The Acute Physiology and Chronic Health Evaluation (APACHE) score is an illness severity score commonly used in critical care medicine to predict mortality upon admission to an intensive care unit. 

Usage

Although designed to calculate mortality in an intensive care unit, the APACHE score has a high sensitivity for predicting complications of acute pancreatitis, such as pancreatic necrosis and organ failure ³.The fourth iteration - APACHE IV - was published in 2006 ⁴; however, the APACHE II score is still frequently used (c. 2023) ⁵.

Classification

APACHE II

It involves two sections - one assessing the severity of the acute illness and another assessing a patient's pre-illness chronic medical status. The worst values the patient achieves in the first 24 hours of admission to the intensive care unit should be used ².

The following criteria are used in the calculation of the APACHE II score ²:

• past history of organ failure or immunocompromised state (e.g. NYHA Class IV heart failure, cirrhosis, CKD requiring dialysis)

• acute kidney injury

• age

• temperature

• mean arterial pressure

• blood pH

• heart rate

• respiratory rate

• sodium

• potassium

• creatinine

• hematocrit

• white blood cell count

• Glasgow Coma Scale

• blood oxygenation

  • A-a gradient (if FiO₂ is greater than or equal to 0.5)

  • PaO₂ (if FiO₂ is less than 0.5)

History and etymology

The APACHE score was first developed in 1981 by the American intensivist William Knaus and his colleagues ¹. It was revised in 1985 to become the APACHE II score ².