HEMATOLOGICAL SYSTEM PART II
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- 1. HEMATOLOGICAL SYSTEM PART II HEMATOLOGY AND ANESTHESIA DENNIS STEVENS CRNA, MSN, ARNP SEPTEMBER 2010 FLORIDA INTERNATIONAL UNIVERSITY ADVANCED BIOSCIENCE IN ANESTHESIOLOGY II NGR 6405
2. HEMATOLOGY AND ANESTHESIA OBJECTIVES State significant anesthetic implications for patients with bleeding or thrombosing tendencies. Explain anesthetic considerations and treatment options for hematologic and thromboembolic disorders. Discuss treatment modalities for acute blood loss. Explain causative factors relating to sickle cell disease. Discuss precipitating factors of an occlusive crisis involving sickle cell disease and treatment modalities associated with a clinical crisis situation. 3. HEMATOLOGY AND ANESTHESIA ANESTHETIC IMPLICATIONS Anesthesia care provider should be familiar with detection, evaluation, and treatment of hemostatic disorders Life-threatening blood loss during surgery may present with an undetected bleeding tendency The greatest challenge to the hemostatic system frequently occurs during surgery Preoperatively, a patients hemostatic system should be in optimal condition 4. HEMATOLOGY AND ANESTHESIA COAGULATION STUDIES Primarily used for evaluating the ability of the hemostasis system to prevent bleeding and control traumatic hemorrhage Platelets, coagulation, and fibrinolytic components can be screened with commonly available coagulation tests Platelet function can be evaluated on the basis of platelet counts and bleeding times Low preoperative platelet counts! BTs provide a good measure of primary hemostasis! Common causes of platelet abnormality! 5. HEMATOLOGY AND ANESTHESIA COAGULATION STUDIES Clotting system can be screened on the basis of activated partial thromboplastin time (APTT), prothrombin time (PT), and thrombin time (TT) Parameters reflect the ability of the blood to coagulate and can be used to screen a specific pathway of the coagulation cascade Prolonged times suggest a potential tendency for bleeding APTT reflects the activity of intrinsic and common coagulation pathways. Common test for heparin therapy PT measure of extrinsic activation of factor X. Common test for monitoring oral anticoagulants 6. HEMATOLOGY AND ANESTHESIA COAGULATION STUDIES TT is a measure of the conversion of fibrinogen to fibrin by thrombin. Screening tool for assessing the end stage of the coagulation cascade Fibrinolytic system can be screened with measurement of fibrinogen, FDP, and D-dimer levels Specific hematologic tests for clarifying abnormal coagulation screening studies are currently available Studies include assays for platelet adhesion and aggregation, clot retraction, specific factors and inhibitors, D-dimer, and others 7. HEMATOLOGY AND ANESTHESIA COAGULATION STUDIES: NORMAL VALUES 8. HEMATOLOGY AND ANESTHESIA COAGULATION STUDIES ABNORMALITIES AND CLINICAL MANIFESTATIONS 9. HEMATOLOGY AND ANESTHESIA PREOPERATIVE ASSESSMENT Best method for identifying patients with bleeding or thrombosing tendencies is a thorough history taking and physical exam Specific questions directed at identifying potential problems associated with hemostasis Coagulation profiles obtained based on history and physical findings Patients with inherited coagulation disorder must undergo an adequate preoperative coagulation workup 10. HEMATOLOGY AND ANESTHESIA PREOPERATIVE ASSESSMENT AND EVALUATION 11. HEMATOLOGY AND ANESTHESIA PREOPERATIVE ASSESSMENT Unexplained abnormal results of preoperative coagulation studies require thorough investigation and possibly hematologic consultation Planning anesthetic management in a patient with a known or suspected preoperative bleeding disorder requires special consideration General anesthesia versus regional anesthesia! Anesthesia providers should be aware of the potential effect of anesthetic agents and techniques on the hemostasis system 12. HEMATOLOGY AND ANESTHESIA INTRAOPERATIVE ASSESSMENT Abnormal intraoperative bleeding can be a life-threatening condition, requiring rapid patient assessment and therapy Initial actions: Administration of blood components Performance of coagulation studies Most common reason for intraoperative bleeding is loss of vascular integrity Certain surgical procedures are frequently associated with intraoperative coagulation abnormalities Intraoperative coagulation monitoring! 13. HEMATOLOGY AND ANESTHESIA INTRAOPERATIVE ASSESSMENT Generalized intraoperative bleeding or oozing may be related to: Dilutional coagulopathy Consumptive coagulopathy Transfusion reaction Intraoperative dilutional coagulopathy usually is the result of massive volume and blood replacement Packed RBCs versus whole blood Treatment! 