Tuesday, September 17, 2013

BLOOD PRODUCTS AND TRANSFUSION

A blood product is a therapeutic substance made from human blood. Transfusion may be needed when a patient has a deficiency or dysfunction of a blood constituent that causes symptoms or puts the patient at risk. It should only be prescribed if a useful improvement is likely to result. Patients who need transfusion require a safe and sufficient supply of blood. Transfusion from a donor is a form of allogeneic transplant and is never risk-free. Wherever possible, alternative treatments should be used . For some patients, transfusion may be avoided by using strategies such as perioperative blood salvage or antifibrinolytic drugs.
A safe blood supply depends on a well-organised supply system that ensures regular donation by healthy individuals who have no excess risk of infections transmissible by blood. Every blood donation must be reliably tested to detect and exclude those containing transmissible agents. In the developed world, this includes hepatitis B, hepatitis C, HIV and human T lymphotropic virus (HTLV) which are detected with tests for antibody to the virus, viral antigen or nucleic acid. Platelet concentrates may be tested for bacterial contamination. The need for other microbiological tests depends on local epidemiology. For example, Chagas disease (p. 355) is transmissible by blood, and blood donations are tested for Trypanosoma cruzi in parts of South America where it is prevalent.
Effective control over the quality of safety testing, blood grouping, processing, storage and pre-transfusion testing of blood is also crucial. In the UK, blood services are licensed and regulated by the Pharmaceutical Regulatory Authority under European Union legislation. Figure 24.16 maps the main steps in blood collection, processing and storage.

FLUID RESUSCITATION IN CRITICALLY ILL PATIENTS
'In patients in the ICU, use of either 4% albumin or normal saline for fluid resuscitation results in similar outcomes at 28 days.'
• Finfer S, et al. Vox Sanguinis. 2004; 87 Suppl 2:S123-131.

RED CELL TRANSFUSION IN CRITICALLY ILL PATIENTS
'In patients in intensive care, mortality and morbidity are similar or better in patients in whom Hb is maintained at 70-90 g/l than in those who received ∼twice as many red cell units to maintain Hb at 100-200 g/dl.'
• Herbert PC, et al. N Engl J Med 1999; 340:409-417.


Safe and effective clinical use of blood depends on:
  • correct storage and handling throughout the life of the product right to the point of administration
  • clinical protocols or guidelines for the management of patients at risk of transfusion
  • a recorded assessment of the likely benefits and risks for each patient
  • correct procedures for ordering and administration following the decision to transfuse.