An evaluation of factors affecting activated coagulation time

Area of Science:

• Cardiovascular Surgery
• Hematology
• Anesthesiology

Background:

• Adequate activated coagulation time (ACT) is crucial for heparinization during cardiopulmonary bypass.
• Antithrombin (AT) deficiency is often cited as a cause of reduced heparin responsiveness, but this link is not fully established.

Purpose of the Study:

• To investigate the relationship between antithrombin (AT) levels and other coagulation factors affecting ACT and heparin sensitivity.
• To determine the causes of inadequate ACT in patients undergoing cardiopulmonary bypass.

Main Methods:

• Observational study involving 203 adult elective cardiac surgical patients.
• Preoperative data included demographics, medical therapy, hemoglobin, platelet count, and AT levels.
• Intraoperative measurements included ACT and anti-Xa activity.

Main Results:

• 10% of patients did not achieve an adequate ACT (≥400 seconds) after full heparinization.
• Subnormal AT activity did not correlate with low ACT or low heparin sensitivity.
• Low hemoglobin and high platelet counts were associated with decreased ACT, while preoperative low-molecular-weight heparin did not affect ACT response.

Conclusions:

• Inadequate ACT is generally not indicative of AT deficiency.
• High platelet counts and low hemoglobin levels may influence ACT measurements and heparin responsiveness.
• Further investigation into factors affecting heparin efficacy during cardiopulmonary bypass is warranted.