Septicaemia will lead to shock and multiorgan failure. Shock is a clinical diagnosis. The signs are a result of circulatory failure. The underlying pathophysiology of septicaemia and the capillary leak syndrome leading to these signs are briefly summarised in the pathophysiology section.

A child in early shock may still be alert and have a normal blood pressure.

Child lucid despite advancing septicaemia

The early signs of shock include:

• Tachycardia
• Cool peripheries (CRT>4 seconds) or toe-core temperature gap of >3 degrees
• Pallor, mottling
  
  
• Decreased urine output (<1ml/kg/hr)
• Tachypnoea – secondary to acidosis and hypoxia

(In patients with meningococcal disease, signs of shock will usually co-exist with symptoms of septicaemia.)

As shock progresses further signs develop:

• Metabolic acidosis with base deficit worse than -5
  
  
• Hypoxia: PaO₂ <10kPa in air or saturation < 95% in air
  
• Increasing tachypnoea, tachycardia and gallop rhythm

Late signs of shock include:

• Drowsiness or agitation
• Hypotension: in children, blood pressure can be normal until shock is advanced