🏥 APACHE II Critical Illness Score
UseUse within 24 h of ICU admission, taking the worst physiologic values, to benchmark severity and estimate gro…
StrataHigher totals correspond to higher group in-hospital mortality; use for severity benchmarking, not individual…
LimitsPopulation calibration — do not use alone to withdraw care for one pa… · Mixing time windows or incomplete chronic-health data distorts predic… · Superseded locally by APACHE IV/SAPSH in some ICUs; know which model …
SourceKnaus WA, et al. APACHE II. Crit Care Med 1985.
This-shift next steps
After scoring: open the scene pack, peer scores, and the matching pathway. Local reference — no HIS write.
Paste the link in Slack, Teams, X, or LinkedIn — the preview image comes from this page’s Open Graph card.
Methodology · worked example, guidelines & full notes
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).
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
Worked calculation
The values below come from this tool's own example placeholders and are computed server-side with the formula shown on this page, so the arithmetic can be checked quickly. It demonstrates how to substitute values only — it is not clinical advice and not a real case.
| Temperature (core) | 37 ℃ |
|---|---|
| Mean arterial pressure MAP | 90 mmHg |
| Heart rate | 90 bpm |
| Respiratory rate | 18 /min |
| FiO₂ | < 0.5 (enter PaO₂) |
| Oxygenation: PaO₂ or A-aDO₂ | 80 mmHg |
| Arterial pH | 7.40 |
| Sodium | 140 mmol/L |
| Potassium | 4.0 mmol/L |
| Serum creatinine Scr | 80 μmol/L |
| Acute renal failure (creatinine points doubled) | Yes |
| Hematocrit Hct | 40 % |
| White blood cells | 10 ×10⁹/L |
| GCS | 3 |
| Age | 60 yr |
| Chronic health (organ failure/immunocompromise) | Yes · nonoperative or emergency postoperative (+5) |
→APACHE II20pts
- Acute Physiology Score (APS)：12
- Age points：3
- Chronic-health points：5
| Temperature (core) | 37 ℃ |
|---|---|
| Mean arterial pressure MAP | 90 mmHg |
| Heart rate | 90 bpm |
| Respiratory rate | 18 /min |
| FiO₂ | < 0.5 (enter PaO₂) |
| Oxygenation: PaO₂ or A-aDO₂ | 80 mmHg |
| Arterial pH | 7.40 |
| Sodium | 140 mmol/L |
| Potassium | 4.0 mmol/L |
| Serum creatinine Scr | 80 μmol/L |
| Acute renal failure (creatinine points doubled) | Yes |
| Hematocrit Hct | 40 % |
| White blood cells | 10 ×10⁹/L |
| GCS | 3 |
| Age | 60 yr |
| Chronic health (organ failure/immunocompromise) | None |
→APACHE II15pts
- Acute Physiology Score (APS)：12
- Age points：3
- In-hospital mortality (approx.)：~25%
Verification & sources · governance
FAQ
Frequently asked questions
- Does APACHE II Critical Illness Score upload patient data? Where is it calculated?
- Calculation runs locally in the browser; inputs and results are not uploaded. For licensed clinicians only; interpret with history, investigations and local protocols — not a diagnosis or prescription.
- How is APACHE II Critical Illness Score calculated in practice? Can you show a worked example?
- Inputs: Temperature (core) 37 ℃, Mean arterial pressure MAP 90 mmHg, Heart rate 90 bpm, Respiratory rate 18 /min, FiO₂ < 0.5 (enter PaO₂), Oxygenation: PaO₂ or A-aDO₂ 80 mmHg, Arterial pH 7.40, Sodium 140 mmol/L… → Result: APACHE II 20 pts（Acute Physiology Score (APS): 12, Age points: 3, Chronic-health points: 5） Inputs: Temperature (core) 37 ℃, Mean arterial pressure MAP 90 mmHg, Heart rate 90 bpm, Respiratory rate 18 /min, FiO₂ < 0.5 (enter PaO₂), Oxygenation: PaO₂ or A-aDO₂ 80 mmHg, Arterial pH 7.40, Sodium 140 mmol/L… → Result: APACHE II 15 pts（Acute Physiology Score (APS): 12, Age points: 3, In-hospital mortality (approx.): ~25%）