Abstract

IMPORTANCE Approximately 15% of patients undergoing cardiac surgery receive frozen plasma (FP) for bleeding. Four-factor prothrombin complex concentrates (PCCs) have logistical and safety advantages over FP and may be a suitable alternative. OBJECTIVES To determine the proportion of patients who received PCC and then required FP, explore hemostatic effects and safety, and assess the feasibility of study procedures. DESIGN, SETTING, AND PARTICIPANTS Parallel-group randomized pilot study conducted at 2 Canadian hospitals. Adult patients requiring coagulation factor replacement for bleeding during cardiac surgery (from September 23, 2019, to June 19, 2020; final 28-day follow-up visit, July 17, 2020). Data analysis was initiated on September 15, 2020. INTERVENTIONS Prothrombin complex concentrate (1500 IU for patients weighing ≤60 kg and 2000 IU for patients weighing >60 kg) or FP (3 U for patients weighing ≤60 kg and 4 U for patients weighing >60 kg), repeated once as needed within 24 hours (FP used for any subsequent doses in both groups). Patients and outcome assessors were blinded to treatment allocation. MAIN OUTCOMES AND MEASURES Hemostatic effectiveness (whether patients received any hemostatic therapies from 60 minutes to 4 and 24 hours after initiation of the intervention, amount of allogeneic blood components administered within 24 hours after start of surgery, and avoidance of red cell transfusions within 24 hours after start of surgery), protocol adherence, and adverse events. The analysis set comprised all randomized patients who had undergone cardiac surgery, received at least 1 dose of either treatment, and provided informed consent after surgery. RESULTS Of 169 screened patients, 131 were randomized, and 101 were treated (54 with PCC and 47 with FP), provided consent, and were included in the analysis (median age, 64 years; interquartile range [IQR], 54-73 years; 28 [28%] were female; 82 [81%] underwent complex operations). The PCC group received a median 24.9 IU/kg (IQR, 21.8-27.0 IU/kg) of PCC (2 patients [3.7%; 95% CI, 0.4%-12.7%] required FP). The FP group received a median 12.5 mL/kg (IQR, 10.0-15.0 mL/kg) of FP (4 patients [8.5%; 95% CI, 2.4%-20.4%] required >2 doses of FP). Hemostatic therapy was not required at the 4-hour time point for 43 patients (80%) in the PCC group and for 32 patients (68%) in the FP group (P = .25) nor at the 24-hour time point for 41 patients (76%) in the PCC group and for 31 patients (66%) patients in the FP group (P = .28). The median numbers of units for 24-hour cumulative allogeneic transfusions (red blood cells, platelets, and FP) were 6.0 U (IQR, 4.0-11.0 U) in the PCC group and 14.0 U (IQR, 8.0-20.0 U) in the FP group (ratio, 0.58; 95% CI, 0.45-0.77; P < .001). After exclusion of FP administered as part of the investigational medicinal product, the median numbers of units were 6.0 U (IQR, 4.0-11.0 U) in the PCC group and 10.0 U (IQR, 6.0-16.0 U) in the FP group (ratio, 0.80; 95% CI, 0.59-1.08; P = .15). For red blood cells alone, the median numbers were 1.5 U (IQR, 0.0-4.0 U) in the PCC group and 3.0 U (IQR, 1.0-5.0 U) in the FP group (ratio, 0.69; 95% CI, 0.47-0.99; P = .05). During the first 24 hours after start of surgery, 15 patients in the PCC group (28%) and 8 patients in the FP group (17%) received no red blood cells (P = .24). Adverse event profiles were similar. CONCLUSIONS AND RELEVANCE This randomized clinical trial found that the study protocols were feasible. Adequately powered randomized clinical trials are warranted to determine whether PCC is a suitable substitute for FP for mitigation of bleeding in cardiac surgery. TRIAL REGISTRATION ClinicalTrials.gov Identifier: NCT04114643.

