L
Serum creatinine
mg/dL
Acute renal failure (doubles creatinine points)
Haematocrit
%
White blood cell count
×10³/mm³
Glasgow Coma Scale
3–15
Chronic health / operative status
Severe organ insufficiency or immunocompromise.
Complete the fields above to see the result.
When to use
- Severity stratification and mortality estimation within 24 h of ICU admission.
Formula
APACHE II = acute physiology score (12 variables, each 0–4) + age points (0–6) + chronic health points (0–5). Range 0–71. Oxygenation uses A-aDO2 when FiO2 ≥0.5, otherwise PaO2.
Pearls and pitfalls
- Use the worst value recorded in the first 24 ICU hours.
- Creatinine points double in acute renal failure.