2.3 Hemostasis: Mechanical Methods

Hemostasis—the cessation of bleeding—is one of the most fundamental aspects of surgery. Without adequate hemostasis, the surgical field becomes obscured, rendering safe dissection impossible, and the patient is placed at risk for hemorrhagic shock. Hemostasis can be achieved through chemical, thermal (e.g., electrocautery), or mechanical means. This section focuses on mechanical hemostasis.

Principles of Mechanical Hemostasis

Mechanical methods achieve hemostasis by physically blocking the flow of blood from a severed or punctured vessel. This is done by applying external pressure or by tying off the vessel lumen.

Hemostatic Clamps

Hemostatic clamps (often simply called "hemostats") are instruments designed to occlude blood vessels. They feature ring handles, a ratcheted locking mechanism, and jaws with serrations to grip tissue.

• Mosquito / Halsted: Small, fine-tipped clamps used for very small vessels, often in pediatric, plastic, or hand surgery.
• Crile: A medium-sized hemostat with serrations running the entire length of the jaw. Very common in general surgery.
• Kelly: Similar to a Crile, but the serrations only cover the distal half of the jaws.
• Pean / Rochester-Pean: A larger, heavier clamp used for grasping larger chunks of tissue and major vessels.
• Mixter (Right-Angle): Features a 90-degree bend at the tip, useful for getting behind a vessel to pass a tie around it.
• Vascular Clamps (e.g., Satinsky, DeBakey, Fogarty): These are non-crushing, atraumatic clamps. Unlike crushing hemostats, vascular clamps feature specialized fine serrations (DeBakey teeth) designed to occlude blood flow through major arteries and veins without damaging the delicate vessel wall (tunica intima).

Technique: When a vessel is cut, the CSFA or surgeon will grasp the bleeding end with the tip of the hemostat. It is crucial to clamp only the vessel and a minimal amount of surrounding tissue to prevent necrosis. Once clamped, the vessel is ready to be ligated or cauterized.

Ligation (Tying)

Ligation is the process of tying a suture around a vessel to occlude it permanently.

1. Free Ties: A single strand of suture material handed to the surgeon or assistant to tie around a clamped vessel. The CSFA often "flashes" the clamp—releasing it slightly as the first knot is tightened—to allow the suture to slip past the tip of the clamp and securely crush the vessel wall.
2. Stick Ties (Suture Ligature): A suture attached to a needle. The needle is passed directly through the center of the vessel or surrounding tissue before being tied. This prevents the ligature from slipping off the end of a pulsating artery. It is the gold standard for large vessels (e.g., renal artery, splenic artery).
3. Instrument Tie (Tie on a Pass): A free tie loaded onto the tip of a tonsil clamp or right-angle clamp. This allows the tie to be passed deep into a cavity where hands cannot easily reach.

Knot Security: The CSFA must be proficient in tying square knots, surgeon's knots (which feature a double throw on the first loop to prevent slippage under tension), and sliding knots (half-hitches). Monofilament suture requires more throws (typically 5 to 6) than multifilament suture (3 to 4) due to lower coefficient of friction and memory.

Surgical Clips

Ligating clips are small, V-shaped devices used to rapidly occlude vessels. They are applied using a specialized clip applier.

• Titanium Clips: The most common type. They are permanent, radiopaque, and MRI-safe. They are squeezed closed around the vessel, mechanically crushing it. Clip sizes are color-coded (e.g., blue for medium, yellow for small, green or orange for medium-large).
• Absorbable Clips: Made from polymers similar to absorbable suture. They degrade over time, which can be advantageous if future imaging (like a CT scan) is anticipated, as metal clips can cause "starburst" artifact on the scan.

Safety with Clips: When applying clips, the CSFA must ensure the clip extends completely across the diameter of the vessel. If a vessel is too large, it must be double-clipped or suture-ligated instead. The clip should be placed approximately 2 to 3 millimeters away from the cut edge of the vessel to prevent it from slipping off as the vessel pulsates.

Bone Wax

Bleeding from cut bone cannot be stopped by clamping or tying, as the vessels are encased in the rigid osseous matrix. Bone wax is a sterile mixture of beeswax, almond oil, and salicylic acid.

• Mechanism: It does not promote clotting chemically; rather, it acts as a mechanical plug. It is smeared across the bleeding trabecular bone, physically sealing the osseous channels.
• Application: The wax must be warmed and softened (usually by kneading it in the gloved fingers) before application.
• Contraindications: Because bone wax is non-absorbable, it acts as a foreign body and inhibits osteogenesis (bone healing). It should be used sparingly, especially in orthopedic procedures where bone fusion is the primary goal. A common water-soluble copolymer alternative is Ostene, which is absorbed by the body and does not inhibit bone healing.

The CSFA's Role in Hemostasis

The surgical first assistant must be proactive. When bleeding occurs, the immediate reaction should be applying direct digital pressure with a sponge. Once the field is cleared of pooled blood using suction, precise clamping or clipping can be executed. Anticipation of the necessary hemostatic agent—having a stick tie or clip applier loaded and ready—prevents minor bleeding from becoming a major hemorrhage.