the author of this app says:
The APACHE II - Acute Physiology and Chronic Health Evaluation - score is a general measure of disease severity based on current physiologic measurements during the first 24 hours and previous health conditions. The score can help in the assessment of patients to determine the level and degree of diagnostic and therapeutic intervention. From the APACHE II score and knowledge of primary clinical diagnoses an estimated risk of death in the hospital can be calculated. APACHE2 software allows users to quickly calculate scores in order to classify the disease severity in critically ill patients.