What are the criteria for sepsis?

Sepsis Criteria: Diagnostic Framework for Early Recognition and Management

Sepsis is defined as life-threatening organ dysfunction caused by a dysregulated host response to infection, diagnosed when infection is documented or suspected along with specific clinical and laboratory parameters indicating systemic inflammatory response and organ dysfunction. 1

Diagnostic Criteria for Sepsis

General Variables

• Fever (core temperature >38.3°C)
• Hypothermia (core temperature <36°C)
• Heart rate >90 beats/min or >2 standard deviations above normal for age
• Tachypnea (respiratory rate >30 breaths/min)
• Altered mental status
• Significant edema or positive fluid balance (>20 mL/kg over 24h)
• Hyperglycemia (plasma glucose >140 mg/dL or 7.7 mmol/L) in absence of diabetes 1

Inflammatory Variables

• Leukocytosis (WBC count >12,000/μL)
• Leukopenia (WBC count <4,000/μL)
• Normal WBC count with >10% immature forms
• Plasma C-reactive protein >2 SD above normal value
• Plasma procalcitonin >2 SD above normal value 1

Hemodynamic Variables

• Arterial hypotension (SBP <90 mmHg, MAP <70 mmHg, or SBP decrease >40 mmHg in adults) 1

Organ Dysfunction Variables

• Arterial hypoxemia (PaO₂/FiO₂ <300)
• Acute oliguria (urine output <0.5 mL/kg/h for at least 2h despite adequate fluid resuscitation)
• Creatinine increase >0.5 mg/dL or 44.2 μmol/L
• Coagulation abnormalities (INR >1.5 or aPTT >60s)
• Ileus (absent bowel sounds)
• Thrombocytopenia (platelet count <100,000/μL)
• Hyperbilirubinemia (plasma total bilirubin >4 mg/dL or 70 μmol/L) 1

Tissue Perfusion Variables

• Hyperlactatemia (>1 mmol/L)
• Decreased capillary refill or mottling 1

Severe Sepsis Definition

Severe sepsis is defined as sepsis plus sepsis-induced organ dysfunction or tissue hypoperfusion, characterized by any of the following due to the infection:

• Sepsis-induced hypotension
• Lactate above upper limits of laboratory normal
• Urine output <0.5 mL/kg/h for >2h despite adequate fluid resuscitation
• PaO₂/FiO₂ <250 in absence of pneumonia as infection source
• PaO₂/FiO₂ <200 in presence of pneumonia as infection source
• Creatinine >2.0 mg/dL (176.8 μmol/L)
• Bilirubin >2 mg/dL (34.2 μmol/L)
• Platelet count <100,000/μL
• Coagulopathy (INR >1.5) 1

Septic Shock Definition

Septic shock is defined as severe sepsis with persistent hypotension despite adequate fluid resuscitation and exclusion of other causes of hypotension. 1

Special Considerations

In Neutropenic Patients

• White blood cell count cannot be used as a criterion to define sepsis
• Other criteria remain applicable 1

In Pediatric Patients

• Signs and symptoms of inflammation plus infection with hyper- or hypothermia
• Tachycardia (may be absent in hypothermic patients)
• At least one indication of altered organ function:
  • Altered mental status
  • Hypoxemia
  • Increased serum lactate
  • Bounding pulses 1

Warning Signs and Predictors of Severe Sepsis

Certain systemic symptoms have been identified as significant predictors for the presence or development of severe sepsis:

• Altered mental status (strongest predictor, OR = 4.29)
• Dyspnea (OR = 2.92)
• Gastrointestinal symptoms (OR = 2.31)
• Muscle weakness (OR = 2.24) 2

Clinical Application

1. Initial Assessment:

   • Evaluate for presence of infection
   • Check for sepsis criteria as outlined above
   • Calculate Sequential Organ Failure Assessment (SOFA) score for organ dysfunction assessment 3

2. Risk Stratification:

   • Monitor patients every 30 minutes to 1 hour depending on risk level
   • Use NEWS2 score to determine risk of severe illness or death 4
   • Measure serum lactate (≥2 mmol/L indicates tissue hypoperfusion)
   • Repeat lactate measurement within 6 hours if initially elevated 4

3. Early Intervention:

   • Obtain blood cultures before starting antibiotics
   • Administer broad-spectrum antibiotics within 1 hour for septic shock and within 3 hours for sepsis without shock
   • Provide crystalloid fluid resuscitation (at least 30 mL/kg within first 3 hours)
   • Identify and control source of infection as rapidly as possible 4

Common Pitfalls and Caveats

• Delayed Recognition: Sepsis presentation can be subtle, particularly in older or immunocompromised patients. Maintain high index of suspicion with any infection. 3

• Biomarker Limitations: No single biomarker is specific enough for definitive diagnosis. Consider panels or combinations of markers with clinical signs. 5

• Overreliance on Fever: Many septic patients present without fever, especially elderly patients. Focus on the complete clinical picture rather than any single parameter. 3

• Inadequate Source Control: Failure to identify and address the infectious source can lead to treatment failure despite appropriate antibiotics and resuscitation. 4

• Inappropriate Fluid Management: Both inadequate and excessive fluid resuscitation can be harmful. Titrate to clinical markers of cardiac output. 4

Early recognition using these criteria and prompt, appropriate intervention are critical for improving outcomes in sepsis, as time to adequate treatment directly impacts mortality and morbidity. 2