Flashcards in Hemostasis, Surgical Bleeding, & Transfusions Deck (86):
Define Hemostatic Process
Process involves interaction between blood vessel walls, platelets, & coagulation proteins
Initial Hemostasis Activity After Injury
Platelets adhere to site of vascular injury
After adhesion, platelets release ADP causing platelet aggregation
Formation of white thrombus
Formation of permanent thrombus with fibrin
Extrinsic: thromboplastin interacts with VII to covert X to Xa
Intrinsic: factors XII, XI, IX, & VIII to convert X to Xa
Common: X, V, II, & I; factor VIII
Deficiency of what factors causes bleeding?
Any EXCEPT XII
What can reduce the effectiveness of clotting?
Evaluation of a Bleeding Patient
Hx: OTC, ASA, clopidogrel (Plavix), warfarin (Coumadin)
Look for signs of bleeding disorder
Labs: platelets, PT, PTT, bleeding time, thrombin time
Signs of a Bleeding Disorder
Bleeding after dental procedures
Family history of bleeding
What does a platelet count verify?
An adequate number of platelets are available in the circulation
What is a normal platelet value?
What are some reasons for low platelets?
Meds: lasix, penicillins, sulfonamids, NSAIDs
What does prothrombin time measure?
Ability of the blood to form stable thrombi
Extrinsic & common pathway
When is a PT normally ordered?
Ratio of a patient's PT to a normal (control) sample
What does a partial thromboplastin time (PTT) measure?
Adequacy of intrinsic & common pathways
When is PTT most commonly used?
Unfractionated heparin therapy
Define Bleeding Time
Time from injury to cessation of bleeding
What may a prolonged bleeding time indicate?
Von Willebrand disease
What does thrombin time evaluate?
Fibrinogen to fibrin conversion with an external source of thrombin
What may a prolonged thrombin time indicate?
Low fibrinogen levels
Fibrin & fibrinogen split products
Blood or coagulation disorders
DIC Chronic liver disease
Von Willebrand's Disease Pathophysiology
Reduced factor VII activity & von Willebrand activity
Main Site of Bleeding for Von Willebrand's Disease
Lab Results for Von Willebrand Disease
Abnormal platelet function
Treatment of Von Willebrand Disease
Pathophysiology of Hemophilia A
Reduced or absent factor VII activity
Main Sites of Bleeding for Hemophilia A
Lab Results of Hemophilia A
Normal platelet function
Treatment of Hemophilia A
Purified factor VII products
Common People who get Hemophilia A
Causes of Acquired Bleeding Disorders
Advanced liver disease
Liver Disease as an Acquired Bleeding Disorder
Inability to synthesize proteins leads to decreased levels of prothrombin & factors V, VII, & X
What liver disorders may lead to clotting factor deficiencies?
MOA of Warfarin (Coumadin)
Depression of clotting factors II, VII, IX, X
How can warfarin (Coumadin) be reversed in an emergency?
MOA of Heparin
Increases speed of antithrombin III binds to & neutralizes factors IXa, Xa, XIa, XIIa, & thrombin
Lab Results on Heparin
Prolonged thrombin time
How is heparin reversed?
3 Mechanisms of Acquired Thrombocytopenia
Decreased platelet production in bone marrow
Increased destruction of platelets in peripheral blood
Splenic pooling in enlarged spleen
Examples of Acquired Thrombocytopenia
Platelets destroyed during surgery
Anticoagulants: warfarin, heparin
Platelet-inhibiting drugs: clopidogrel, ASA, NSAIDs
OTC meds: dong quai (angelica), garlic, giner, gingko biloba, ginseng, St. Johns wort
How is intra-operative bleeding controlled?
Reasons for Post-Op Bleeding During Surgery
Altered liver function
Classification of Post-Op Bleeding
Post-Op Bleeding: Primary
Occurs during operation
Monitor with drains post-op
Post-Op Bleeding: Reactive
Occurs within 24 hours of operation
Post-Op Bleeding: Secondary
7-10 days post procedure
Erosion of the blood vessels: usually due to infection
Intravascular coagulation & thrombosis that is diffuse instead of localized at the site of injury
What does DIC result in?
Systemic deposition of platelet-fibrin micro thrombi that causes diffuse tissue injury
Etiology of DIC
Release of tissue debris into bloodstream after trauma or obstetric catastrophe
Endothelial damage to vascular wall
Operations with large blood loss
How is DIC diagnosed?
Diminished levels of coagulation factors & platelets
Labs for DIC
Prolonged PTT & PT
Presence of fibrin & fibrinogen products
Treatment of DIC
Remove precipitating factors
5 Types of Blood Transfusions
Divided or pediatric unit RBCs
Factors in Deciding When to Infuse
Reason for anemia
Degree & acuity/chronicity of anemia
Underlying medical condition
Anticipated future transfusions
How much does 1 unit of PRBCs raise the hematocrit & hemoglobin?
Hg: 1 g/dL
What does FFP not contain?
Indications for FFP
Coagulation factor deficiency with clinical bleeding
Need for invasive procedure
Indications for Platelets
Patients with thrombocytopenia due to platelet dysfunction
Complications with Blood Transfusions
Most Common Metabolic Derangements with Blood Transfusions
When are metabolic derangements usually seen with blood transfusions?
Large volume transfused
Older blood products
How does hypocalcemia occur in blood transfusions?
Rapid rate of transfusion
Presentation of Hypocalcemia
Delayed T waves
When does hyperkalemia occur in blood transfusions?
Units of blood frozen longer than 35 days
How does hypokalemia occur in blood transfusions?
After transfusion, potassium is taken up by the red cell
How to prevent hypothermia in blood transfusions?
Need to be placed in a warmer
Types of Immunologic Reactions with Blood Transfusions
Acute & delayed hemolytic reactions
Graft vs. host disease
Presentation of Febrile Reaction to Blood Products
What can you pretreat a blood transfusion with to prevent a febrile reaction?
*Leukocyte reduced RBCs*
What are hemolytic reactions generally caused by?
Presentation of Hemolytic Reactions
Low back pain
Acute renal failure
Treatment of Hemolytic Reactions
When does a graft vs. host disease occur?
Immunosuppressed patients receive donor leukocytes
Presentation of Graft vs. Host Disease
Prevention of Graft vs. Host Disease
Infectious Agents in Transfusion of Blood Products
Bacteria: usually platelets
Viruses: Hep B, Hep C, HIV
Presentation of Bacteria Infection with Blood Transfusion
When do transfusion-related lung injuries usually occur?
Units transferred that contain plasma
What is transfusion-related lung injury characterized by?
Treatment of Transfusion-Related Lung Injury
Define Massive Transfusions
10+ PRBCs in 24 hours
Patient's total blood volume in 24 hours
1/2 patients blood volume in 1 hour
Complications of Massive Transfusions
Oxygen transport abnormalities
Define Autologous Blood
Collection & re-infusion of a patient's own blood
Collection of Autologous Blood
Intra-operative cell saver