Lakshman R. Sehgal

Evaluation of oxygen extraction ratio as a physiologic transfusion trigger in coronary artery bypass graft surgery patients

BACKGROUND: Approximately 20 percent of all allogeneic blood transfusions are administered in connection with coronary artery bypass graft (CABG) operations. Transfusion practices vary across the country. The whole‐body oxygen extraction ratio (O2 ER) reflects the adequacy of the patients response to acute normovo‐lemic anemia with an O2 ER of approximately 50 percent being shown to be an appropriate transfusion trigger. The present study monitored the O2 ER in patients undergoing CABG and determined if transfusion practices would have been different if an O2 ER ≥45 percent were used as a transfusion trigger.

Complement, fetal antigen, and shaking rigors in parturients

Objectives. To assess the relationship, if any, between complement, fetal antigen, and shaking rigors during labor and delivery. Methods. We recruited 13 volunteers for serial blood sampling during labor and childbirth. Results. Complement levels had a small but significant drop (11–15%) immediately following childbirth but had no association with fetal antigen levels or shaking rigors. Fetal antigen levels failed to show any consistent relationship with shaking rigors or the labor and delivery process. Conclusion. Shaking rigors do not appear to be associated with changes in either complement or fetal antigen levels. Complement levels remain stable during labor but drop immediately following birth.

Novel in vitro perfusion model to study the interaction between coagulation and blood‐borne metastasis

The association between cancer and hemostasis has long been studied in cell culture, animal models, and cancer patients developing thrombosis. The variety of biologic mechanisms involved in malignancy and metastasis makes the understanding of the relative importance of each mechanism difficult. We have developed a novel in vitro perfusion model that allows for the isolated study of the interactions between tumor cells and components of the hemostatic system under normal physiologic conditions. Segments of denuded umbilical cord or saphenous vein are cut longitudinally and mounted in a perfusion chamber under sterile conditions. Human breast cancer cells are perfused for 24 h under venous flow conditions with either whole blood (WB), platelet‐rich plasma (PRP), platelet‐poor plasma (PPP), or serum. Tissue samples are fixed and stained with hematoxylin and eosin as well as with pan‐cytokeratin. Morphometric analysis is performed to quantify cancer cell adhesion. With PRP, this model maintains normal human physiologic conditions for the duration of the experiment. It differentiates between previously characterized high and low metastatic breast cancer cell lines. In addition, different vein tissue types do not alter tumor cell attachment. This model appears to be an accurate representation of the pathophysiology of in vivo metastasis. This model may serve as a useful bridge between cell culture studies and animal models. It may be a useful tool to elucidate the role of selected hemostatic systems in blood‐borne metastasis and may potentially serve as a screening tool for the development of antimetastatic pharmaceutical agents.