Blood products in ICU Flashcards
Describe the transfusion trigger in the ICU
Generally: Hb of < 7g/dL
Exceptions
1. Active bleeding
2. Active ischaemia
3. Evidence of poor tissue oxygenation
Then the trigger is Hb < 10g/dL
Summarise the types of acute transfusion reactions
ACUTE and potentially life threatening
- TRALI (donor anti-HLA or anti-PMN antibodies)
- TACO
- Acute hemolysis (ABO incompatibility)
- Anaphylaxis
- Sepsis
- Allergic (Itching and hives)
- Febrile non-haemolytic (Fever only - cytokine release)
- Hypotensive (vasoactive kinins - bradykinin - associated with recipient on ACEI)
OTHER associated effects
TRIM - Transfusion Related Immunomodulation
- Immunosuppressant effect
STORAGE Lesions
- Prolonged storage of blood products leads to:
1. Depletion 2.3 DPG (reduced O2 carriage)
2. Hyperkalaemia, Hypocalcaemia, Hyponatraemia)
3. Acid/Base abnormality
4. Reduced RBC deformability
What is the differential diagnosis for low platelets in the critically ill patients
NB - exclude plt clumping:
Plt s can clump in EDTA tube. Repeat in heparin or citrate tube and correlate.
- DIC
- Infections (Increased phagocytosis of plts by macrophages)
- HIV - plts destroyed via immune mechanisms
- Hypersplenism
- TTP
- HELLP
- HITT: Heparin Induced Thrombocytopaenia
- Drugs: Bactrim. Rifampicin
What are the different types of HITT
Heparin Induced Thrombocytopaenia
Type 1 - Direct toxic effect of heparin
Type 2 - Ag-Ab response against heparin-PF4 complex. Leads to activation of plts that are cleared by the RES.
What is DIC
Disseminated Intravascular Coagulation
Widespread endothelial damage due to sepsis/trauma leads to TF activation.
- Activation of coagulation cascade (Fibrinogen, plts drop with increase PTT)
- Inhibition of anticoagulant pathways
- Activation of fibrinolytic pathways (Increase D-dimers)
Net result is widespread microvascular thrombosis which may lead to multi-organ dysfunction
Describe how the diagnosis of DIC is made
Score global coagulation tests
- Platelets: > 100 = 0. <100 = 1. <50 = 2.
- D-dimer: No increase 0. > 0.4 = 2. > 4.0 = 3.
- Prothrombin time < 3 secs = 0. > 3 secs = 1. > 6 secs = 2
- Fibrinogen > 1 = 0. < 1 = 1.
Calculate score:
If > or = to 5 then compatible with DIC
If < 5 unlikely DIC. Repeat 1-2 days time
Describe the causes of abnormal platelet function
- Drug related (Aspirin/Plavix)
- Renal failure - Impaired fibrinogen binding to platelets and abnormalities in vWF –> so platelets cannot anchor to damaged endothelium
What can be used to treat platelet dysfunction secondary to uraemia
- Premarin (oestrogen)
- ? mechanism
- Works < 24 hrs and lasts 2 weeks - DDAVP
- Increase endothelial release of vWF and factor VIII
What are the limitations of adminstration of DDAVP for platelet dysfunction in uraemia
Tachyphylaxis can develop
Limit use to 3 - 4 days
What are the indications for a platelet transfusion
< 10 000 in adult stable patient
< 20 000 if risk of bleeding significant (e.g. PUD)
< 50 000 if broncho-endoscopic biopsy planned. (Except neurosurgery or eye surgery: > 100 000)
What is the target Plts for a trauma patient with massive transfusion?
> 100 000 to decrease risk of ICH
What is the concern with transfusing platelets to patients with TTP or HIT
Increase risk of thrombosis
What platelet level can a CVP, bone marrow aspirate/biopsy be done
Platelets > 10 000 provided platelet function is normal
What is HIV related TTP and what is the pathophysiology
Thrombotic Thrombocytopaenic Purpura
Deficiency of a specific von Willebrand factor-cleaving protease (ADAMTS13) - autoantibodies directed against ADAMTS13.
- leads to accumulation of abnormally large vWF multimers –> platelet clumping and deposition of platelet rich thrombi in tissues
What is the management of TTP
- Start ARVS
- FFPs: 30 ml/kg/day until normalization of platelet count
- Unresponsive patients should be referred for plasma exchange +- biologicals
What is the dose of FFPs and when are they indicated, how fast can they be administered and why
Replace coagulation factors (Prolonged r time)
Dose: 15 - 20 ml/kg
Admin: 1 Unit over 15 - 20 minutes as they are hyperosmolar (Na and Gluc)
What are the indications for FFPs
If active bleeding and abnormal coagulation screening tests
1. DIC
2. Massive T/F
3. Liver disease
4. Warfarin Toxicity (rather use prothrombin complex concentrate) - consists of 7,9,10)
What is cryoprecipitate
It is the cold soluble fraction of FFP
Obtained by thawing of FFPs
How much cryoprecipitate does 1 unit FFP give you. And how mcuh is generally pooled
30 ml cryoprecipitate per unit FFP.
Usually 10 units are pooled into 300 ml cryoprecipitate
What is the predominant composition of cryoprecipitate
FIBRINOGEN
Fibronectin
vWF
8
13
Describe how Heparin is reversed
Protamine Sulphate
- Immediate effect
- 1 mg neutralizes 100U
- Aim to neutralise the amount of heparin administered in the past 4 hours
Can protamine be used to reverse clexane
Yes but effect will be less pronounced
How long does Vitamin K take to start working
8 - 16 hours
Describe the dosing of vitamin K
Life threatnening bleeding + INR > 3
–> Vitamin K 10 mg IV
–> FFP or PCC
No bleeding and INR < 6 and no surgery planned
–> Hold warfarin
No bleeding, no surgery and INR 6 - 10
–> Vit K 2 mg IV
No bleeding. No surgery and INR > 10
–> Vit K 4 mg IV
