🏥 APACHE II Critical Illness Score
APACHE II, an ICU severity-of-illness score combining acute physiology, age, and chronic health to estimate in-hospital mortality.
APACHE II Critical Illness Score
Temperature (core) (℃)
Mean arterial pressure MAP (mmHg)
Heart rate (bpm)
Respiratory rate (/min)
FiO₂
Oxygenation: PaO₂ or A-aDO₂ (mmHg)
Arterial pH
Sodium (mmol/L)
Potassium (mmol/L)
Serum creatinine Scr (μmol/L)
Acute renal failure (creatinine points doubled)
Hematocrit Hct (%)
White blood cells (×10⁹/L)
GCS
Age (yr)
Chronic health (organ failure/immunocompromise)
When to use
Use within 24 h of ICU admission, taking the worst physiologic values, to benchmark severity and estimate group mortality risk.
How it works
Acute Physiology Score (12 items) + age points + chronic-health points (0–71); rising totals map to higher predicted mortality (e.g. 0–4 ~4%, 15–19 ~25%, 25–29 ~55%, > 34 ~85%).
Key points
- APACHE II is a population benchmark, not an individual outcome predictor — never use it to decide a single patient's prognosis (original synthesis · not guideline verbatim).
- Use the worst value within the first 24 h for each variable; mixing time points distorts the score.
- The creatinine points double in acute renal failure, reflecting the added severity of AKI.
References
- Knaus WA, et al. APACHE II. Crit Care Med 1985.
- Vincent JL, Moreno R. Scoring systems in the critically ill. Crit Care 2010.
Decision support for licensed clinicians only; not a substitute for clinical judgement, diagnosis or local protocols.