Anticoagulation management during cardiopulmonary bypass (CPB) remains a cornerstone of safe cardiac surgery. Ensuring adequate anticoagulation prevents thrombosis within the extracorporeal circuit, while excessive anticoagulation or inadequate reversal may increase bleeding complications. A recent Europe-wide survey titled “Contemporary Clinical Practices in Anticoagulation Management During Cardiopulmonary Bypass” provides valuable insight into how cardiac surgery teams currently manage anticoagulation across different institutions. The study evaluated responses from 114 cardiac surgery centers spanning 29 European countries, offering one of the most comprehensive snapshots of real-world practice in this field.
The investigators designed a 27-question electronic survey focusing on several domains of perioperative anticoagulation. These included heparin dosing strategies, activated clotting time (ACT) monitoring, protamine reversal protocols, post-reversal hemostasis assessment, management of heparin resistance, and the integration of viscoelastic testing technologies such as thromboelastography (TEG) and rotational thromboelastometry (ROTEM). Most responding institutions were high-volume cardiac surgery centers performing more than 500 CPB procedures annually, suggesting that the findings reflect experienced clinical programs.
Consensus in Initial Anticoagulation Practices
One of the strongest findings from the survey was the existence of broad consensus regarding initial heparin administration and monitoring during CPB. Approximately 78% of centers reported using written heparinization protocols, demonstrating widespread institutional standardization for initiating anticoagulation. The most common initial heparin dose was 300 IU/kg, used by more than 60% of centers. This practice aligns with recommendations from major cardiovascular surgical societies and reflects established safety standards.
ACT monitoring remains the dominant method for evaluating anticoagulation during CPB. Over 93% of centers reported relying on ACT measurements, most frequently performed every 30 minutes during bypass. Target ACT thresholds before initiating CPB typically ranged between 400 and 480 seconds, values generally consistent with guideline recommendations designed to prevent clot formation in extracorporeal circuits.
These findings indicate that the foundational aspects of anticoagulation management during CPB are relatively standardized across European cardiac surgery programs. Such consistency likely reflects decades of clinical experience combined with widely disseminated practice guidelines.
Major Variability in Protamine Reversal Strategies
Despite consensus in initial anticoagulation strategies, the survey revealed substantial variability in protamine dosing and anticoagulation reversal protocols. Protamine sulfate is administered at the conclusion of CPB to neutralize heparin and restore coagulation. However, the optimal dosing strategy remains controversial.
The study found that 57% of centers used a 1:1 heparin-to-protamine ratio, while nearly 37% used ratios lower than 1:1, and a smaller minority used higher ratios. This variability is clinically significant because both insufficient and excessive protamine dosing can lead to complications. Underdosing may result in residual anticoagulation and postoperative bleeding, while overdosing can produce coagulopathy or hypotension.
Interestingly, contemporary patient blood management guidelines recommend using protamine ratios lower than 1:1, yet many centers continue to follow historical or institutional dosing protocols. This discrepancy highlights a persistent gap between guideline recommendations and real-world clinical practice.
Lack of Standardized Post-Reversal Monitoring
Another notable finding was the lack of standardized targets for post-protamine ACT monitoring. Approximately 70% of centers reported not having a universal ACT target after reversal, and most institutions assessed adequate heparin neutralization by achieving an ACT value “close to baseline.”
This approach introduces a degree of subjectivity into anticoagulation management. Post-reversal ACT values have been associated with bleeding risk and transfusion requirements, yet no universally accepted threshold exists. As a result, clinicians frequently rely on a combination of laboratory measurements and visual assessment of surgical bleeding.
The absence of standardized post-reversal metrics represents an important area for future research. Establishing evidence-based targets could help reduce practice variability and improve patient outcomes following cardiac surgery.
Underutilization of Advanced Hemostasis Monitoring
Although viscoelastic testing technologies such as TEG and ROTEM were available in over 90% of centers, their integration into clinical decision-making varied widely. Nearly half of the surveyed institutions reported that transfusion decisions were based solely on clinical judgment rather than objective viscoelastic data.
This finding is particularly notable because multiple studies have demonstrated that viscoelastic-guided transfusion algorithms can reduce blood product usage and postoperative bleeding complications. Potential barriers to adoption may include cost, training requirements, and the absence of standardized institutional protocols.
Expanding the use of these technologies represents a promising opportunity for improving patient blood management strategies during cardiac surgery.
Challenges in Managing Heparin Resistance and High-Risk Patients
The survey also examined approaches to managing heparin resistance, a condition in which patients fail to achieve adequate anticoagulation despite standard heparin dosing. The most common intervention reported was administration of antithrombin III, used by approximately half of the responding centers. Others reported increasing the heparin dose as an initial strategy.
More concerning was the finding that over 80% of centers lacked a dedicated protocol for managing patients at high risk of bleeding. This highlights an important gap in perioperative hemostasis management and underscores the need for broader adoption of patient blood management programs.
Implications for Future Research and Clinical Practice
Overall, the survey illustrates a clear pattern in European cardiac surgery practice: strong consensus in the early phases of anticoagulation management but substantial variability in reversal and hemostasis assessment. The authors emphasize that this variability likely reflects limited high-quality evidence guiding these later stages of care.
Because most institutions have not recently updated their anticoagulation protocols, further research—particularly large prospective or randomized trials—will be necessary to determine optimal strategies for protamine dosing, post-reversal monitoring, and transfusion management.
The findings also provide a valuable foundation for developing future quality improvement initiatives aimed at harmonizing anticoagulation practices across institutions. Greater standardization may ultimately improve surgical outcomes, reduce bleeding complications, and optimize resource utilization in cardiac surgery programs.
