Defects in Hemostasis

Hemophilia (Factor VII)

This is a sex-linked recessive disorder resulting in a failure to synthesize normal factor VII. Incidence is 1 in 10000. There are many degrees of severity of the disease with as little as 5% of normal factor VIII controlling bleeding. Patients may present early in life with bleeding complications or later in life secondary to sustained trauma. Patients may also present with hemarthrosis, retroperitoneal bleeds or intestinal hematomas and obstruction.

Management

The half life of factor VII is 8-12 hours. In most circumstances hemostasis can be maintained with as little as 3-5% of normal levels, however, active bleeding may require levels of closer to 30%. Cryoprecipitate is given as 1 unit/kg to raise the level by 1 percent. Patients undergoing major procedures should have levels raised to 30% for 10 days following the procedure. Even minor cases should achieve these levels.

Christmas Disease

This is a factor IX deficiency and is X-linked recessive. Severe disease results with less than 1% normal activity. All patients require substitution therapy when surgery is performed.

von Willebrand Disease

This factor assists in the binding of platelets to endothelium. The most important receptor involved in its function is platelet glycoprotein-Ib. This disease occurs in approximately 1 in 1000 people and is inherited as an autosomal dominant trait. It is associated with abnormal vWF and decreased stabilization of factor VIII with a prolonged bleeding time. Ristocetin fails to cause platelet aggregation in 70% of patients with the disease. Treatment with cryoprecipitate day before surgery and continue for 4 days.

Platelet Dysfunction

Thrombocytopenia is probably the most common defect encountered in the surgical population. Platelet disorders can be qualitative or quantitative. Quantitative deficits can be the result of consumption, decreased production, increased destruction or sequestration.

Table 3.4. Etiologies of thrombocytopenia

Quantitative Defect

Drugs

Viral

Immune

Thiazides

H2 blockers (cimetadine)

Heparin

Penicillin

Cephalosporins

Sulfonamides

Alcohol

Herpes simplex Sepsis

Drugs (heparin, quinidine, sulfonamides)

Qualitative Defect

Drugs

Other

Aspirin

NSAIDS

Corticosteroids

Antibiotics (Penicillin, cephlasporin, etc)

Antihistamines

Alpha/beta blockers

DextranSurosemide

Heparin

Lidocaine

Uremia

Hypothyroidism

Counts >50 k do not require treatment. One unit of platelets will increase count by 10k. Spontaneous bleeding <20 k treat. Surgery safely performed as long as count is >50k.

Heparin-Induced Thrombocytopenia

Reported in 0.6% of patients receiving heparin. Likely immune mediated. Counts decrease to 4-15 days after initial treatment. Treat by stopping the heparin. If patient requires anticoagulation alternative therapy includes RefludanĀ® (Table 3.4).

Diffuse Intravascular Coagulation (DIC)

Introduction of thromboplastic agents into circulation. Associated with extra-corporeal circulation, sepsis, lymphoma and a prolongation in TT, PTT, PT. Diagnosed by a reduced fibrinogen, increased FDP, decreased platelets. Management consists of controlling the underlying problem. Replace with FFP, cryoprecipitate, and platelets if the patient is actively bleeding. In most instances the DIC leads to thrombotic complications. Heparin combined with component therapy to control both the loss of coagulation factors and thrombotic tendency. Epsilon aminocaproic acid (EACA) is an inhibitor of fibrinolysis and is prone to induce thrombosis. Therefore any patient receiving this should receive heparin.

Head Injury

The brain is the richest source of tissue thromboplastin. Closed head injury may be associated with coagulopathy from this release. Treatment involves replacement of clotting factors with FFP and close monitoring for DIC.

There are several protein deficiencies that affect the normal process of coagulation and can lead to a hypercoaguable state. Most of these are serine protease inhibitors.

Antithrombin III Deficiency (ATIII)

ATIII inhibits thrombin in vivo and in accelerated 1000-10,000 fold in the presence of heparin. Inherited as an AD disorder. Patients with this disorder have a 50% risk of thrombotic events in their lifetime. They also are not sensitive to heparin.

Protein C or S Deficiency

Both are serine proteases and serve to inactivate factor Va and VIIIa with protein S serving as a cofactor for APC (activated protein C).

Factor V Leiden

This results from a mutant factor V. This mutant when activated is resistant to APC. Approximately 5% of the US population is heterozygous for this defect.

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