Coagulation/transfusion Flashcards
Major cross match
mixing of donor RBCs and recipient serum
Minor Cross Match
donor plasma and recipient RBCs
Tenase vs prothrombinase complexes
Tenase: FIXa + PS + FVIIIa
Prothrombinase: FVa + PS + FXa
PS: activated serine protease
Occur on platelet surface
Anticoagulant properties of endothelial cells
- Heparin sulfated proteoglycans –> bind AT –> inactivates thrombin
- Negative charge
- Thrombomidulin: binds with thrombin –> activates protein C–> aProC+ aProS–> irreversibly cleave FVa + FVIIIa–> no more thrombin generation
AND aProC-ProS –> inactivates PAI-1 (resuling in creased fibrinolysis)
- TFPI –> irreversibly binds FXa –> Making TFPI, FXa, FVIIa, TF complex –> prevent further activation/formation of thrombin
Virchows triad
3 areas of predisposition of thrombotic Disease
- Endothelial dysfunction
- Hypercoaguability of blood
- Blood stasis/altered blood flow
Function of thrombin
thrombin = FII
Propagation
- activates plt, FXIa & FVa
-Cleaves vWF off FVIII–> FVIIIa & increased platelets
Amplification
- Binds thrombomodulin on EC surface –> activates TAFI & aPrC–> aPrC + PrS
- Cleaves fibrinopeptide A from fibrinogen –> fibrin
Prothrombinase complex
FXa + FVa –> activates thrombin
INtrinsic Tenase
FIXa + FVIIIa
- Binds on platelet surface (propogation)
- Generates F Xa on surface
*50x more efficient at activating FX than extrinsic tenase
Extrinsic Tenase
FVIIa + TF (initiation)
-Activates small amounts FIX & X
-Activates more FVII
Dense granule contents
- ADP
- ATP
- Histamine
- Epinephrine
- Serotonin
- Calcium ions
- polyphosphates
- Sphingosine - 1- phosphate
Pneumonic: CAN: cations, Amines (hist, epi, sero) & nucleotides (ATP, ect)
Alpha granules
Platelet function test (pneumonic)
- PDF: platelet derived growth factor
- P selectin
- Fibronectin
- FI, FV, FVIII, vWF
- Fibrinolytics: PAI-1, TAFI
- TGF & endostatin –> proangiogenesis
- beta thromboglobulin
- Mitogens: IGF-1, VEGF = wound healing
- Cytokines: IL-8, PF4
Lysosomes
-Released from platelets - unclear role
- Need more agonists to release
- Acid hydrolases: glucorinadase, cathepsins, aryl sulfatase, galactosidase, elastase, collagenase
Subendothelial procoagulant macromolecules
-vWF
- Fibronectin
- Fibulin
- Laminin
- Thrombospondin
Actions of CIRCULATING vWF
- Primary source is Endothelial cells
- Binds:
collagen
GPIb-alpha
Itself!!
GPIba
- Platelet tethering to subendothelial vWF
- leads to formation of platelet monolayer
- bindings of platelet, collagen and vWF
α2bβ3
Platelet integrin –> activated by intracellular calcium
- Binds:
Fibrinogen/fibrin bound
vWF
If activated, can bind soluble fibrin - May form bridges with fibrinogen in middle between activated platelets
P2Y1
Platelet receptor
Agonist:
ADP
P2Y12
Platelet receptor
Agonist:
ADP
TPalpha & TPbeta
Platelet receptor
Agonist:
TXA2
PAR1
Platelet receptor
Agonist:
Thrombin
PAR4
Platelet receptor
Agonist:
Thrombin
Alpha2A
Platelet receptor
Agonist: epinephrine
IP
Platelet receptor
Agonist: PGI2
Causes of hypotension
- Decreased Preload
- Hypovolemia –> address underlying problem & give IVF
- Obstructive (Mes Volvulous, GDV, pericardial effusion, PTE, pleural space disease)
–> centesis, relieve obstruction, thrombolysis, IVF - Decreased Contractility
- Primary: valve disease, cardiomyopathy, arrhythmias–> treat with primary inotrope, antiarrhythmic, treat CHF
- Secondary: SIRS, electrolyte abnormalities, hypoxia, acidosis/alkalosis –> treat with inotrope and underlying disease - Decreased systemic vascular resistance
- drug/toxin –> treat with pressors, IVF, treat underlying issues
Determining metHgb presence
- blood chocolate brown
- Drop blood on white paper - If >10% metHgb wil be brown
- co-oximeter definitive
- Saturation Gap
–> SpO2 to PaO2 - >5% difference
If MetHgb >30% –> SpO2 plateaus 85%
Allergic transfusion reactions
Type I Hypersensitivity Reactions (IgE + Mast Cells)
- Occurs within 4 hours
- Diagnosis based off signs:
–> Cutaneous: urticaria, angioedema, pruritis
–> Respiratory (cats): stridor, dyspnea, wheezing, hypoxia
–> Cardiovascular: drop BP, syncope
Transfusion associate dyspnea
Acute transfusion reaction characterized by developement of acute respiratory distress during or within 24 hrs of transfusion where TACO, TRALI, allergic reaction, & underlying pulmonary disease have been ruled out
TACO
- acute, nonimmunologic reaction
- Secondary to increase in blood volume mediated by blood transfusion characterized by acute resp distress & hydrostatic pulmonary edema
- Occurs within 6 hours of transfusion
- Rads or echo confirm LA hypertension or volume overload
- Responds to diuretics