Anaesthesia / Critical Care Emergency Medicine Strong — Crit Care Med 1985

APACHE II Score

Acute Physiology and Chronic Health Evaluation II. 14-parameter score predicting ICU mortality from acute physiology (12 variables), age, and chronic health points. Range 0–71.

Used in: Acute Pancreatitis

Rectal Temperature (°C)*

Mean Arterial Pressure (MAP, mmHg)*

MAP = (SBP + 2 × DBP) / 3

Heart Rate (bpm)*

Respiratory Rate (breaths/min)*

Use spontaneous rate. If ventilated, use set rate.

Oxygenation*

If FiO₂ ≥0.5 (50%): use A-a gradient. If FiO₂ <0.5 (<50%): use PaO₂ (mmHg)

Arterial pH*

Serum Sodium (mmol/L)*

Serum Potassium (mmol/L)*

Serum Creatinine (μmol/L)*

Score is DOUBLED if acute renal failure (ARF) is present. Select the row that matches creatinine AND ARF status.

Haematocrit (%)*

White Cell Count (× 10⁹/L)*

Glasgow Coma Scale (GCS)*

APACHE II contribution = 15 − GCS. Select the patient's current GCS total.

Age (years)*

Chronic Health Points*

Organ insufficiency = hepatic (cirrhosis / portal hypertension), cardiovascular (NYHA IV), respiratory (chronic hypoxia / hypercapnia / pulmonary hypertension), renal (on dialysis), or immunocompromised

Score interpretation

Very Low Risk 0–4

APACHE II 0–4: Minimal physiological derangement. Hospital death rate ~4 % non-operative / ~1 % post-operative (Knaus 1985).

→ Routine ICU monitoring. Standard supportive care. Daily reassessment.

Low Risk 5–9

APACHE II 5–9: Mild physiological derangement. Hospital death rate ~8 % non-operative / ~3 % post-operative (Knaus 1985).

→ Close monitoring. Address reversible causes. Organ support as required. Daily reassessment.

Moderate Risk 10–14

APACHE II 10–14: Moderate physiological derangement. Hospital death rate ~15 % non-operative / ~7 % post-operative (Knaus 1985).

→ Intensified monitoring and intervention. Organ support as needed. Multidisciplinary ICU review.

Moderate-High Risk 15–19

APACHE II 15–19: Significant physiological derangement. Hospital death rate ~24 % non-operative / ~12 % post-operative (Knaus 1985).

→ Active organ support. Vasopressors, mechanical ventilation, and/or renal support as indicated. Senior ICU consultant review.

High Risk 20–24

APACHE II 20–24: Severe physiological derangement. Hospital death rate ~40 % non-operative / ~30 % post-operative (Knaus 1985).

→ Aggressive resuscitation and multi-organ support. Consider escalation or limitation of treatment discussions. Goals of care documentation.

Very High Risk 25–29

APACHE II 25–29: Very severe derangement. Hospital death rate ~55 % non-operative / ~35 % post-operative (Knaus 1985).

→ Maximum organ support. Goals of care discussion with patient and family. Early palliative care involvement if appropriate. DNACPR consideration.

Critical — High Mortality 30–71

APACHE II ≥30: Critical illness. Hospital death rate ~73 % at 30–34; 85 % non-operative / 88 % post-operative at 35 or more (Knaus 1985).

→ Discuss treatment futility. Intensive goals of care discussion with family. Document DNACPR and ceiling of treatment decisions. Specialist ethics consultation if needed.

Interpretation bands for the APACHE II. Apply clinical judgement and local guidance.

References

Knaus WA et al. APACHE II: A severity of disease classification system. Crit Care Med. 1985;13(10):818–829.

Curated clinical cross-links plus same-class fallbacks.

Calculators

Drugs

Pathways

Decision support only — verify against a current formulary, NICE, or your local guideline before clinical use.

Score interpretation

References

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