Critical Care

APACHE II Score

Acute Physiology and Chronic Health Evaluation II — ICU mortality prediction from 12 physiological variables.

When to use: Calculated within 24 hours of ICU admission to estimate hospital mortality risk. Used for ICU benchmarking, clinical trials, and severity stratification. Higher scores correlate with increasing mortality.

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Temperature

Mean Arterial Pressure

Heart Rate

Respiratory Rate

Oxygenation (PaO₂/FiO₂ or A-aDO₂)

Arterial pH

Serum Sodium

Serum Potassium

Creatinine

Hematocrit

WBC

GCS Points (15 − GCS score)Enter 15 minus actual GCS (e.g., GCS 11 → enter 4)

Age

Chronic Health Points

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Formula

APACHE II = APS (12 variables, 0–4 pts each) + Age points (0–6) + Chronic health points (0–5) Max score = 71. GCS contribution = 15 − actual GCS.

Key Points for NEET PG

APACHE II developed in 1985; APACHE II score >25 associated with very high ICU mortality
Unlike SOFA (organ-specific), APACHE II uses raw physiological values — more complex to calculate
Chronic health criteria: severe organ insufficiency or immunocompromised state adds 2 pts (elective) or 5 pts (emergency/non-op)
APACHE II commonly used in clinical trial eligibility criteria for ICU studies
SAPS (Simplified Acute Physiology Score) is the European equivalent of APACHE II

References

APACHE II: a severity of disease classification system · Critical Care Medicine (1985)

For educational purposes only. Not for clinical decision-making without professional oversight.