Association of perioperative red blood cell transfusion with postoperative venous thromboembolism in pediatric patients: A propensity score matched analysis

Comparison of red blood cell transfusions and hemostatic transfusions and their relation to thromboses in pediatric patients receiving extracorporeal membrane oxygenation therapy

OBJECTIVE

To evaluate the association of RBC transfusions with thrombosis in pediatric patients on extracorporeal membrane oxygenation (ECMO) and compare this with the transfusion of other blood products and their association with thrombosis.

METHODS

This was a secondary analysis of the Bleeding and Thrombosis during ECMO (BATE) study, which was a multicenter prospective observational study involving patients less than 19 years of age treated with ECMO.

RESULTS

514 patients were analyzed, of which 282 (55%) were neonates (≤31 days) and 302 (58.7%) were male. When analyzing the entire cohort independently of other blood products, each 10 mL/kg of packed red blood cells (PRBCs) was associated with a 1.0% increase in the average number of thromboses (1.010; 1.008,1.013; p < .001). In neonates, each 10 mL/kg of PRBC was associated with a 0.9% increase in the average number of thromboses (1.009; 1.003,1.013; p < .001). In pediatric patients, each 10 mL/kg of PRBC was associated with a 1.2% increase in the average number of thromboses (1.012; 1.008,1.012; p < .001). The percent increase in the average number of thromboses was similar between PRBCs, platelets, and FFP, but increased significantly with cryoprecipitate.

CONCLUSIONS

RBC transfusions and hemostatic transfusions are likely associated with thromboses in pediatric patients on ECMO.

Storage of packed red blood cells impairs an inherent coagulation property of erythrocytes

Storage of packed red blood cells is associated with changes in erythrocytes that over time increasingly impair cellular function and potentially contribute to adverse effects associated with blood transfusion. Exposure of phosphatidylserine at the outer membrane leaflet of erythrocytes and shedding of microvesicles (MVs) during packed red blood cell storage are alterations assumed to increase the risk of prothrombotic events in recipients. Here, we used rotational thromboelastometry to study the coagulation process in blood samples with erythrocytes from stored PRBCs reconstituted with freshly prepared platelet-rich plasma. We explored the influence of following effects on the coagulation process: 1) PRBC storage duration, 2) differences between erythrocytes from stored PRBCs compared to freshly drawn erythrocytes, and 3) the contribution of added MVs. Interestingly, despite of a higher fraction of PS-positive cells, erythrocytes from PRBCs stored for 6 weeks revealed longer clotting times than samples with erythrocytes stored for 2 or 4 weeks. Further, clotting times and clot formation times were considerably increased in samples reconstituted with erythrocytes from stored PRBCs as compared to fresh erythrocytes. Moreover, MVs added to reconstituted samples elicited only comparably small and ambiguous effects on coagulation. Thus, this study provides no evidence for an amplified clotting process from prolonged storage of PRBCs but on the contrary implicates a loss of function, which may be of clinical significance in massive transfusion. Our observations add to the increasing body of evidence viewing erythrocytes as active players in the clotting process.

Risk for deep venous thrombosis in pediatric cancer patients undergoing surgery

PURPOSE

Cancer is a well-established risk factor for deep venous thrombosis (DVT). We sought to assess the incidence of DVT in pediatric cancer patients undergoing select surgical procedures at our institution and to identify additional factors associated with DVT development.

METHODS

We performed a retrospective review of cancer patients who underwent select surgical procedures and developed a DVT within 30 days of their operation from 2000 to 2018 at our institution. Catheter-associated DVTs were excluded from this analysis. Major oncologic operations were selected.

RESULTS

From 2000 to 2018, 3031 major oncologic operations were performed following which 14 symptomatic DVTs occurred, for an overall incidence of 0.46%. Procedures associated with post-operative DVT included: mass biopsy (7), pulmonary wedge resection (2), inguinal lymph node excision (1), colectomy (1), nephrectomy (1), lower extremity limb-sparing revision (1), and femur resection (1).

CONCLUSIONS

Our data suggest that surgery does not put children with cancer at significant risk for DVT. Given the low incidence of perioperative DVT, routine pharmacologic prophylaxis for children with cancer undergoing surgery does not seem warranted.

LEVEL OF EVIDENCE

II.

Perioperative red blood cell infusion and deep vein thrombosis in patients with femoral and pelvic fractures: a propensity score matching

BACKGROUND

The relationship between perioperative red blood cell (RBC) infusion and deep vein thrombosis (DVT) has not been determined.

OBJECTIVES

To analyze the time-event relationship between perioperative RBC infusion and DVT in patients with femoral and pelvic fractures after adjusting for confounding factors and to provide reference for optimizing DVT risk factors.

METHODS

The clinical data of 569 patients with femoral and pelvic fractures who received surgical treatment from May 2018 to December 2019 were retrospectively analyzed. Propensity score matching (PSM) was performed on 20 covariates of DVT. With the formation or progression of DVT after RBC infusion as the end point, the time-event relationship between perioperative RBC infusion and DVT in patients was analyzed by binary logistic regression.

RESULTS

After 1:1 PSM of 569 patients included in this study, 126 patients were in the transfusion group and the non-transfusion group, respectively. Before PSM (P = 0.023, OR = 1.496 [95% CI, 1.058-2.115]), perioperative RBC infusion was associated with DVT formation for femoral and pelvic fractures. This conclusion was still obtained after PSM (P = 0.038, OR = 1.728, 95% CI = (1.031, 2.896)). The risk of DVT in patients with RBC infusion of 2-4U and > 4U is 1.833 and 2.667 times that of ≤ 2U, respectively. After excluding patients who received preoperative RBC infusion and had DVT formation or progression prior to RBC infusion, perioperative RBC infusion was still associated with the formation of DVT in femoral and pelvic fractures (P = 0.037, OR = 2.231 [95% CI, 1.049-4.745]).

CONCLUSION

Perioperative RBC infusion is one of the causes of DVT in patients with femoral and pelvic fractures, and the risk of DVT is positively correlated with the amount of RBC infusion.

Red Blood Cell Contribution to Hemostasis

Red Blood Cells (RBCs) have been increasingly recognized to play important roles in hemostasis and the mechanisms by which they do so continue to be elucidated. First and foremost, RBC biomechanics are the principal determinant of viscosity and flow dynamics of blood, which strongly influence all features of hemostasis. Of note, morphologic pathology, such as that found in sickle cell disease, leads to increased risk of thrombotic disease. RBC surface interactions govern signaling between platelets and RBCs and also aid in the conversion of prothrombin to thrombin. Additionally, RBCs generate microparticles which have been shown to reduce clotting time. Finally, blood clot structure and maturation are dependent on the inclusion of RBCs in forming thrombi. Here, we review the above mechanisms of RBC contribution to hemostasis.