Wednesday, July 20, 2011

10 Questions and Answers About Mx of DISORDERS OF HEMOSTASIS in DENTISTRY

  1. How do you screen a patient for potential bleeding problems?
The best screening procedure for a bleeding disorder is a good medical history. If the review of the medical history indicates a bleeding problem, a more detailed history is needed. The following questions are basic:
1. Is there a family history of bleeding problems?
2. Has bleeding been noted since early childhood, or is the onset relatively recent?
3. How many previous episodes have there been?                               
4. What are the circumstances of the bleeding?
5. When did the bleeding occur? After minor surgery, such as tonsillectomy or tooth extraction? After falls or participation in contact sports?
6. What medications was the patient taking when the bleeding occurred?
7. What was the duration of the bleeding episode(s)? Did the episode involve prolonged oozing or a massive hemorrhage?
8. Was the bleeding immediate or delayed?

 2. What laboratory tests should be ordered if a bleeding problem is suspected?
• Platelet count: normal values = 150,000—450,000
• Prothrombin time (PT): normal value = 10—13.5 seconds
• Partial thromboplastin time (PTT): normal value = 25—36 seconds
• Bleeding time: normal value = < 9 minutes (bleeding time is a nonspecific  predictor of platelet function)
Normal values may vary from one laboratory to another. It is important to check the normal values for the laboratory that you use. If any of the tests are abnormal, the patient should be referred to a hematologist for evaluation before treatment is performed.

  3. What are the clinical indications for use of 1-deamino-8 vasopressin (DDAVP) in dental patients?
DDAVP (desmopressin) is a synthetic  antidiuretic hormone that controls bleeding in patients with type I von Willebrand’s disease, platelet defects secondary to uremia related to renal dialysis, and immunogenic thrombocytopenic purpura (ITP). The dosage is 0.3 mg/kg. DDAVP should not be used in patients under the age of 2 years; caution is necessary in elderly patients and patients receiving intravenous fluids.

  4. When do you use epsilon aminocaproic acid or tranexamic acid?
Epsilon aminocaproic acid (Amicar) and tranexamic acid are antifibrinolytic agents that inhibit activation of plasminogen. They are used to prevent clot lysis in patients with hereditary clotting disorders. For epsilon aminocaproic acid, the dose is 75—100 mg/kg every 6 hours; for tranexamic acid, it is 25 mg/kg every 8 hours.

  5. What is the minimal acceptable platelet count for an oral surgical procedure?
Normal platelet count  is 150,000—450,000. In general, the minimal count for an oral surgical procedure is 50,000 platelets. However, emergency procedures may be done with as few as 30,000 platelets if the dentist is working closely with the patient’s hematologist and uses excellent techniques of tissue management.

  6. For a patient taking warfarin (Coumadin), a dental surgical procedure can be done without undue risk of bleeding if the PT is below what value?
Warfarin affects clotting factors II, VII, IX, and X by impairing the conversion of vitamin K to its active form. The normal PT for a healthy patient is 10.0—13.5 seconds with a control of 12 seconds. Oral procedures with a risk of bleeding should not be attempted if the PT is greater than 1½ times the control or above 18 seconds with a control of 12 seconds.

  7. Is the bleeding time a good  indicator of pen, and postsurgical bleeding?
The bleeding time is used to test for platelet function. However, studies have shown no cor relation between blood loss during cardiac or general surgery and prolonged bleeding time. The best indicator of a bleeding problem in the dental patient is a thorough medical history. The bleeding time should be used in patients with no known platelet disorder to help predict the potential for bleeding.

  8. Should oral surgical procedures be postponed in patients taking aspirin?  
Nonelective oral surgical procedures in the absence of a positive medical history for bleeding should not be postponed because of aspirin therapy, but the surgeon should be aware that bleeding may be exacerbated in a patient with mild platelet defect. However, elective procedures, if at all possible, should be postponed in the patient taking aspirin. Aspirin irreversibly acetylates cyclooxygenase, an enzyme that assists platelet aggregation. The effect is not dose-dependent and lasts for the 7—10-day life span of the platelet.

  9. Are patients taking nonsteroidal medications likely to bleed from oral surgical procedures?
Nonsteroidal antiinflammatory medications produce a transient inhibition of platelet aggregation that is reversed when the drug is cleared from the body. Patients with a preexisting platelet defect may have increased bleeding.

  10. If a patient presents with spontaneous gingival bleeding, what diagnostic tests should be ordered?
A patient who presents with spontaneous gingival bleeding without a history of trauma, tooth brushing, flossing, or  eating should be assessed for a systemic cause. Etiologies for gingival bleeding include inflammation secondary to localized periodontitis, platelet defect, factor deficiency, hematologic malignancy, and metabolic disorder. A thorough medical history should be obtained, and the following laboratory tests should be ordered: (1) PT, (2) PIT, and (3) complete blood count (CBC).

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