Why use it

Blast lung injury is the most lethal form of primary blast injury in survivors of explosions. The BLI severity score provides standardized triage, guides mechanical ventilation settings (especially protective lung ventilation to minimize secondary barotrauma), informs clinical decision-making about prone positioning and ECMO, and predicts ARDS risk and mortality.

About

The Blast Lung Injury (BLI) Severity Score classifies primary blast lung injuries into three grades based on clinical presentation, chest radiographic findings, arterial blood gas values, and ventilator requirements. It was developed to standardize the assessment of blast-induced pulmonary barotrauma resulting from high-pressure blast waves, which cause unique injury patterns including pulmonary contusion, alveolar rupture, air embolism, and direct tissue destruction. Grades I–III correspond to mild, moderate, and severe blast lung injury with distinct management algorithms and prognoses.

When to use

Any patient exposed to a blast/explosion with respiratory symptoms or radiographic abnormalities
Guiding ventilator management decisions in blast-injured patients
Predicting need for advanced respiratory support (prone positioning, HFOV, ECMO)
Mass casualty incidents: triage and resource allocation in blast scenarios
Military and civilian blast trauma care protocols

Formula

BLI Grade Classification: Grade I — Mild: • Dyspnea, tachycardia, tachypnea • CXR: localized infiltrate or contusion • PaO₂/FiO₂ > 200 (or SpO₂ ≥ 90% on <40% O₂) • No mechanical ventilation required Grade II — Moderate: • Above symptoms + more prominent signs • CXR: bilateral patchy infiltrates (≤ 2 lung zones) • PaO₂/FiO₂ 100–200 • Mechanical ventilation typically required Grade III — Severe: • Severe respiratory failure • CXR: bilateral dense opacities or whiteout (≥ 3 lung zones) • PaO₂/FiO₂ < 100 • High-level ventilatory support required; ARDS criteria met

Pearls & pitfalls

Blast lung injury may be occult — always obtain CXR or chest CT in blast survivors, even those initially asymptomatic.
Air embolism is a feared complication — AVOID positive pressure ventilation when possible in Grade I; use with great caution in Grade II.
Nasogastric tubes and procedures requiring Valsalva should be minimized to reduce air embolism risk.
Clinical deterioration can be rapid — reassess severity every 2–4 hours in the first 24 hours.
PaO₂/FiO₂ ratio (P:F ratio) is the single most important physiological variable in the BLI score.
ARDS criteria may overlap with Grade III blast lung — use BERLIN definition alongside BLI grading.
Concomitant non-blast injuries (penetrating wounds, TBI) frequently coexist and must be managed simultaneously.

Next steps

Grade I (Mild): Supportive care; supplemental oxygen; close monitoring for progression; avoid high-risk procedures (IPPV, NGT). Grade II (Moderate): Low-pressure mechanical ventilation (TV 5–6 mL/kg IBW, peak pressure <40 cmH₂O); avoid excessive PEEP; watch for air embolism; monitor for deterioration to Grade III. Grade III (Severe): High-level ICU support; lung-protective ventilation; consider HFOV; prone positioning; evaluate ECMO candidacy; prepare for prolonged ICU course.

Evidence

Pizov R et al. (Chest 1999) and Avidan V et al. (J Trauma 2005) defined the BLI grading system from Israeli military and civilian blast experience. Grades correlate with mortality: Grade I ~0%, Grade II ~5–15%, Grade III ~30–50%. Endorsed in NATO and US military trauma protocols.

References

Pizov R et al. Blast lung injury from an explosion on a civilian bus. Chest. 1999;115(1):165-172. — link
Avidan V et al. Blast lung injury: clinical manifestations, treatment, and outcome. Am J Surg. 2005;190(6):945-950. — link
Ritenour AE, Baskin TW. Primary blast injury: update on diagnosis and treatment. Crit Care Med. 2008;36(7 Suppl):S311-7. — link

Blast Lung Injury Severity Score

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