Low activated coagulation time during cardiopulmonary bypass does not increase postoperative bleeding.

Area of Science:

• Cardiovascular Surgery
• Anesthesiology
• Hematology

Background:

• Activated coagulation time (ACT) is a common method for monitoring anticoagulation during cardiopulmonary bypass.
• However, there is a lack of data defining a specific ACT threshold below which adverse outcomes are likely to occur.

Purpose of the Study:

• To investigate the relationship between ACT values and clinical outcomes, specifically clot formation and postoperative bleeding, following a standardized heparin dose before cardiopulmonary bypass.
• To evaluate whether a minimum ACT threshold for adequate anticoagulation can be established.

Main Methods:

• A single dose of heparin (300 U/kg) was administered to 193 patients undergoing cardiopulmonary bypass.
• ACT and heparin levels were measured at various intervals post-administration.
• Outcomes assessed included clot formation in the bypass circuit and postoperative chest tube drainage.

Main Results:

• No clots were observed in any perfusion circuit.
• Patients with ACT values below 400 seconds (including some below 300 seconds) did not exhibit increased postoperative bleeding compared to those with higher ACT values.
• Postoperative bleeding did not correlate with measured heparin levels.

Conclusions:

• The study suggests that the established minimum ACT value for adequate heparinization during cardiopulmonary bypass is less than 400 seconds.
• Current data do not support a definitive minimum ACT threshold to predict adverse outcomes.
• Further research is needed to precisely define the optimal ACT range for safe and effective anticoagulation in this setting.