Criteria

A variety of approaches have been proposed for diagnosing sepsis in children. Some of these focus on the formal criteria, while others aim to improve earlier recognition by focusing on symptoms and signs that indicate a child is at high risk of developing sepsis.

Expert consensus has now recommended adopting the new Phoenix Sepsis Score in children in place of the criteria for systemic inflammatory response syndrome (SIRS).[5]​ This change comes about mostly due to limitations of the criteria for SIRS including its poor predictive properties and use of the term 'severe sepsis', which is now deemed redundant. Survey data also found that most paediatric clinicians used the term sepsis to refer to infection with life-threatening organ dysfunction, which differs from the prior paediatric sepsis criteria that was used in the SIRS criteria.[5]

It is important to note that the Phoenix Sepsis Score is indicated for diagnosis of sepsis (i.e., infection with life-threatening organ dysfunction) and not as a screening tool for possible sepsis before organ dysfunction is overt.[5]​ It is highly recommended that local screening tools to recognise the early signs of sepsis should continue to be used. Phoenix criteria are not designed to replace existing screening tools.

Phoenix Criteria for Pediatric Sepsis and Septic Shock, 2024[5][7]​​

The novel Phoenix sepsis criteria for sepsis and septic shock in children has been validated by the the Society of Critical Care Medicine Pediatric Sepsis Definition Task Force and are intended to identify life-threatening organ dysfunction due to infection - it is not a screening tool for sepsis.

The score is based on points relating to a composite 4-organ system model which includes criteria for respiratory, cardiovascular, coagulation and neurological dysfunction, and also factors in age.

A Phoenix Sepsis Score of 2 points or higher in children with suspected or confirmed infection potentially identifies sepsis with life-threatening organ dysfunction. Septic shock can be identified by a cardiovascular score of at least 1 point in children with sepsis.

The Phoenix Sepsis Scoring criteria was based on retrospective data from multiple countries including USA, Colombia, Bangladesh, China and Kenya - thus representing both high and low resource settings. This novel Phoenix criteria for sepsis diagnosis in children was validated as being of superior performance as compared to the existing guidelines of the 2005 International Pediatric Sepsis Consensus Conference.[3] Using a modified Delphi consensus method, the Phoenix criteria for diagnosing sepsis and septic shock in children was also validated by the Pediatric Sepsis Definition Task Force, comprising of 35 experts in paediatrics from six continents, that was convened by The Society of Critical Care Medicine.[5]

International Consensus Conference on Pediatric Sepsis definitions[3]

The following standardised definitions were initially developed by the International Consensus Conference on Pediatric Sepsis to standardise entry criteria for large multi-centre clinical trials. It should be noted that clinical diagnosis of sepsis must occur earlier in the care pathway than classification allows.

Infection:

  • Suspected or proven infection with any pathogen.

Systemic inflammatory response syndrome (SIRS):

  • Generalised inflammatory response defined by the presence of 2 or more of the following criteria (abnormal temperature or white cell count must be one of the criteria):

    • Abnormal core temperature (<36°C or >38.5°C [<97°F or >101°F])

    • Abnormal heart rate (>2 standard deviations above normal for age, or <10th percentile for age if child is <1 year of age)

    • Raised respiratory rate (>2 standard deviations above normal for age, or mechanical ventilation for acute lung disease)

    • Abnormal white cell count in circulating blood (above or below normal range for age, or >10% immature white cells).

Sepsis:

  • SIRS in the presence of infection.

Severe sepsis:

  • Sepsis in the presence of cardiovascular dysfunction, acute respiratory distress syndrome, or dysfunction of 2 or more organ systems.

Septic shock:

  • Sepsis with cardiovascular dysfunction persisting after at least 40 mL/kg fluid resuscitation in 1 hour.

Refractory septic shock:

  • Fluid-refractory septic shock: shock persisting after ≥60 mL/kg of fluid resuscitation

  • Catecholamine-resistant septic shock: shock persists despite therapy with catecholamines (i.e., dopamine and/or adrenaline [epinephrine], or noradrenaline [norepinephrine] infusion).

