Pathophysiology
Clinical meaning
The Sequential Organ Failure Assessment (SOFA) score and Acute Physiology and Chronic Health Evaluation II (APACHE II) score are validated clinical scoring systems used in critical care to quantify illness severity, predict mortality, guide treatment intensity, and facilitate clinical communication. The SOFA score evaluates six organ systems โ respiratory (PaO2/FiO2 ratio), coagulation (platelet count), hepatic (bilirubin), cardiovascular (mean arterial pressure and vasopressor requirements), central nervous system (Glasgow Coma Scale), and renal (creatinine or urine output) โ each scored 0โ4 for a maximum score of 24. In the Sepsis-3 definition, an acute increase in SOFA score โฅ 2 from baseline defines organ dysfunction attributable to sepsis, with associated mortality increasing from 10% (SOFA 0โ6) to > 50% (SOFA โฅ 15). The qSOFA (quick SOFA) serves as a bedside screening tool outside the ICU: altered mental status (GCS < 15), systolic blood pressure โค 100 mmHg, and respiratory rate โฅ 22 breaths/minute โ 2 or more positive criteria prompt full SOFA assessment and sepsis evaluation. APACHE II uses 12 acute physiologic variables (temperature, MAP, heart rate, respiratory rate, oxygenation, arterial pH, sodium,...