Platelet concentrate, standard

Code 'Blood Service'

E6642V00

NIHDI Code

Hospitalized: 752 684

Non-hospitalized: 752 673

A "standard" delegated platelet concentrate is prepared from donations of "whole blood. The blood is divided by centrifugation and mechanical separation into 3 fractions, including the buffy coat (BC) containing the platelets. The BCs are pooled by 5 or 6 and with the addition of a platelet additive solution (PAS) to form a 'pool' of BCs from which the platelet concentrate is separated by a second centrifugation. The plasma to storage solution ratio is approximately 40/60.

From the pooled platelet concentrate (PLC), white blood cells are almost completely removed by filtration.
Each PLC undergoes an additional treatment to inactivate pathogens that would be present in the product notwithstanding prior safety measures (donor selection, laboratory control). For this pathogen inactivation, the Intercept method (Cerus) is used. This is a photochemical method based on the following 2 elements:

• The addition of a photoactive agent or "photosensitizer" (i.c., the synthetic psoralen amotosalen) that settles between the nucleic acids of the pathogens
• UV light exposure (UV-A) that induces covalent bonds between the amotosalen and the pyrimidine bases; as a result, irreversible cross-links are formed in the nucleic acids, preventing multiplication of the pathogens

After this treatment, the amotosalen is absorbed away from the PLC.

 The platelet concentration in a "standard" PLC is 0.8 - 1.9 x¹⁰⁶ /µl.

The absolute number of platelets is expressed in EEE (Single Unit Equivalent, defined according to the number of platelets that could originally be obtained from one whole-blood donation). One EEE corresponds to 0.5 x¹⁰¹¹ platelets. A "standard" PLC contains 5 to 11 EEE. The exact platelet content is listed on the label of each concentrate.

All PLC are deukocyzed and contain less than 1 x¹⁰⁶ leukocytes/concentrate. The remaining white blood cells are completely and permanently eliminated by pathogen inactivation.

Prevention or treatment of bleeding in severe thrombocytopenia or thrombocytopathy. The transfusion threshold for prophylactic platelet transfusion ranges from 10 x¹⁰³ platelets/µl for patients without additional risk factors, over 20 x¹⁰³ platelets/µl for patients with fever, coagulation problems, hyperleukocytosis or sepsis to 50 x¹⁰³ platelets/µl for common invasive procedures and 100 x¹⁰³ platelets/µl for brain surgery and internal eye surgery.

Het gebruik van bloedplaatjesconcentraten is gecontra-indiceerd bij patiënten met een voorgeschiedenis van allergische reacties op amotosalen of psoralenen. Bloedplaatjesconcentraten dienen niet te worden voorgeschreven aan neonatale patiënten die behandeld zij met fototherapie-apparaten die een piekgolflengte van minder dan 425 nm afgeven, en/of een lagere limiet van de emissiebandbreedte van <375 nm hebben. 

Dose

Standard dose = 1 EEE/10 kg body weight

Transfusion of such dose increases platelet concentration in an adult by an average of 20,000/µl (or about 3,000/µl per EEE).

This yield is about 20% lower than for non-pathogen-reduced PLC.

Because of this, the FAMHP imposes a minimum dose of ^3x1011 platelets (6 EEE) for pathogen-reduced platelets for adult patients (FAMHP Circular No. 631 dated 2-Sep-2016).

To evaluate the efficiency of a platelet transfusion in a comparable manner at different doses and individuals, the corrected count increment (CCI) can be calculated. The CCI represents, for a given individual, and at an assumed body surface area of 1^m2, the increase in platelet concentration (in^103/µl) after transfusion of ^1x1011 platelets.

CCI = ([PLT]* 1 hour after transfusion - [PLT]* before transfusion) x body surface area** x¹⁰¹¹

                                   number of platelets administered

Body surface area** = √ (length°x weight°°/3,600)

(* thrombocyte count expressed as 103 per µl)

(** body surface area in m²)

(°length in cm)

(°°weight in kg)

CCI is calculated from the platelet count 10 to 60 minutes after transfusion (1-hour CCI) or from the platelet count 24 hours after transfusion (24-hour CCI).

A 1-hour CTI of less than 7,000/µl indicates refractoriness. Such deficient yield occurs with fever, sepsis, hypersplenism, diffuse intravascular coagulation, massive hemorrhage and use of certain antibiotics. A low 1-hour PCI value in the absence of the above factors indicates immunologic refractoriness due to anti-HLA and/or anti-HPA antibodies. This may be an indication to administer HLA- and/or HPA-compatible single-donor platelet concentrates .

Special precautions

Platelets are preferably administered ABO-compatible. 'Standard' PLC of blood group O are not tested for the presence of anti-A and anti-B hemolysins but given the pooling of 5 or 6 BCs and the addition of preservative solution, the risk of hemolysins in high titers is considered small.  

