Murray Score for Acute Lung Injury

Why Use

Provides a relatively standardized method of assessing severity of lung injury in the setting of ARDS and helps guide which patients may benefit from extracorporeal life support. ECMO has expanded management options for patients with severe forms of ARDS; however, optimal criteria and timing of ECMO for initiation are unestablished. The Murray Score is one system that may help guide practitioners in selecting appropriate candidates for this treatment.

When to Use

Patients with severe hypoxemic respiratory failure from acute respiratory distress syndrome (ARDS). May be used in conjunction with other clinical factors (e.g. age, comorbidities, etiology of respiratory failure, presence of other organ dysfunction, duration of endotracheal intubation) to help determine whether a patient may benefit from extracorporeal life support.

Formula

Pearls / Pitfalls

Indicates severity of ARDS; should not be used by itself to determine candidacy for ECMO. Should not be used to characterize severity of other forms of acute or chronic respiratory failure, or to assign severity to patients with ARDS manifested by severe, uncompensated respiratory acidosis. Not applicable to patients being considered for ECMO for cardiac failure.

Management

Once the decision is made to initiate ECMO, the patient should be transferred and managed at a center experienced at treating patients with extracorporeal life support. The following algorithm highlights the basic considerations for types of ECMO cannulation strategies based on the different pathophysiological indications. Once the patient is supported on extracorporeal life support with direct oxygenation and removal of carbon dioxide from the blood, it may be possible to apply low-volume, low-pressure ventilation strategies, which is the underlying principle for ARDS management. Adapted from the ELSO Red Book, 5th Edition (Brogan et al).

Critical Actions

The Murray Score is only a guide and should not supercede clinical judgement by clinicians about the appropriateness of ECMO initiation. In the only modern clinical trial evaluating ECMO for ARDS (the CESAR Trial in Lancet 2009 ), the indications for ECMO in patients with ARDS included Murray Scores 3-4 or a pH <7.20 despite optimal conventional treatment. Patients with Murray Scores >2 and P/F ratio <150 should be considered for transfer to an ECMO center.

Advice

According to the Extracorporeal Life Support Organization (ELSO) guidelines: Patients with ARDS and a Murray Score of 3-4 may be considered for ECMO cannulation in the correct clinical setting. Patients with a Murray Score >2 could be considered for transfer to a center with ECMO capabilities. It is important to consider all other patient factors as well as contraindications and risks of ECMO. Relative contraindications include: Any condition that would limit the benefit of ECMO (such as severe neurologic injury or advanced malignancy). Any contraindication to anticoagulation. High FiO ₂ requirements or high-pressure mechanical ventilation >7 days. Limited vascular access.

More Information

Interpretation: Murray Score Severity 0 No lung injury 0.1–2.5 Mild to moderate >2.5 Severe If Murray Score ≥3.0, then patient should be considered for ECMO referral.