PURPOSE: Inflammatory mediators are known to be elevated in critically ill burn patients. Recent data suggests that certain serum cytokine profiles may be used as predictors of outcome in this population.
METHODS: We recently reported results of a prospective randomized trial comparing high frequency percussive ventilation (HFPV) to conventional low tidal volume ventilation (LTV) in burn intensive care unit (BICU) patients (n=62) with respiratory failure which demonstrated no difference in our primary and major secondary outcomes. Given that elevations in inflammatory mediators are associated with increased multiple organ failure and death in the critically ill, we hypothesized that there would be observable alterations in cytokine profiles in association with poor outcomes. We analyzed selected serum biomarkers at 1, 3 and 7 days after randomization in each arm. The log intensity of Interleukin (IL)-β, IL-6, IL-8, GM-CSF, and TNF-α were used for analysis.
RESULTS: Greater than 90% of values for IL-β, GM-CSF, and TNF-α fell below the lower limit of quantitation (LLOQ) and thus were not analyzed. Univariate analysis demonstrated higher levels of IL-6 (2.4 ±0.4 vs. 1.7 ±0.5 log pg/mL, p =0.0003), and IL-8 (2.3 ±0.5 vs. 1.7 ±0.5 log pg/mL, p =0.028) in patients who died when compared to survivors in day 7. Multiple logistic regression analysis with backward elimination revealed that elevated IL-8 on days 1, 3 or 7 significantly increase the likelihood of the combined end-point of ventilator associated pneumonia (VAP) or death after correcting for covariates. At Day 1, the OR was 7.9 (95% CI 1.9-33.4, p = 0.005), At Day 3 the OR was 26.6 (95% CI 4.0-178.7, p = 0.0007). At Day 7 the OR was 7.3 (95% CI 1.9-28.4, p = 0.004).
CONCLUSION: Early increases in IL-6 and IL-8 are associated with a multi-fold increase in the occurrence of VAP or death.
CLINICAL IMPLICATIONS: Serum IL-6 and IL-8 levels can be elevated early in BICU patients. Measuring IL-6 and IL-8 on admission can help identify those patients at risk for poor outcomes.
DISCLOSURE: Mehdi Shelhamer, No Financial Disclosure Information; No Product/Research Disclosure Information