Assessment of Haemostasis

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ASSESSMENT OF PRIMARY HEMOSTASIS
1.BLEEDING TIME
Bleeding time is used to measure the duration of bleeding after a measured skin incision. Bleeding time may be measured by one of three methods: template, Ivy, or Duke. The template method is the most commonly used and the most accurate because the incision size is standardized. Bleeding time depends on the elasticity of the blood vessel wall and on the number and functional capacity of platelets. Although this test is usually performed on patients with a personal or family history of bleeding disorders, it's also useful- along with a platelet count for preoperative screening.The test is usually not recommended for patients with a platelet count of less than 75,000/u1. Purpose

• To assess overall hemostatic function (platelet response to injury and functional capacity of vasoconstriction). • To detect congenital and acquired platelet function disorders. Bleeding time is used most often to detect qualitative defects of platelets, such as Von Willebrand's disease. The test helps identify people who have defects in their platelet function. This is the ability of blood to clot following a wound or trauma. Normally, platelets interact with the walls of blood vessels to cause a blood clot. There are many factors in the clotting mechanism, and they are initiated by platelets. The bleeding time test is usually used on patients who have a history of prolonged bleeding after cuts, or who have a family history of bleeding disorders. Also, the bleeding time test is sometimes performed as a preoperative test to determine a patient's likely bleeding response during and after surgery. However, in patients with no history of bleeding problems, or who are not taking anti-inflammatory drugs, the bleeding time test is not usually necessary. Precautions

Before administering the test, patients should be questioned about what medications they may be taking. Some medications will adversely affect the results of the bleeding time test. These medications include anticoagulants, diuretics, anticancer drugs, sulfonamides, thiazide, aspirin and aspirin-containing preparations, and nonsteroidal anti-inflammatory drugs. The test may also be affected by anemia (a deficiency in red blood cells). Since the taking of aspirin or related drugs are the most common cause of prolonged bleeding time, no aspirin should be taken two weeks prior to the test. Patient preparation

• Explain to the patient this test is used to measure the time required to form a clot and stop bleeding. • Tell him who will perform the test and when it will take place. • Inform him that he need not restrict food or fluids before the test. • Reassure the patient that, although he may feel some discomfort from the incisions, the antiseptic, and the tightness of the blood pressure cuff, the test takes only 10 to 20 minutes to perform. • Advise the patient that the incisions will leave two small, hairline scars that should be barely visible when healed. • Check the patient's history for recent use of drugs that prolong bleeding time, including sulfonamides, thiazide diuretics, antineoplastics, anticoagulants, non steroidal anti-inflammatory drugs, aspirin and aspirin compounds, and some non narcotic analgesics. If the patient has taken such drugs, check with the laboratory for special instructions. If the test is being used to identify a suspected bleeding disorder, it should be postponed and the drugs discontinued. If the test is being used preoperatively to assess hemostatic function, it should proceed as scheduled. Equipment

Blood pressure cuff, disposable lancet, template with 9-mm slits (template method), 70% alcohol or povidone-iodine solution, filter paper, small pressure bandage, stopwatch. Procedure
There are four methods to perform the bleeding test. The Ivy method is the traditional format for this test. In the Ivy method, a blood pressure cuff is placed on the...
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