Impact of serum high-mobility group box 1 protein elevation on oxygenation impairment after thoracic aortic aneurysm repair

High-mobility group box 1 protein (HMGB1) is a late mediator of inflammatory responses that can cause acute lung injury. We examined the significance of serum HMGB1 elevation in the development of systemic inflammatory response syndrome (SIRS) and lung oxygenation impairment (LOI) after thoracic aortic aneurysm (TAA) repair. Serial measurements of the serum HMGB1 level and SIRS score for 7 days after surgery were determined in 20 patients with TAA who underwent surgical repair. Arterial oxygen tension was measured serially for at least 4 days after surgery, and LOI was defined as the lowest PaO₂/FiO₂ ratio ≤200 mmHg. The serum HMGB1 level was markedly increased after surgery, peaking on day 2, and remained significantly elevated on day 7. Peak HMGB1 level positively correlated with SIRS duration and the cumulative SIRS score during postoperative days 1-7 (P = 0.0013 and P = 0.0004, respectively). Peak HMGB1 level and cumulative SIRS score were higher in patients with LOI than in those without (P = 0.01 and P = 0.044, respectively). Peak HMGB1 level was negatively correlated with the lowest PaO₂/FiO₂ ratio (P = 0.0077) and positively correlated with postoperative length of hospitalization (P = 0.042). A greater serum HMGB1 elevation after TAA repair was associated with more severe SIRS and a higher incidence of LOI. HMGB1 might play a key role in the pathogenesis of SIRS and LOI after surgical TAA repair.