Platelets

Main Uses

• Treatment of bleeding due to

               - Severely decreased platelet production
               - Functionally abnormal platelets

• May be used in treating some patients with platelet consumption or dilutional thrombocytopenia.
• May be useful if given prophylactically to patients with very low or rapidly falling counts usually <10 x10^9 /L secondary to cancer or chemotherapy.
• Not usually effective or indicated in patients with rapid platelet destruction.
• May be of use peri-operatively where platelet count is <50x 10^9 /L.

Precautions

• Consider the need for platelets. Is a platelet transfusion required?
• Caution is needed with volume.

Dosage

Compatibility testing is not necessary in routine platelet transfusion. Platelet components should preferably be ABO and Rh (D) type compatible with the recipient. However, ABO-incompatible platelets may be used if ABO-compatible platelets are not available. In some patients (particularly children), plasma present in platelet units which are ABO-incompatible with the patient's red cells may cause a positive direct antiglobulin test and possible low-grade haemolysis due to isoagglutinins present in the plasma.

Immunisation to donor red cell antigens may occur because of the presence of small but variable numbers of red cells in platelet units. When Rh (D) positive platelets are transfused to an Rh(D) negative female of childbearing potential, prevention of Rh (D) immunisation by use of Rh (D) Immunoglobulin should be considered. Usually 250 IU of Rh( D) Immunoglobulin given IM per therapeutic platelet dose provides sufficient cover. If intravenous Rh (D) Immunoglobulin administration is required, WinRho SDF should be used.

Transfuse platelets through an intravenous line approved for blood administration and incorporating a clean standard (170 to 200 micron) filter. Transfusion of each unit may proceed as fast as tolerated but should be completed within four hours of commencing transfusion. The number of platelet units to be administered depends on the clinical situation of each patient. One unit of platelets (either pooled or apheresis) would be expected to increase the platelet count of a 70 kg adult by 20 - 40 x 10^9/L.  The usual adult dose in an adult patient is one unit.  One unit of paediatric apheresis platelets would be expected to increase the platelet count of an 18 kg child by 20 x 10^9/L. 

For prophylaxis this dose may need to be repeated in 1 - 3 days because of the short life span of transfused platelets. Both immune and non-immune mechanisms may contribute to reduced platelet recovery and survival.

Consent and Safety

Patient Identification

Always check the identity of the patient when taking sample for blood grouping or crossmatch and before commencing the transfusion

Remember:

• Only one patient should be bled / processed at a time.
• Never pre-label the specimen tubes.
• Check identity by ASKING the patient to state and spell his/her name AND check the wrist band.
• Check that the request form and sample match the patient and wrist band.
• Remember to sign the sample and request form.

Consent

Consent should be obtained and documented. Check your local institutional guidelines

Always cover the following when gaining consent:

• Explain

- Cause / likelihood of bleeding or the low blood count (including any uncertainty)?
- Nature of the proposed transfusion therapy - what is involved?
- Benefits expected?
- Risks - common & rare but serious?
- Alternatives - including the risk of doing nothing?

• Ask

- Is there anything else you would like to know?
- Is there anything you do not understand?

• Provide

- Interpreter for non-English speaking patients
- Written information

Click for more detailed information.

Administration

Transfusion Set-Up

• Compatibility testing is not required routinely. Platelets should be ABO and Rh (D) type compatible.
• Administer blood through a clean standard blood giving set with a 170 - 220 micron administration filter (large particle filter which only removes aggregates and other large particles). Platelets should not be transfused through an IV line after red cells, however red cells can be transfused through the line after platelets.
• For platelets requiring bed-side leucodepletion (i.e. platelet components that have not been pre-storage leucocyte depleted), a "white cell filter" is required. These filters are designed to remove small particles such as white cells but allow red cells, platelets and proteins to go through. Specific set-up is required - see product inserts and talk to you local Transfusion/ Haematology Nurse Consultant or Transfusion Service provider. Do not "flush" these filters after use.
• Units labelled as leucodepleted product do not need a "white cell filter" at the bedside BUT still require a standard blood administration set incorporating a 170 - 200 micron filter (see above).

Consider

• If Rh (D) positive platelets are given to a Rh (D) negative female of child bearing potential prevention of immunisation using Rh (D) immunoglobulin should be considered.
• Dose is 250IU Rh (D) immunoglobulin per therapeutic dose given.
• Refractory patients may require HLA selected platelets - contact ARCBS to arrange.

Patient Monitoring

• Check patient vital signs (pulse rate, respiration rate, blood pressure and temperature) at the start of transfusion AND at least after 15 minutes, at the end of transfusion AND if there is ANY reaction. Record observations in patient's notes.

When to Transfuse?

• Plan ALL transfusions during business hours. Emergency transfusions should be the only transfusions given after hours.
• Transfuse ONE unit at a time.

How Long Should a Transfusion Take?

• For the first 15 minutes, the rate should be no more than 5mL/min, unless otherwise clinically indicated.
• Each unit must be transfused within 4 hours of starting.
• May be given faster in acute bleeding situations.