What are the criteria and treatment for severe sepsis?

Severe Sepsis Criteria and Treatment

Severe sepsis is defined as sepsis-induced tissue hypoperfusion or organ dysfunction, characterized by any of the following criteria thought to be due to infection: sepsis-induced hypotension, lactate above upper limits of normal, organ dysfunction, or tissue hypoperfusion. 1

Diagnostic Criteria for Severe Sepsis

Severe sepsis requires the presence of:

1. Infection (documented or suspected)

2. Sepsis (infection plus some of the following manifestations):

   • General variables: fever, hypothermia, tachycardia, tachypnea, altered mental status, edema
   • Inflammatory variables: leukocytosis, leukopenia, elevated CRP or procalcitonin
   • Hemodynamic variables: hypotension (SBP <90 mmHg, MAP <70 mmHg, or SBP decrease >40 mmHg)
   • Organ dysfunction variables: hypoxemia, oliguria, increased creatinine, coagulopathy, ileus, thrombocytopenia, hyperbilirubinemia
   • Tissue perfusion variables: hyperlactatemia, decreased capillary refill or mottling

3. Plus at least one of the following organ dysfunction criteria 1:

   • Sepsis-induced hypotension
   • Lactate above upper limits of laboratory normal
   • Urine output <0.5 mL/kg/h for more than 2 hours despite adequate fluid resuscitation
   • PaO₂/FiO₂ <250 in the absence of pneumonia as infection source
   • PaO₂/FiO₂ <200 in the 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 (international normalized ratio >1.5)

Treatment Algorithm for Severe Sepsis

1. Initial Resuscitation (First 6 Hours)

• Implement protocolized, quantitative resuscitation with the following targets 1:
  • Central venous pressure: 8-12 mmHg
  • Mean arterial pressure (MAP): ≥65 mmHg
  • Urine output: ≥0.5 mL/kg/h
  • Central venous oxygen saturation: ≥70% (or mixed venous oxygen saturation ≥65%)
• Administer at least 30 mL/kg of intravenous crystalloid fluid within the first 3 hours 2
• For patients with elevated lactate, target resuscitation to normalize lactate as rapidly as possible 1

2. Diagnosis and Source Control

• Obtain at least 2 sets of blood cultures (both aerobic and anaerobic) before starting antibiotics 1
• Perform prompt imaging studies to confirm potential infection source 1
• Identify anatomical source of infection rapidly and implement source control measures within 12 hours when feasible 1, 2

3. Antimicrobial Therapy

• Administer effective intravenous antimicrobials within the first hour of recognition of septic shock and severe sepsis 1
• Use broad-spectrum agents with activity against all likely pathogens 1, 2
• Reassess antimicrobial regimen daily for potential de-escalation 1
• Typical duration of therapy is 7-10 days, though may be longer based on clinical response 1

4. Fluid Therapy and Vasopressors

• After initial fluid resuscitation, continue fluid challenges if patient remains fluid-responsive 2
• If hypotension persists despite fluid resuscitation, initiate vasopressors 1, 2
• Norepinephrine is the first-choice vasopressor 2
• Consider adding vasopressin (up to 0.03 U/min) to reduce norepinephrine requirements 2
• For myocardial dysfunction with persistent hypoperfusion, consider dobutamine 1, 2

5. Additional Supportive Measures

• Provide DVT prophylaxis with daily subcutaneous low-molecular-weight heparin 1
• Implement stress ulcer prophylaxis using proton pump inhibitors in patients with bleeding risk factors 1
• Target blood glucose ≤180 mg/dL using a protocolized approach 1
• Consider mechanical ventilation with lung-protective strategies for patients with ARDS 1

Monitoring and Evaluation

• Monitor urine output (target ≥0.5 mL/kg/h) 1, 2
• Perform serial lactate measurements to guide resuscitation 2
• Use dynamic variables (pulse pressure variation, stroke volume variation) to predict fluid responsiveness 2
• Reassess after each fluid bolus for signs of improved perfusion and fluid overload 2

Common Pitfalls and Caveats

• Delay in antibiotic administration significantly increases mortality - ensure administration within the first hour of recognition 1, 2
• Inadequate source control is associated with treatment failure - identify and address infectious source promptly 1
• Over-resuscitation with fluids can be harmful - reassess frequently and use dynamic parameters 2
• Failure to recognize organ dysfunction may delay appropriate treatment - systematically assess for all potential organ dysfunctions 1
• Not all patients with severe sepsis present with SIRS criteria - focus on organ dysfunction 3

The early recognition and prompt treatment of severe sepsis are crucial for improving outcomes and reducing mortality. Following this structured approach can help ensure timely and appropriate management of this life-threatening condition.