|Year : 2020 | Volume
| Issue : 7 | Page : 36-37
|Date of Web Publication||15-Jul-2020|
Source of Support: None, Conflict of Interest: None
|How to cite this article:|
. Anticoagulation. Indian J Nephrol 2020;30, Suppl S1:36-7
The HD circuit has a large extracorporeal surface area, and the passage of blood through the circuit results in the activation of coagulation cascade. The consequences of clotting are blood loss and loss of dialyzer surface area, leading to reduced solute clearance. Anticoagulation is required to prevent clotting during a session and also to prolong the life of the dialyzer for reuse. Unfractionated heparin is traditionally used for anticoagulation. Low-molecular-weight heparin (LMWH), trisodium citrate, fondaparinux, and prostacyclin (all of which are expensive) may be used in specific situations. The long-term safety of these agents has not been completely established in dialysis.
| Factors Favoring Clotting of Extracorporeal Circuit|| |
- Low blood flow
- High hematocrit
- High UF rate
- Dialysis access recirculation
- Intradialytic blood and blood product transfusion
- Intradialytic lipid infusion
- Use of drip chambers (air exposure, foam formation, and turbulence).
We recommend the following precautions to prevent dialyzer clotting:
- Follow the correct priming technique to prevent retained air in dialyzer (refer guideline on priming technique)
- Ensure adequate priming of heparin infusion line.
- Use correct loading dose (see below)
- Use correct heparin pump setting for constant infusion.
- Starting of heparin pump in timely manner.
- Ensuring timely release of heparin line clamp.
- Allow time after loading dose for systemic heparinization to occur.
- Ensure adequate blood flow by correct needle and catheter position.
- Correct needle position to prevent recirculation.
- Maintain adequate uninterrupted blood flow by preventing repeated machine alarm situation.
We recommend that
- The heparinization schedule should be decided taking into consideration the risk of bleeding and other comorbidities.
- Low-risk patients and those without comorbidities such as central nervous system (CNS) bleed, GI hemorrhage, or pericarditis are routinely treated with full-dose heparinization.
- Patients at slightly increased risk of bleeding and those in whom heparin-free dialysis is unsuccessful due to frequent clotting should receive tight heparinization.
- Heparin-free dialysis should be considered for those with pericarditis, recent surgery with bleeding complications or risks (vascular and cardiac surgery, eye surgery, renal transplant, and intracranial surgery), coagulopathy, thrombocytopenia, intracerebral hemorrhage, and active bleeding from any other site.
- We recommend that a baseline liver function test be done and repeated periodically to detect transaminitis from heparin and avoid unnecessary investigations later. A baseline platelet count which is repeated periodically for a month to detect late-onset, delayed-onset, heparin-induced thromobocytopenia is also recommended. In situ ations where the use of heparin is contraindicated (e.g., heparin-induced thrombocytopenia [HIT] and heparin-free dialysis is not advisable, a shift to peritoneal dialysis is recommended). Using argatroban 250 μg/kg or fondaparinux 2.5 mg at the start of dialysis and repeated after 2 h is an expensive alternative.
- LMWH may ameliorate hyperkalemia and have less effect on lipid profile and the osteoblast compared to unfractionated heparin. However, it is more expensive, effects last much beyond the dialysis session, and it is not as readily neutralized by protamine when compared to unfractionated heparin.
We recommend not using LMWH in routine dialysis or substituting it for unfractionated heparin in HIT.
- A baseline activated partial thromboplastin time (aPTT) is also advised to detect the occasional Anti Phospholipid antibody (APLA). Using LMWH or using unfractionated heparin with monitoring factor X antibodies is a suitable alternative in this situation.
We recommend the following heparinization protocols:
Routine anticoagulation with unfractionated heparin
Either intermittent or continuous delivery techniques should be used.
a) Intermittent bolus: Bolus loading dose of 35–55 U/kg followed by intermittent maintenance dose of 10–20 IU/kg boluses every hour. No heparin to be given during the last half hour of dialysis.
b) Constant infusion: Bolus loading dose of 35–55 U/kg followed by constant infusion.
Body weight between 50 and 90 kg: no change in dose.
Body weight outside these limits: bolus dose 75–100 U/kg; infusion dose 750–1000 U/h.
We recommend termination of heparin infusion in the following protocol:
- AVF – 30 min before the end of dialysis
- Venous catheters – At the end of dialysis.
Reversal of overheparinization
- We recommend the use of injection protamine 1 mg for reversing the effects of every 100 U of heparin. As heparin has a half- life of 30–60 min, only half of the previous hour's dose needs to be neutralized
- Effect of heparin is lost after 4 to 5 half-lives and hence, we suggest that interventional procedures be considered 5 h after HD.
- We recommend the following delivery technique for tight heparinization: Bolus dose followed by constant infusion
- We recommend not using intermittent boluses in this technique as it will lead to rising and falling clotting times.
- Initial bolus dose: 750 U
- Heparin infusion rate: 600 U/h
- Termination of heparin infusion: Continue till the end of dialysis.