Pathophysiology
Clinical meaning
Sepsis is defined as life-threatening organ dysfunction caused by a dysregulated host response to infection (Sepsis-3 definition). Pathogen-associated molecular patterns (PAMPs) activate innate immune cells, triggering a cytokine storm (TNF-alpha, IL-1, IL-6). This produces systemic vasodilation (low SVR), increased capillary permeability, and microthrombi formation. The result is distributive shock with relative hypovolemia and maldistribution of blood flow. Lactate accumulates as tissues shift to anaerobic metabolism from hypoperfusion. Organ dysfunction manifests as acute kidney injury (oliguria), ARDS (refractory hypoxemia), hepatic dysfunction (coagulopathy, jaundice), and encephalopathy (altered mental status). The nurse implements the sepsis bundle, manages fluid resuscitation and vasopressors, performs serial reassessments, and coordinates the interdisciplinary response.