What is Topical Thrombin?
Topical thrombin is a potent hemostatic agent used in medical and surgical settings to control minor bleeding and oozing from capillaries and small venules. By converting fibrinogen to fibrin at the site of application, it rapidly forms a clot and promotes hemostasis. It is critical to note that topical thrombin is for external use only and must never be injected into the circulatory system, as this can cause extensive and fatal intravascular clotting.
Forms of Topical Thrombin
Topical thrombin is available in several forms, which differ primarily in their source of origin and preparation methods. The choice of product may depend on patient history, as some individuals may have sensitivities to materials of animal origin.
Recombinant Human Thrombin (e.g., Recothrom)
This form is produced using recombinant DNA technology and is functionally similar to natural human thrombin. It is less likely to cause an immune response compared to bovine-derived products. It comes as a sterile powder for reconstitution with a supplied diluent.
Bovine Thrombin (e.g., Thrombin-JMI)
Derived from bovine (cow) sources, this product has been in use for many years. It is supplied as a sterile powder for reconstitution and can be used directly or with an absorbable gelatin sponge. A key safety consideration is the potential for patients to develop antibodies against bovine thrombin or factor V, which can cause severe bleeding or thrombosis upon re-exposure.
Human Thrombin (e.g., Evithrom)
Derived from human plasma, this formulation carries a low risk of viral transmission due to donor screening and viral inactivation processes. It is generally considered a lower immunogenicity risk than bovine-derived products.
Preparing Topical Thrombin for Application
Preparation procedures vary by product and application method. Always follow the manufacturer’s instructions explicitly, as provided in the product's prescribing information.
Reconstitution Process
Typically, topical thrombin is supplied as a sterile, freeze-dried powder. Reconstitution is performed under sterile conditions:
- Introduce the supplied diluent (usually 0.9% sterile sodium chloride) into the thrombin vial using a sterile syringe or transfer device.
- Gently swirl the vial to dissolve the powder completely. Avoid vigorous shaking, which can cause foaming.
- For most applications, a specific concentration is used, but this can vary depending on the procedure and product.
- Once reconstituted, the solution should be used promptly. It can often be refrigerated for a short period (e.g., up to 24 hours) if not used immediately, but always consult the specific product labeling.
Methods for Applying Topical Thrombin
The method chosen depends on the surgical site, the type of bleeding, and the specific kit available. Before any application, the bleeding surface should be gently sponged to remove excess blood, not wiped, to avoid disrupting any initial clotting.
Direct Flooding Technique
For broad or inaccessible bleeding surfaces, the liquid solution can be applied directly.
- Step 1: Reconstitute the thrombin solution according to the manufacturer's instructions.
- Step 2: Draw the solution into a sterile syringe.
- Step 3: Flood the surface of the bleeding tissue with the solution.
- Step 4: Allow the solution to mix freely with the blood and form a clot. Do not sponge or wipe the treated surface afterward.
Using an Absorbable Gelatin Sponge
This technique is useful for packing specific bleeding sites and applying pressure.
- Step 1: Prepare the thrombin solution as directed.
- Step 2: Immerse the absorbable gelatin sponge in a sterile bowl containing the solution.
- Step 3: Knead the sponge vigorously with moistened, gloved fingers to expel trapped air and ensure complete saturation.
- Step 4: Apply the saturated sponge directly to the bleeding area.
- Step 5: Apply moderate pressure with a gauze or cotton pledget until hemostasis is achieved.
Using a Spray Applicator Kit
For broader, diffuse bleeding, a spray applicator provides an even distribution of the solution.
- Step 1: Follow the kit's specific instructions for reconstituting the thrombin and assembling the spray pump or syringe tip.
- Step 2: Hold the vial upright or at a slight angle and prime the pump or syringe until the solution is expelled.
- Step 3: Spray the solution onto the bleeding site from an appropriate distance to achieve an even mist.
- Step 4: Avoid sponging the area to allow clot formation.
Comparison of Topical Thrombin Application Methods
| Feature | Direct Flooding | Spray Applicator | Absorbable Gelatin Sponge |
|---|---|---|---|
| Bleeding Type | Oozing, minor bleeding, broad surfaces | Broad, diffuse, or hard-to-reach areas | Minor bleeding, packing sites, applying pressure |
| Speed of Application | Fast, direct contact | Moderate, requires assembly | Moderate, requires sponge saturation |
| Precision | Low, covers a wide area | Moderate, can be focused | High, can be cut to precise size and shape |
| Pressure Needed | Minimal, relies on coagulation cascade | Minimal, relies on coagulation cascade | Manual pressure required to hold in place |
| Best For | General surgical hemostasis | Diffuse capillary or venule bleeding | Controlling bleeding in cavities or bone |
Important Safety Precautions
Proper handling and administration are paramount to prevent severe adverse events.
- Topical Use Only: Intravascular injection of thrombin can cause fatal systemic thrombosis, widespread clotting, heart failure, and death. Always use auxiliary labels to prevent accidental injection.
- Never Inject: Do not inject topical thrombin into the circulatory system or within open vessels.
- Hypersensitivity: Do not use in patients with a history of hypersensitivity to the product's components, including bovine-derived materials or hamster proteins (for recombinant products).
- Contraindications: Avoid use in massive or brisk arterial bleeding, as this is not a suitable application. Some forms are also contraindicated for closing skin incisions.
- Patient Monitoring: Patients should be monitored for signs of systemic clotting (e.g., leg tenderness, chest pain, shortness of breath) and allergic reactions (e.g., hives, swelling, difficulty breathing).
- Repeat Exposure: Patients previously exposed to bovine thrombin may develop antibodies. Re-exposure should be avoided if antibodies are suspected or known.
Conclusion
Topical thrombin is an effective tool for controlling minor surgical bleeding, but its application demands strict adherence to professional medical standards. By carefully following the steps for preparation and choosing the appropriate application method—whether direct flooding, spraying, or using an absorbable sponge—healthcare professionals can safely and effectively aid hemostasis. The paramount rule is that topical thrombin is for external use only; recognizing and preventing the risks associated with accidental intravascular injection is the most critical safety precaution. Always consult the manufacturer's specific labeling for complete instructions and precautions for the product being used.
For more detailed product information, refer to specific manufacturer prescribing information, such as the FDA's documents for various topical thrombin products.
