HUMAN BLOOD PRODUCTS
These are classified as blood components prepared in the blood transfusion center (red cells, platelets, fresh frozen plasma, and cryoprecipitate) or plasma derivatives manufactured from pooled plasma donations in plasma fractionation centers (such as albumin, coagulation factors, and immunoglobulins). Plasma derivatives are covered by the Medicines Act and, like any other drug, must be prescribed by a licensed practitioner. Since 1999, as a vCJD risk-reduction measure, all plasma derivatives used in the UK are manufactured using donations from countries with a low risk of vCJD.
3.3.1: Blood components
Whole blood is now rarely used for transfusion. Blood component therapy makes clinical sense as most patients require a specific element of blood, such as red cells or platelets, and the dose can then be optimized. Each component is stored under ideal conditions (e.g. red cells must be refrigerated, platelets must not) and the use of precious blood donations become more efficient. The use of blood components in clinical practice is covered in Chapters 7 to 10.
The process of producing blood components and plasma derivatives is summarised in Figure 3.1.
3.3.2: Labelling of blood components
22.214.171.124: Blood component labels
The content of blood pack labels attached at the transfusion center is prescribed by the Blood Safety and Quality Regulations 2005 (BSQR). Key information is present in both eye-readable and barcoded form and allows the donor origin (via a unique donation number) and processing steps of the product to be traced as well as indicating the blood group, any special requirements (such as CMV negative or irradiated), expiry date and storage conditions. Work is in progress to review the content of blood component labels and improve their clarity. Up-to-date information is available in the Guidelines for Blood Transfusion Services in the UK (http://www.transfusionguidelines.org.uk).
126.96.36.199: Blood compatibility labels
These are attached to the pack in the hospital transfusion laboratory and uniquely identify the patient for whom the component has been selected. At the final bedside check, the donation number and other details on the compatibility label must match those on the blood pack label and the patient details must exactly match those on the recipient’s ID band (see Chapter 4 for a detailed discussion of safe blood administration).
188.8.131.52: Specifications of blood components
Whole blood donations of 405–495 mL (mean 470 mL) are collected into 63 mL of citrate phosphate dextrose (CPD) anticoagulant.
All blood donations are filtered to remove white blood cells (pre-storage leucodepletion) to leave <1×106 leucocytes in the pack. This was introduced in 1998 as a vCJD risk-reduction measure but also reduces the incidence of febrile transfusion reactions and alloimmunization to white cell (including HLA) antigens.
Indicative contents of commonly available components are noted below, based on quality assurance data from NHS Blood and Transplant (see http://www.blood.co.uk/hospitals/products for more detail and an up-to-date compendium).