RhD-negative female recipients younger than 50 years of age are preferably treated with platelets from RhD-negative donors. If RhD-positive platelets are nevertheless used for these patients, RhD immunization can be prevented - if necessary - by intramuscular or subcutaneous administration of anti-D immunoglobulins. A 300 µg dose provides protection over a 6-week period for up to 15 RhD-positive platelet concentrates.

Pathogen-reduced PLC should not be irradiated prior to administration to patients with severe immune deficiency. T lymphocytes present in the product are inactivated so that they cannot cause transfusion-related graft-versus-host disease (TA-GVHD).

Pathogen-reduced PLC can be considered CMV-safe. A CMV-seronegative status of the donor is not necessary to administer this PLC to patients at risk for CMV infection.

User Manual

A platelet concentrate is administered intravenously through an infusion set with standard filter (170-260 µ). The platelets are infused slowly for the first 10-15 minutes during which the patient is monitored for any transfusion reaction. Then the infusion rate is increased according to clinical condition (10-20 ml per minute). The average duration of administration is 30 to 60 minutes. Aseptic technique must be used during administration. Any residues are disposed of as medical waste.

The most frequent side effects of transfusion of platelet concentrates are chills, fever and symptoms of an allergic nature such as urticaria and itching.

Serious to life-threatening side effects may include circulatory overfilling with pulmonary edema, transfusion-related acute lung disease (TRALI),

hemolytic transfusion reaction due to plasma incompatibility and severe allergic reactions such as anaphylactic shock.

Furthermore, posttransfusion purpura and chemical disruption in mass transfusion (citrate toxicity) may occur.

If an acute transfusion reaction occurs, transfusion should be stopped immediately and appropriate therapy initiated.

In case of a mild allergic transfusion reaction (itching, redness, urticaria), the transfusion can be continued if necessary after administration of antihistamines or corticosteroids.

PR inactivates T lymphocytes in the PLC, preventing TA-GVHD after platelet transfusion.

PR prevents the growth of bacteria present in a realistic amount in the PLC at the time of treatment. This minimizes the risk of bacterial sepsis after platelet transfusion.

The risk of infection with the known transfusion-transmitted viruses (HIV, HBV, HCV, HTLV, CMV) is further reduced by PR.

The probability of transmission of other - known or unknown - pathogenic organisms (viruses, bacteria, protozoa) is generally very much reduced by pathogen inactivation, but is determined for each specific situation by the ratio between the degree of contamination with the pathogen in question and the activity of pathogen inactivation against it.

Prions are not eliminated by pathogen inactivation.

A platelet concentrate should not be mixed with drugs or infusion solutions.

Platelets should be stored under conditions that maintain optimal viability and hemostatic activity. A PLC is in a gas-permeable storage bag and is ideally stored with the label facing down, on a shaker with movement in a horizontal plane. The storage temperature for a platelet concentrate is between +20°C and +24°C. The storage period is five days. Properly stored PLC containing functional platelets show a refractive effect (swirling) observable as a vortex when observed against the light. A platelet concentrate should not be used after the expiration date, in the absence of the swirling effect and with signs of damage or deterioration.

Blood is drawn from voluntary, non-remunerated donors, selected in accordance with the standards laid down by Belgian legislation and the procedures of the Blood Service of Belgian Red Cross-Flanders.

With each donation, the donor is inspected by a physician and tested for antibodies against the human immunodeficiency viruses (anti-HIV-1 and HIV-2), for antibodies against the hepatitis C virus (anti-HCV), for the hepatitis B virus surface antigen (HBsAg) and for antibodies against Treponema pallidum. HIV, HBV and HCV are also detected by NAT testing.
Products from donations with positive test results are destroyed.

When products prepared from human blood are administered, transmission of an infectious agent cannot be completely excluded. The residual risk of transmission of HIV, HBV or HCV by unit transfusion is estimated at 1 in 4 to 6 x¹⁰⁶, 1 in 0.3 to 1 x¹⁰⁶ and 1 in 700,000, respectively, and is primarily due to the "window period" for laboratory detection. This residual risk is reduced to almost zero by pathogen inactivation. Due to its broad spectrum of action, pathogen inactivation also significantly protects against transmission of less or unknown pathogens ('emerging infectious diseases'). However, such transmission can never be excluded.

The risk of bacterial contamination of PLC is very much reduced by pathogen inactivation. Sterility control on PLC is therefore no longer performed.

Prions are not eliminated by pathogen inactivation and cannot be detected in donors by routine lab tests. Protection against transmission of prions by transfusion relies on careful donor selection.

By medical prescription.