APACHE II Calculator
Calculate APACHE II severity score from physiology, labs, and chronic health points for ICU patients.
What Is APACHE II?
APACHE II (Acute Physiology and Chronic Health Evaluation II) is a severity-of-illness score used in intensive care within the first 24 hours of admission. It combines age, chronic health status, vital signs, Glasgow Coma Scale, oxygenation, and laboratory values into a single score that can estimate hospital mortality risk.
How Scoring Works
Each physiologic variable is assigned points using standard APACHE II tables. Glasgow Coma Scale contributes 15 − GCS points. When FiO₂ is 50% or higher, oxygenation is scored with the A-a gradient; below 50%, PaO₂ is used instead. Acute renal failure doubles creatinine points. Chronic health adds 0, 2, or 5 points depending on operative status.
Mortality Estimation
Estimated hospital mortality uses the original APACHE II logistic model, adjusted for operative status: nonoperative and emergency postoperative patients use one intercept, elective postoperative patients use a lower intercept, reflecting different baseline risk.
Frequently Asked Questions
When should I use PaO₂ vs. A-a gradient?
Use PaO₂ when FiO₂ is below 50%. Use the A-a gradient when FiO₂ is 50% or above, per standard APACHE II rules.
How are GCS points calculated?
GCS points equal 15 minus the Glasgow Coma Scale score. A GCS of 15 adds 0 points; a GCS of 3 adds 12 points.
What does acute renal failure do to creatinine scoring?
Acute renal failure doubles the creatinine points from the standard table. Chronic renal failure uses the standard creatinine table without doubling.
Can WBC be entered in thousands?
Yes. Choose × 1,000 / mm³ or enter the absolute count per mm³. The calculator converts to the correct scale for scoring.
Is this for clinical decision-making?
No. This is an educational calculator. Always use validated institutional tools and clinical judgment for patient care.
Related Tools
Tetrahedron Calculator
Language Detector
Fraction Simplifier
Extra Spaces Remover
JSON to One Line
Coffee Kick Calculator
Lean Body Mass to Strength Calculator
Dog Age To Human Years Converter
Binary String Converter
Checksum Calculator
Basic Auth Generator
Blood Volume Calculator
Sin Calculator
House Cleaning Cost Calculator
JSON To BigQuery Schema
LRINEC Score Calculator
Gravitational Acceleration Calculator
Average Rate of Change Calculator
JSON To JSDoc
Sierpinski Sieve Generator