Abstract

Importance: Excessive bleeding is a common complication of cardiac surgery. An important cause of bleeding is acquired hypofibrinogenemia (fibrinogen level <1.5-2.0 g/L), for which guidelines recommend fibrinogen replacement with cryoprecipitate or fibrinogen concentrate. The 2 products have important differences, but comparative clinical data are lacking. Objective: To determine if fibrinogen concentrate is noninferior to cryoprecipitate for treatment of bleeding related to hypofibrinogenemia after cardiac surgery. Design, Setting, and Participants: Randomized clinical trial at 11 Canadian hospitals enrolling adult patients experiencing clinically significant bleeding and hypofibrinogenemia after cardiac surgery (from February 10, 2017, to November 1, 2018). Final 28-day follow-up visit was completed on November 28, 2018. Interventions: Fibrinogen concentrate (4 g; n = 415) or cryoprecipitate (10 units; n = 412) for each ordered dose within 24 hours after cardiopulmonary bypass. Main Outcomes and Measures: Primary outcome was blood components (red blood cells, platelets, plasma) administered during 24 hours post bypass. A 2-sample, 1-sided test for the ratio of the mean number of units was conducted to evaluate noninferiority (threshold for noninferiority ratio, <1.2). Results: Of 827 randomized patients, 735 (372 fibrinogen concentrate, 363 cryoprecipitate) were treated and included in the primary analysis (median age, 64 [interquartile range, 53-72] years; 30% women; 72% underwent complex operations; 95% moderate to severe bleeding; and pretreatment fibrinogen level, 1.6 [interquartile range, 1.3-1.9] g/L). The trial met the a priori stopping criterion for noninferiority at the interim analysis after 827 of planned 1200 patients were randomized. Mean 24-hour postbypass allogeneic transfusions were 16.3 (95% CI, 14.9 to 17.8) units in the fibrinogen concentrate group and 17.0 (95% CI, 15.6 to 18.6) units in the cryoprecipitate group (ratio, 0.96 [1-sided 97.5% CI, -infinity to 1.09; P < .001 for noninferiority] [2-sided 95% CI, 0.84 to 1.09; P = .50 for superiority]). Thromboembolic events occurred in 26 patients (7.0%) in the fibrinogen concentrate group and 35 patients (9.6%) in the cryoprecipitate group. Conclusions and Relevance: In patients undergoing cardiac surgery who develop clinically significant bleeding and hypofibrinogenemia after cardiopulmonary bypass, fibrinogen concentrate is noninferior to cryoprecipitate with regard to number of blood components transfused in a 24-hour period post bypass. Use of fibrinogen concentrate may be considered for management of bleeding in patients with acquired hypofibrinogenemia in cardiac surgery. Trial Registration: ClinicalTrials.gov Identifier: NCT03037424.

Abstract

BACKGROUND Cerebral microembolization during cardiopulmonary bypass may lead to cognitive decline after cardiac surgery. Transfusion of the unprocessed shed blood (major source of lipid microparticulates) into the patient during cardiopulmonary bypass is common practice to reduce blood loss and blood transfusion. Processing of shed blood with cell saver before transfusion may limit cerebral microembolization and reduce cognitive decline after surgery. METHODS AND RESULTS A total of 226 elderly patients were randomly allocated to either cell saver or control groups. Anesthesia and surgical management were standardized. Epiaortic scanning of the proximal thoracic aorta was performed in all patients. Transcranial Doppler was used to measure cerebral embolic rates. Standardized neuropsychological testing was conducted 1 week before and 6 weeks after surgery. The raw scores for each test were converted to Z scores, and then a combined Z score of 10 main variables was calculated for both study groups. The primary analysis was based on dichotomous composite cognitive outcome with a 1-SD rule. Cognitive dysfunction was present in 6% (95% confidence interval, 1. 3% to 10. 7%) of patients in the cell saver group and 15% (95% confidence interval, 8% to 22%) of patients in the control group 6 weeks after surgery (P=0. 038). The severity of aortic atheroma and cerebral embolic count were similar between the 2 groups. CONCLUSIONS The present report demonstrates that processing of shed blood with cell saver results in clinically significant reduction in postoperative cognitive dysfunction after cardiac surgery. These findings emphasize the clinical importance of lipid embolization in contributing to postoperative cognitive decline in patients exposed to cardiopulmonary bypass.

