Rates of delayed hemolytic transfusion reactions observed in a trauma center.

BACKGROUND: Delayed hemolytic transfusion reactions (DHTRs) are reported to be rare occurrences but may be more frequently observed in the trauma setting where patients are heavily transfused, followed over long inpatient admissions, and have frequent subsequent blood counts as they undergo multiple surgical interventions. STUDY DESIGN AND METHODS: We examined the rates of DHTRs on a per transfusion and per patient basis in an academic county hospital with a level 1 trauma center serving a four-state region and over a 3-year period. DHTRs were entered sequentially into a registry as they were observed, and a retrospective review of all new alloantibodies detected was performed to identify any additional DHTRs. The number of units of red blood cells (RBCs), the number of unique patients, types of alloantibodies, and number of transfusions were extracted from blood bank records. RESULTS: Twenty-nine DHTRs were observed from January 1, 2017, through December 31, 2019, from newly observed alloantibodies after a median of 12 red blood cells (RBCs) transfusions per patient. These reactions occurred in response to 24,633 unique transfusions in 6905 unique patients, so the observed rates were about 1:849 RBC transfusions and 1:238 transfused patients. Evidence of delayed hemolysis was seen in five additional patients who were transfused during emergency resuscitation and later found to have had known RBC antibodies. DISCUSSION: We report a higher rate of DHTRs than previously described to demonstrate that DHTRs are not rare in trauma centers.

The gut microbiome and thromboembolism.

The gut microbiome plays a critical role in various inflammatory conditions, and its modulation is a potential treatment option for these conditions. The role of the gut microbiome in the pathogenesis of thromboembolism has not been fully elucidated. In this review, we summarize the evidence linking the gut microbiome to the pathogenesis of arterial and venous thrombosis. In a human host, potentially pathogenic bacteria are normal residents of the human gut microbiome, but significantly outnumbered by commensal anaerobic bacteria. Several disease states with an increased risk of venous thromboembolism (VTE) are associated with an imbalance in the gut microbiome characterized by a decrease in commensal anaerobic bacteria and an increase in the abundance of pathogenic bacteria of which the most common is the gram-negative Enterobacteriaceae (ENTERO) family. Bacterial lipopolysaccharides (LPS), the glycolipids found on the outer membrane of gram-negative bacteria, is one of the links between the microbiome and hypercoagulability. LPS binds to toll-like receptors to activate endothelial cells and platelets, leading to activation of the coagulation cascade. Bacteria in the microbiome can also metabolite compounds in the diet to produce important metabolites like trimethylamine-N-oxide (TMAO). TMAO causes platelet hyperreactivity, promotes thrombus formation and is associated with cardiovascular disease. Modulating the gut microbiome to target LPS and TMAO levels may be an innovative approach for decreasing the risk of thrombosis.