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Surgery > Hemostasis, Surgical bleeding, and Transfusions > Flashcards

Hemostasis, Surgical bleeding, and Transfusions Flashcards

1
Q

What is the hemostatic process?

A
  • involves interaction b/t blood vessel wall, platelets and coagulation proteins
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2
Q

What occurs after an injury (hemostasis)?

A
  • vasoconstriction for about 60 sec
  • next platelets adhere to site of vascular injury
  • after adhesion, platelets release adenosine diphoshate (ADP) causing platelet aggregation
  • formation of initial white thrombus
  • formation of permanent thrombus w/ fibrin
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3
Q

What is the coagulation pathway - diff pathways?

A

use of various coag factors to generate fibrin
- extrinsic coag pathway:
begins w thromboplastin - interacts w/ factor VII to conver factor X to Xa
- intrinsic coag pathway: reqrs factors XII, XI, IX and VIII to convert factor X to Xa
- common coagulation pathway: involves factor X, V, II (prothrombin) and I (fibrinogen), factor XIII (fibrin-stabilizing factor)
- bleeding may occur w/ deficiency of any factors except for factor XII

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4
Q

Eval of pt’s hemostasis?

A
  • hx: most impt step, ask about meds:
    OTC, ASA, clopidogrel (Plavix), warfarin (coumadin)
  • PE: look for signs of bleeding disorder:
    easy bruising, petechiae, bleeding after dental surgery, menses, family hx, frequent nose bleeds
  • Test:
    platelet count
    PT
    PTT
    bleeding time
    thrombin time
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5
Q

What does platelet count tell us? Normal values?

A
  • verifies that adequate number of platelets are available in circulation
  • if abnormal can order blood smear to look at platelets under a microscope
  • normal values: 150,000-400,000
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6
Q

What does PT measure (prothrombin time)?

A
  • measures ability of blood to form stable thrombi
  • evaluates factors VII, X, and V, prothromin, and fibrinogen, and extrinsic pathway
  • MC use is monitoring warfarin
  • PT is reported w/ INR
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7
Q

What doe PTT measure (partial thromboplastin time)?

A
  • eval adequacy of fibrinogen, prothrombin, factors V, VIII, IX, X, XI, XII
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8
Q

How is bleeding time done? Normal range? Prolonged time may indicate what?

A
  • 2 incisions w/ lancet on forearm
  • time from injury to cessation of bleeding from both wounds is measured
  • normal range is 5-10 minutes
  • prolonged time may indicate:
    thrombocytopenia
    meds (ASA)
    von Willebrand disease
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9
Q

What does Thrombin time eval? What would prolongation mean?

A
  • eval fibrinogen to fibrin conversion w/ an external source of thrombin
  • prolongation:
    low fibrinogen levels, abnormal fibrinogen, fibrin and fibrinogen split products, heparin

(causes: blood and coag disorders, DIC, chronic liver disease)

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10
Q

Loss of blood during surgery etiologies?

A
  • pts can loose large volumes of blood from generalized oozing post op
  • some operations are assoc w/ large blood loss
  • may be from preexisting hemostatic defects:
  • congenital bleeding disorders, acquired bleeding disorders, med-assoc bleeding
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11
Q

von Willebrand Disease:

  • incidence
  • PP
  • site of bleeding
  • inheritance
  • lab studies
  • tx?
A
  • 1% of US pop
  • PP: reduced factor VIII activity and von Willebrand activity
  • mucocutaneous bleeding
  • autosomal dominant
  • males and females
  • lab studies:
    prolonged PTT
    normal PT
    abnormal platelet fxn

tx:
- cryoprecipitate infusions
- desmopressin (DDAVP)

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12
Q 
Hemophilia A:
incidence
PP
site of bleeding
labs
tx?
A
  • 25/100,000 in US
  • PP: reduced or absent factor VIII activity
  • site of bleeding: jts and intramuscular
  • only males
  • labs:
    prolonged PTT
    normal PT
    normal platelet fxn
  • tx:
    purified factor VIII products
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13
Q

Causes of acquired bleeding disorders?

