Accuracy of drawing coagulation samples from heparinized arterial lines

Area of Science:

• Cardiovascular Medicine
• Hematology
• Medical Diagnostics

Background:

• Accurate coagulation monitoring is crucial for patients undergoing percutaneous transluminal coronary angioplasty (PTCA).
• Heparinized arterial lines are commonly used for blood sampling in these patients.
• The impact of discard volume on the accuracy of coagulation tests drawn via arterial lines is not well-established.

Purpose of the Study:

• To evaluate the accuracy of activated partial thromboplastin time (aPTT) and prothrombin time (PT) when blood samples are collected through heparinized arterial lines.
• To determine the optimal discard volume from arterial lines for reliable aPTT and PT measurements.

Main Methods:

• A study involving 90 blood samples from 30 male PTCA patients (mean age 65) was conducted.
• Arterial line samples were drawn using three random discard volumes: deadspace, deadspace + 2 mL, and deadspace + 4 mL.
• Venous blood samples served as controls, with matched discard volumes.

Main Results:

• Mean arterial aPTT values were significantly higher than venous values.
• No significant difference in aPTT was observed among different discard volumes.
• A significant interaction between sample source and discard volume indicated differences between deadspace and larger discard volumes.

Conclusions:

• A discard volume of catheter deadspace plus 2 mL (total 3.6 mL) is recommended for accurate aPTT measurements from arterial lines in PTCA patients.
• This finding helps optimize blood sampling techniques for critical coagulation monitoring.