Overview
The Phoenix Sepsis Score is the organ-dysfunction component of the 2024 international consensus criteria for pediatric sepsis and septic shock. It replaces older pediatric sepsis definitions that relied heavily on systemic inflammatory response syndrome (SIRS) and adult-derived organ failure scores. Phoenix was developed and validated in large multicenter cohorts and published in JAMA in 2024 alongside the consensus definitions.
The score sums dysfunction across four domains: respiratory (0–3 points), cardiovascular (0–6 points), coagulation (0–2 points), and neurologic (0–2 points), for a total range of 0 to 13. In a child with suspected or confirmed infection:
- Sepsis is defined as a Phoenix total score ≥ 2.
- Septic shock is sepsis plus a cardiovascular score ≥ 1 (at least one cardiovascular dysfunction point).
This calculator implements the same logic as the open-source phoenix R package used in the primary publications. It is intended for education and clinical support; final diagnosis and management require physician judgment, source control, antimicrobials, and resuscitation per institutional protocols.
Why pediatric sepsis definitions changed
Prior criteria (including pediatric SIRS-based sepsis and pediatric Sequential Organ Failure Assessment, pSOFA) had limitations: poor specificity in febrile children, variable performance across ages, and misalignment with how clinicians identify life-threatening organ dysfunction in infection. The Phoenix workgroup sought a definition grounded in measurable organ dysfunction rather than inflammatory markers alone.
Phoenix emphasizes four organ systems most associated with mortality and morbidity in pediatric sepsis trials. The score is designed for children from birth through 18 years (≤ 216 months), term gestation at birth, and evaluation outside the birth hospitalization. Age is entered in months and is not corrected for prematurity in the reference implementation.
Prerequisites for applying Phoenix
Phoenix organ-dysfunction points are interpreted only when infection is present or strongly suspected. Clinical infection may be defined by positive cultures, clinical syndrome with antimicrobial treatment, or site-specific evidence (pneumonia, meningitis, cellulitis, and similar). Without infection, organ dysfunction may reflect another primary diagnosis (cardiogenic shock, trauma, aspiration) and should not be labeled sepsis by score alone.
Data should reflect the patient''s status at the time of assessment (PICU admission, emergency department presentation, or ward deterioration). Serial scoring can track response to resuscitation, though this tool computes a single time point from entered values.
Respiratory domain (0–3 points)
Respiratory dysfunction integrates gas exchange indices with support requirements:
- PaO₂:FiO₂ (P/F ratio) using arterial PaO₂ (mmHg) and FiO₂ as a decimal (0.21 for room air to 1.0).
- SpO₂:FiO₂ (S/F ratio) using SpO₂ percent and FiO₂, calculated only when SpO₂ is ≤ 97% (per Phoenix software rules).
- Invasive mechanical ventilation (IMV).
- Other respiratory support: supplemental oxygen, high-flow nasal cannula, noninvasive positive pressure ventilation, or IMV.
Ratio thresholds align with pediatric acute lung injury strata:
| Measure | 0 points | 1 point | 2 points | 3 points |
|---|---|---|---|---|
| PaO₂:FiO₂ | ≥ 400 | < 400 | < 200 | < 100 |
| SpO₂:FiO₂ | ≥ 292 | < 292 | < 220 | < 148 |
The executable respiratory score combines IMV, other support flags, and ratio cutoffs exactly as in the phoenix package (not simply the worst ratio tier in isolation). If PaO₂ or SpO₂ is missing, the reference software treats that limb as a favorable ratio for scoring purposes. FiO₂ must be entered accurately when the patient receives supplemental oxygen or ventilator support.
Cardiovascular domain (0–6 points)
Cardiovascular dysfunction is the sum of three parallel subscores, each contributing 0, 1, or 2 points:
Vasoactive medications (0–2 points)
Count distinct systemic infusions among:
- Dobutamine
- Dopamine
- Epinephrine
- Milrinone
- Norepinephrine
- Vasopressin
0 agents = 0 points; 1 agent = 1 point; 2 or more agents = 2 points. Inotropes and vasopressors signal hemodynamic instability and are central to the septic shock definition when any cardiovascular point is present.
Lactate (0–2 points)
- < 5 mmol/L: 0 points
- 5 to < 11 mmol/L: 1 point
- ≥ 11 mmol/L: 2 points
Elevated lactate reflects tissue hypoperfusion and is a key resuscitation target in pediatric sepsis bundles. Use a contemporaneous venous or arterial lactate from the same clinical window.
Mean arterial pressure for age (0–2 points)
MAP may be measured invasively or estimated from blood pressure: MAP ≈ DBP + (SBP − DBP) / 3. Age-specific hypotension thresholds (in months) are:
| Age (months) | 0 MAP points | 1 MAP point | 2 MAP points |
|---|---|---|---|
| 0 ≤ age < 1 | MAP ≥ 31 | 17 ≤ MAP < 31 | MAP < 17 |
| 1 ≤ age < 12 | MAP ≥ 39 | 25 ≤ MAP < 39 | MAP < 25 |
| 12 ≤ age < 24 | MAP ≥ 44 | 31 ≤ MAP < 44 | MAP < 31 |
| 24 ≤ age < 60 | MAP ≥ 45 | 32 ≤ MAP < 45 | MAP < 32 |
| 60 ≤ age < 144 | MAP ≥ 49 | 36 ≤ MAP < 49 | MAP < 36 |
| 144 ≤ age ≤ 216 | MAP ≥ 52 | 38 ≤ MAP < 52 | MAP < 38 |
If age or MAP is not provided, the reference implementation applies default values that yield no MAP points; enter both for accurate cardiovascular scoring.
