Appendix 1: What happens to blood donations?
New Zealand Blood Service: Managing the safety and supply of blood products.
| The Blood Service uses what it calls a "vein-to-vein" business model. This means that it is responsible for all aspects of blood transfusion, from collecting blood, testing it and processing it into blood products, to distributing blood products to hospitals. This Appendix outlines the main processes involved. Collecting blood The Blood Service contacts registered donors and asks them to make an appointment to donate their blood at one of 11 Blood Service blood donation centres or at a mobile collection site. Blood Service staff interview donors, who are then required to fill in an eligibility and health check questionnaire each time they arrange to donate. A successful whole blood donation results in a completed questionnaire, the collection of one unit (470 millilitres) of blood in a sterile bag, and a small amount (15 millilitres) for testing. The Blood Service then dispatches the collected blood units under controlled conditions to one of its four processing centres (in Auckland, Hamilton, Wellington, and Christchurch). At the same time, the Blood Service sends the test samples to one of its two testing centres (in Auckland and Christchurch). Processing donations All whole blood donations go through a filtering process called leucodepletion. This removes most white blood cells (leucocytes). Research has shown that doing this reduces the risk of certain diseases and adverse transfusion reactions in patients who receive donated blood. Blood units then go into a specialist centrifuge machine that spins them at a controlled speed and temperature. Centrifugation separates the main (remaining) components of blood. Specialist machines then extract and bag these separated components. The relatively heavy red blood cells settle at the bottom of the bag, where they can be carefully removed. Red blood cells carry oxygen and carbon dioxide through the body. They are used during surgery, and for treating people who get anaemia from diseases such as cancer. A lighter component of blood called plasma moves towards the top of the bag. Plasma, a straw-coloured fluid, makes up more than half the volume of blood. It contains and carries water, proteins, white blood cells, red blood cells, and platelets around the body. Plasma is used to treat burns victims and people who have had surgery or organ transplants. Plasma can be made into many specialist products using a process called fractionation. Fractionated plasma products can last up to two years and are used for many purposes, including:
Centrifugation creates a thin layer between the red cells and plasma. This "buffy coat" contains platelets and white blood cells. Platelets (and some important clotting factors found in plasma) play a major role in blood clotting. They are used to treat blood diseases, cancer, and for controlling bleeding after surgery or trauma. There are not enough platelets in a single whole blood donation unit to treat a patient. Therefore, platelets are pooled and processed further. Apheresis Apheresis is an automated alternative to collecting whole blood. After the Blood Service collects blood, a special cell separator machine separates the red blood cells from the plasma or platelets. The red blood cells are then returned to the donor. Apheresis provides larger quantities of plasma or platelets than standard whole blood donation. Because apheresis donors do not give red blood cells, they can donate more often than donors of whole blood. Testing blood products At the Auckland and Christchurch testing centres, the Blood Service tests samples of donated blood in parallel to processing the donated unit of blood. It tests every donation to confirm blood type, check for red cell antibodies, and screen for infectious diseases. Blood Service staff do not label blood products until after all processing and testing, and the electronic collating and validating of results and medical information. Storing and distributing The Blood Service must store blood products in strictly controlled temperatures and conditions, from collecting them to their being issued for use in patients. For example, red blood cells, which have a shelf life of 35 days, must be stored at between 2°C and 6°C. Platelets, which can only be used within five days of being donated, must be kept at 22°C and agitated gently and continuously. Fresh plasma must be frozen at a controlled temperature of below –25°C and may be stored for up to two years. Hospital blood banks order final products, which are distributed by logistics teams in the Blood Service's "hubs'" at Auckland, Hamilton, Wellington, and Christchurch. These teams manage inventory, seek to minimise waste because of product expiring, and ensure that supply meets demand. Delivering blood products from blood banks to hospitals and patients The Blood Service has blood banks in six of the country's largest hospitals: Auckland City, Waikato, Palmerston North, Wellington, Christchurch, and Dunedin. The blood banks ensure that patients get the right product, on time, and in good condition. This includes pre-transfusion testing to determine patients' blood types and to match them to blood products. Local DHB staff run all other hospital blood banks, but the Blood Service has overall responsibility for national blood banking services and oversees these other blood banks. After blood products have been dispatched from the blood banks to hospitals, medical staff prescribe and infuse the products into patients. |