Predicting Acute Respiratory Distress Syndrome in Severe Blunt Trauma: The Utility of Interleukin-18.

Background

In trauma, direct pulmonary injury and innate immune response activation primes the lungs for acute respiratory distress syndrome (ARDS). The inflammasome-dependent release of interleukin-18 (IL-18) was recently identified as a key mediator in ARDS pathogenesis, leading us to hypothesize that plasma IL-18 is a diagnostic predictor of ARDS in severe blunt trauma. Patients and

Methods

Secondary analysis of the Inflammation and Host Response to Injury database was performed on plasma cytokines collected within 12 hours of severe blunt trauma. Trauma-related cytokines, including IL-18, were compared between patients with and without ARDS and were evaluated for association with ARDS using regression analysis. Threshold cytokine concentrations predictive of ARDS were determined using receiver-operating curve (ROC) analysis.

Results

Cytokine analysis of patients without ARDS patients (n = 61) compared with patients with ARDS (n = 19) demonstrated elevated plasma IL-18 concentration in ARDS and IL-18 remained correlated with ARDS on logistic regression after confounder adjustment (p = 0.008). Additionally, ROC analysis revealed IL-18 as a strong ARDS predictor (area under the curve [AUC] = 0.83), with a threshold IL-18 value of 170 pg/mL (Youden index, 0.3). Unlike in patients without ARDS, elevated IL-18 persisted in patients with ARDS during the acute injury phase (p ≤ 0.02). Other trauma-related cytokines did not correlate with ARDS.

Conclusions

In severe blunt trauma, IL-18 is a robust predictor of ARDS and remains elevated throughout the acute injury phase. These findings support the use of IL-18 as a key ARDS biomarker, promoting early identification of trauma patients at greater risk of developing ARDS. Timely recognition of ARDS and implementation of advantageous supportive care practices may reduce trauma-related ARDS morbidity and costs.