A
  • these are more common than congenital bleeding disorders

causes:

  • advanced liver disease
  • anticoagulation therapy
  • acquired thrombocytopenia
  • platelet-inhibiting drugs
  • uremia
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14
Q

Why does liver disease cause abnormal bleeding?

A
  • common cause of acquired bleeding
  • inability to synthesize proteins leads to decreased levels of prothrombin and factors V, VII, and X
  • obstructive jaundice and cirrhosis may lead to clotting factor deficiencies: responds well to vit K
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15
Q

Mechanism of warfarin? Reversal of it?

A
  • depression of clotting factors: II, VII, IX, X

- can be reversed w/ FFP or vit K in an emergency

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16
Q

Mechanism of heparin? Reversal?

A
  • increased speed of antithrombin III binds to and neutralized factors IXa, Xa, Xia, XIIa, and thrombin
  • prolongs PTT and thrombin time
  • reversed w/ protamine sulfate (cardiovascular surgeries - common)
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17
Q

3 mechanisms of acquired thrombocytopenia?

A
  • decreased platelet production in bone marrow
  • increased destruction of platelets in peripheral blood
  • splenic pooling in enlarged spleen
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18
Q

What are the platelet inhibiting drugs?

A
  • ASA: should stop 1 wk b/f surgery
  • plavix: should stop 7-10 days b/f surgery
  • NSAIDs: stop atleast 5 days b/f
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19
Q

Bleeding disorder of uremia? Tx?

A
  • platelet dysfxn

- pts who are bleeding and need surgery reqr dialysis to correct platelet dysfxn

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20
Q

What meds are assoc w/ bleeding?

A 
- anticoagulants: 
warfarin (coumadin)
heparin
- platelet-inhibitng drugs:
plavix
ASA
- OTC meds:
herbal -
dong quai 
garlic
ginger
gingko biloba
ginseng
st.  john's wort
21
Q

Management of intraoperative bleeding? What can shock do?

A
  • shock can aggravate consumptive coagulopathy
  • Massive transfusion of packed RBCs
  • bleeding from needle holes, vascular suture line, or extensive dissection
  • controlled w/:
    gelfoam
    surgical
    floseal
    tisseel
22
Q

Causes of post-op bleeding?

A
  • 50% is caused by poor hemostasis during surgery
  • other causes:
    residual heparin
    shock
    altered liver fxn
23
Q

Classification of post-op bleeding?

A
  • primary bleeding
  • reactive bleeding
  • secondary bleeding
24
Q

3 main categories of post-op bleeding?

A
  • primary bleeding: occurs in OR
  • reactive bleeding: w/in 24 hrs
  • secondary bleeding : 2-10 days after procedure, erosion into blood vessels, usually cause is an infection
25
Q

What is DIC?

A
  • characterized by intravascular coag and thrombosis that is diffuse instead of localized at site of injury
  • results in systemic deposition of platelet-fibrin microthrombi that causes diffuse tissue injury
26
Q

Etiology of DIC?

A
  • release of tissue debris into bloodstream after trauma or an obstretic catastrophe
  • extenstive endothelial damage to vascular wall
  • hypotension
  • operations with large blood loss:
    prostate, lung, malignant tumors
27
Q

How is DIC dx?

A
  • by diminished levels of coag factors and platelets
  • labs:
    prolonged PTT and PT
    hypofibrinogenemia
    thrombocytopenia
    presence of fibrin and fibrinogen products
28
Q

Tx of DIC?

A
  • most impt is remove the precipitating factors
  • severe DIC:
  • cryoprecipitate best method to replace fibrinogen loss
  • platelet transfusion may be necessary
  • FFP helps replace other deficits
29
Q

MC cause of fatal transfusion rxns?

A
  • ABO incompatabilities
30
Q

Rhesus antigen?

A
  • only D antigen tested
  • D antigen on RBC then Rh+
  • no D antigen on RBC then Rh-
31
Q

5 types of RBC transfusion products?

A
  • whole blood
  • packed RBCs
  • washed RBCs
  • leukoreduced RBCs
  • divided or pediatric unit RBCs
  • used for massive transfusions and life saving transfusions
32
Q

Factors that go into deciding if transfusion should be done?

