Serial change of C1 inhibitor in patients with sepsis--a preliminary report.

Objective: C1 inhibitor (C1INH) regulates not only the complement system but also the plasma kallikrein-kinin, fibrinolytic, and coagulation systems. The biologic activities of C1INH can be divided into the regulation of vascular permeability and anti-inflammatory functions. The objective was to clarify the serial change of C1INH in patients with sepsis.

Methods: We serially examined C1INH activity values (reference range, 70%-130%) and quantitative values (reference range, 160-330 μg/mL) in patients with sepsis admitted into the intensive care unit of the Trauma and Acute Critical Care Center at Osaka University Hospital (Osaka, Japan) during the period between December 2012 and February 2013. We also analyzed their clinical course. We defined "refractory shock" as septic shock requiring steroid administration to maintain hemodynamics.

Results: The serial change of C1INH was evaluated in 5 patients (4 survivors and 1 nonsurvivor). Two patients were diagnosed as having refractory shock. In the nonsurvivor after refractory shock, C1INH activity on admission was 97.2%, and the quantitative value was 133.1 μg/mL. In the other patient with refractory shock, C1INH activity on admission was 94.4%, and the quantitative value was 126.7 μg/mL. This patient's general condition had improved by day 6, with increases in C1INH activity (139.9%) and quantitative value (250.1 μg/mL). In the 3 nonrefractory shock patients, C1INH activity on admission was 130.6%±8.7%, and the quantitative value was 215±26.5 μg/mL.

Conclusions: Enhancement of C1INH activity was not observed in the refractory shock patients, and the C1INH quantitative values were low. Further evaluation of the serial change of C1INH and the validity of C1INH replacement therapy in patients with septic shock may lead to a new strategy for sepsis management.