APACHE II Background

APACHE stands for Acute Physiological and Chronic Health Evaluation APACHE II on the Wikipedia

Who was it developed by

A conceptual model for the APACHE prognostic scoring system was formulated in 1979 and introduced in 1981 by by Dr. William A. Knaus et.al. George Washington University Medical Center. APACHE was validate in many centers since then and shown to be a strong and stable predictor of hospital survival.

• APACHE II was developed in 1985.
• APACHE III was developed in 1991.

Purpose

Designed to be a objective and quantitative measure of the severity of illness of acutely ill patient in ICU. The severity of disease classification system also assists in the ability to prognosticate outcome or evaluate the impact of subsequent care in ICU. APACHE scores can help identify those patient that would or would not benefit from ICU admission and treatment.

What are the components

• APS— The Acute Physiology Score captures acute severity of illness. (max score = 60). 12 physiological variables from one or more of the body’s seven major vital physiologic systems:
  • neurological (Glasgow Coma Scale)
  • cardiovascular
  • respiratory
  • gastrointestinal
  • renal
  • metabolic
  • hematologic
• Age group (max score = 6)
• History of a underlying Chronic Health condition reflecting diminished physiologic reserve (max score = 5).

Max Total Apache Score = 71

Weighting of scores

• Each physiological variable selected has been weighted with a score ranging from 0-4 points to reflect severity.
• Physiological variables with the worst deviation from normal have been assigned the higher points.
• Note about renal scoring (see also ARF_(APACHE)):
  • The point scores for serum creatinine are doubled if ARF_(APACHE) is checked (which would be if Kidney, acute renal failure NOS is present). Note that even relatively small rises in serum creatinine are associated with higher rates of death for ICU patients, as indicated in Small Acute Increases in Serum Creatinine Are Associated with Decreased Long-Term Survival in the Critically Ill
• See APACHE Scoring table for details

Timing of collection

Deviation in physiologic variables are selected during a patients' first 24 hours while "in the ICU". The clock start at the actual Arrive DtTm, (Admit date and time) into the ICU.

How were these Variables Selected

Knaus and his team, which included a panel of 7 experienced ICU physicians from major centers and specialies, reviewed literature for measurements that had demonstrated promise in estimating severity of illness and that were generally tested and recorded in most ICU’s. The weighted score that the panel assigned to particular physiologic values was based on the fact that the more deviated from normal the value was, the more concern and by inference, the more severly ill a patient is.

References

• Knaus WA, Zimmerman JE, Wagner DP, Draper EA, Lawrence DE. APACHE - Acute Physiology and Chronic Health Evaluation: A physiologically based classification system. Critical Care Medicine, Vol 9: 591-597, 1981.

• Knaus WA, Draper EA, Wagner DP, Zimmerman JE, Birnbunm, ML, Cullen DJ, Kohles MK, Baedhyo S, Snyder JV: Evaluating Outcome from Intensive Care: A preliminary multihospital comparison. Critical Care Medicine, Vol 10: 491-496, 1982.

• Knaus WA, Draper EA, Wagner DP, Zimmerman JE. APACHE II: A severity of disease classification system. Critical Care Medicine 1985; 13818-29.

• Knaus WA, Draper EA, Wagner DP, Zimmerman JE. An Evaluation of Outcome from the Intensive Care in Major Medical Centers. Annuals of Internal Medicine, Vol 104: No 3: 410-418, 1986.