Hemostasis is the process of halting blood flow, and in the surgical setting, it is a primary concern for patient safety and procedural success. Uncontrolled bleeding can rapidly compromise a patient’s health and obscure the surgeon’s view, making precise work nearly impossible. Modern surgery utilizes a combination of physical tools, advanced energy devices, and specialized biological materials to minimize blood loss and manage bleeding across various scenarios.
Physical Methods of Stopping Blood Flow
The most fundamental approaches to stopping blood flow involve direct mechanical action on the vessel itself. Surgeons frequently use specialized clamps, known as hemostats, to grasp and temporarily compress a severed vessel. This action immediately occludes the vessel lumen, providing a momentary block to the flow while the surgical team prepares for a permanent solution.
For larger vessels, or in situations demanding a definitive closure, the application of ligatures is the standard technique. A ligature is a piece of suture material used to permanently tie off the blood vessel. This creates a secure knot around the vessel, preventing any further blood flow through that specific channel.
In cases of diffuse bleeding, direct pressure and packing materials are employed. Gauze or surgical sponges are pressed firmly onto the site, which encourages the body’s natural clotting process to stabilize a temporary fibrin plug. This mechanical pressure, or tamponade, is often a temporary measure but can be effective for controlling widespread, low-pressure venous or capillary bleeding.
Utilizing Energy to Seal Vessels
Energy-based devices have become central to modern surgical practice, allowing for simultaneous cutting and sealing of tissue. Electrocautery is the most common of these, using a high-frequency electrical current to generate heat that coagulates tissue proteins. This process causes blood vessels to seal, which controls bleeding.
Monopolar electrocautery uses a single active electrode at the surgical site to deliver the current. The electrical circuit is completed by a grounding pad placed elsewhere on the patient’s body, meaning the current passes through the patient’s tissues to return to the generator. This method is highly versatile and is often used for cutting tissue and controlling bleeding over a large surgical area.
Bipolar electrocautery restricts the electrical current flow to the tissue held between two tips of a forceps-like instrument. Because the current travels only between these two points, it does not pass through the rest of the patient’s body. This technique is preferred for delicate surgeries and working with smaller vessels where precision is paramount, as it minimizes the risk of collateral thermal damage.
Beyond electrical current, ultrasonic devices like the harmonic scalpel utilize high-frequency mechanical vibration to achieve hemostasis. The active blade of this instrument vibrates rapidly, generating friction that denatures tissue proteins. This protein denaturation forms a coagulum, effectively sealing vessels up to five millimeters in diameter without relying on an electrical current passing through the patient.
Topical Agents and Surgical Sealants
When mechanical or energy-based methods are impractical, such as with diffuse surface bleeding or in hard-to-reach spaces, surgeons turn to topical hemostatic agents. These materials are applied directly to the wound to enhance or accelerate the body’s intrinsic coagulation cascade. They are broadly categorized based on their mechanism of action, either providing a passive physical scaffold or actively introducing clotting factors.
Passive agents, such as gelatin sponges or oxidized regenerated cellulose, function primarily by providing a physical matrix. The porous structure of these materials absorbs blood and concentrates platelets and clotting factors, creating a favorable environment for clot formation. Oxidized cellulose also acts as a physical support and is easy to manipulate in the surgical field.
Active hemostats and surgical sealants work by introducing components of the body’s clotting system directly to the site. Fibrin sealants contain fibrinogen and thrombin, which are the final components needed to form a stable fibrin clot. These sealants mimic the final stage of natural coagulation, providing a strong biological closure and are particularly useful for sealing cut surfaces of solid organs.
Managing Systemic Clotting Factors
Controlling bleeding extends beyond the immediate surgical site to include managing the patient’s overall physiological status. Pre-operative assessment is a foundational step, including a detailed review of all medications, especially anticoagulants or antiplatelet agents. These medications often need to be temporarily discontinued or reversed before surgery to ensure the patient’s blood can clot normally.
During the procedure, the body’s intrinsic ability to clot is highly sensitive to changes in core temperature and blood pressure. Surgeons and anesthesiologists work closely to maintain a patient’s normal body temperature, as hypothermia significantly impairs platelet function and enzyme activity in the clotting cascade. Maintaining adequate blood pressure is also necessary to prevent poor tissue perfusion, which can exacerbate bleeding.
In cases of significant blood loss or pre-existing clotting disorders, transfusions are necessary to restore blood volume and circulating clotting factors. This may involve transfusing whole blood, packed red blood cells to carry oxygen, or specific blood products like cryoprecipitate or fresh frozen plasma, which replenish fibrinogen and other factors. For patients with known deficiencies, such as hemophilia, specific factor concentrates may be administered throughout the operation.