Calculator Inputs
Enter the worst values measured in the first 24 hours. Choose one oxygenation pathway only. Leave unused oxygenation fields blank.
Example Data Table
These sample rows are for illustration and training only.
| Case | Age | Temp | MAP | HR | RR | Oxygen Path | pH | Na | K | Cr | Hct | WBC | GCS | Chronic | Total |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Case A | 35 | 37.0 | 82 | 96 | 20 | PaO2 82 | 7.40 | 140 | 4.1 | 0.9 | 38 | 8.0 | 15 | None | 0 |
| Case B | 67 | 39.2 | 65 | 128 | 28 | PaO2 68 | 7.30 | 148 | 3.2 | 1.8 | 32 | 18.0 | 11 | Severe / Nonoperative | 29 |
| Case C | 78 | 34.8 | 45 | 182 | 40 | A-aDO2 420 | 7.18 | 121 | 6.2 | 3.8 + ARF | 27 | 0.9 | 7 | Severe / Emergency postop | 56 |
Formula Used
APACHE II Total = Acute Physiology Score + Age Points + Chronic Health Points
Acute Physiology Score = sum of 12 variable scores using the worst value recorded during the first 24 hours.
GCS contribution = 15 − actual Glasgow Coma Scale.
Oxygenation branch uses A-aDO2 when FiO2 is 0.50 or higher, PaO2 when FiO2 is below 0.50, and serum bicarbonate only when no arterial blood gas is available.
Creatinine adjustment doubles creatinine points when acute renal failure is present.
How to Use This Calculator
- Collect the worst physiologic values from the first ICU day.
- Enter age, vital signs, laboratory values, and actual GCS.
- Select the correct oxygenation pathway for the available data.
- Mark acute renal failure if creatinine points should be doubled.
- Select chronic health status and the correct admission type.
- Press the calculate button to show the score above the form.
- Review the component table, graph, and interpretation message.
- Use the CSV or PDF buttons to save the calculation output.
Frequently Asked Questions
1. What does APACHE II measure?
It summarizes acute physiologic disturbance, age effect, and chronic health burden into one ICU severity score. Higher values generally reflect greater physiologic derangement and greater concern.
2. Which values should I enter?
Enter the worst values recorded during the first 24 hours in ICU. The score is designed around the most abnormal measurements, not average values.
3. Why are there different oxygenation options?
APACHE II switches oxygenation scoring by the data available. Use PaO2 for lower FiO2 settings, A-aDO2 for higher FiO2 settings, or bicarbonate only when no arterial blood gas exists.
4. Why is GCS entered as the actual score?
The calculator converts it automatically. APACHE II uses 15 minus the observed GCS, so a lower GCS adds more points to the acute physiology score.
5. Why can creatinine points double?
When acute renal failure is present, the creatinine component is weighted more heavily. This can materially increase the acute physiology score.
6. Does the total score equal a diagnosis?
No. It is a severity classification aid. It should be interpreted alongside examination findings, diagnoses, imaging, treatment response, and ICU context.
7. Can I use this as the only clinical decision tool?
No. The score supports structured assessment, but it should never replace clinician judgment, protocols, or direct patient evaluation.
8. What do the download buttons save?
They save the component table and totals after calculation. CSV works well for spreadsheets, while PDF is useful for documentation and sharing.