What are the criteria for diagnosing sepsis?

Sepsis Diagnosis Criteria

Sepsis is defined as life-threatening organ dysfunction caused by a dysregulated host response to infection, with diagnosis based primarily on the Sequential Organ Failure Assessment (SOFA) score and clinical evidence of infection. 1

Current Diagnostic Framework

Sepsis Definition

• Sepsis is defined as life-threatening organ dysfunction caused by a dysregulated host response to infection 1, 2
• Organ dysfunction is represented by an increase in the SOFA score of 2 points or more 2
• This definition replaced older concepts that relied heavily on SIRS (Systemic Inflammatory Response Syndrome) criteria 2

Primary Diagnostic Tools

NEWS2 Score for Initial Risk Assessment

• The National Early Warning Score 2 (NEWS2) is recommended for initial evaluation of sepsis risk 1
• NEWS2 interpretation for sepsis risk:
  • Score of 0: Very low risk of severe illness or death 1
  • Score of 1-4: Low risk of severe illness or death 1
  • Score of 5-6: Moderate risk of severe illness or death 1
  • Score of ≥7: High risk of severe illness or death 1
• A score of 3 in any single parameter may indicate increased risk from sepsis 1

SOFA Score for Definitive Diagnosis

• SOFA score is the primary tool for diagnosing sepsis-related organ dysfunction 2
• Includes assessment of:
  • Respiratory function (PaO2/FiO2 ratio)
  • Cardiovascular function (blood pressure, vasopressor requirements)
  • Hepatic function (bilirubin)
  • Coagulation (platelet count)
  • Renal function (creatinine, urine output)
  • Neurological function (Glasgow Coma Scale) 1, 2
• An increase of ≥2 points indicates organ dysfunction and confirms sepsis in the presence of infection 2

Quick SOFA (qSOFA) for Rapid Assessment

• qSOFA is a bedside tool to quickly identify patients at risk of poor outcomes 2
• Consists of three criteria (1 point each):
  • Respiratory rate ≥22/min
  • Altered mental status
  • Systolic blood pressure ≤100 mmHg 2
• A score of ≥2 should prompt consideration of possible sepsis, especially outside the ICU setting 2
• While qSOFA is simpler to use in emergency settings, it has lower sensitivity than the full SOFA score 3, 4

Clinical Signs and Laboratory Markers

Infection Indicators

• Documented or suspected infection is a prerequisite for sepsis diagnosis 1
• Common infection indicators include:
  • Fever (>38.3°C) or hypothermia (<36°C)
  • Leukocytosis (WBC >12,000/μL) or leukopenia (WBC <4,000/μL)

  • 10% immature neutrophils

  • Elevated C-reactive protein or procalcitonin (>2 SD above normal) 1

Organ Dysfunction Markers

• Respiratory: PaO2/FiO2 <300, SpO2 ≤90% 1
• Cardiovascular: Systolic BP <90 mmHg, mean arterial pressure <70 mmHg, or decrease >40 mmHg 1
• Renal: Urine output <0.5 mL/kg/h for >2h despite fluid resuscitation, creatinine increase >0.5 mg/dL 1
• Hepatic: Hyperbilirubinemia (plasma total bilirubin >4 mg/dL) 1
• Coagulation: Thrombocytopenia (<100,000/μL), INR >1.5 or aPTT >60s 1
• Neurological: Altered mental status, confusion 1
• Metabolic: Hyperlactatemia (>1 mmol/L) 1
• Tissue perfusion: Decreased capillary refill or skin mottling 1

Special Considerations

Sepsis-Induced Coagulopathy (SIC)

• SIC is a specific complication of sepsis affecting the coagulation system 1
• Diagnostic criteria include:
  • Platelet count
  • PT-INR
  • SOFA score 1
• SIC can progress to disseminated intravascular coagulation (DIC) if not addressed 1
• Patients with SIC have higher mortality rates and may benefit from specific interventions 1

Monitoring and Re-evaluation

• Patients should be re-evaluated based on risk stratification:
  • High risk: Every 30 minutes
  • Moderate risk: Every hour
  • Low risk: Every 4-6 hours
  • Very low risk: According to local protocol 1
• Deterioration or lack of improvement should prompt re-evaluation of risk 1

Antibiotic Management Based on Risk

• High risk: Antibiotics within 1 hour
• Moderate risk: Antibiotics within 3 hours
• Low risk: Antibiotics within 6 hours 1

Common Pitfalls in Sepsis Diagnosis

• Over-reliance on SIRS criteria alone, which has lower specificity than SOFA 2
• Failure to recognize sepsis in patients with subtle presentations, especially elderly or immunocompromised patients 1
• Delay in calculating SOFA score, which can lead to delayed recognition of organ dysfunction 4
• Not considering sepsis in patients with normal vital signs but deteriorating clinical status 1
• Overlooking physical signs such as mottled skin, non-blanching rash, or cyanosis, which may indicate severe sepsis regardless of NEWS2 score 1