Hemostasis Hemostasis Definition The arrest of bleeding through

Hemostasis

Hemostasis • Definition: The arrest of bleeding through natural or artificial means.

History • From Egyptian artifacts and writings surgery dates back to thousands of years ago. It is believed that the first surgical procedures were probably performed to control hemorrhage and to close war injuries.

History • Around 1000 BC the Greek method for caring for battle wounds were cleansing, controlling hemorrhaging with crushed roots and leaves and then covering them compresses. • Hippocrates was the first to note the analgesic action of temperature. He used ice and snow to control bleeding. He also recommended hot irons to stop hemorrhage.

History • It was known even in early times that the loss of blood meant the loss of life. However, the circulation of blood was not understood. • The writings of Aristotle reveal that veins were thought to contain all or most of the blood and arteries were thought to contain air with only a small amount of blood.

History • In 1500 s William Harvey realized that blood circulated and moved in one direction only. • Through the middle ages, gangrene as thought to be a natural result of a wound. The accepted treatment for bleeding and infection was boiling oil and hot irons.

History • In the early 19 th century, the pus and infection present in wounds were thought to be caused by sutures because the long ends left hanging from the wounds sloughed out. • Most surgical procedures were performed for either major injuries or life-threatening conditions.

History • The first attempt to transfer blood occurred in 1818 when James Blundell of London salvaged vaginal blood from a postpartum hemorrhage and reinfused it by syringe into the patient. • Later in 1886 John Duncan transfused blood directly from the surgical field into a trauma patient by femoral injection.

Mechanisms of Hemostasis • The natural method of hemostasis is coagulation or formation of a blood clot. • The clotting takes place in several different stages by enzyme reaction. • When severed by an incision or traumatic injury, a blood vessel constricts and the ends contract. Platelets rapidly clump and stick to connective tissue at the end of the constricted vessel.

Mechanisms of Hemostasis (Cont. ) • Interaction with collagen fibers causes platelets to release: 1. Adenosine Diphosphate (ADP) 2. Epinephrine 3. Serotonin In turn ADP causes other platelets to clump to the initial layer and to each other, forming a platelet plug. This may be sufficient in small vessels to provide primary hemostasis.

Reaction of Plasma • The reaction of plasma from vessels with connective tissue cells at the site of injury activates clotting factors and causes a series of other reactions. • Prothrombin, which is normally present in the blood, reacts with thromboplastin, which is released when tissues are injured.

Reaction (Cont. ) • Prothrombin and thromboplastin, along with calcium ions in the blood form thrombin. This requires several minutes. • Thrombin unites with fibrinogen, a blood protein, to form fibrin, which is the structural material of blood clots. This reaction is very rapid.

Reaction (Cont. ) • The fibrin strands reinforce the platelet plug to form a hemostatic plug capable of withstanding arterial pressure when the constricted vessel relaxes. • Massive thrombosis within the vessels would occur once coagulation is initiated, if it continued. However, fibrin is digested during the process.

Summary 1. Platelets release ADP, EPI. And Serotonin which additional platelets for platelet plug. 2. Plasma with connective tissue activates clotting factors. 3. Prothrombin (normally found in the blood) with thromboplastin (released in injuries) and clacium ions form thrombin. 4. Thrombin unites with fibrinogen (Blood protein) to form fibrin.

Types of Bleeding • Basically 2 types of bleeding that occur during surgical procedures: 1. Gross bleeding 2. Diffuse bleeding The need to control gross bleeding is obvious; but continuous loss of blood from small vessels and capillaries can become significant if oozing is uncontrolled.

Incomplete Hemostasis • Incomplete hemostasis may cause the formation of a hematoma. • Hematoma is the collection of blood in a body cavity, space or tissue caused by uncontrolled bleeding or oozing. It may be painful and firm to touch. • Some hematomas require evacuation to prevent infection; others reabsorb with time.

Methods of Hemostasis • Numerous agents, devices and equipment are used to achieve hemostasis and wound closure. These methods can be classified as: 1. 2. 3. Chemical Mechanical Thermal