anticoagulation therapy in hemodialysis

1. ANTICOAGULATION
THERAPY IN
HAEMODIALYSIS

2. COAGULATION CASCADE

3. HEPARIN
• sulfated polysaccharide with a molecular weight range of 3000 to 30 000 Da (mean,
15 000 Da)
• Inactivates THROMBIN and ACTIVATED FACTOR X (factor Xa) through an
antithrombin (AT)-dependent mechanism

5. MEAUSURING BLOOD CLOTTING
DURING HAEMODIALYSIS
• a.APTT
b. Activated Clotting Time (ACT)
Blood must be taken from arterial line, proximal to any heparin
infusion!

6. TARGET ACT
TEST BASELINE Heparin
Normal
(Desired
Range)
Heparin
Tight
(Desired
Range)
During HD End of HD During HD End of HD
+80% +40% +40% +40%
ACT 120s-150s 200-250 170-190 170-190 170-190

7. ISSUES
• ACT monitoring ideally should be done hourly
• In a busy NGO and government hospital, impractical
• Some suggestions is to do it for new patients or patients with
frequent clotting or easy bleeding during dialysis

8. ANTICOAGULATION DURING
HAEMODIALYSIS
• Why is it needed?
• -prevent blood clotting in extracorporeal circuit (blood tubing,
dialyzer, drip chambers)
-prevent thrombosis in Vascular access and Dialysis catheters

9. Daugirdas, Handbook of Hemodialysis, 3rd Edition

10. CONSEQUENCES OF
INADEQUATE ANTICOAGULATION
 Thrombus in Fistula and Dialysis Access Catheter
 Thrombus breeds bacteria
 Inadequate dialysis
 Catheters are Costly
• Eg Cuff Catheter-cost alone is RM1000
• Temporary Catheter costs is RM 800
• Dialyzers, Tubing are costly
• Nurse time is costly
• Loss of time, loss of vehicle, loss of earnings?

11. CONSEQUENCES OF
INADEQUATE ANTICOAGULATION
 Clot formation in Dialyzer-ruined, cannot be reused-wastage and cost
 Interruption to dialysis treatment-staff forced to change dialyzer
 Anaemia-blood volume in dialyzer and tubing can be up to 200mls
 Emboli-HD staff attempt to return blood to patient—including the blood
clots

14. WARNING SIGNS OF UNDER-
ANTICOAGULATION
‘Black Streaking’ in the dialyser,
excessively raised Transmembrane pressure (TMP)
evidence of thrombus in the venous bubble trap – indicated by
dark blood
swelling of the trap or rising venous pressure (VP)

16. WHAT’S TMP??
• Transmembrane Pressure (TMP)-caused by pressure difference
between Blood Compartment and Dialysate compartment
• In modern dialyzers with volumetric control of ultrafiltration, TMP’s
primary role is to help monitor filter function:
↓ A drop in TMP could be due to a leak or filter rupture
↑ A rise in TMP could be due to filter clotting

18. VENOUS PRESSURE
• Venous Pressure-Rule of Thumb-Should not be more than half of the
prescribed Blood Flow Rate, Qb (some places advocate not more than 60%)
• eg Qb = 300ml/min
 then Venous Pressure around 150-160 mmHg maximum

19. ANTICOAGULATION PRESCRIPTION
FOR HEPARIN
Heparin Free
Heparin Tight
Heparin Normal

20. BLEEDING RISK STRATIFICATION
Bleeding Risk Features
High Platelet count <100 k/uL
Coagulopathy
Wafarinized
Post Major Operation
Liver failure
High urea
Medium Platelet count >100 k/uL
Coagulopathy
Low Normal platelet counts
Normal coagulation profile

21. HEPARIN NORMAL
• Heparin Bolus 50 U/kg (consider reducing in very uraemic
patients)
• Wait 3-5 minutes for heparin dispersion
• Heparin infusion rate 10-20 units/kg per hour (1000 units/hr)
• Consider increasing to 1100 to 1200 units/hr if patient on Cuff
Catheter, and history of clotting-Watch out for bleeding

22. HEPARIN TIGHT
 Bolus Dose 10-25 IU/lg
 Maintenance Dose 5-10 IU/Kg/hr (500 units/hr)
 Monitor ACT every 30 minutes (where feasible)

23. HEPARIN FREE
Need a high Qb to prevent clotting
May need to use small area Dialyzer or reduce QD if high Qb not
tolerated by patient (eg on inotropes)
Attentive staff-need to flash with Normal saline periodically 100-
200ml every 15-30 minutes-arterial line
Ultrafiltration of saline flush

24. TRULY HEPARIN FREE??
• Priming the system –use heparinized saline
• If really want 100% heparin free, have to use normal saline to do
priming

25. WHEN TO USE HEPARIN FREE
High Risk bleeding
Recent Major Operation
Coagulopathy
Invasive procedures
ICB
UGIH
First HD
High Urea

26. FACTORS AFFECTING CLOTTING
• DIALYZER PRIMING
• -Retained air in Dialyzer (inadequate priming or poor priming
technique)
-inadequte priming of heparin infusion line
 )

27. FACTORS AFFECTING CLOTTING
 HEPARIN ADMINISTRATION
 -Incorrect heparin pump setting
 -incorrect loading dose
 -delay in starting heparin pump
 -Failure to release heparin line clamp
 -insufficient time lapse after loading dose for systemic heparinization to
occur (ideally wait 3-5 minutes for heparing to circulate prior to starting HD

28. FACTORS CAUSING CLOTTING
• VASCULAR/PATIENT FACTORS
• -Inadequate Blood Flow due to Needle or Catheter Position
• -Needle or Catheter Clotting
• -Excessive Recirculation due to Needle Position
• -Frequent interruption of Blood flow due to Machine alarm

29. ALL CHRONIC HD PATIENTS
“HEPARIN NORMAL”?
• Everyone gets same dose-3000 units loading and 1000 units maintenace
regardless of size, age
• Some patients on Double Antiplatelets (DAPT) or Warfarin
• patients with Liver failure
• Some patients Big sized 80-100kg, some 30kg
• Problems with this approach-Bleeding, inadequate anticoagulation-thrombosis (AVF,
Perm Cath(

30. SUGGESTIONS
• bigger patients eg More than 80kg
i go for 5000 units loading, 1200-1500 units maintenance
• Smaller, elderly patients, hx of bleeding- Have to adjust
• May need to do ACT or PT/PTT 2 hours midway during HD