Sepsis is life-threatening organ dysfunction caused by a dysregulated host response to infection. The current international definition, known as Sepsis-3, moved the emphasis away from inflammatory markers and towards evidence of organ dysfunction, because it is organ failure rather than infection alone that drives mortality.
Almost any infection can trigger sepsis, though respiratory, urinary, abdominal and skin or soft tissue sources account for the majority of cases. Certain groups are at higher risk: the very young and very old, people who are pregnant or recently postnatal, those with impaired immunity, people with indwelling lines or catheters, and anyone who has had recent surgery or trauma.
Early recognition is difficult because the initial presentation can look like any acute illness. In UK acute care, the National Early Warning Score 2 (NEWS2) is widely used to flag physiological deterioration, and structured sepsis screening tools prompt clinicians to consider infection when a patient scores highly. Warning signs include a very high or low temperature, rapid breathing, low blood pressure, confusion or a new reduction in urine output.
Septic shock is a subset of sepsis in which circulatory and metabolic abnormalities are severe enough to substantially increase mortality. It is identified clinically by persistent low blood pressure requiring vasopressors to maintain an adequate mean arterial pressure, together with a raised serum lactate despite adequate fluid resuscitation.
Treatment is bundled and urgent. Blood cultures are taken before antibiotics where this does not cause delay, broad spectrum antimicrobials are given rapidly, intravenous fluids are used to restore perfusion, and lactate and urine output are monitored to gauge response. Source control, for example draining an abscess or removing an infected line, is just as important as the antibiotic choice. Once cultures return, therapy is narrowed in line with antimicrobial stewardship principles.
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