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
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
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
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
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
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
7
Q
What doe PTT measure (partial thromboplastin time)?
A
- eval adequacy of fibrinogen, prothrombin, factors V, VIII, IX, X, XI, XII
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
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)
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
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)
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
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
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
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
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)
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
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
19
Q
Bleeding disorder of uremia? Tx?
A
- platelet dysfxn
- pts who are bleeding and need surgery reqr dialysis to correct platelet dysfxn
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
What is DIC?
- 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
Etiology of DIC?
- 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
How is DIC dx?
- by diminished levels of coag factors and platelets
- labs:
prolonged PTT and PT
hypofibrinogenemia
thrombocytopenia
presence of fibrin and fibrinogen products
28
Tx of DIC?
- 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
MC cause of fatal transfusion rxns?
- ABO incompatabilities
30
Rhesus antigen?
- only D antigen tested
- D antigen on RBC then Rh+
- no D antigen on RBC then Rh-
31
5 types of RBC transfusion products?
- whole blood
- packed RBCs
- washed RBCs
- leukoreduced RBCs
- divided or pediatric unit RBCs
- used for massive transfusions and life saving transfusions
32
Factors that go into deciding if transfusion should be done?
- reason for anemia
- degree and acuity/chronicity of anemia
- underlying medical condition
- anticipated future transfusions
- hemodynamic instability
33
Effect of one unit of packed RBCs?
- into an avg 70 kg person - raise HCT by 3% and hemoglobin by 1 g/dL
34
What is FFP? Indication for use?
- 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
When are platelets needed? Labs to determine this?
- 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
complication SEs of blood transfusions?
- metabolic derangements
- immunologic rxns
- infection complications
- volume overload
- pulmonary complications
- considerations on mass transfusions
37
What are the metabolic derangements that can occur w/ blood transfuison? When is this seen?
- seen w/ large volume or older blood products
- MC are:
hypocalcemia
hyper/hypokalemia
hypothermia
38
When do you see hypocalcemia? Presentation?
```
- seen w/ rapid transfusion
presents w/:
-muscle tremors
-ST segment prolong
-delayed T waves
```
39
When do yu see hyper/hypokalemia?
- 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
How can hypothermia be prevented?
- if mult tranfusions being done - need to be through fluid warmer
41
Immunologic rxns from complicated blood transfusions?
- febrile rxns
- acute and delayed hemolytic rxns
- thrombocytopenia
- anaphylactic shock
- urticaria
- graft vs host disease
- immune suppression
42
Febrile rxn presentation that can occur w/ blood transfusion? MC cause? Tx?
- MC as result of antileukocyte abs
- present w/:
fever/chills
tachycardia
- pretx w/ ASA, antipyretics, and antihistamines
- alt: use leukocyte reduced RBCs
43
MC cause of hemolytic rxns w/ blood tranfusion? Presentation?
- MC cause: ABO-mismatched blood
- present w/:
hot or cold flushing
chest pain
low back pain
fever
hypotension
- stop transfusion and recheck blood
44
When does graft vs host disease occur in blood transfusions? Presentation? Prevention?
- 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
Infectious agents of blood products?
- 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
What is a transfusion related lung injury? Tx?
- 1/5000 transfusions
- MC w/ units that contain plasma
- characterized by pulmonary edema after transfusion
- tx is supportive: may reqr intubation
47
What is considered a massive transfusion? Complications?
```
- 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
What is an autologous blood tranfusion? Collection? Reasons behind this?
- 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
