L. K. Winer1, M. D. Goodman1,2, C. Caldwell1, V. Nomellini1,2 1University Of Cincinnati,Division Of Research, Department Of Surgery,Cincinnati, OH, USA 2University Of Cincinnati,Division Of Trauma, Critical Care, and Acute Care Surgery, Department Of Surgery,Cincinnati, OH, USA
Introduction: Patients who survive the acute phase of sepsis can progress to persistent inflammation, immunosuppression and catabolism syndrome (PICS), which is associated with organ failure and death. Although acute sepsis-associated coagulopathy is well described, coagulopathy of chronic critical illness is poorly defined. Given that acute sepsis leads to early depletion of coagulation factors, and PICS represents ongoing inflammation, we hypothesized that PICS is associated with consumptive coagulopathy driven by microthrombotic disease.
Methods: Male CD-1 mice underwent 33% cecal ligation with a 25-gauge needle puncture and were sacrificed after 8 days, when mice concurrently display all PICS characteristics. Spleen megakaryocytes were enumerated using flow cytometry and hematoxylin and eosin (H&E) staining. Pulmonary microvascular thrombi were quantified with Martius Scarlet Blue (MSB) staining. Whole blood was anticoagulated, and complete blood counts and native and extrinsic thromboelastometry (NATEM, EXTEM) assays were conducted. Student t-tests were performed; p<0.05 was considered statistically significant.
Results: In our murine model of PICS, the spleen becomes markedly enlarged with increased splenocytes. To determine whether PICS splenomegaly was also related to megakaryocyte production, we used complementary methods of flow cytometry and histology. This demonstrated that during PICS, there is a greater than two-fold rise in splenic megakaryopoiesis (p<0.05) without a concomitant increase in peripheral platelets. Next, to determine whether the discrepancy between splenic megakaryocyte and platelet production was contributed to a consumptive process, we used microscopy. This revealed a nearly seven-fold increase in pulmonary microvascular thrombi in PICS compared with healthy mice (p<0.05). Finally, thromboelastometry was conducted to characterize coagulation. NATEM, a test of native coagulation, showed significantly delayed clot initiation time (CT), unchanged clot formation time (CFT), and significantly increased mean clot firmness (MCF) in PICS mice. When specifically examining the extrinsic pathway of coagulation (EXTEM), CT and CFT were decreased, and MCF was increased in PICS mice (all p<0.05).
Conclusion: Using a murine model of PICS, we demonstrated changes in splenic megakaryopoiesis, pulmonary microthrombi formation, and whole blood viscoelastic properties, suggesting a dysregulation of coagulation. Based on these findings, we propose that consumptive coagulopathy may constitute another cardinal feature of PICS. Altogether, these findings suggest that early identification of coagulation abnormalities may help predict and define PICS, as well as stratify those at greatest risk for subsequent organ failure and death.