Immune system ↗Infection starts in a tissue
Lung, urinary, abdominal, skin, device, bloodstream, and other infections can progress according to organism, source control, reserve, and host response.
IMMUNE / 09
Local defense becomes
systemic failure.
Sepsis is a life-threatening emergency in which the response to infection becomes dysregulated and organ function deteriorates. It is not simply “infection in the blood” or a single cytokine pathway.
Signals exceed local containment
Pathogen products, damage signals, cytokines, complement, coagulation, and neural-endocrine responses become broadly distributed.
Barrier and tone are altered
Endothelial activation changes permeability, vasodilation, vasoconstriction, adhesion, glycocalyx integrity, and responsiveness to pressure signals.
Clotting and anticoagulant balance shift
Tissue factor, thrombin, platelets, natural anticoagulants, fibrinolysis, and complement interact; microthrombi and bleeding can coexist.
Hyperinflammation and suppression overlap
Strong mediator release can coexist with lymphocyte loss, exhausted signaling, impaired antigen presentation, and susceptibility to secondary infection.
Perfusion becomes maldistributed
Vascular leak, altered tone, capillary obstruction, shunting, edema, and reduced red-cell deformability impair tissue delivery unevenly.
Energy and redox handling change
Hypoxia, mitochondrial stress, inflammatory signaling, substrate shifts, and membrane dysfunction can limit effective cellular work.
Gas-exchange barriers may fail
Inflammatory permeability and alveolar injury can cause edema, impaired oxygen transfer, and high breathing or ventilatory-support demand.
Filtration and tubular function fall
Perfusion, inflammation, microvascular change, toxins, congestion, and medicines can combine in acute kidney injury.
Delirium can signal dysfunction
Inflammation, perfusion, medications, sleep disruption, metabolic change, and organ failure can cause confusion or reduced alertness.
Pump and metabolic support can weaken
Myocardial depression, arrhythmia, vasoplegia, cholestasis, coagulation changes, and impaired clearance alter systemic reserve.
No single symptom or test is sufficient
Confusion, fever or low temperature, clammy skin, fast breathing, rapid heart rate, low pressure, severe pain, and low urine can occur in combinations.
Clinicians identify infection and organ injury
History, examination, cultures, imaging, blood tests, lactate, oxygenation, urine output, and serial response guide cause-specific care.
Likely pathogens are treated promptly
Empiric treatment is selected from source, severity, allergies, local resistance, prior exposure, and organ function, then refined with results.
The infected focus may need removal
Drainage, device removal, debridement, or surgery can be essential when medicines cannot eliminate the source alone.
Flow and function are maintained
Fluids, vasopressors, oxygen or ventilation, kidney support, glucose and electrolyte management, and other measures are individualized.
Do not wait for the graph
Sepsis can progress quickly; suspected sepsis requires immediate professional assessment and treatment.