What are the diagnostic criteria and initial treatment for septic shock?

Septic Shock Diagnostic Criteria

Septic shock is defined as sepsis with persistent hypotension (systolic BP <90 mmHg, MAP <65 mmHg, or SBP decrease >40 mmHg) despite adequate fluid resuscitation (at least 30 mL/kg crystalloid), requiring vasopressors to maintain MAP ≥65 mmHg, plus evidence of tissue hypoperfusion (elevated lactate >2 mmol/L). 1, 2

Core Diagnostic Components

Infection Requirement

• Documented or suspected infection must be present, confirmed by obtaining at least two sets of blood cultures (aerobic and anaerobic) before antimicrobial therapy 1
• At least one blood culture should be drawn percutaneously and one through each vascular access device unless recently inserted (<48 hours) 1

Hemodynamic Criteria

• Persistent hypotension after crystalloid fluid challenge of 30 mL/kg body weight, defined as: 1, 2
  • Systolic blood pressure <90 mmHg, OR
  • Mean arterial pressure <65 mmHg, OR
  • Systolic blood pressure decrease >40 mmHg from baseline
• Requirement for vasopressors to maintain MAP ≥65 mmHg 1

Tissue Hypoperfusion Markers

• Hyperlactatemia >1 mmol/L (with >2 mmol/L indicating significant hypoperfusion requiring aggressive resuscitation) 1, 3, 4
• Decreased capillary refill or skin mottling 3, 4
• Oliguria (urine output <0.5 mL/kg/h for ≥2 hours despite adequate fluid resuscitation) 3, 4
• Altered mental status 3, 5

Organ Dysfunction Indicators

• Acute lung injury with PaO₂/FiO₂ <250 (without pneumonia) or <200 (with pneumonia) 3
• Creatinine >2.0 mg/dL or increase ≥0.5 mg/dL 3, 4
• Bilirubin >2 mg/dL 3
• Platelet count <100,000/μL 3, 4
• Coagulopathy (INR >1.5 or aPTT >60 seconds) 3, 4

Initial Treatment Protocol (Hour-1 Bundle)

Immediate Actions (Within 1 Hour)

• Measure lactate immediately and remeasure within 2-4 hours if elevated; target lactate normalization as resuscitation endpoint 1, 6
• Administer at least 30 mL/kg IV crystalloid bolus within first 3 hours for sepsis-induced hypoperfusion, infused rapidly over 5-10 minutes 1, 6
• Start broad-spectrum IV antimicrobials within 1 hour of recognition—each hour of delay decreases survival by approximately 7.6% 1, 6, 5
• Initiate vasopressors if hypotension persists despite adequate fluid resuscitation, with norepinephrine as first-line agent targeting MAP ≥65 mmHg 1, 6

Fluid Resuscitation Strategy

• Use crystalloids (balanced crystalloids or normal saline) as initial fluid of choice 6
• Continue fluid administration as long as hemodynamic factors improve based on dynamic variables (pulse pressure variation, stroke volume variation) or static variables (arterial pressure, heart rate, capillary refill, skin mottling) 6
• Never use hydroxyethyl starches—they are contraindicated in sepsis due to increased acute kidney injury risk 1, 6
• Consider albumin when patients require substantial amounts of crystalloids 6

Vasopressor Management

• Norepinephrine is the first-line vasopressor agent 6
• Target MAP ≥65 mmHg (strong recommendation, moderate quality evidence) 1
• Place arterial catheter as soon as practical for continuous blood pressure monitoring in all patients requiring vasopressors 1

Source Control

• Identify and control infection source within 12 hours when feasible 6
• Use least physiologically invasive effective intervention (percutaneous drainage preferred over surgical drainage when possible) 6
• Remove intravascular access devices promptly if they are possible infection source 6

Risk Stratification Using NEWS2 Score

• NEWS2 ≥7 indicates high risk: Initiate sepsis treatment within 1 hour, reassess every 30 minutes 3
• NEWS2 5-6 indicates moderate risk: Initiate treatment within 3 hours, reassess every hour 3
• Critical override criteria (mottled/ashen appearance, non-blanching rash, cyanosis) warrant immediate treatment regardless of NEWS2 score 3

Common Pitfalls to Avoid

• Do not delay antimicrobials beyond 45 minutes waiting for blood cultures if obtaining them is difficult 6
• Do not rely on qSOFA alone for diagnosis—it has poor sensitivity (31-50%) and should not delay treatment initiation 6
• Do not use static measurements alone (CVP, PAOP) to guide fluid resuscitation; use dynamic assessment of fluid responsiveness 1
• Do not use low-dose dopamine for renal protection—it is ineffective 1
• Avoid protocolized rigid approaches—recent trials show protocol-based care offers little advantage over individualized management guided by frequent reassessment 7

Ongoing Monitoring Requirements

• Reassess hemodynamic status frequently after initial fluid bolus: capillary refill, skin temperature, mental status, urine output (target >0.5 mL/kg/hour), and lactate clearance 6
• Target hemoglobin 8-9 g/dL for acute anemia, adjusting based on clinical tolerance 6
• Provide DVT prophylaxis (pharmacological or mechanical) 6
• Reassess antimicrobial therapy daily for potential de-escalation once culture results available 6