Coagulation domain (0–2 points)
One point is assigned for each abnormality, with a hard cap of 2 points total:
- Platelets < 100 × 10³/µL
- INR > 1.3
- D-dimer > 2 mg/L FEU (fibrinogen-equivalent units)
- Fibrinogen < 100 mg/dL
In the phoenix reference software, omitted laboratories are treated as normal (0 points) for that analyte. This matches development assumptions but means incomplete labs may underestimate coagulation dysfunction. When disseminated intravascular coagulation is suspected, obtain full coagulation panels rather than relying on imputed normals.
Neurologic domain (0–2 points)
- Bilaterally fixed pupils: 2 points (maximum neurologic score).
- Glasgow Coma Scale total ≤ 10: 1 point when pupils are not bilaterally fixed.
- Missing GCS: treated as 15 (no impairment from GCS) in reference software.
The neurologic score is capped at 2. Encephalopathy from infection, metabolic derangement, or hypoperfusion may present with depressed consciousness before fixed pupils appear; GCS should be recorded at the same time as other Phoenix inputs.
Total score and clinical definitions
Total Phoenix score = respiratory + cardiovascular + coagulation + neurologic (range 0–13).
| Total score (with infection) | Cardiovascular score | Interpretation |
|---|---|---|
| 0–1 | Any | Does not meet Phoenix sepsis threshold |
| ≥ 2 | 0 | Sepsis without septic shock by Phoenix |
| ≥ 2 | ≥ 1 | Septic shock (sepsis plus cardiovascular dysfunction) |
Higher totals generally indicate more extensive multiorgan dysfunction and correlate with worse outcomes in validation cohorts, but the binary sepsis threshold (≥ 2) is the primary epidemiologic and trial-enrollment cut point in the 2024 consensus.
Clinical application in practice
Phoenix supports several workflows:
- Early recognition in emergency departments and general wards when a febrile or infected child deteriorates.
- PICU triage and research using a standardized organ-dysfunction metric comparable across centers.
- Quality and registry reporting aligned with the 2024 consensus definitions.
- Communication among teams about which organ systems are driving the score.
Phoenix does not replace clinical sepsis bundles: timely antibiotics, fluid resuscitation, source control, escalation of respiratory support, and vasoactive infusion when perfusion remains inadequate remain essential regardless of the numeric total.
Comparison with prior pediatric scores
SIRS-based pediatric sepsis required two SIRS criteria plus infection but had limited specificity in fever without severe illness. pSOFA adapted adult SOFA to children but was not designed as a standalone sepsis definition and performed differently across age strata. Phoenix was calibrated specifically as a sepsis organ-dysfunction score with explicit shock criteria tied to the cardiovascular domain, improving alignment with outcomes studied in modern PICU datasets.
Clinicians may still document SIRS or pSOFA for research continuity, but international consensus now centers on Phoenix for sepsis and septic shock nomenclature in pediatrics.
Special populations and documentation notes
Neonates and ex-premature infants: The score was not gestational-age corrected; interpret cautiously in premature neonates and very young infants where normal MAP and SpO₂ physiology differ.
Congenital heart disease: Baseline hypoxemia, prior palliation, and chronic vasoactive support complicate respiratory and cardiovascular domains; Phoenix points may reflect underlying cardiac physiology rather than new sepsis-related dysfunction.
Chronic lung disease: Home oxygen or baseline ventilator dependence requires careful attribution of respiratory support flags.
Immunocompromised hosts: Infection may present without fever; Phoenix still applies when infection is documented and organ dysfunction is present.
Limitations
- Phoenix requires infection context; the score alone does not diagnose sepsis.
- Missing laboratories and vitals are handled as normal in reference software, which can underestimate dysfunction if data are incomplete.
- Respiratory scoring follows package-specific combination rules; manual mental math from ratio tables alone may disagree with the official algorithm.
- Validation cohorts emphasized term infants and children through 18 years; extrapolation outside these bounds is uncertain.
- Phoenix does not specify antimicrobial choice, fluid volumes, or escalation triggers; local bundles and specialist consultation remain mandatory.
- Fixed pupils and very low GCS may reflect non-infectious processes (trauma, intoxication, intracranial hemorrhage); clinical synthesis is required.
How to use this calculator
- Enter age in months (0–216 for the validated range).
- Complete respiratory inputs: FiO₂, optional PaO₂ and SpO₂, IMV, and other respiratory support.
- Complete cardiovascular inputs: vasoactive agents, lactate (mmol/L), and MAP or blood pressure for age-specific hypotension scoring.
- Enter available coagulation labs (platelets, INR, D-dimer, fibrinogen); leave blank only if you accept normal imputation per Phoenix rules.
- Enter neurologic data: GCS total and whether pupils are bilaterally fixed.
- Review domain subscores, total (0–13), and whether thresholds for sepsis (≥ 2) and septic shock (sepsis with cardiovascular ≥ 1) are met in the setting of infection.
Use the Formula Explained tab for threshold tables and domain caps. Confirm critical results against institutional policies and the phoenix reference implementation when research or registry accuracy is required.
Disclaimer: This content is for educational purposes only and is not medical advice. Pediatric sepsis management requires qualified clinicians, timely resuscitation, and adherence to local protocols and specialist guidance.