Protamine Test Dose: Impact on Activated Clotting Time and Circuit Integrity

Area of Science:

• Cardiovascular Surgery
• Anesthesiology
• Hematology

Background:

• Clot formation in cardiopulmonary bypass circuits after protamine test doses (PTDs) raised concerns.
• The impact of PTDs on patient activated clotting times (ACTs) required investigation.

Purpose of the Study:

• To evaluate the effect of protamine test doses on activated clotting times during cardiopulmonary bypass.
• To assess the variability and predictability of ACT responses to PTDs.

Main Methods:

• Prospective data collection from 120 cardiac surgery patients undergoing cardiopulmonary bypass.
• ACT measurements were taken before bypass termination, after PTDs, and after full protamine doses.
• Paired t-test was used for statistical analysis.

Main Results:

• PTDs averaged 11% of the full protamine dose, with significant variability.
• A 40% average drop in ACT was observed after PTD administration (650 to 376 seconds).
• 81% of patients had post-PTD ACTs below the safety threshold of 480 seconds.

Conclusions:

• Patient ACT response to PTDs is unpredictable.
• Clot formation risk increases with PTD administration, especially with continuous pump suction.
• Discontinue mediastinal shed blood recovery before protamine administration to mitigate risks.