Hematologic Disorders. Assistant professor of anesthesia

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1 Preoperative Evaluation Hematologic Disorders Dr M.Razavi Assistant professor of anesthesia

2 Anemia Evaluation needs to consider the extent and type of surgery, the anticipated blood loss, and the patient's comorbid conditions that may influence oxygenation. Red blood cells should not be transfused solely because of a hemoglobin level but rather because of risk for complications from inadequate oxygenation.

3 Anemia Preoperative patients at risk for anemia : history of: colon cancer, gastrointestinal or genitourinary bleeding, metrorrhagia, chronic infections, inflammatory diseases, nutritional deficiencies. history and physical examination : palpitations, fatigue, chest pain, black or bloody stools, weight loss, pallor, murmurs, hepatospenomegaly, or lymphadenopathy.

4 Preoperative Testing CBC-(MCV)& reticulocyte count, further testing such as iron studies, vitamin B 12, or folate levels, depending on the findings on the smear and the MCV. MCV, iron, ferritin and TIBC : iron deficiency anemia. (or normal )MCV and TIBC, and (or normal) iron and ferritin: anemia associated with chronic disease. MCV and vitamin B 12 or folate levels : macrocytic anemia

5 Coagulopathies Routine screening for coagulopathies with a PT, aptt, or a bleeding time without an indication is not indicated. Asking about excessive bruising, prolonged bleeding after cuts, heavy menstrual cycles, and bleeding gums is sensitive but not specific. If specific causes of bleeding are suspected or known, such as liver disease or malnutrition, targeted testing with liver enzyme, protein, and albumin levels and a PT is needed.

6 Preoperative Testing PT (without a history of warfarin use) the most common cause is laboratory error, liver disease, or malnutrition Evaluation of liver enzymes and a hepatitis panel may be warranted, depending on the surgery. A trial of vitamin K (1 to 5 mg orally once a day for 3 days) can be initiated.

7 Preoperative Testing aptt can result from both hypocoagulable and hypercoagulable conditions. Further testing for a prolonged aptt : a repeat aptt aptt mixing study lupus anticoagulant evaluation of coagulation factors VII, IX, XI, XII checking von Willebrand factor (vwf) antigen ristocetin cofactor levels.

8 Hemophilias Hemophilia A (factor VIII deficiency) and hemophilia B (or Christmas disease) are X- linked recessively inherited disorders that occur almost exclusively in males. prolonged aptt and normal PT Orthopedic procedures account for 50% of operations in hemophiliacs. Hemophilia A accounts for 85% of all cases of hemophilia.

9 Hemophilias Typically, factors VIII and IX are maintained at 75% to 100% in the immediate perioperative period and then at 50% until any risk of bleeding is past Each unit of recombinant or purified factor concentrate raises the factor level by 2% per kilogram

10 Von Willebrand's Disease vwd is an inherited disorder of factor VIII and vwf that affects both genders. the most common congenital coagulopathy vwd is diagnosed by measuring ristocetin cofactor, vwf antigen and factor VIII. Most patients with vwd will have a history of bleeding, but in some the diagnosis will not be made until a second challenge to coagulation occurs, including major surgery or exposure to drugs such as aspirin or NSAIDs.

11 Von Willebrand's Disease Desmospressin : release of factor VIII, vwf, and plasminogen activator from endothelial cells. Iv dose of 0.3 µg/kg (given over a period of 15 to 30 minutes to avoid hypotension, flushing, and tachycardia) typically raises vwf threefold to fourfold. *Desmopressin is contraindicated in patients with type 2B because it increases abnormal vwf and may result in thrombocytopenia.

12 Thrombocytopenia Platelet count lower than 150,000/mm 3 and results from decreased production, increased destruction, or sequestration. Cause: malignancies, drugs, autoimmune disorders, preeclampsia, hereditary disease, and disseminated intravascular coagulation. repeat the test, examine the peripheral smear, and collect blood for a platelet count in a tube without EDTA.

13 heparin-induced thrombocytopenia (HIT) Generally occurs within 5 to 10 days after exposure to heparin. Immediate discontinuation of heparin and testing for heparin-induced platelet antibodies are indicated. LMWH is contraindicated Alternative anticoagulants are danaparoid sodium, lepirudin, and argatroban

14 Idiopathic thrombocytopenic purpura Is a chronic autoimmune disorder with autoantibodies against platelets that results in increased destruction. Patients are treated with corticosteroids and splenectomy. Patients often have minimal bleeding at even very low platelet levels, probably because of increased turnover and a predominance of young platelets.

