What are the criteria for diagnosing severe sepsis (Systemic Inflammatory Response Syndrome)?

From the Guidelines

Severe sepsis is defined as sepsis associated with organ dysfunction, hypotension, or hypoperfusion, as indicated by criteria such as lactataemia, oliguria, or alteration in mental status 1.

Key Criteria for Severe Sepsis

• Organ Dysfunction: Characterized by signs such as respiratory failure with a PaO2/FiO2 ratio < 250 mmHg, cardiovascular dysfunction requiring vasopressor support, renal dysfunction with a creatinine increase, or coagulation abnormalities with a platelet count < 100,000 cells/mm^3 1.
• Hypoperfusion: Indicated by lactate levels above upper normal limits, urine output < 0.5 mL/kg/hr for >2 hours despite adequate fluid resuscitation, or a decrease in systolic blood pressure of > 40 mmHg from baseline 1.
• Sepsis-Induced Hypotension: Defined as a systolic blood pressure < 90 mmHg or mean arterial pressure < 70 mmHg, or a systolic blood pressure decrease > 40 mmHg 1.

Diagnostic Considerations

The diagnosis of severe sepsis involves identifying signs of infection along with systemic manifestations of infection, such as fever, tachycardia, tachypnea, or altered mental status, and evidence of organ dysfunction or tissue hypoperfusion 1.

Important Laboratory and Clinical Findings

• Elevated lactate levels (> 1 mmol/L) 1.
• Acute oliguria (urine output < 0.5 mL/kg/hr) despite adequate fluid resuscitation 1.
• Creatinine increase > 0.5 mg/dL or > 44.2 μmol/L 1.
• Coagulopathy (INR > 1.5) or thrombocytopenia (platelet count < 100 x 10^3/μL) 1.

From the Research

Criteria for Diagnosing Severe Sepsis

The criteria for diagnosing severe sepsis, also known as Systemic Inflammatory Response Syndrome (SIRS), have undergone significant changes over the years. According to the study by 2, the term "severe sepsis" is now considered redundant, and sepsis should be defined as life-threatening organ dysfunction caused by a dysregulated host response to infection.

Clinical Criteria

The clinical criteria for diagnosing sepsis include:

• An increase in the Sequential Organ Failure Assessment (SOFA) score of 2 points or more, which is associated with an in-hospital mortality greater than 10% 2
• A quickSOFA (qSOFA) score of 2 or more, which includes:
  • Respiratory rate of 22/min or greater
  • Altered mentation
  • Systolic blood pressure of 100 mm Hg or less 2, 3

Organ Dysfunction

Organ dysfunction is a key component of sepsis, and can be assessed using the SOFA score or qSOFA score. The SOFA score evaluates six organ systems, including respiratory, cardiovascular, hepatic, coagulation, renal, and neurological systems 2. The qSOFA score is a simplified version of the SOFA score and can be used at the bedside to rapidly identify patients with sepsis 2, 3.

Other Factors

Other factors that may be associated with severe sepsis include:

• Hypophosphatemia (<0.8 mmol/l) 4
• Hypoproteinemia (<62 g/l) 4
• Non-adapted antibiotherapy at the onset of severe sepsis 4
• Heart rate/systolic blood pressure ratio <1.1 4
• C-reactive protein <80 mg 4

Long-term Organ Dysfunction

Long-term organ dysfunction after severe sepsis is a significant concern, with variable rates of dysfunction reported in different studies 5. Further research is needed to characterize the true prevalence of long-term organ dysfunction and to develop effective treatments for prevention.