What are the components of a septic screen in pediatric patients?

Paediatric Septic Screen: Australian Guidelines

A comprehensive paediatric septic screen should include blood cultures, complete blood count, inflammatory markers, and site-specific cultures before initiating antimicrobial therapy, while ensuring this process does not substantially delay treatment within 1 hour of sepsis recognition. 1

Clinical Recognition and Initial Assessment

Diagnostic Criteria

• Identify sepsis using the inflammatory triad plus evidence of organ dysfunction:
  • Fever (>38.5°C) or hypothermia (<35°C)
  • Tachycardia (may be absent in hypothermia)
  • At least one of: altered mental status, hypoxemia, increased lactate, or bounding pulses 1

Vital Signs Assessment

• Monitor and document:
  • Heart rate and blood pressure (noting pulse pressure)
  • Respiratory rate and work of breathing
  • Temperature
  • Capillary refill time (>2 seconds indicates poor perfusion)
  • Mental status changes (irritability, drowsiness, confusion, lethargy)
  • Urine output (<1 mL/kg/hr indicates poor perfusion) 1

Laboratory Investigations

Essential Components

1. Blood Cultures:

   • Obtain before antimicrobial therapy if this does not substantially delay treatment
   • Minimum 1 mL blood (ideally 2-5 mL depending on child's size) 1

2. Complete Blood Count:

   • White cell count (leukocytosis >12×10³/μL or leukopenia <4×10³/μL)
   • Presence of immature forms (>10% bands)
   • Platelet count (thrombocytopenia <100×10³/μL indicates organ dysfunction) 1

3. Inflammatory Markers:

   • C-reactive protein
   • Procalcitonin (when available)
   • Lactate level (elevated lactate indicates tissue hypoperfusion) 1

4. Coagulation Studies:

   • INR/PT and aPTT (coagulopathy defined as INR >1.5 or aPTT >60s) 1

5. Biochemistry:

   • Electrolytes, urea, creatinine
   • Liver function tests (bilirubin, ALT, AST)
   • Glucose (hyperglycemia >140 mg/dL may indicate sepsis) 1

6. Blood Gas Analysis:

   • Arterial or venous sample to assess:
     • Acid-base status
     • Oxygenation (PaO₂/FiO₂ ratio <300 indicates respiratory dysfunction)
     • Ionized calcium 1

Site-Specific Cultures

Based on clinical presentation, obtain samples from suspected sources:

• Urine culture and urinalysis
• Cerebrospinal fluid analysis and culture (if meningitis suspected)
• Respiratory specimens (nasopharyngeal aspirate, sputum)
• Wound swabs or tissue samples
• Stool culture (if diarrhea present) 1

Timing Considerations

• In septic shock: Obtain cultures and initiate antimicrobials within 1 hour of recognition 1
• In sepsis-associated organ dysfunction without shock: Complete evaluation and start antimicrobials within 3 hours 1
• Do not delay antimicrobial therapy while awaiting all culture results 1

Antimicrobial Therapy

• Start empiric broad-spectrum antibiotics to cover all likely pathogens
• Use pharmacokinetic/pharmacodynamic principles to optimize dosing
• Reassess daily for de-escalation opportunities based on clinical improvement and culture results 1, 2

Monitoring Response

• Assess therapeutic endpoints:
  • Normalization of capillary refill (≤2 seconds)
  • Normal pulses with no differential between peripheral and central quality
  • Warm extremities
  • Urine output >1 mL/kg/hr
  • Improved mental status
  • Normalization of blood pressure, glucose, and ionized calcium 1

Special Considerations

• Neonates and immunocompromised children may require additional investigations
• Consider lumbar puncture in children with altered mental status, especially if <3 months of age
• In resource-limited settings, prioritize blood cultures and basic laboratory tests that will most directly impact management 1

Implementation Considerations

• Use systematic screening tools tailored to your institution to improve early recognition 1, 3
• Implement a protocol/guideline for management of children with septic shock or sepsis-associated organ dysfunction 1
• Ensure laboratory capabilities for rapid processing of septic screen components 4

The early recognition and comprehensive evaluation of sepsis in children is critical for reducing morbidity and mortality. Following this systematic approach to septic screening will help ensure timely diagnosis and appropriate management.