Abstract

OBJECTIVE Use of antifibrinolytic agents reduces the risk of bleeding and decreases the need for blood product use in patients undergoing cardiac surgery. The purpose of this study was to determine whether perioperative use of tranexamic acid decreases the rate of saphenous vein graft patency in the early postoperative period after conventional coronary artery bypass grafting surgery. METHODS A total of 312 patients scheduled for elective coronary artery bypass grafting surgery with cardiopulmonary bypass were randomized to receive either tranexamic acid 100 mg/kg (n = 147) or placebo (n = 165) in a double-blinded fashion before the initiation of cardiopulmonary bypass. Saphenous vein graft patency was assessed with magnetic resonance imaging 5 to 30 days after surgery. RESULTS Both groups were comparable with respect to baseline demographic data and surgical characteristics. A total of 237 (76%) patients underwent magnetic resonance imaging assessment. A total of 297 saphenous vein grafts were performed and 253 (85. 2%; 95% confidence interval, 83. 5%-86. 9%) were seen in the tranexamic acid group, and 265 saphenous vein grafts were performed and 231 (87. 2%; 95% confidence interval, 85. 5%-88. 9%) were seen in the placebo group (P = . 4969). The blood loss and blood product transfusion rates in the tranexamic acid group were significantly lower than in the placebo group. There was no difference between groups with respect to postoperative morbidity and mortality. CONCLUSIONS The administration of tranexamic acid before cardiopulmonary bypass did not seem to compromise early venous graft patency rates but reduced perioperative blood product transfusion rates. Consequently, tranexamic acid could be advocated for routine use in patients undergoing conventional coronary artery bypass grafting surgery.

Abstract

OBJECTIVE Prophylactic administration of tranexamic acid (TA), an antifibrinolytic agent, decreases bleeding after cardiac surgery with systemic hypothermia (25 degrees C to 29 degrees C). Warmer systemic temperatures during cardiopulmonary bypass (CPB) may reduce bleeding and thus alter the requirement for TA. The effect of three different doses of TA on bleeding after cardiac surgery with mild systemic hypothermia (32 degrees C) is evaluated. DESIGN Double-blind, prospective, randomized study. SETTING University hospital. PARTICIPANTS One hundred fifty adult patients undergoing aortocoronary bypass or valvular cardiac surgery. INTERVENTIONS Patients received TA, 50 (n = 50), 100 (n = 50), or 150 (n = 50) mg/kg intravenously before CPB with mild systemic hypothermia. MEASUREMENTS AND MAIN RESULTS Blood loss through chest drains over 6, 12, and 24 hours after surgery and total hemoglobin loss were measured. Autotransfused blood, transfused banked blood and blood products, and coagulation profiles were measured. Analysis of variance on log-transformed data for blood loss and confidence intervals (CIs) of 0.95 were calculated and transformed to milliliters of blood. No patient was re-explored for bleeding. Blood loss at 6 hours was statistically greater in the 50-mg/kg group compared with the other two groups (p = 0.03; p = 0.02). Total hemoglobin loss was statistically greater in the 50-mg/kg group compared with the 150-mg/kg group (p = 0.04). There was no statistical difference in blood tranfusion rate or coagulation profiles among the three groups. However, preoperative hemoglobin level was statistically lower in the 150-mg/kg group compared with the other two groups (p = 0.01). CONCLUSION Of the three doses of TA studied, the most efficacious and cost-effective dose to reduce bleeding after cardiac surgery with mild hypothermic systemic perfusion is 100 mg/kg.

Abstract

This prospective, double-blind, randomized trial assessed the effectiveness of high-dose tranexamic acid given in the preoperative period on blood loss in patients undergoing cardiopulmonary bypass. One hundred fifty patients scheduled to undergo cardiac operations with cardiopulmonary bypass were randomized into three groups of equal size. The first group received 10 gm of tranexamic acid intravenously over 20 minutes before sternotomy and a placebo infusion over 5 hours. The second group received 10 gm of tranexamic acid over 20 minutes and then another 10 gm infused intravenously over 5 hours. The control group received a placebo bolus and a placebo infusion over 5 hours (0.9% normal saline solution). The blood loss after the operation was measured at 6 hours and 24 hours. The homologous blood and blood products given during and up to 48 hours after operation were recorded. Eighteen percent of the control group patients shed more than 750 ml blood in 6 hours compared with only 2% in both tranexamic acid groups. Patients who shed more than 750 ml blood required 93% more red blood cell transfusions than patients without excessive bleeding. Tranexamic acid (10 gm) given intravenously in the period before cardiopulmonary bypass reduced blood loss over 6 hours by 50% and over 24 hours by 35%. Continued tranexamic acid infusion (10 gm over 5 hours) did not reduce bleeding further. There was no difference in the coagulation profile before operation between patients with and without excessive bleeding. However, coagulation tests done in the postoperative period indicated ongoing fibrinolysis and platelet dysfunction in patients with excessive bleeding.