Characteristics of Septic Shock

Definition and Diagnostic Criteria

The Society of Critical Care Medicine defines septic shock as a subset of sepsis in which profound circulatory, cellular, and metabolic abnormalities substantially increase mortality risk, characterized by hypotension requiring vasopressors to maintain mean arterial pressure ≥65 mmHg and serum lactate >2 mmol/L despite adequate fluid resuscitation 1, 2
Septic shock requires the presence of both persistent hypotension requiring vasopressor therapy to maintain MAP ≥65 mmHg and serum lactate >2 mmol/L despite adequate fluid resuscitation 1, 2, 3

Hypotension that persists despite adequate fluid resuscitation is a key characteristic of septic shock, with a definition of systolic BP <90 mmHg, MAP <70 mmHg, or decrease in systolic BP >40 mmHg from baseline 1, 4
Vasopressor support, typically norepinephrine as first-line agent, is required to maintain adequate perfusion in septic shock patients 3

Elevated serum lactate (>2 mmol/L) is a key indicator of tissue hypoperfusion and cellular metabolic dysfunction in septic shock patients 1
Metabolic acidosis is often present in septic shock due to lactic acidosis and other metabolic derangements 1, 2

Acute alteration in mental status, such as confusion or lethargy, is a common manifestation of organ dysfunction in septic shock patients 1, 5
Oliguria, defined as urine output <0.5 mL/kg/h for >2 hours, despite adequate fluid resuscitation, is a sign of kidney dysfunction in septic shock 1, 4

A dysregulated host response to infection, with activation of inflammatory signaling pathways, is a key feature of septic shock 1, 2
Recognition of pathogen-associated molecular patterns (PAMPs) and damage-associated molecular patterns (DAMPs) triggers an immune response in septic shock patients 1, 2

Immediate fluid resuscitation with crystalloids (at least 30 mL/kg) is recommended for septic shock patients 3, 4
Vasopressors, typically norepinephrine, should be initiated if hypotension persists after fluid challenge in septic shock patients 3
The target mean arterial pressure (MAP) during hemodynamic support in septic shock is ≥65 mmHg 6, 3