m Mohammad Shehata
2010
Department of I.C.U.and
Anesthesia
Platelets and hemostasis
Preparation
it is a long journey
random donor
Single donor
Preparation
centrifugation
pheresis
How much plt.
Each unit donates:
55x109 /l in 40-70 ml plasma
300x109 /l in 200-400 ml plasma
advantage
to keep PH > 6.2
Increase count by 5x109/l
In 70 kg person
Increase by 30-50x109/l
-Less costy
-Only one donor
-Less incidence of
refractoriness,
HLA typing
-Available
General considerationS
:
1.Each unit
contain(minimal) RBCs..what about
-ABO incompatibility.
- pediatric with small blood volume ( dose is…..)
-RH negative receipient ( women of childbearing period )
2. stored at
(room temperature=20-24c) so a common complication is….
3.Warming > 43c : impairs plt function.
4. Shelf life = 3-5 days, so there is finite supply.
5.Continous gentle agitation : prevent plt. Aggregates
6.Infusion through filter: not through the ordinary fluid infusion set :
- Must be (170-260 micron filter).
- not microaggregate filter (20-40m) : remove most of plt.
7.You should minimize the need for transfusion:
..investigate the cause of thrombocytopenia
..use adjunctive therapy(dialysis for renal failure…
… IVIG for I.T.P….)
..Discontinue anticoagulant and antiplatelet therapy before
surgery
Def : platelet count < 150 000
causes
Decreased production:
B.M.suppression due to:
Congenital
Aquired : Viruses, sepsis,
malignancy…
Other causes :
Dilutional : massive
transfusion(1-1.5 bl.volume)
Ratio of RBC: plt :FFP
transfusion is 1:1:1
Distributional ;
Congestive splenomegaly
Increased destruction
Non immune: D.I.C.
Immune mediated: I.T.P.
Post transfusion , drugs..
Heparin ( H.I.T.)
Valporic acid,,carbamazepine
penicillin / Beta lactam
interferon
Amiodarone,,digoxin
Antiplatelet therapy
a daily challenge
Mechanism of action
When to stop :
risk /benefit
Thienopyridine ( clopidogrel)
Pt at low risk:7-10 days
Pt at high risk : 5 days
(platelet function test should be
done)
-Aspirin
As long as the platelet life
span(why..)
Gp IIb/IIIa inhibitor:
1) Abciximab
2) aggrestat
Evidence based indications
Decision to tranfuse should not be based only on Plt. Count but should be
supported by the need to prevent or treat bleeding ( always keep in mind)
1. prophylactic
2.Perioperative
Ophthalmic surgery
The trigger to avoid spontanous
bleeding is
< 10 000 not < 20 000
Chronic patient : + active
bleeding
When to redose ;
Shorter life span =??
-
<100 x 109/l (why)
Neurosurgery
Epidural insertion or
removal…
<50-80 x 109/l
Lumbar puncture…
< 50 x 109 /l
Invasive
(surgery as laparotomy …)
vaginal delivery..
< 50 x109/ l
Minimal invasive(..central line)
< 30 x109/ l
1.Heparin induced thrombocytopenia.
2.Hemolytic uremic syndrome.
No prophylactic transfusion because they are thrombotic
Only treat clinical bleeding
3.Idiopathic thrombocytopenic purpura
No benefit = quickly removed..( immunely destructed )
transfuse only before procedure or treat clinical bleeding
-calculate the corrected count increment •
Corrected count increment (CCI) = •
(post-transfusion plt count – pre-transfusion •
plt count) x (B.S.A.) / number of platelets
transfused.
accepted result : •
-C.C.I. > 7.5 after 1 hour,,,or ,,. »
-C.C.I > 4.5 after 24 hours.
if not it is called…..
Def : failure to obtain satisfactiory response
after two consecutive transfusion episodes.
Causes : •
1) Immune
Platelet alloantibodies :
-HLA
-HPA
2) Non immune
-sepsis
-splenomegaly
- D.I.C.
-random donor platelet is more risky •
-directly related to number of transfusion •
•
Dr.Colin Brown
RISKS OF TRANSFUSION
1.T.R.A.L.I.( a phresis platelets is more risky)
My own experience…it is a serious complication
It is immune mediated non cardiogenic pulmonary edema
Management: stop the infusion.
supportive therapy.
2.transfusion associated sepsis ( stored at …..)
It is the largest overall infectious risk in blood transfusion
Platelets should be screened for bacterial contamination (specific
concern)
3.Non hemolytic febrile reaction (incidence is 1:20)
4.Transmitted infections (H.I.V ,, H.C.V.)
-My dear professors who •
teach me
-My dear colleagues who I •
really love
-My lovely parents and my •
darling wife
References
1-Update on platelets :
ASA guidelines 2006
2-proposed guidelines
for platelet transfusion
( Bc medical journal )