15 Surgery Surgery can be performed safely in patients with platelet counts higher than 50,000/mm. The risk of bleeding is inversely related to platelet counts lower than 50,000/mm 3. Anemia, fever, infections, and drugs that affect platelet function increase bleeding at any platelet level. Centroneuraxial anesthesia is safe with platelet counts higher than 100,000/mm

16 Thrombocytosis Is a platelet count greater than 500,000/mm 3 physiologic (exercise, pregnancy) primary (myeloproliferative disorder) secondary (iron deficiency, neoplasm, surgery, chronic inflammation) *Platelet >1,000,000/mm 3 place patients at risk for thrombotic events

17 Thrombocytosis Patients with primary thrombocytosis (essential thrombocythemia) have a bleeding tendency that is worsened by exposure to drugs such as aspirin. Older patients and those with a previous history of bleeding or thrombosis may be at increased risk. Hydroxyurea, anagrelide (these drugs decrease production, so 7 to 10 days is needed), or plasmapheresis (removes platelets, so the effect is immediate) may be used to lower the platelet count.

18 Polycythemia Hct > 54% : primary (polycythemia vera) secondary to chronic hypoxia (COPD, high altitude, congenital heart disease) *High hematocrits are associated with increased atherosclerosis (carotid stenosis, stroke) and cardiovascular disease (heart failure, MI).

19 Polycythemia The preoperative evaluation (history and physical examination) focuses on the pulmonary and cardiovascular systems. Examination for cyanosis, clubbing, wheezing, and murmurs is necessary. Oxygen saturation, an ECG, and possibly arterial blood gas analysis and a chest radiograph are needed in patients with polycythemia.

20 Risk of Thromboembolism or Pulmonary Emboli Fatal pulmonary embolism occurs in 0.1% to 0.8% of patients undergoing elective general surgery. risk venous thrombosis : previous venous thromboembolism, obesity, varicose veins, diabetes, cancer, heart failure, pregnancy, paralysis, the presence of an inhibitor deficiency state, age younger than 50 years

21 Thromboembolism The risk of perioperative venous thromboembolism: surgical procedure (degree of invasiveness, trauma, and immobilization) patient-related variables ( inflammatory bowel disease, acute illness, smoking, malignancy, obesity, increasing age, previous thromboembolism, estrogen use, hypercoagulable state)

22 Thromboembolism American Society of Regional Anesthesiologists guidelines specifically state that if a single dose of warfarin has been administered within the previous 24 hours, it is safe to perform neuraxial anesthesia.

23 DVT&Surgery Recent arterial or DVT requires perioperative interventions or postponement of nonlifesaving procedures. Without anticoagulation, the risk for recurrent DVT within 3 months of a proximal DVT is approximately 50%. A month of warfarin treatment reduces the risk to 10%, and 3 months reduces it to 5%.

24 DVT&Surgery(higher risk) Patients with a hereditary hypercoagulable state (e.g., antithrombin III or protein C or S deficiency, prothrombin gene mutation, Factor V Leiden), cancer, or multiple episodes of DVT. Patients with nonvalvular atrial fibrillation who have had a previous cerebral embolism. Patients with mechanical heart valves, especially multiple valves, are at risk for embolism. Risk is greater with mitral than with aortic valves.

25 Preoperative evaluation Elective surgery should be postponed in the first month after an episode of venous or arterial thromboembolism. If postponement is not possible, the patient should receive preoperative heparin while the INR is below 2.0 Ideally, 3 months of anticoagulation is recommended before elective surgery.

26 Preoperative evaluation withholding warfarin for 5 days will allow the PT/INR to fall to normal. During the time without warfarin, patients may be at risk for recurrent thromboembolism, but the risk is relatively small in all but the highest-risk patients. It is controversial whether patients require bridging or heparin during this period. patients can receive subcutaneous LMWH at home without the need for monitoring.

27 Risk for Bleeding With Surgical or Invasive Procedures Risk Type of Procedure Examples Low Moderate High Nonvital organs involved, exposed surgical site, limited dissection Vital organs involved, deep or extensive dissection Bleeding likely to compromise surgical result, bleeding complications frequent Lymph node biopsy, dental extraction, cataract extraction, most cutaneous surgery, laparoscopic procedures, coronary angiography Laparotomy, thoracotomy, mastectomy, major orthopedic surgery, pacemaker insertion Neurosurgery, ophthalmic surgery, cardiopulmonary bypass, prostatectomy or bladder surgery, major vascular surgery, renal biopsy, bowel polypectomy

28 Preoperative Hemostatic Evaluation Surgical Risk Low Moderate or high Consultation History Negative or minimal for bleeding Suggestive of bleeding disorder Routine Screening Approach History only History, PT, aptt, platelet count PT, aptt, platelet count, biochemical profile, complete blood count with differential, review of peripheral smear Add to above as indicated: platelet function tests, von Willebrand antigen, ristocetin cofactor, factor VIII, factor IX, factor XI, factor XIII assays