6.1 Hemostasis Modalities and Topical Hemostatic Agents

6.1 Hemostasis Modalities and Topical Hemostatic Agents

Intraoperative hemostasis—the arrest of bleeding from severed or traumatized blood vessels—is one of the most critical responsibilities shared by the surgical team. Uncontrolled hemorrhage obscures the operative field, prolongs operative time, compromises sterile visibility, increases the risk of inadvertent structural damage, precipitates hypovolemic shock, and drastically elevates the incidence of postoperative hematoma and surgical site infection (SSI). For the certified surgical technologist, mastering the physiological mechanisms of coagulation, the mechanical tools of vessel occlusion, and the pharmacological properties, preparation techniques, and contraindications of topical hemostatic agents is paramount to patient survival and procedural success.

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1. Physiological Coagulation Cascade and Clot Formation

Natural physiological hemostasis occurs through three sequential, overlapping phases: vascular spasm, platelet plug formation (primary hemostasis), and coagulation cascade activation (secondary hemostasis).

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|                   PHYSIOLOGICAL PHASES OF NATURAL HEMOSTASIS                |
|                                                                             |
|   [PHASE 1: VASCULAR SPASM]                                                 |
|   - Immediate smooth muscle vasoconstriction reduces local blood flow.      |
|   - Triggered by direct mechanical trauma and local endothelin release.     |
|                                                                             |
|   [PHASE 2: PRIMARY HEMOSTASIS (Platelet Plug Formation)]                  |
|   - Platelet Adhesion: Platelets bind exposed collagen via von Willebrand   |
|     factor (vWF).                                                           |
|   - Platelet Activation & Release: Degranulation releases ADP and           |
|     Thromboxane A2.                                                         |
|   - Platelet Aggregation: Platelets cross-link via GP IIb/IIIa receptors   |
|     to form an unstable primary plug.                                       |
|                                                                             |
|   [PHASE 3: SECONDARY HEMOSTASIS (Coagulation Cascade)]                     |
|   - Extrinsic Pathway (Tissue Factor) + Intrinsic Pathway (Contact Factor)  |
|     converge on the Common Pathway (Factor X -> Factor Xa).                 |
|   - Prothrombin (Factor II) is cleaved into active Thrombin (Factor IIa).   |
|   - Thrombin converts soluble Fibrinogen (Factor I) into insoluble Fibrin   |
|     strands (Factor Ia).                                                    |
|   - Factor XIII cross-links fibrin into a stable, permanent thrombus.       |
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The Common Coagulation Pathway

Regardless of whether the initial stimulus originates from extrinsic tissue trauma (Factor VII/Tissue Factor) or intrinsic intravascular contact (Factors XII, XI, IX, VIII), both pathways converge at Factor X activation:

$\text{Factor Xa} + \text{Factor Va} + \text{Platelet Phospholipids} + \text{Calcium (Ca}^{2+}\text{)} \longrightarrow \text{Prothrombinase Complex}$

The prothrombinase complex cleaves circulating Prothrombin (Factor II) into active Thrombin (Factor IIa). Thrombin then acts as a potent proteolytic enzyme that hydrolyzes soluble Fibrinogen (Factor I) into insoluble Fibrin monomers (Factor Ia), which polymerize and are cross-linked by Factor XIII (Fibrin-stabilizing factor) to entrap erythrocytes and stabilize the clot.

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2. Classification of Surgical Hemostatic Modalities

In the operating room, hemostasis is categorized into three primary modalities: mechanical, thermal, and chemical/pharmacological.

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|                    TRIAD OF SURGICAL HEMOSTASIS MODALITIES                  |
|                                                                             |
|     [ MECHANICAL ]             [ THERMAL ]            [ PHARMACOLOGICAL ]   |
|   - Direct Pressure         - Monopolar ESU         - Gelatin Matrices      |
|   - Sponges (Ray-Tec/Laps)  - Bipolar Forceps       - Oxidized Cellulose    |
|   - Hemostatic Clamps       - Ultrasonic Shears     - Collagen (Avitene)    |
|   - Ligatures / Ties        - Advanced Bipolar      - Topical Thrombin      |
|   - Suture Ligatures        - Argon Beam Coagulator - Fibrin Glues/Sealants |
|   - Hemostatic Clips        - Lasers (CO2, Nd:YAG)  - Bone Wax (Tamponade)  |
|   - Pledgets / Bolsters     - Electrocautery        - Systemic Agents       |
|   - Tourniquets / Pressure  - Hypothermia/Cryo        (TXA, Protamine, Vit K)|
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Mechanical Hemostasis Devices and Techniques

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3. Passive (Mechanical) Topical Hemostatic Agents

Passive topical hemostats provide a physical, structural matrix that accelerates platelet adherence, initiates contact activation, and concentrates clotting factors at the bleeding site. They do not contain intrinsic biological clotting proteins and depend on the patient's own functional coagulation cascade.

