Which drug is used in haemodialysis to prevent blood clots?

DSSSB 13 August 2024

Pharmacology

Easy

Appeared in: DSSSB 13 August 2024

Explanation

Heparin is the standard, fast-acting anticoagulant used to prevent blood from clotting in the extracorporeal circuit (dialyzer and blood lines) during hemodialysis.
Its mechanism of action involves potentiating antithrombin III, which in turn inactivates key clotting factors like thrombin and Factor Xa.
The rapid onset and short duration of action make it ideal for use during the procedure, as its effects can be managed and wear off relatively quickly after dialysis is complete.
It is administered into the blood circuit to maintain patency and ensure the efficiency of the dialysis treatment.

Option A: Aspirin is an antiplatelet drug, not a primary anticoagulant. Its action of inhibiting platelet aggregation is not strong enough to prevent clotting in the high-risk environment of an extracorporeal circuit.
Option B: Protamine (as protamine sulfate) is the specific antidote for heparin. It neutralizes heparin's anticoagulant effect, so administering it during dialysis would cause the circuit to clot, which is the opposite of the desired effect.
Option D: Atropine is an anticholinergic medication that has no effect on the coagulation cascade. Its primary use is to treat symptomatic bradycardia (abnormally slow heart rate).

Clinical Relevance

Nursing practice connection: Knowing Anticoagulation in Hemodialysis helps nurses interpret findings accurately and avoid errors in routine assessment, medication administration, and patient teaching.
Nurses are responsible for administering the correct heparin dose and monitoring the dialysis circuit for signs of clotting (e.g., rising venous pressure, dark streaks in the dialyzer) and the patient for signs of bleeding (e.g., oozing from the access site, bruising, drop in blood pressure).
The dose of heparin is individualized and may be adjusted based on the patient's clotting time (like aPTT), previous clotting or bleeding issues, and the duration of the dialysis session.
What if the patient has a history of Heparin-Induced Thrombocytopenia (HIT)? In this case, heparin is strictly contraindicated. The nurse must ensure an alternative anticoagulant, such as regional citrate anticoagulation or a direct thrombin inhibitor (e.g., argatroban), is used as per the nephrologist's order.

How to Approach the Question

First, identify the clinical context of the question: 'haemodialysis'. This involves extracorporeal blood circulation (blood outside the body).
Next, understand the physiological challenge: Blood exposed to foreign surfaces like the dialysis tubing and filter will initiate the clotting cascade.
Determine the necessary intervention: A drug is needed to prevent this clotting. This requires a fast-acting anticoagulant.
Review the options based on their primary pharmacological action.
Recall that Heparin is the standard anticoagulant for procedural use like dialysis due to its rapid onset.
Eliminate the other options: Aspirin is an antiplatelet (different mechanism, less potent), Protamine is a heparin antidote (opposite effect), and Atropine is unrelated to coagulation.

Concept Tested & Keywords

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