APACHE II Calculator
Assess ICU mortality risk using the Acute Physiology and Chronic Health Evaluation II scoring system
APACHE II Assessment
Critical Care Tool: This calculator is for trained medical professionals in ICU settings only. APACHE II scores should be used alongside clinical judgment for treatment decisions. This tool cannot replace professional medical assessment.
Patient Characteristics
APACHE II is for patients ≥16 years old
NYHA IV, dialysis, cirrhosis, immunocompromised
Clinical judgment required for acute vs chronic classification
Physical Examination
Score from 3 (worst) to 15 (best)
MAP = (SBP + 2×DBP) / 3
Partial pressure of oxygen
Laboratory Test Results
Percentage of RBCs in blood
Normal: 3,000-15,000/μL
Normal: 7.33-7.50
Normal: 3.5-5.5 mmol/L
Normal: 130-150 mmol/L
Normal: 0.6-1.5 mg/dL
APACHE II Score Results
Clinical Recommendation
Maximum intensive care and family discussion
Score Components
High Risk Score - Enhanced Care Needed
This high APACHE II score indicates significant mortality risk. Consider intensive monitoring, aggressive treatment, and family discussions about prognosis and care goals.
Clinical Example
Case: 65-year-old Male ICU Admission
Demographics: Age 65, no organ insufficiency
Vitals: Temp 38.8°C, HR 95, RR 22, MAP 85
Neurologic: GCS 12 (confused)
Respiratory: FiO₂ 40%, PaO₂ 75
Lab Values: Hct 35%, WBC 12,000
Chemistry: pH 7.28, K⁺ 4.2, Na⁺ 138
Renal: Creatinine 1.8 (acute)
APACHE II Calculation
Total Score: 17 (High Risk - ~25% mortality)
Score Interpretation
Low Risk
~5-10% mortality
Standard ICU care
Moderate
~15-25% mortality
Enhanced monitoring
High Risk
~25-40% mortality
Intensive care
Very High
≥40% mortality
Maximum care
APACHE II Components
Patient Characteristics
Age, chronic health, renal failure
Vital Signs
Temperature, MAP, heart rate, respiratory rate
Neurological
Glasgow Coma Scale
Oxygenation
A-a gradient or PaO₂
Laboratory
Hematocrit, WBC, pH, electrolytes, creatinine
ICU Assessment
APACHE II calculated within first 24 hours of ICU admission
Use worst physiological values in 24-hour period
Combine with clinical judgment for treatment decisions
Understanding the APACHE II Scoring System
What is APACHE II?
The Acute Physiology and Chronic Health Evaluation II (APACHE II) is a severity-of-disease classification system developed in 1985. It's one of the most widely used ICU scoring systems worldwide for predicting mortality risk and comparing patient outcomes.
Clinical Applications
- •Mortality risk assessment
- •ICU resource allocation
- •Quality improvement initiatives
- •Research and clinical trials
Scoring System
Score Range: 0-71 points
- • Age: 0-6 points
- • Chronic health: 0-5 points
- • Physiologic variables: 0-60 points
Data Collection
- • First 24 hours of ICU admission
- • Worst physiological values used
- • 12 physiological variables
- • Age and chronic health status
Important Clinical Notes
Limitations:
- • Not validated for certain populations (children, cardiac surgery)
- • May overestimate mortality in some groups
- • Requires experienced ICU staff for accurate data
- • Should not be the sole basis for treatment decisions
Best Practices:
- • Use in conjunction with clinical judgment
- • Calculate within first 24 hours of admission
- • Ensure accurate data collection
- • Consider patient and family preferences