AIM: Post-cardiac arrest syndrome (PCAS) is characterized by a sepsis-like inflammatory response and hemodynamic instability. We investigated the associations between systemic inflammation, endothelial damage and hemodynamic parameters including vasopressor support in patients with out-of-hospital cardiac arrest (OHCA).

METHODS: In this post-hoc study, we analysed data from 163 comatose patients included at a single center in the Target Temperature Management (TTM) trial, randomly assigned to TTM at 33°C or 36°C for 24h. Inflammatory biomarkers (interleukin (IL)-6, IL-10, procalcitonin and Tumor Necrosis Factor-α (TNF-α)) and endothelial biomarkers (thrombomodulin, sE-selectin, syndecan-1 and VE-cadherin) were measured at randomization and 24, 48 and 72h after OHCA. Corresponding hemodynamic status, heart rate (HR), mean arterial pressure (MAP) and Cumulative Vasopressor Index (CVI) was reported.

RESULTS: At randomization, level of IL-6 correlated negatively with MAP (r=-0.19, p=0.03) and positively with HR (r=0.29, p=0.0002). Serial IL-6 levels correlated consistently with CVI at 24h: (r=0.19, p=0.02) 48h: (r=0.31, p=0.0001) and 72h: (r=0.39, p<0.0001). Thrombomodulin (r=0.23, p=0.004) and syndecan-1 (r=0.27, p=0.001) correlated with CVI at 48h. All inflammatory markers excerpt IL-10 and all endothelial markers correlated with CVI at 72h. Multivariable regression models adjusting for potential confounders confirmed that IL-6 (β=0.2 (95% CI: 0.06-0.3), p=0.004) and TTM-group (TTM36: β=-0.5 (95% CI: -0.9 to 0.1), p=0.01) were associated with CVI at 48h. At 72h after OHCA, IL-6 (β=0.3 (95% CI: 0.03-0.6), p<0.0001), TNF-α (β=-0.4 (95% CI:- 0.5 to 0.2), p<0.0001) and TTM-group (TTM36: β=-0.4 (95% CI: -0.8 to 0.1), p=0.008) were associated with CVI. An overall two-fold increase in levels of IL-6 (β=0.2 (95% CI: 0.1-0.3), p<0.0001) and IL-10 (β=-0.2 (95% CI: -0.3 to 0.06), p=0.005) within 72h after OHCA were significantly associated with CVI. TTM-group modified the interaction between CVI and IL-6 (pinteraction=0.008), but not with IL-10 (pinteraction=0.23).

CONCLUSIONS: In comatose survivors after OHCA, increasing systemic inflammation and endothelial injury was associated with increased need of vasopressor support. Systemic inflammation, in particular IL-6, was consistently associated with vasopressor support, however endothelial injury may also play a role in PCAS associated cardiovascular dysfunction after OHCA.