HEMATOLOGICAL SYSTEM PART II

HEMATOLOGICAL SYSTEMPART II

HEMATOLOGY AND ANESTHESIA

DENNIS STEVENS CRNA, MSN, ARNPSEPTEMBER 2010

FLORIDA INTERNATIONAL UNIVERSITYADVANCED BIOSCIENCE IN ANESTHESIOLOGY II

NGR 6405


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.


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 patient’s hemostatic system should be in optimal condition…


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…!


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


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


COAGULATION STUDIES: NORMAL VALUES

HEMATOLOGY AND ANESTHESIACOAGULATION STUDIES

ABNORMALITIES AND CLINICAL MANIFESTATIONS


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


PREOPERATIVE ASSESSMENT

AND EVALUATION


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


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…!


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…!


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


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


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


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


HEMATOLOGIC DISORDERS Anemia characterized by a hemoglobin concentration

that is less than normal for an individual’s 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


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


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

HEMATOLOGY AND ANESTHESIAHEMATOLOGIC 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


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%


Precipitating factors of an occlusive crisis involving sickle cell disease: Fever Infection Acidosis Hypoxia Stress Hypothermia

Treatment is primarily supportive…! Anesthetic management…!


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


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 patient’s international normalized ratio (INR) is below 1.5


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). NurseAnesthesia. (3rd Ed.) St. Louis, MO: Elsevier-Saunders.

HEMATOLOGICAL SYSTEM PART II

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