14. HEMATOLOGY AND ANESTHESIA INTRAOPERATIVE ASSESSMENT Coagulation findings suggesting consumptive coagulopathy (DIC) include decreased PCs and fibrinogen levels, prolonged PT or APTT, and increased FDP and D- dimer levels DIC is a result of an imbalance in the coagulation and fibrinolytic systems Characterized by a rapid and extensive depletion of coagulation factors and excessive fibrinolysis Bleeding occurs due to consumption of coagulation factors during clotting, platelet depletion or dysfunction, interference fibrin formation, and lysis of clots by plasmin 15. HEMATOLOGY AND ANESTHESIA INTRAOPERATIVE ASSESSMENT Acute DIC occurs secondary to a variety of conditions: Patients with gram-negative sepsis Gram-positive, fungal, and viral infections Women in late stages of pregnancy presenting with placental abruption or placental previa, dead fetus, or amniotic fluid embolism Also associated with prolonged surgery, burns, malignancies, certain vascular disorders, chronic liver disease, heatstroke, and acute promyelocytic leukemia Treatment is primarily supportive and complex 16. HEMATOLOGY AND ANESTHESIA POSTOPERATIVE ASSESSMENT Postoperative patient must be monitored closely for signs and symptoms of bleeding or thrombosis Factors increasing likelihood of postoperative bleeding include abnormal preoperative clotting and elevated postoperative blood pressure Most frequent cause of postoperative bleeding is lack of hemostasis at either a suture line or surgically traumatized tissue Common reasons for abnormal postoperative APTT/PT! Certain types of surgical procedures present increased risk 17. HEMATOLOGY AND ANESTHESIA POSTOPERATIVE ASSESSMENT Patients with increased risk of thrombosis may receive preoperative, intraoperative, and postoperative anticoagulant therapy Caution with epidural analgesia and anticoagulant therapy Postoperative care should include continued monitoring of anticoagulant activity and normalization of arterial blood pressure Hemostatic screening should include coagulation tests for identification of hemostatic defects and guiding treatment 18. HEMATOLOGY AND ANESTHESIA HEMATOLOGIC DISORDERS Anemia characterized by a hemoglobin concentration that is less than normal for an individuals age and sex Common hematologic disorder that decreases the oxygen- carrying capacity and reserve against tissue hypoxia Causes of anemia: Iron deficiency anemia Megaloblastic anemia Vitamin B12 and folate deficiency Hemolytic anemia Sickle cell disease 19. HEMATOLOGY AND ANESTHESIA HEMATOLOGIC DISORDERS Mild asymptomatic anemia not an absolute contraindication to anesthesia and surgery Preoperatively, anemic patients must be evaluated for their ability to compensate by increasing their cardiac output Signs and symptoms of lack of compensation! Decision to transfuse must be individualized Anesthesia management should minimize drug-induced decreases in CO or leftward shift of the oxygen dissociation curve 20. HEMATOLOGY AND ANESTHESIA HEMATOLOGIC DISORDERS Symptoms of a blood loss greater than 20% of the blood volume include! Treatment for acute blood loss includes: Administration of blood products Administration of crystalloid solutions Sickle cell disease; one of the more commonly encountered hemoglobinopathies Inherited disease in which valine replaces glutamic acid at the sixth-position beta chain of hemoglobin Desaturated hemoglobin S forms long, rigid stacks that clump together 21. HEMATOLOGY AND ANESTHESIA HEMATOLOGIC DISORDERS Individuals may have either sickle cell trait or sickle cell disease Sickle cell trait: Heterozygous disorder seen in 10% black population Hemoglobin S levels are normally 30-50% Sickling seen with a PO2 of 20-30 mm Hg Sickle cell disease: Homozygous disorder seen in 0.5-1% black population Majority of hemoglobin is hemoglobin S Sickling is seen with PO2 of 30-40 mm Hg 22. HEMATOLOGY AND ANESTHESIA HEMATOLOGIC DISORDERS Suggested that sickle cell disease is associated with increased surgical risk Sickle cell crisis may be caused by: Decrease in oxygen saturation and temperature Infections Dehydration Stasis Acidosis General guideline for preoperative preparation: Hemoglobin A level of at least 50% Hematocrit of 35% 23. HEMATOLOGY AND ANESTHESIA HEMATOLOGIC DISORDERS Precipitating factors of an occlusive crisis involving sickle cell disease: Fever Infection Acidosis Hypoxia Stress Hypothermia Treatment is primarily supportive! Anesthetic management! 24. HEMATOLOGY AND ANESTHESIA THROMBOEMBOLIC DISORDERS Venous thromboembolism includes both deep venous thrombosis (DVT) and pulmonary embolism (PE) DVT associated with numerous surgical procedures Therapies are available for the prevention of DVT following anesthesia and surgery: Minimal-dose heparin Coumadin Low-molecular weight heparins Occlusive stockings 25. HEMATOLOGY AND ANESTHESIA THROMBOEMBOLIC DISORDERS Most surgical procedures require the patient not to be anticoagulated Patients taking anticoagulants on a chronic basis: History of atrial fibrillation Placement of mechanical heart valve Other disorders Most surgical procedures can be completed if the patients international normalized ratio (INR) is below 1.5 26. HEMATOLOGY AND ANESTHESIA REFERENCES Morgan, G.E., Mikhail, M.S., and Murray, M.J. (2006). Clinical Anesthesiology. (4th Ed.) New York, NY: McGraw-Hill. Nagelhout, J.J. and Zaglaniczny, K.L. (2005). Nurse Anesthesia. (3rd Ed.) St. Louis, MO: Elsevier- Saunders.