INDICATIONS FOR USE OF PLATELET CONCENTRATES:
The indications for transfusion below are taken from UK national guidelines for the use of blood components. Although it is accepted that clinical judgement plays an essential part in the decision to transfuse or not, the purpose of drawing available transfusion guidelines together is to help clinicians decide when blood transfusion is appropriate, and to minimise unnecessary exposure to transfusion. Each indication has been assigned a number, e.g. P1, which should be written on the transfusion request form when ordering platelets. You may be referred to a haematologist if you request platelets for any reason which does not fall into one of the categories below:
Bone marrow failure
P1. To prevent spontaneous bleeding when the platelet count <10 x 109/l.
P2. To prevent spontaneous bleeding when the platelet count < 20 x 109/l in the presence of additional risk factors for bleeding such as sepsis or haemostatic abnormalities.
P3. To prevent bleeding associated with invasive procedures. The platelet count should be raised to >50 x 109/l before lumbar puncture, epidural anaesthesia, insertion of intravascular lines, transbronchial and liver biopsy, and laparotomy, and to >100 x 109/l before surgery in critical sites such as the brain or the eyes. If an invasive procedure is planned where bleeding is a particular risk the target platelet level and use of platelets should be discussed with a haematologist.
Central neuraxial blockade (spinal and epidural anaesthesia) is not usually performed with a platelet count of less than 100 x 109/l. The anaesthetist will need to discuss the risk/benefit balance with the patient and take advice on the use of platelet therapy from a haematologist.
P4. Massive blood transfusion. The platelet count can be anticipated to be < 50 x 109 /l after 1.5-2 x blood volume replacement. Aim to maintain platelet count > 50 x 109 /l. Counts should be monitored every three to four hours
P5. Bleeding, not surgically correctable and associated acquired platelet dysfunction e.g. post-cardiopulmonary bypass, possibly combined with the use of potent anti-platelet agents such as clopidigrel.
P6. Acute disseminated intravascular coagulation (DIC) in the presence of bleeding and severe thrombocytopenia.
P7. Inherited platelet dysfunction e.g. Glanzmanns thrombasthenia with bleeding or as prophylaxis before surgery.
P8. Autoimmune thrombocytopenia, in the presence of major haemorrhage Large amounts (2-4 adult doses) of platelets may be required to achieve haemostasis due to the presence of autoantibodies and their affect on platelet survival.
P9. Post-transfusion purpura, in the presence of major haemorrhage.
P10.Neonatal alloimmune thrombocytopenia, to treat bleeding or as prophylaxis to maintain the platelet count >50 x 109 /l
NOT USUALLY INDICATED:
- Prophylactic use long-term for chronic failure of platelets as in aplastic anaemia or myelodysplasia, although may be required during unstable periods associated with infection.
- Thrombotic Thrombocytopenic Purpura (TTP) patients should not be transfused platelets except in life threatening haemorrhage. Can cause rapid deterioration and death.
- Post-Transfusion Purpura (PTP) patients should not be transfused platelets, even if they are prepared from donors who are negative for the appropriate human platelet alloantigen (HPa). However, they may be used to control severe bleeding in the acute phase.
- Heparin Induced Thrombocytopenia (HIT) – platelet transfusions should not be given as acute thrombosis can result.
- Use a sterile blood giving set or a blood component (platelet) giving set.
- A fresh set must be used for platelets.
- Never put platelets in the refrigerator.
- Start infusion as soon as pack received from the blood bank. Return to lab for safe storage if infusion is not started within 30 minutes.
- Infuse over not more than 30 minutes (or as instructed).
RESPONSE TO PLATELET TRANSFUSIONS
It is important to monitor the response to platelet transfusions as this will serve as a guide to further platelet supportive care.
If the patient is bleeding, the clinical response is an important indication of the effectiveness of the transfusion. The response to a prophylactic platelet transfusion is assessed by measuring the increase in platelet count following the transfusion.
R(%)=PI x BV x PD-100
R = % rate recovery
PI = platelet increment
BV= blood volume (litres)
PD= platelet dose transfused (x10-1)
Although a successful transfusion may produce a platelet recovery of 67% in a stable patient, the minimum standard for a successful transfusion may be considered as a platelet recovery of > 30% at 1 hour post transfusion and > 20% at 20 hours post transfusion.
In practice, however, an increase of less than 20 x 10 9/l at 20-24 hours after the transfusion is often used as a measure of a poor response.
Poor responses to platelet transfusions may be due to immune or non-immune causes.
Seek further advice from a Haematologist.
REACTIONS AFTER PLATELET TRANSFUSIONS
A number of reactions may follow platelet transfusions. They are the same as those which can occur after the transfusion of red cell concentrates:
- Febrile Reactions
- Urticarial Reactions
- Anaphylactic Reactions
- Reaction to a bacterially contaminated unit.
All blood components should be visually inspected for pack integrity and colouration prior to transfusion. Check that platelet packs do not show clumping or appear more cloudy than usual.