Diagnostic Criteria for Sepsis
Sepsis is defined as life-threatening organ dysfunction caused by a dysregulated host response to infection, with diagnosis primarily based on the Sequential Organ Failure Assessment (SOFA) score and clinical evidence of infection. 1
Primary Diagnostic Tools
- The Sequential Organ Failure Assessment (SOFA) score is the gold standard for diagnosing sepsis-related organ dysfunction, evaluating respiratory, cardiovascular, hepatic, coagulation, renal, and neurological function 1
- The National Early Warning Score 2 (NEWS2) is recommended for initial evaluation of sepsis risk, with scores ≥7 indicating high risk of severe illness or death 1
- A score of 3 in any single parameter of NEWS2 may indicate increased risk from sepsis 1
Sepsis-3 Diagnostic Criteria
- Documented or suspected infection is a prerequisite for sepsis diagnosis 1, 2
- Organ dysfunction is determined by an increase in the SOFA score by ≥2 points from baseline 3
- For simplified surveillance purposes, the CDC's Adult Sepsis Event uses electronic SOFA (eSOFA) criteria which include: 3
- Vasopressor initiation
- Mechanical ventilation initiation
- Lactate ≥2.0 mmol/L
- Doubling in creatinine
- Doubling in bilirubin to ≥2.0 mg/dL
- ≥50% decrease in platelet count to <100 cells/μL
Clinical Signs and Laboratory Markers
- Common infection indicators include: 1, 2
- Fever or hypothermia
- Leukocytosis or leukopenia
- Elevated C-reactive protein or procalcitonin
- Organ dysfunction markers include: 1
- Respiratory: PaO2/FiO2 <300, SpO2 ≤90%
- Cardiovascular: systolic BP <90 mmHg
- Renal: urine output <0.5 mL/kg/h
- Hepatic: hyperbilirubinemia
- Coagulation: thrombocytopenia
- Neurological: altered mental status
- Mid-regional proadrenomedullin (MR-proADM) has shown utility in detecting multiple types of organ failure in sepsis (respiratory, coagulation, cardiovascular, neurological and renal) 4
Sepsis-Induced Coagulopathy (SIC)
- SIC is a specific complication of sepsis affecting the coagulation system 1
- SIC diagnostic criteria include: 5
- Platelet count: 2 points for <100 × 10^9/L, 1 point for ≥100 to <150 × 10^9/L
- PT ratio: 2 points for >1.4,1 point for >1.2 to ≤1.4
- SOFA score: 2 points for ≥2,1 point for 1
- Total score ≥4 confirms SIC diagnosis
- SIC represents an early phase of disseminated intravascular coagulation (DIC) in sepsis 5
- Patients with SIC have higher mortality rates and may benefit from specific interventions 5
Two-Step Diagnostic Approach for Sepsis-Associated Coagulopathy
- Step 1: Screen sepsis patients with thrombocytopenia (platelet count <150 × 10^9/L) using SIC diagnostic criteria 5
- Step 2: If SIC is present, evaluate for overt DIC using ISTH overt DIC criteria 5
- ISTH overt DIC criteria include: 5
- Platelet count: 2 points for <50 × 10^9/L, 1 point for ≥50 to <100 × 10^9/L
- Fibrin-related markers (D-dimer/FDP): 3 points for strong increase, 2 points for moderate increase
- PT prolongation: 2 points for ≥6 seconds, 1 point for ≥3 to <6 seconds
- Fibrinogen: 1 point for <100 g/mL
- Total score ≥5 confirms overt DIC
Monitoring and Re-evaluation
- Patients should be re-evaluated based on risk stratification: 1
- High-risk patients: every 30 minutes
- Moderate-risk patients: every hour
- Low-risk patients: every 4-6 hours
- Deterioration or lack of improvement should prompt re-evaluation of risk and management strategy 1, 6
Common Pitfalls and Caveats
- Relying solely on biomarkers without clinical context can lead to misdiagnosis; organ dysfunction is what separates sepsis from routine infections 2
- No single biomarker is routinely recommended for sepsis diagnosis in current clinical practice 2
- The SOFA score components may not be routinely recorded in all hospitals' electronic health record systems, limiting its utility for wide-scale sepsis surveillance 3
- Delayed recognition of sepsis increases mortality; early identification allows for evidence-based interventions such as prompt antibiotics and goal-directed resuscitation 7