Platelets and hemostasisPlatelets and hemostasis

donor randomSingle donor

Preparationcentrifugationpheresis

How much plt.Each unit donates:

55x109 /l in 40-70 ml plasma

Increase count by 5x109/l

In 70 kg person

300x109 /l in 200-400 ml plasma

to keep PH > 6.2

Increase by 30-50x109/l

advantage-Less costy

-Available

-Only one donor-Less incidence of

refractoriness,HLA typing

General considerationS

:

1.Each unit contain(minimalminimal) RBCs..what about

--ABO incompatibilityABO incompatibility..

- -pediatric with small blood volume ( dose is…..)pediatric with small blood volume ( dose is…..)

--RH negative receipient ( women of childbearing period )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 thrombocytopeniathe 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 000causes

Antiplatelet therapyAntiplatelet therapy a daily challenge a daily challenge

When to stopWhen to stop : :

risk risk /benefit/benefit

Thienopyridine ( clopidogrelThienopyridine ( clopidogrel))Pt at low risk:7-10 daysPt at low risk:7-10 days

Pt at high risk : 5 daysPt at high risk : 5 days

))platelet function test should be platelet function test should be donedone((

--AspirinAspirin

As long as the platelet life span(why..)

Gp IIb/IIIa inhibitorGp IIb/IIIa inhibitor::

11 ) )AbciximabAbciximab

22 ) )aggrestataggrestat

Mechanism of actionMechanism of action

Evidence based indicationsEvidence based indications

11 . .prophylacticprophylactic22..PerioperativePerioperative

The trigger to avoid spontanous bleeding is

< <1010 000000 not < 20 000

-Chronic patient : + active bleeding

When to redose;

Shorter life span??=

Ophthalmic surgery

Neurosurgery<100 x 109/l (why)

Epidural insertion or removal…

Lumbar puncture…

<50-80 x 109/l

<50 x 109 /l

Invasive )surgery as laparotomy (…

vaginal delivery.. Minimal invasive(..central line)

<50 x109/ l

<30 x109/ l

Decision to tranfuse should not be based only on Plt. Count but should be

supported by the need to prevent or treat bleeding the need to prevent or treat bleeding ( always keep in mind)( always keep in mind)

1.Heparin induced thrombocytopenia.

2.Hemolytic uremic syndrome.

No prophylactic transfusion because they are thrombotic

Only treat clinical bleeding

3.Idiopathic thrombocytopenic purpuraNo benefit = quickly removed..( immunely destructed )

transfuse only before procedure or treat clinical bleeding

•Def Def : failure to obtain satisfactiory response after two consecutive transfusion episodes.

•Causes:

•-random donor platelet is more risky

•-directly related to number of transfusion

1 (Immune2 (Non immune

:Platelet alloantibodies-HLA-HPA

-sepsis-splenomegaly

-D.I.C.

Dr.Colin BrownDr.Colin Brown

RISKS OF TRANSFUSION

11..T.R.A.L.I.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 .

22..transfusion associated sepsis transfusion associated sepsis ( stored at …..)

It is the largest overall infectious risk in blood transfusionIt is the largest overall infectious risk in blood transfusionPlatelets should be screened for bacterial contamination )specific concern)Platelets should be screened for bacterial contamination )specific concern)

33..Non hemolytic febrile reaction Non hemolytic febrile reaction (incidence is 1:20)

44..Transmitted infections Transmitted infections (H.I.V ,, H.C.V.)

•--My dear professors who My dear professors who teach meteach me

•--My dear colleagues who I My dear colleagues who I really lovereally love

•--My lovely parents and my My lovely parents and my darling wifedarling wife

ReferencesReferences

1-Update on platelets: ASA guidelines 2006

2-proposed guidelines for platelet transfusion

)Bc medical journal)