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Control of oral anticoagulation in patients using long-term internal jugular catheters for haemodialysis access
Insights
For patients on long-term haemodialysis catheters, a simple blood draw technique from the catheter itself can accurately measure prothrombin time (PT) for oral anticoagulant dosing. This method avoids difficult peripheral blood draws, ensuring reliable anticoagulation management.
Area of Science:
- Nephrology
- Hematology
- Clinical Chemistry
Background:
- Long-term haemodialysis often requires indwelling jugular catheters.
- Maintaining catheter patency necessitates oral anticoagulation.
- Peripheral blood sampling for prothrombin time (PT) can be challenging in these patients.
Purpose of the Study:
- To evaluate a novel method for obtaining accurate PT measurements from haemodialysis catheters.
- To provide a reliable alternative to peripheral venipuncture for anticoagulant monitoring.
Main Methods:
- A specific protocol involving discarding initial catheter blood and performing a heparinized saline flush was employed.
- Blood for PT measurement was drawn from the arterial limb of the double-lumen catheter post-flush.
- Simultaneous activated partial thromboplastin time (aPTT) measurements were used to assess accuracy.
Main Results:
- PT measurements from the arterial catheter limb after a 10 ml flush closely correlated with peripheral vein PT measurements.
- Accuracy was confirmed when simultaneously measured aPTT was normal.
- Elevated aPTT indicated residual heparin, potentially affecting PT accuracy, necessitating repeat testing.
Conclusions:
- A reliable and easy method for obtaining PT measurements directly from haemodialysis catheters has been established.
- This technique aids in the accurate regulation of oral anticoagulant doses for patients with long-term haemodialysis access.
- It offers a practical solution to the difficulties associated with peripheral blood sampling in this population.
Abstract:
Patients using long-term double-lumen silastic jugular catheters for haemodialysis access frequently require oral anticoagulants to maintain patency of the catheter. It may be difficult or impossible to obtain peripheral vein blood samples for PT measurements to regulate the oral anticoagulant dose. Our studies have shown that removal of 3 mls of blood from the catheter limb containing the heparin (to be discarded) followed by 10 mls as a heparin wash-out (to be returned to the patient) allows blood to be taken from the arterial limb of the catheter for PT measurement. The PT measurement obtained from the arterial limb after a 10 ml wash-out is nearly always identical with the PT measurement on blood obtained from a peripheral vein. If the simultaneously measured aPTT is normal the PT is predictably and consistently accurate. If the aPTT is raised due to traces of residual heparin then the PT may be inaccurate and should be repeated. This method is easy and reliable and can be recommended as an aid to regulation of the oral anticoagulant dose.