Abstract

PURPOSE Blood transfusions are frequently administered in cardiac surgery. Despite a large number of published studies comparing a "restrictive" strategy with a "liberal" strategy, no clear consensus has emerged to guide blood transfusion practice in cardiac surgery patients. The purpose of this study was to identify, critically appraise, and summarize the evidence on the overall effect of restrictive transfusion strategies compared with liberal transfusion strategies on mortality, other clinical outcomes, and transfusion-related outcomes in adult patients undergoing cardiac surgery. SOURCE We searched MEDLINE (OvidSP), EMBASE (OvidSP) and Cochrane CENTRAL (Wiley) from inception to 1 December 2017 and queried clinical trial registries and conference proceedings for randomized-controlled trials of liberal vs restrictive transfusion strategies in cardiac surgery. PRINCIPAL FINDINGS From 7,908 citations, we included ten trials (9,101 patients) and eight companion publications. Overall, we found no significant difference in mortality between restrictive and liberal transfusion strategies (risk ratio [RR], 1.08; 95% confidence interval [CI], 0.76 to 1.54; I(2) = 33%; seven trials; 8,661 patients). The use of a restrictive transfusion strategy did not appear to adversely impact any of the secondary clinical outcomes. As expected, the proportion of patients who received red blood cells (RBCs) in the restrictive group was significantly lower than in the liberal group (RR, 0.68; 95% CI, 0.64 to 0.73; I(2) = 56%; 5 trials; 8,534 patients). Among transfused patients, a restrictive transfusion strategy was associated with fewer transfused RBC units per patient than a liberal transfusion strategy. CONCLUSIONS In adult patients undergoing cardiac surgery, a restrictive transfusion strategy reduces RBC transfusion without impacting mortality rate or the incidence of other perioperative complications. Nevertheless, further large trials in subgroups of patients, potentially of differing age, are needed to establish firm evidence to guide transfusion in cardiac surgery. TRIAL REGISTRATION PROSPERO (CRD42017071440); registered 20 April, 2018.

Abstract

Tranexamic acid (TXA) reduces transfusion requirements in cardiac surgery and total hip and knee arthroplasty, where it has become standard of care. Our objective is to determine the efficacy and safety of TXA in other surgeries associated with a high risk for red blood cell (RBC) transfusion. We identified randomized controlled trials in Medline, Embase, CENTRAL, and CAB abstracts from inception to June 2019. We included trials evaluating intraoperative IV TXA in adult patients undergoing a non-cardiac and non-hip and knee arthroplasty surgeries at high-risk for RBC transfusion, defined as a baseline transfusion rate ≥5% in comparator arm. We assessed risk of bias using the Cochrane Risk of Bias tool. We used GRADE methodology to assess certainty of evidence. From 8565 citations identified, we included 69 unique trials, enrolling 6157 patients. TXA reduces both the proportion of patients transfused RBCs (relative risk (RR) 0.59; 95% confidence interval (CI) 0.48 to 0.72; low certainty evidence) and the volume of RBC transfused (MD -0.51 RBC units; 95%CI -0.13 to -0.9 units; low certainty evidence) when compared to placebo or usual care. TXA was not associated with differences in deep vein thrombosis, pulmonary embolism, all-cause mortality, hospital length of stay, need for re-operation due to hemorrhage, myocardial infarction, stroke or seizure. In patients undergoing a broad range of non-cardiac and non-hip and knee arthroplasty surgeries at high risk for RBC transfusion, perioperative TXA reduced exposure to RBC transfusion. No differences in thrombotic outcomes were identified; however, summary effect estimates were limited by lack of systemic screening and short duration of follow-up.

Abstract

PURPOSE Thromboelastography and rotational thromboelastometry are point-of-care (POC) viscoelastic tests used to help guide blood product administration. It is unclear whether these tests improve clinical or transfusion-related outcomes. The objective of this study was to appraise data from randomized trials evaluating the benefit of POC testing in cardiac surgery patients. Primary outcomes were the proportion of patients transfused with blood products and all-cause mortality. SOURCE Medline (Ovid), EMBASE (Ovid), CENTRAL (the Cochrane Library-Wiley), Web of Science, Biosis, Scopus, and CINAHL databases, as well as clinical trial registries and conference proceedings were queried from inception to February 2018. PRINCIPAL FINDINGS We identified 1,917 records, 11 of which were included in our analysis (8,294 patients). Point-of-care testing was not associated with a difference in the proportion of patients transfused with any blood product (risk ratio [RR], 0.90; 95% confidence interval [CI], 0.79 to 1.02; I(2) = 51%; four trials, 7,623 patients), or all-cause mortality (RR, 0.73; 95% CI, 0.47 to 1.13; I(2) = 5%; six trials, 7,931 patients). Nevertheless, POC testing was weakly associated with a decrease in the proportion of patients receiving red blood cells (RBC) (RR, 0.91; 95% CI, 0.85 to 0.96; I(2) = 0%; seven trials, 8,029 patients), and heterogeneous reductions in frozen plasma (FP) (RR, 0.58; 95% CI, 0.34 to 0.99; I(2) = 87%; six trials, 7,989 patients) and platelets (RR, 0.66; 95% CI, 0.49 to 0.90; I(2) = 65%; seven trials, 8,029 patients). Meta-analysis of the number of units of RBCs and FP was not possible due to heterogeneity in reporting, however POC testing significantly reduced the units of platelets transfused (standard mean difference, -0.09; 95% CI, -0.18 to 0.00; four trials, 7,643 patients). CONCLUSION Our review indicates that in cardiac surgery patients, POC viscoelastic hemostatic testing is not associated with a reduction in the proportion of patients receiving any blood product or all-cause mortality. However, viscoelastic testing is weakly associated with a reduction in proportion of patients transfused with specific blood products. Presently, the benefits associated with viscoelastic testing in cardiac surgery patients are insufficiently robust to recommend routine implementation of this technology. TRIAL REGISTRATION PROSPERO (CRD4201706577). Registered 11 May 2017.