A
  • reason for anemia
  • degree and acuity/chronicity of anemia
  • underlying medical condition
  • anticipated future transfusions
  • hemodynamic instability
33
Q

Effect of one unit of packed RBCs?

A
  • into an avg 70 kg person - raise HCT by 3% and hemoglobin by 1 g/dL
34
Q

What is FFP? Indication for use?

A
  • FFP is platelet poor plasma removed from whole blood
  • doesn’t contain RBC, leukocytes, or platelets
  • indication for use:
    lab evidence of coagulation factor deficiency w/ clinical bleeding
  • need for invasive procedure
35
Q

When are platelets needed? Labs to determine this?

A
  • indicated for pts w/ thrombocytopenia due to platelet dysfxn
  • labs:
    bleeding time
    whole blood platelet fxn testing
  • transfusion of 6 platelets raise count by 50,000-100,000
36
Q

complication SEs of blood transfusions?

A
  • metabolic derangements
  • immunologic rxns
  • infection complications
  • volume overload
  • pulmonary complications
  • considerations on mass transfusions
37
Q

What are the metabolic derangements that can occur w/ blood transfuison? When is this seen?

A
  • seen w/ large volume or older blood products
  • MC are:
    hypocalcemia
    hyper/hypokalemia
    hypothermia
38
Q

When do you see hypocalcemia? Presentation?

A 
- seen w/ rapid transfusion
presents w/:
-muscle tremors
-ST segment prolong
-delayed T waves
39
Q

When do yu see hyper/hypokalemia?

A
  • hyperkalemia: high levels of K are found in units of blood frozen longer than 35 days
  • after transfusion infused K is taken up by the red cell causing hypokalemia
40
Q

How can hypothermia be prevented?

A
  • if mult tranfusions being done - need to be through fluid warmer
41
Q

Immunologic rxns from complicated blood transfusions?

A
  • febrile rxns
  • acute and delayed hemolytic rxns
  • thrombocytopenia
  • anaphylactic shock
  • urticaria
  • graft vs host disease
  • immune suppression
42
Q

Febrile rxn presentation that can occur w/ blood transfusion? MC cause? Tx?

A
  • MC as result of antileukocyte abs
  • present w/:
    fever/chills
    tachycardia
  • pretx w/ ASA, antipyretics, and antihistamines
  • alt: use leukocyte reduced RBCs
43
Q

MC cause of hemolytic rxns w/ blood tranfusion? Presentation?

A
  • MC cause: ABO-mismatched blood
  • present w/:
    hot or cold flushing
    chest pain
    low back pain
    fever
    hypotension
  • stop transfusion and recheck blood
44
Q

When does graft vs host disease occur in blood transfusions? Presentation? Prevention?

A
  • happens when immunosuppressed press receive donor leukocytes
  • onset of sxs are delayed:
    fever
    rash
    liver dysfxn
    diarrhea
  • prevent w/ leukocyte reduced red cells or irradiated red cells
45
Q

Infectious agents of blood products?

A
  • bacteria: most likely from platelets, this will present w/ fever/chills, tachycardia, hypotension
  • viruses:
    Hep B: 1/200,000
    Hep C: 1/2 mill
    HIV: 1/2mill
  • parasites
46
Q

What is a transfusion related lung injury? Tx?

A
  • 1/5000 transfusions
  • MC w/ units that contain plasma
  • characterized by pulmonary edema after transfusion
  • tx is supportive: may reqr intubation
47
Q

What is considered a massive transfusion? Complications?

A 
- over 10 packed RBCs in 24 hrs or pt's total blood volume in 24 hrs, or half pt's blood volume in 1hr 
 complications:
- dilutional coagulopathy
- O2 transport abnormalities
- lyte/acid-base derangements
- hypothermia
- disease transmission
- ARDS
48
Q

What is an autologous blood tranfusion? Collection? Reasons behind this?

A
  • collection and re-infusion of pt’s own blood
  • collection:
  • pre-surgical donation
  • intraop cell saver (CABG)
  • reasons:
  • fully compatible
  • no risk of transmission
  • less dependent on blood bank
  • pts w/ rare blood types

Surgery (19 decks)

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