Overview
Definition:
Topical hepatic hemostats are agents applied directly to bleeding surfaces of the liver during surgery to achieve hemostasis
They work through various mechanisms including promoting clot formation, absorbing blood, and mechanical compression.
Epidemiology:
Liver bleeding is a significant concern in hepatic surgery, contributing to morbidity and mortality
The incidence of severe intraoperative bleeding varies with the complexity of the procedure, ranging from 5-15% for major resections
The choice and effectiveness of hemostatic agents are crucial for patient safety.
Clinical Significance:
Effective control of intraoperative bleeding during liver surgery is paramount
It reduces operative time, decreases the need for blood transfusions, minimizes the risk of postoperative complications such as hematoma formation and bile leaks, and ultimately improves patient outcomes and reduces hospital stay
Topical agents offer a valuable adjunct to standard surgical techniques.
Types Of Topical Hemostats
Absorbable Hemostats:
These agents are derived from natural or synthetic polymers and are absorbed by the body over time
Examples include oxidized regenerated cellulose (ORC), gelatin sponges, and microfibrillar collagen
They provide a scaffold for clot formation and can be impregnated with thrombin or other procoagulant agents.
Non Absorbable Hemostats:
These agents are not absorbed and may require removal after hemostasis is achieved
They often provide mechanical compression
Examples include some types of hemostatic gauzes and sealants
They are less commonly used for diffuse parenchymal oozing in the liver compared to absorbable agents.
Biologic Sealants And Adhesives:
These are derived from proteins like fibrinogen and thrombin, or synthetic polymers
They form a stable fibrin clot or polymer matrix to seal blood vessels and tissue defects
Examples include fibrin sealants, cyanoacrylate glues, and polyethylene glycol-based sealants
They are particularly effective for sealing small vessels and raw surfaces.
Active Hemostats:
These agents contain specific active components that directly accelerate the coagulation cascade or enhance platelet aggregation
Examples include thrombin, factor XIII, and recombinant activated factor VII
They are often used in conjunction with other hemostatic materials.
Indications For Use
Diffuse Parenchymal Oozing:
When small, multiple vessels are bleeding from the cut surface of the liver after resection or biopsy, topical agents provide effective control.
Difficult To Ligate Vessels:
Small venules or arterioles that are difficult to identify and ligate individually can be controlled with topical hemostats.
Biopsies And Drainage Tracts:
After hepatic biopsies or placement of drains, topical agents can be applied to the entry site to prevent bleeding.
Adjunct To Mechanical Methods:
Topical hemostats are frequently used in conjunction with sutures, electrocautery, and surgical clips to achieve comprehensive hemostasis.
Application Techniques
Preparation Of The Field:
The bleeding surface must be adequately visualized, and any significant active bleeding controlled with standard surgical techniques
Excess blood and clots should be gently suctioned or wiped away to allow direct contact of the hemostat with the bleeding tissue.
Direct Application:
Most topical hemostats are applied directly to the bleeding surface
This may involve gently pressing a hemostatic sponge or pad onto the area, or painting on liquid sealants
Care must be taken not to dislodge already formed clots.
Layering And Packing:
For larger or more persistent bleeding, multiple layers of hemostatic materials may be applied
In some cases, particularly with sponges, gentle packing of the area may be performed to provide sustained pressure.
Combination Therapy:
Often, a combination of hemostatic agents is used
For example, a collagen sponge impregnated with thrombin may be applied, followed by a fibrin sealant to reinforce the seal
Active hemostats like thrombin are frequently applied to absorbable gelatin or cellulose materials.
Specific Agents And Their Use
Oxidized Regenerated Cellulose:
Available as sheets, pads, and powders
It acts as a mechanical barrier and scaffold for clot formation
Useful for diffuse oozing
Can be soaked in saline or thrombin
Should not be used in infected wounds or as an internal suture.
Gelatin Sponges:
Porous sponges that absorb blood and provide a matrix for clot formation
Available in various sizes and densities
Can be used dry or moistened with saline or thrombin
They are fully absorbable
Commonly used for liver wedge resections and biopsies.
Microfibrillar Collagen:
Powder or pad form that promotes platelet adhesion and aggregation, initiating the clotting cascade
Effective for oozing from raw surfaces
Not typically used in cases of massive hemorrhage
Can cause a foreign body reaction if not fully absorbed.
Fibrin Sealants:
Composed of fibrinogen and thrombin
They mimic the final stage of the coagulation cascade, forming a stable fibrin clot
Excellent for sealing parenchymal defects and reinforcing sutures
Generally safe but can transmit viral infections if not properly processed
human and recombinant versions available.
Potential Complications And Considerations
Allergic Reactions:
Rare, but can occur with protein-based hemostats
Careful patient history and monitoring are important.
Infection:
As with any foreign material, topical hemostats can act as nidus for infection, especially if not fully absorbed or if applied in contaminated fields.
Adhesions:
Some hemostats, particularly non-absorbable ones or those causing significant inflammation, can contribute to adhesion formation postoperatively.
Mechanical Obstruction:
Large amounts of residual hemostatic material can potentially cause obstruction, though this is rare with absorbable agents.
Failure Of Hemostasis:
Inadequate or improper application, or severe coagulopathy, can lead to failure of topical hemostats to control bleeding.
Key Points
Exam Focus:
Understand the mechanisms of action, indications, contraindications, and common complications of various topical hepatic hemostats
Be prepared to discuss specific agent choices for different surgical scenarios.
Clinical Pearls:
Always ensure the surgical field is as dry as possible before applying topical hemostats for maximal efficacy
Combine agents judiciously based on the type and extent of bleeding
Never use topical hemostats as a substitute for meticulous surgical technique and control of major vessels.
Common Mistakes:
Over-reliance on topical hemostats without addressing underlying surgical causes of bleeding
Inadequate application or preparation of the surgical field
Using agents in contraindications like infected wounds or when significant coagulopathy is not addressed.