Sepsis involves a dysregulated immune response to an infection, causing systemic inflammation and organ dysfunction. It is a life-threatening medical emergency. A high degree of suspicion and low threshold for initiating investigations and treatment for suspected sepsis is required, especially in younger children and neonates, where signs and symptoms can be non-specific. Refer to local policies and guidelines and involve seniors when treating patients.
Pathophysiology
Macrophages, lymphocytes and mast cells recognise pathogens and release cytokines, such as interleukins and tumour necrosis factor, that activate the immune system. This immune activation leads to systemic inflammation and the release of other chemicals, such as nitric oxide (which causes vasodilation).
Many of these cytokines cause the endothelial lining of blood vessels to become more permeable, allowing fluid to leak from the intravascular space (the blood) into the extracellular space, resulting in oedema and reduced intravascular volume. Tissue oedema and reduced effective circulating volume impair oxygen delivery and diffusion to tissues.
Activation of the coagulation system leads to fibrin deposition and the formation of blood clots (thrombi) throughout the circulation, compromising organ and tissue perfusion. The formation of blood clots consumes platelets and clotting factors, leading to thrombocytopenia (low platelets) and a risk of bleeding (haemorrhage). This clotting dysfunction is called disseminated intravascular coagulopathy (DIC).
Septic Shock
Septic shock occurs when sepsis leads to cardiovascular dysfunction and impaired organ perfusion. This can present with prolonged capillary refill time, tachycardia, weak pulses, reduced urine output, altered mental state and, later, hypotension. Impaired tissue oxygen delivery and altered metabolism lead to raised lactate and metabolic acidosis.
Septic shock may require careful treatment with IV fluids to improve blood pressure and tissue perfusion. For children under 16, the NICE guidelines recommend an initial 10 mL/kg bolus of a glucose-free crystalloid containing sodium of between 130-154 mmol/L (e.g., 0.9% sodium chloride), up to a maximum of 250 mL. Each fluid bolus should be followed by careful reassessment. Excess fluid can be harmful in children with sepsis, for example, causing pulmonary and tissue oedema, worsening oxygen delivery.
Patients should be escalated to high dependency or intensive care for treatment with vasopressors or inotropes, such as noradrenaline, guided by a specialist. Vasopressors cause vasoconstriction (narrowing of blood vessels), increasing systemic vascular resistance and, consequently, mean arterial pressure (MAP), helping to improve tissue perfusion. Positive inotropes increase heart contractility, thereby increasing cardiac output (CO).
Initial Assessment
The first step in assessing any unwell child is to observe their appearance and behaviour, considering whether they look well or unwell. A child who is running around the waiting room, playing and laughing, is less likely to have sepsis than a lethargic and drowsy child in their parent’s arms.
Their physical observations can be used to calculate the Paediatric Early Warning Score (PEWS) using age-specific ranges:
- Temperature
- Respiratory rate
- Heart rate
- Oxygen saturation
- Capillary refill time and blood pressure
- Consciousness level
Key factors to consider when assessing a child for suspected sepsis include:
- History of fever
- Recent presentations (e.g., to their GP or A&E)
- Poor oral intake
- Reduced urine output
- Reduced consciousness
- Reduced body tone (floppy)
- Weak cry or inconsolable
- Skin colour changes (cyanosis, mottled, pale or ashen)
- Non-blanching rashes (meningococcal disease)
- Skin breaks that could lead to infection (e.g., cuts)
A normal temperature does not exclude sepsis, especially in very young or immunocompromised patients. For example, neonates with sepsis are often afebrile, and children receiving chemotherapy who develop neutropenic sepsis may also have no fever.
Where children are low risk and managed at home, parents need clear verbal and written safety-net advice about when and how to seek further medical attention.
TOM TIP: All infants under 3 months with a temperature of 38ºC or above are at high risk for serious illness and need urgent assessment. This includes an emergency hospital referral if it occurs in the community.
Immediate Management
Sepsis is a medical emergency and needs to be managed urgently. Call for senior help early for experienced support. Initial management will involve an ABCDE approach, and include:
- Giving oxygen if the patient has evidence of shock or oxygen saturations are below 94%
- Obtaining IV access (cannulation)
- Blood tests, including a FBC, U&E, LFT, CRP and clotting screen
- Blood gas for lactate and glucose
- Blood cultures, ideally before giving antibiotics, provided it does not cause a delay
- Urine sample for dipstick testing and sent to the lab for microscopy, culture and sensitivities
- IV antibiotics within 1 hour for suspected sepsis with high-risk features, according to local guidelines
- IV fluids for shock or signs of poor perfusion
Further Management
Additional investigations may be performed depending on the suspected infection:
- Chest x-ray if pneumonia is suspected
- Abdominal and pelvic ultrasound if intra-abdominal infection is suspected
- Lumbar puncture if meningitis is suspected
- Meningococcal PCR blood test if meningococcal disease is suspected
- Serum cortisol if adrenal crisis is suspected
The antibiotic choice and duration are adjusted once a source of infection is found and an organism is isolated. Bacterial culture and sensitivities help guide antibiotic selection. Microbiology can provide advice, where necessary.
Last updated May 2026
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