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Platelet transfusion

• Trasfused platelets survive on average 5 days

• Platelets should be transfused within 10 minutes.

• Transfuse platelets using a filter to reduce leukocytes.

• Platelet count may be done after 45-60 minutes to assess

efficacy

• Platelets for transfusion stored at room temperature (20- 24

C), in a gently agitated state.

• Platelet transfusion does not require cross-matching. Group-

compatibility of donor platelets/ plasma may be ideal. But do

not withhold emergency platelet transfusion on that account.

• Unwarranted platelet transfusion generates alloimmunisation,

reducing efficacy of future transfusions.

Critical bleeding

The most critical bleeding are the:

• intracranial

• intraocular (retinal)

• intraabdominal

Though such bleeding is infrequent, it is

mandatory that all patients are assessed

for such potential risks.

Risk of bleeding

– platelet count

– cause of thrombocytopenia

– comorbid disease

– drugs

5 Mechanisms of Thrombocytopenia

1. Pseudothrombocytopenia

2. Decreased platelet production

3. Increased platelet destruction

4. Splenomegaly or splenic sequestration

5. Dilutional Thrombocytopenia

Approach to thrombocytopenia

THROMBOCYTOPENIA

rule out pseudothrombocytopenia

SEQUESTRATION PRODUCTION DESTRUCTION

 

look for splenomegaly bone marrow investigation look for underlying disorders

• immune

Causes of • aplasia auto-immune (ITP, SLE)

splenomegaly • infiltration drugs

• infection • fibrosis infections

• inflammation • ineffective hemopoiesis allo-immune

• congestion eg. MDS • non-immune

• maligancy sepsis

• red cell disorders DIC, TTP, HUS

• storage diseases hypertensive dis. of pregnancy

Clinical Presentation

• Asymptomatic

• Mucosal or cutaneous

bleeding

• Petechiae

• Purpura

• Ecchymoses

Initial Approach

Investigations to include:

• Complete blood counts (including reticulocyte count, peripheral blood

smear for morphology and abnormalities of platelets/ RBC/ WBC)

• Blood Biochemistry-especially renal/ liver function tests, LDH, vitamin

B12/ Folate, and ferritin levels

• Bone-marrow study

• Coagulation profile

• Serology- viral and for connective tissue disorders

• Special tests- platelet function tests, platelet antibodies

• Imaging studies- Ultrasonography, CT scans as required

• Investigations for primary disease

ITP

• idiopathic autoimmune platelet destruction

• Main cause of isolated thrombocytopenia in

healthy young persons

• a diagnosis of exclusion Cines et al. NEJM 346:995-1008, 2002

ITP: Clinical features

• occurs in any age or sex, but typically young female

• can be preceeded by viral infection

• signs and symptoms depend on platelet count

• onset usually insidious

ITP: Laboratory features

• no sensitive and specific test for ITP

• isolated thrombocytopenia

• increased MPV

• normal PT, PTT

ITP: Treatment

Patient is not bleeding

• plt > 50: not indicated

• plt 20-50: monitor closely

• plt < 20: indicated with one or more of:

• prednisone

• IVIG

• splenectomy if relapsing severe ITP

(No role for prophylactic platelet transfusion, even if

plt = 0) ITP: Treatment

Patient is bleeding

• For serious bleeding (eg. CNS, retroperitoneal,

GI)

– Prednisone and IVIG

– Transfuse platelets

– consider urgent splenectomy

– Provide other supportive/resuscitative care as

needed ITP: Prognosis

• Children: usually permanent remission

• Adults: usually relapsing (chronic ITP), but

course is relatively benign. Consider:

– Immunosuppressive drugs (Azatioprine,

cyclophosphamide, cyclosporine, anti-CD20)

– Inhibitor of platelet clearance (danzol, vinca

alcaloids, colchicine, accessory splenectomy)

– Experimental (BMT, throbopoietin etc)

Figure 131-01

Copyright © 2005 Elsevier Inc. (USA) All rights reserved.

Disseminated Intravascular

Coagulation (DIC)

• DIC is characterized by

– the systemic activation of the coagulation system

followed by activation of fibrinolytic system

– high thrombin and plasmin generation

• DIC is not a disease itself, but is a manifestation of a

serious underlying disorder.

Causes of DIC

• Infection - bacterial sepsis, viral infections

• Neoplasm - AML, adenocarcinoma

• Obstetrical dis. - retained dead fetus,

abruptio placentae

• Trauma/surgery - brain injury, crush, burns, etc.

• Others - acute hemolytic transfusion

reaction, etc.

Pathophysiology of DIC

PATHOPHYSIOLOGIC LABORATORY CLINICAL

EVENTS MANIFESTATIONS MANIFESTATIONS

underlying disorder depletion of clotting factors

prolonged PT, PTT

tissue factor release thromboctyopenia

activation of intrinsic pathway hemorrhage

(consumption)

of coagulation

(systemic thrombin depletion of physiologic anticoagulants

generation) decreased fibrinogen

generalized intravascular microangiopathic hemolytic anemia

fibrin deposition thrombosis/infarction

activation of

fibrinolytic system increased FDP and D-dimer

(systemic plasmin generation) Treatment of DIC

• treat the underlying disease

• replacement therapy

• cryoprecipitate

• FFP

• platelet concentrate

• packed red cells

• consider additional pharmacologic therapy

– controversial or investigational agents

• heparin, antifibrinolytic agents.

Microangiopatie trombotiche

(TTP/HUS)

• Disordini occlusivi del microcircolo vascolare

con aggregazione piastrinica sistemica,

piastrinopenia e danno agli eritrociti

TTP (porpora trombotica

trombocitopenica)

• Descritta nel 1924 da Moschowitz

• Presenza di microtrombi

– Anemia emolitica microangiopatica (schistociti)

– Piastrinopenia

– Manifestazioni neurologiche

– Febbre

– Insufficienza renale

• Difetto ereditario o acquisito di ADAMTS13

(metalloproteasi)

SCHISTOCITI

HUS sindrome uremico-emolitica

• Stesso quadro della TTP ma con predominanza

dell’aspetto renale

• Non sempre distinguibile da TTP

• Prognosi buona (tranne che nelle forme ereditarie)

• Terapia di TTP e HUS:

– Plasma fresco, steroidi, splenectomia, vincristina,

Rituximab, dialisi-trapianto renale

Decreased Platelet Production

• Bone marrow suppression or damage

• Viral illness

• HIV (direct damage to Megakaryocytes)

• Chemo- or radiation therapy

• Congenital or acquired bone marrow aplasia or

hypoplasia or dysplasia

• Direct EtOH toxicity

• Vit. B12 or Folate deficiency

Figure 23-01

Copyright © 2005 Elsevier Inc. (USA) All rights reserved.

Table 23-01

Copyright © 2005 Elsevier Inc. (USA) All rights reserved.


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DETTAGLI
Esame: Ematologia
Corso di laurea: Corso di laurea magistrale in medicina e chirurgia (a ciclo unico - 6 anni)
SSD:
Università: Foggia - Unifg
A.A.: 2012-2013

I contenuti di questa pagina costituiscono rielaborazioni personali del Publisher kalamaj di informazioni apprese con la frequenza delle lezioni di Ematologia e studio autonomo di eventuali libri di riferimento in preparazione dell'esame finale o della tesi. Non devono intendersi come materiale ufficiale dell'università Foggia - Unifg o del prof Liso Arcangelo.

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