Organ dysfunction definitions[3]

Standardised criteria for organ dysfunction (i.e., cardiovascular, respiratory, neurological, haematologic, renal, and hepatic dysfunction) are defined below as per the International Consensus on Pediatric Sepsis guidelines.

Cardiovascular dysfunction:

  • Hypotension (defined as systolic BP <5th percentile for age or systolic BP >2 standard deviations below normal for age), or

  • Requirement for a vasoactive drug to treat hypotension, or

  • Any 2 of the following abnormalities:

    • Metabolic acidosis (base deficit >5 mmol/L [>5 mEq/L])

    • Elevated arterial serum lactate (>twice upper normal limit)

    • Oliguria (urine output <0.5 mL/kg/hour)

    • Prolonged capillary refill (>5 seconds)

    • Raised core to peripheral temperature gap (>3°C [>5.4°F])

  • These abnormalities must be persistent after administration of a 40 mL/kg fluid bolus in 1 hour.

Respiratory dysfunction:

  • Arterial blood gas abnormalities:

    • P/F ratio (PaO₂/fraction of inspired oxygen [FiO₂]) <40 (in the absence of cyanotic heart disease or known pre-existing pulmonary disease), or

    • PaCO₂ >8.64 kPa (>65 mmHg), or 2.66 kPa (20 mmHg) above the baseline level, or

    • Requirement for FiO₂ >0.5 to maintain pulse oximeter saturations >92%, or

    • Requirement for mechanical ventilation (invasive or non-invasive).

Neurological dysfunction:

  • Glasgow Coma Scale (GCS) score <12, or

  • Acute decrease in GCS of >3 points from an abnormal baseline.

Haematological dysfunction:

  • Platelet count <80 × 10⁹/L (<80,000/microlitre), or

  • Platelet count decrease of 50% from highest value in past 3 days, or

  • INR >2.

Renal dysfunction:

  • Serum creatinine >2 times upper limit of normal, or

  • Increase in serum creatinine >2 times baseline level.

Hepatic dysfunction:

  • Total bilirubin >68 micromol/L (>4 mg/dL) (outside neonatal age range), or

  • Alanine aminotransferase >2 times upper normal limit.

It should be noted that the standardised criteria for each organ dysfunction are not based on evidence related to clinical outcomes.

Sepsis: recognition, diagnosis and early management (National Institute for Health and Care Excellence, 2024[50]

The National Institute for Health and Care Excellence has published guidance on the recognition, diagnosis, and early management of sepsis, which includes specific criteria for risk stratification of children and neonates with suspected sepsis based on the age groups:

Using specific criteria relating to patient history, behaviour, appearance, and clinical evaluations (e.g., respiratory, circulation, hydration, and temperature), patients can be stratified as low risk, moderate to high risk, or high risk of severe illness and death from sepsis.

Classification of neonatal sepsis

Neonatal sepsis is defined as a clinical syndrome of sepsis, and/or isolation of a pathogen in the blood stream, in an infant in the first 28 days of life.[8] Symptoms and clinical signs are often less apparent or more subtle than in older children. Sepsis in newborns is usually classified in terms of timing of onset in relation to birth:

  • Early-onset neonatal sepsis: neonatal sepsis occurring in the first 72 hours of life[9]

  • Late-onset neonatal sepsis: neonatal sepsis occurring after the first 72 hours of life.[10]

Classification by age group

For the purposes of consistent classification, the following age groups are used for referencing normal ranges of physiological variables and laboratory values:[3]

  • Newborn: 0 days to 1 week

  • Neonate: 0 days to 1 month

  • Infant: 1 month to <2 years

  • Toddler and preschool: ≥2 years to <6 years

  • School-age child: ≥6 years to <13 years

  • Adolescent and young adult: ≥13 years to <18 years.

Note that preterm infants are not classified in this age scheme.

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