Systemic Inflammatory Response Syndrome Diagnosis and Criteria

Definition and Diagnosis

The American College of Critical Care Medicine recommends that Systemic Inflammatory Response Syndrome (SIRS) be defined clinically by the presence of at least two of the following criteria: temperature >38°C or <36°C, heart rate >90 beats/min, respiratory rate >20 breaths/min or PaCO2 <32 mmHg, and white blood cell count >12,000/mm³ or <4,000/mm³ or >10% immature (band) forms 1, 2, 3
SIRS represents a clinical expression of the acute phase reaction that can be triggered by various events including infection, trauma, and surgery 1, 4

Septicemia requires confirmation of bacteria in the bloodstream through blood cultures and pathological confirmation is essential for definitive diagnosis 4, 5
Septic shock is defined as sepsis with circulatory and cellular/metabolic abnormalities and requires evidence of infection plus vasopressor requirement to maintain mean arterial pressure ≥65 mmHg and lactate >2 mmol/L 2, 4
Hemorrhagic shock is defined by clinical signs of inadequate tissue perfusion resulting from blood loss and while initial assessment is clinical, diagnosis requires confirmation of blood loss and its source through imaging, laboratory tests, or direct visualization 1

SIRS is diagnosed solely based on clinical parameters and basic laboratory values that can be obtained at the bedside, without requiring pathological specimens or cultures 2, 3
The presence of SIRS should prompt a thorough search for the underlying cause rather than being considered a final diagnosis 3