ICU Calculators-RNSH
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APACHE means Acute Physiology And Chronic Health Evaluation. The APACHE II score was published in 1985 ; APACHE IV is the latest version, published in 2006. Built on the study of a more recent patient population and standard of care, it has now become the recommended score to be used instead of APACHE II and III.

APACHE scores are probably the most widely used in Intensive care, to quantify the severity of the illness of the patients. They represent a usefull tool to compare populations of patients, in clinical studies, or in quality audit.

Like APACHE II, APACHE IV provides the basis for the calculation of an estimated risk of death. Also provides an estimation of the length of stay.

From APACHE II to APACHE IV, the scoring system has been complexified, taking into account a greater number of variable (and extracting scores from several variable in a slightly different way), and making reference to a large database of coefficient individualized for an increased number of disease, for the calculation of the risk of death and length of stay.
APACHE III and IV are very similar, using the same variables. Only the disease-specific coefficients have been updated.

The APS score in the Acute Physiology Score, which is the part of the score calculated without taking into account patient's age and Chronic Health Condition details.

- Step 1 : fill out the form in column 1, by entering patient's values. The worst value obtained during the first 24h must be used.
If the patient has been intubated / ventilated at any time during the first 24h, "Yes" facing "Mecanical ventilation" should be ticked.
The appropriate situation must then be selected in the drop-down menus : FiO2 > 50%, or FiO2 < 50%. The software will calculate the Alveolo-arterial gradient, using 0.8 as a Respiratory Quotient, and 760 mmHg for the Atmopheric pressure. Those default values can be changed by clicking on "Change the value for AaDO2" at the bottom of the page.
The GCS score must be completed if possible : if it can not be properly assessed (patient paralysed or on sedation), then the "Not available" box shoul be ticked. This box should not be used in case of intubation alone ; an estimation of the Verbal response should be hypotethized instead.

- Step 2 : Details of the Chronic Health Condition must be provided in the right column, by ticking the appropriate boxes.

- Step 3 : Details on the Admission conditions must then be filled out, by entering the length of stay prior to ICU admission, the origin of the patient (selection inside the drop-down menu), and wether it's the patient's first admission (readmission or not), and if the admission is requested after an emergency surgical procedure.

- Step 4 : The admission diagnosis (the current diagnosis, for which the patient required intensive care) must then be completed : first select the correct situation, postoperative or medical situation. Then select in the first drop-down menu the system affected (by the primary diagnosis), and select in the second drop-down menu the most appropriate admission diagnosis.
In case of acute myocardial infarction, choice is given to tick wether the patient was thrombolysed or not.

- Step 5 : click "Calculate" button to obtain APACHE and APS score, and corresponding estimated mortality rate.





Chronic Health Condition :
CRF / HD Lymphoma
Leukemia / Myeloma
Hepatic Failure Immunosuppression
Metastatic Carcinoma AIDS

Admission Information :
Pre-ICU LOS (days)
Readmission No Yes
Emergency Surgery

Admission Diagnosis :
Non operative Postoperative
Thrombolysis : No Yes


APS Score
Estimated Mortality Rate %
Estimated Length of Stay
Values used for AaDO2 calculation :  
Respiratory Quotient
Atmospheric Pressure (mmHg)
Age (ans)
Temperature (°C)
MAP (mmHg)
HR (/min)
RR (/min)
No Yes
FiO2 (%)
pO2 (mmHg)
pCO2 (mmHg)
Na+ (mEq/L)
Urine Output (mL/24h)
Creatinine (mg/dL)
Urea (mEq/L)
BSL (mg/dL)
Albumin (g/L)
Bilirubin (mg/dL)
Ht (%)
WBC (x1000/mm3)
GCS : Not available
- Eyes
- Verbal
- Motor

Change values used for AaDO2 calculation