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|                       PASSIVE TOPICAL HEMOSTATIC AGENTS                     |
|                                                                             |
|   [1. ABSORBABLE GELATIN] (Gelfoam, Surgifoam, Gelfilm)                     |
|   - Animal skin/collagen derivative. Absorbs 40-50x its weight in blood.    |
|   - Used dry or soaked in sterile saline or active topical thrombin.        |
|   - Absorbed completely in 4 to 6 weeks.                                    |
|                                                                             |
|   [2. OXIDIZED REGENERATED CELLULOSE] (Surgicel, Nu-Knit, Fibrillar)        |
|   - Plant/cellulose derivative. Forms dark gelatinous clot upon contact.    |
|   - Acidic pH (~2.5-3.0) provides local antimicrobial properties.           |
|   - MUST BE APPLIED DRY. Absorbed in 7 to 14 days.                          |
|                                                                             |
|   [3. MICROFIBRILLAR COLLAGEN HEMOSTAT] (Avitene, UltraFoam)                |
|   - Purified bovine corium collagen fibrils. Direct platelet trap.          |
|   - Attracts and aggregates platelets instantaneously across irregular bone.|
|   - MUST BE APPLIED WITH TOTALLY DRY INSTRUMENTS AND GLOVES.                |
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Absorbable Gelatin (Gelfoam, Surgifoam, Gelfilm)

• Form and Handling: Available as sterile compressed sponges, dry powder, or thin films (Gelfilm). The surgical technologist cuts the sponge into precise, procedure-specific sizes (e.g., small squares for vascular anastomoses or craniotomies).
• Mechanism: When applied to bleeding tissue, it absorbs 40 to 50 times its weight in whole blood, expanding slightly to exert gentle tamponade and providing an expansive physical matrix for fibrin deposition.
• Preparation: Can be applied dry or saturated with sterile isotonic saline or topical thrombin solution. When soaked, the technologist compresses the sponge between gloved fingers or flat gauze to expel trapped air bubbles before handing it to the surgeon on a bayonet forceps or cottonoid patty.
• Absorption: Absorbed in vivo within 4 to 6 weeks without significant scar formation.
• Precautions: Should not be tightly packed into confined bony cavities (e.g., optic foramen, spinal canal) because expansion upon fluid absorption can cause compressive neurological ischemia.

Oxidized Regenerated Cellulose (Surgicel, Surgicel Nu-Knit, Surgicel Fibrillar)

• Form and Handling: Knitted fabric sheets, high-density weaves (Nu-Knit), or loose fiber layers (Fibrillar) derived from plant cellulose.
• Mechanism: On contact with blood, it swells into a dark brown or black gelatinous mass that serves as an artificial clot. Its low pH (~2.5 to 3.0) exerts a direct local caustic/coagulating effect and confers broad-spectrum bactericidal activity against both Gram-positive and Gram-negative pathogens.
• Application Rule: MUST BE APPLIED COMPLETELY DRY. Saturating oxidized cellulose with saline or thrombin inactivates its coagulation effect because thrombin is deactivated by the low pH.
• Absorption: Rapidly absorbed within 7 to 14 days.
• Precautions: Always remove excess material once hemostasis is verified if placed near neural foramina or the spinal cord, as swelling can cause localized nerve compression.

Microfibrillar Collagen Hemostat (MCH / Avitene, UltraFoam)

• Form and Handling: Shredded, flour-like white fibrous powder, pre-packed sheets, or sponge wafers derived from purified bovine skin (corium).
• Mechanism: When placed on bleeding surfaces, MCH binds directly to platelets, triggering immediate platelet degranulation, release of ADP and Thromboxane A2, and physical clot formation within 2 to 5 minutes even in heparinized patients.
• Application Rule: APPLY DRY WITH DRY INSTRUMENTS. The surgical technologist and surgeon must ensure instruments and gloves are completely dry; MCH adheres aggressively to wet metal surfaces and damp gloves, pulling away from the bleeding wound bed.
• Precautions: Excess collagen should be irrigated and aspirated away after hemostasis is achieved. Contraindicated in contaminated wounds or for skin closure (interferes with epithelial healing).

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4. Active Biologics and Fibrin Sealants

Active hemostatic agents contain biological components—predominantly thrombin and fibrinogen—that participate directly in the final enzymatic reactions of the clotting cascade, functioning independently of the patient's intrinsic clotting factor reserves.

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|                        ACTIVE BIOLOGICAL HEMOSTATIC AGENTS                  |
|                                                                             |
|   [1. TOPICAL THROMBIN] (Thrombin-JMI, Evithrom, Recothrom)                 |
|   - Lyophilized sterile powder reconstituted with sterile saline diluent.   |
|   - Directly converts fibrinogen to fibrin at the bleeding interface.       |
|   - ABSOLUTE CONTRAINDICATION: NEVER INJECT INTRAVASCULARLY!                |
|                                                                             |
|   [2. FIBRIN SEALANTS / GLUES] (Tisseel, Evicel)                            |
|   - Dual-barrel delivery system: Component 1 (Fibrinogen + Factor XIII)     |
|     and Component 2 (Thrombin + Calcium Chloride).                          |
|   - Mixes at applicator tip to form immediate, watertight fibrin clot.      |
|   - Requires specialized thawing/warming protocols prior to delivery.       |
|                                                                             |
|   [3. FLOWABLE GELATIN-THROMBIN MATRICES] (FloSeal, Surgiflo)               |
|   - Prefilled syringe of bovine gelatin granules mixed with active thrombin.|
|   - Conforms to deep, irregular, recessed surgical cavities.               |
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Topical Thrombin (Thrombin-JMI, Evithrom, Recothrom)

