What is the Murray Lung Injury Score?
The Murray Lung Injury Score, also called the Murray score or lung injury score, is a bedside severity score used to describe the severity of acute lung injury and acute respiratory distress syndrome. It combines oxygenation, chest radiograph involvement, ventilator support, and static respiratory system compliance into a single average score.
PulmTools uses the Murray score as an ARDS severity signal and as part of a larger respiratory-first ECMO decision support workflow. A high score should not be treated as a standalone ECMO indication, but it can help clinicians recognize severe lung injury and decide when to review VV ECMO referral criteria.
Murray Score Formula
The Murray Lung Injury Score is calculated by averaging the available component scores. Each component is scored from 0 to 4, with higher values reflecting more severe lung injury.
Murray Score = sum of component scores ÷ number of components used
When all four standard components are available, PulmTools averages chest radiograph score, PaO₂/FiO₂ score, PEEP score, and static compliance score.
Murray Lung Injury Score Components
| Component | 0 | 1 | 2 | 3 | 4 |
|---|---|---|---|---|---|
| Chest radiograph involvement | No quadrants involved | 1 quadrant | 2 quadrants | 3 quadrants | 4 quadrants |
| PaO₂ / FiO₂ ratio | > 300 | 225–299 | 175–224 | 100–174 | < 100 |
| PEEP, cm H₂O | ≤ 5 | 6–8 | 9–11 | 12–14 | ≥ 15 |
| Static compliance, mL/cm H₂O | ≥ 80 | 60–79 | 40–59 | 20–39 | < 20 |
Murray Score Interpretation
Low score based on the selected components. Continue to interpret within the full clinical picture.
Meaningful lung injury. Review ARDS management, oxygenation trajectory, ventilator settings, and response to therapy.
Severe range. Review lung-protective ventilation, proning/rescue therapy status, contraindications, and VV ECMO referral criteria.
Murray Score and ECMO Referral
The Murray score has historical importance in ARDS and ECMO literature, but it should not be used alone to decide ECMO candidacy. PulmTools intentionally frames the score as a severity marker that can feed into a broader referral workflow.
If the score is severe, the next step is not “ECMO now.” The next step is to review whether severe ARDS referral triggers are present, whether lung-protective ventilation and proning have been attempted when appropriate, and whether major contraindications or transfer barriers exist.
Recommended PulmTools workflow
- 1. Calculate Murray Lung Injury Score for ARDS severity.
- 2. Review oxygenation, pH/PaCO₂, ventilator days, plateau pressure, and rescue therapies.
- 3. Open the VV ECMO Referral Criteria tool if severe ARDS or refractory gas exchange failure is present.
- 4. Review contraindications and generate a concise handoff summary for the ECMO center.
Murray Score vs Berlin ARDS Definition
The Berlin ARDS definition and the Murray Lung Injury Score are related, but they are not the same tool. Berlin ARDS severity is commonly organized around oxygenation severity, especially PaO₂/FiO₂ ratio under appropriate ventilator conditions.
The Murray score is broader because it incorporates imaging, PEEP, and respiratory system compliance in addition to the PaO₂/FiO₂ ratio. That makes it useful as a practical ARDS severity calculator, but also means it should be interpreted alongside the patient's trajectory, ventilator strategy, hemodynamics, and goals of care.
Limitations of the Murray Score
- It does not determine ECMO candidacy, acceptance, or transfer eligibility.
- It does not replace EOLIA-style severe ARDS criteria, ELSO guidance, local ECMO center criteria, or multidisciplinary consultation.
- Chest radiograph scoring can be subjective and may vary by reader.
- Static compliance can be affected by ventilator mode, measurement technique, body habitus, pleural pressure, abdominal pressure, and chest wall mechanics.
- The score should be interpreted with trajectory, reversibility, contraindications, and response to ARDS rescue therapies.
Murray Score FAQ
What is the Murray Lung Injury Score?
The Murray Lung Injury Score is a bedside scoring system used to describe the severity of acute lung injury and ARDS. It combines chest radiograph involvement, oxygenation impairment, PEEP requirement, and respiratory system compliance into a single average score from 0 to 4.
How do you calculate the Murray score?
Assign 0 to 4 points for each available component: chest radiograph quadrants involved, PaO₂/FiO₂ ratio, PEEP, and static compliance. Add the selected component scores and divide by the number of components used. PulmTools averages all four standard components when all are available.
What Murray score is considered severe?
A Murray Lung Injury Score greater than 2.5 is commonly interpreted as severe lung injury. A score near or above 3 should prompt careful review of ARDS optimization, trajectory, and whether VV ECMO referral criteria should be reviewed.
Is the Murray score the same as the Berlin ARDS definition?
No. The Berlin ARDS definition classifies ARDS severity largely by PaO₂/FiO₂ ratio under specified ventilator conditions. The Murray score is a broader lung injury score that also includes radiographic involvement, PEEP, and static compliance.
Does a high Murray score mean the patient needs ECMO?
No. A high Murray score does not automatically mean the patient should receive ECMO. It should be treated as a severity marker that may trigger review of lung-protective ventilation, proning, rescue therapies, contraindications, and VV ECMO referral criteria.