What is the current definition of sepsis, including the organ dysfunction criteria and the required increase of ≥2 points in the Sequential Organ Failure Assessment (SOFA) score?

Current Definition of Sepsis

Sepsis is defined as life-threatening organ dysfunction caused by a dysregulated host response to infection, operationalized as an acute increase in the Sequential Organ Failure Assessment (SOFA) score of ≥2 points from baseline, which correlates with in-hospital mortality exceeding 10%. 1, 2, 3

Core Diagnostic Components

Sepsis requires both of the following elements to be present:

• Documented or suspected infection (any source, including intra-abdominal, pulmonary, urinary, or soft tissue) 1, 2
• Acute organ dysfunction represented by an increase in SOFA score ≥2 points, which must be acute and attributable to the infection 1, 3, 4

SOFA Score Criteria

The SOFA score assesses six organ systems, with each system scored 0-4 points based on severity of dysfunction: 1

Respiratory System

• PaO₂/FiO₂ <400: 1 point
• PaO₂/FiO₂ <300: 2 points
• PaO₂/FiO₂ <200 with mechanical ventilation: 3 points
• PaO₂/FiO₂ <100 with mechanical ventilation: 4 points 1

Cardiovascular System

• MAP <70 mmHg: 1 point
• Dopamine ≤5 mcg/kg/min OR any dose dobutamine: 2 points
• Dopamine >5 mcg/kg/min OR epinephrine ≤0.1 mcg/kg/min OR norepinephrine ≤0.1 mcg/kg/min: 3 points
• Dopamine >15 mcg/kg/min OR epinephrine >0.1 mcg/kg/min OR norepinephrine >0.1 mcg/kg/min: 4 points 1

Renal System

• Creatinine 1.2-1.9 mg/dL: 1 point
• Creatinine 2.0-3.4 mg/dL: 2 points
• Creatinine 3.5-4.9 mg/dL OR urine output <500 mL/day: 3 points
• Creatinine ≥5.0 mg/dL OR urine output <200 mL/day: 4 points 1

Hepatic System

• Bilirubin >1.2 mg/dL begins scoring on SOFA scale 1

Coagulation System

• Platelet count <150,000/μL begins scoring, with lower counts receiving higher points 1

Neurological System

• Glasgow Coma Scale score is used, with lower scores indicating worse dysfunction 1

Septic Shock Definition

Septic shock is a subset of sepsis with particularly profound circulatory, cellular, and metabolic abnormalities associated with mortality rates exceeding 40%. 1, 3

Septic shock is clinically identified by both of the following criteria:

• Vasopressor requirement to maintain MAP ≥65 mmHg despite adequate fluid resuscitation 1, 3
• Serum lactate >2 mmol/L (>18 mg/dL) in the absence of hypovolemia 1, 3

Key Changes from Previous Definitions

Elimination of "Severe Sepsis"

• The term "severe sepsis" is now obsolete and should not be used, as all sepsis is considered severe by definition 1, 3
• The previous model suggesting a continuum from SIRS to sepsis to severe sepsis to shock was misleading and has been abandoned 3, 4

Removal of SIRS Criteria

• Systemic Inflammatory Response Syndrome (SIRS) criteria are no longer part of the sepsis definition due to inadequate specificity and sensitivity 3, 4
• The excessive focus on inflammation in previous definitions failed to capture the dysregulated host response that characterizes sepsis 3, 5

Bedside Screening: qSOFA

For rapid identification outside the ICU, the quick SOFA (qSOFA) score identifies patients with suspected infection at higher risk for poor outcomes: 1, 6, 3

A qSOFA score ≥2 indicates higher risk and warrants full SOFA assessment. The three criteria are:

• Respiratory rate ≥22 breaths/min (1 point) 1, 3
• Altered mental status (Glasgow Coma Scale <15) (1 point) 1, 3
• Systolic blood pressure ≤100 mmHg (1 point) 1, 6, 3

Important caveat: qSOFA is a screening tool only and should not be used as a definitive diagnostic criterion—full SOFA scoring is required for sepsis diagnosis 6

Special Populations

Elderly Patients

• The same SOFA ≥2 point increase definition applies to all adults including the elderly 2
• Altered mental status may be the primary or sole presenting sign in elderly patients with sepsis 2
• Avoid attributing mental status changes to dementia or delirium without investigating for underlying infection, as this leads to delayed diagnosis 2

Clinical Implementation Algorithm

Step 1: Identify suspected or documented infection 1

Step 2: Calculate baseline SOFA score (or assume 0 if previously healthy) 1

Step 3: Calculate current SOFA score across all six organ systems 1

Step 4: Determine if SOFA has increased ≥2 points—if yes, diagnose sepsis 1, 3

Step 5: If on vasopressors for MAP ≥65 mmHg AND lactate >2 mmol/L despite adequate fluids, diagnose septic shock 1, 3