• Origins: Derived from bovine plasma (Thrombin-JMI), pooled human plasma (Evithrom), or recombinant DNA technology (Recothrom).
• Preparation & Labeling: Supplied as a sterile lyophilized powder with a dedicated vial of sterile saline diluent. The surgical technologist reconstitutes the solution immediately before use, swirling gently without shaking to avoid foaming and protein denaturation.

[!CAUTION] BLACK BOX WARNING — STRICT TOPICAL USE ONLY: Topical thrombin must NEVER, UNDER ANY CIRCUMSTANCE, BE INJECTED INTRAVASCULARLY OR DRAWN INTO A STANDARD PARENTERAL SYRINGE. Accidental injection into systemic circulation or blood vessels causes immediate, catastrophic, widespread intravascular thrombosis, massive pulmonary embolism, and death. The surgical technologist must keep reconstituted thrombin in a dedicated, clearly labeled bowl or use a specialized spray applicator tip. Never place thrombin in an unlabeled syringe on the sterile field where it could be mistaken for local anesthetic or irrigation.

Fibrin Sealants and Glues (Tisseel, Evicel)

• Biochemical Action: Fibrin sealants replicate the final stage of the common coagulation pathway. A dual-chamber syringe delivers concentrated human Fibrinogen + Factor XIII from one barrel and Thrombin + Calcium Chloride from the second barrel. The two components mix in the disposable applicator tip, polymerizing within seconds into a flexible, elastic, watertight fibrin matrix.
• Clinical Indications: Suture line sealing in vascular grafts, dural closures in neurosurgery, spleen/liver laceration repair, and sealing air leaks in pulmonary parenchymal resections.
• Preparation: Often stored frozen at -20°C. Must be thawed at room temperature or in a dedicated warming unit (37°C) prior to use. Once thawed, it must not be refrozen.

Flowable Hemostatic Matrices (FloSeal, Surgiflo)

• Design: Combines a bovine or porcine gelatin matrix with human or bovine thrombin in a syringe-to-syringe mixing system.
• Clinical Utility: The flowable consistency enables the surgeon to inject the matrix directly into deep, inaccessible, irregular bleeding crevices (e.g., pelvic sidewall, posterior spinal decortication sites, parotid bed). Excess matrix not incorporated into the clot is gently irrigated away with warm saline after 2 to 3 minutes.

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5. Specialized Mechanical Hemostatic Agents: Bone Wax and Pledgets

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|                     SPECIALIZED MECHANICAL HEMOSTATS MATRIX                 |
|                                                                             |
|   AGENT         COMPOSITION         MECHANISM          SURGICAL USE         |
|   -----------   ------------------  -----------------  ------------------   |
|   Bone Wax      Beeswax + Isopropyl Mechanical plug of Sternotomy edges,    |
|                 palmitate           Haversian canals   craniotomy cuts,     |
|                                     (No active clot)   orthopedic cuts      |
|   -----------   ------------------  -----------------  ------------------   |
|   Pledgets      Polytetrafluoro-    Bolster cushion to Aortic root repair,  |
|                 ethylene (PTFE)     distribute suture  carotid cutdowns,    |
|                                     tension on friable friable myocardial   |
|                                     vessels            wall repair          |
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Bone Wax: Preparation and Clinical Rules

• Composition: Refined sterile beeswax combined with a softening agent (isopropyl palmitate or paraffin).
• Mechanism: Acts strictly as an inert, physical mechanical tamponade that blocks open Haversian canals and bleeding diploic veins in cut bone surfaces. It does not possess any chemical or physiological procoagulant properties.
• Handling by Surgical Technologist: The technologist opens the foil package, pinches off small amounts, and rolls them between warm gloved fingertips into small, pea-sized spheres. These spheres are placed on the tip of a Freer elevator, osteotome, or paper wrapper ready for immediate transfer to the surgeon.
• Precautions: Bone wax is non-absorbable and remains in the body permanently as a foreign body. It impairs osteogenesis (bone fusion) and inhibits local bacterial clearance. Surgeons must use the minimum amount necessary to stop bleeding, wiping away excess material from bone edges before closure.

Pledgets and Bolsters

• Application: In friable, calcified, or structurally weakened vessels (e.g., geriatric aorta, inflamed vascular pedicles), standard sutures can slice through tissue when tied under tension. Pledgets act as mechanical bolsters, distributing suture tension across a broad surface area to prevent tissue cut-through.

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6. Systemic Pharmacological Hemostatic Agents

In addition to topical agents, the surgical team manages systemic medications administered by anesthesia to enhance coagulation or reverse anticoagulation.

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7. Comparative Properties of Topical Hemostats Matrix