APACHE II Calculator

Written by Great Medico

Updated September 24, 2026 •2 min read

Share Print Save

In acute care, a score can support a rapid shared language, but it cannot replace the patient in front of you. APACHE II Calculator calculates the specific bedside score or index from the fields shown in this tool.

What this calculator does

APACHE II Calculator uses Age, Severe organ insufficiency / immunocompromised, Acute renal failure, Rectal temperature, GCS, Mean arterial pressure, and the remaining displayed fields to produce the apache ii score used by this calculator. It only uses the fields shown in this calculator; it does not silently add tests, diagnoses, symptoms, or clinical variables that are absent from the interface. Rebuilt to the current APACHE II patient-characteristics, vital-sign, oxygenation, hematology and chemistry flow with standard point tables.

How to use it

Enter or select Age, Severe organ insufficiency / immunocompromised, Acute renal failure, Rectal temperature, GCS, and the remaining displayed fields. Use the actual observations or labs from the assessment time point intended by the score. If an input is unknown, it is better to leave the calculation unresolved than to invent a value.

How the calculation works

APACHE II converts acute physiologic values to points for temperature, mean arterial pressure, heart rate, respiratory rate, oxygenation, pH, sodium, potassium, creatinine, hematocrit, WBC, and GCS. It then adds age points and chronic-health points; the creatinine contribution is doubled when acute renal failure is selected.

Example

Using the calculator’s prefilled demonstration values, the primary output is 2 points, labeled “APACHE II score”; Acute physiology is 0 and Age points is 2. That sample is useful for checking the calculation path, but real interpretation should use verified measurements from the same clinical or study context.

How to interpret the result

Read apache ii score as a structured snapshot of the entered data. The score can support communication or risk stratification, but deterioration, resuscitation needs, clinical gestalt, and diagnoses not represented in the variables can override the numeric category.

Limitations and notes

APACHE II is an ICU severity-of-illness score developed for groups, not a bedside prediction of what will happen to one patient. Timing of data collection, diagnostic category, treatments, and calibration in the local ICU population affect interpretation.