Introduction
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Vasoplegic syndrome (VS) following heart surgery using cardiopulmonary bypass (CPB) has been recently recognized and implicated in life-threatening complications.  The aim of this study was to identify associated factors for the development of VS after CPB. 

Methods
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We performed a nested case--control study of 50 patients undergoing CPB, 27 (54%) men and 23 (46) women, mean age 66.5 (SD 9.6) years.  VS was defined as systemic vascular resistance index \<1,600 dyn∙seg/cm^5^/m^2^and cardiac index \>2.5 l/min/m^2^within the first postoperative 4 hours.  Vasoplegic shock was defined as vasoplegic patients that needed norepinephrine for at least 4 hours, after failure to respond to appropriate volume expansion.  Excessive bleeding was defined as blood loss \>1 l/24 hours, while total bleeding was considered as blood loss until chest tube withdrawal.  Demographic variables, surgical procedures and postoperative variables were collected.  We recorded data related to coagulation, fibrinolysis, complement, inflammation, blood loss at different time points, preoperative, at 0, 4 and 24 hours after surgery, and hemoderivative requirements.  We used the Pearson chi-squared test, the Fisher exact test, the Student *t*test and the Mann--Whitney U test for nonparametric variables.  SPSS version 12.1 was used. 

Results
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Seventeen (34%) patients had VS, 11 (65%) men and six (35%) women.  Longer aortic clamping time (*P*= 0.007) and CPB time (*P*= 0.013) were associated with VS.  These patients showed a higher cardiac index at 4 hours (*P*\< 0.001) and lactic acid within the first 24 hours.  Seven of these patients (41%) fulfilled vasoplegic shock criteria (*P*\< 0.001).  We found higher levels of IL-6 at 0 hours (*P*= 0.02) and 4 hours (*P*= 0.001), and soluble TNF receptor at 0 hours (*P*= 0.044).  At ICU admission (0 hours) there was a higher coagulation activation: INR (*P*= 0.005), fibrinogen (*P*= 0.001), antithrombin (*P*= 0.007); lower levels of plasminogen activator inhibitor-1 (*P*= 0.023) as well as lower plasminogen activator inhibitor-1/tissue-plasminogen activator ratio (*P*= 0.021), and higher levels of D-dimer (*P*= 0.041); lower levels of C3 (*P*= 0.023), B factor (*P*= 0.013), C4 (*P*= 0.015) as well as a significantly higher decrease between preoperative and 0-hour levels of C1-inhibitor, C4, C3 and B factor.  Lower levels of leptins at 0, 4 and 24 hours were found.  Vasoplegic patients showed higher blood losses along all time points (Figure [1](#F1){ref-type="fig"}), higher incidence of excessive bleeding (60% vs 40%; *P*= 0.011) and required more hemoderivatives during the ICU stay, plasma (*P*= 0.016) and platelets (*P*= 0.002). 

![]( cc5414-1){#F1}

Conclusion
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VS post-CPB was associated with activation of serin protease systems, which leads to higher blood loss and excessive bleeding.