Blood, plasma, and other blood components utilized in clinical and research environments are required to be stored and transported at specific temperatures. This is necessary as the different components of blood—such as red blood cells, white blood cells, platelets, and nutrients—interact with each other through chemical reactions that are often reliant on temperature to function. The body's ambient temperature is around 37 degrees Celsius, where reactions normally happen, while higher temperatures cause molecules to break down, and cooler temperatures slow down and stop interactions. Being able to slow the interactions is important once samples or donations are obtained so blood can be stored without the risk of spoiling.
Further, the other components of blood, such as blood plasma and platelets, once removed through centrifugation, have other storage conditions to preserve the essential cells, proteins, and molecules for testing, research, and clinical procedures.
Just as with different foods, vaccines, and other protective products, there are various storage conditions for blood. Blood storage conditions are generally applied and include a cold chain for the preservation of blood products in transportation. Red blood cells require a blood bank refrigerator and should be stored in cabinets between 2 and 6 degrees Celsius. Meanwhile, blood bags have specific shelf lives, depending partially on the temperature of the room, with a shelf life of 42 days for a blood bag in a blood refrigerator.
Plasma has to be frozen quickly after donating, to a minimum of negative 40 degrees Celsius. This stops the plasma from coagulating. The shelf life for frozen plasma, if correctly maintained, is about one year. Before plasma is used, it has to be brought to an approved temperature. Keeping blood and blood-related products within the necessary temperature range requires various storage equipment, such as ultra-deep freezers, blood cabinets, freezer cabinets, and outdoor coolers, with systems capable of temperature control. This can stop potentially fatal conditions from occurring when storage conditions are not met and blood is contaminated, such as potentially fatal bleeding.
Blood refrigerators are used to store and protect refrigerated whole blood, blood components, and blood products. These refrigerators must maintain a uniform temperature and utilize rapid recovery systems that equalize the temperature set point when the door is opened and closed. Blood refrigerators are available in various models and sizes and can include lockable doors, chart recorders, and alarms to warn of power loss and temperature deviations. Refrigerators for blood storage must meet the requirements of the AABB, the American National Red Cross, and the U.S. Food and Drug Administration, among others. These requirements include the following:
- Forced air circulation to maintain temperature uniformity
- Directional airflow for fast temperature recovery after uniformity
- Temperature adjustable between 1 and 8 degree Celsius
- Visual and audible alarms for over and under temperatures or power failure
- Battery backup system
As fridges become more competitive among manufacturers, as users have more requirements for their fridges, and as more requirements are made from local and international regulations, refrigerators have included more specialized features. These include the following:
- High-quality cabinet construction, including heavy walled and CFC-free installation to minimize energy use and ensure temperature stability
- Time and temperature-sensitive auto-defrost cycles with automatic condensation removal to minimize equipment downtime
- Stainless steel roll-out drawers and insulated self-closing glass doors for easy view and access and to prevent temperature excursions from doors left open
- Doors can be locked to control access
- Directed and monitored forced-air circulation for temperature stability and for quick temperature recovery post-door opening
- At least two temperature sensors or probes at various points to provide complete cabinet temperature data for compliance with blood storage standings, as well as built-in or freestanding chart recorders for logging and monitoring temperature data
- Visual and audible alarms and alerts for the tracking of events such as temperature deviations and power failures, with battery backups to ensure alarm functionality in the event of a power failure
Part of the refrigeration and storage of blood and blood products is the cold chain, which is sometimes referred to as the blood cold chain in the transportation of blood. This cold chain tends to be a massive undertaking on a global scale, working to give access to a secure blood supply for effective healthcare around the world. According to the World Health Organization, more blood is donated in high-income countries, and this approximately answers the needs for blood there, while populous, low-income countries are consistently undersupplied in blood.
The cold chain is composed of various pieces of equipment that allow for the systematic processes necessary for the safe storage and transportation of blood and blood components. This cold chain works to keep blood and blood components at the correct temperatures at all times, from blood collection to administration. The cold chain is composed of refrigerators, plasma freezers, platelet agitators and incubators, and blood transport boxes. The proper containment and transport of blood can reduce the blood that is lost or needs to be disposed of at the end of a day. For example, in an ambulance that carries blood for emergency situations, proper storage on the ambulance can extend the life of blood products.
The lack of donated blood is not the only problem facing many low-income countries. The equipment necessary to maintain appropriate temperatures through the cold chain can be expensive, and in some low-income countries, the expense of refrigeration on-site, let alone for transportation, may prove prohibitively costly. Often, these countries also experience challenging environments where temperature conditions can change drastically. And many of these countries cannot afford to produce, let alone store, blood derivatives.
Proper equipment is vital at all levels of the cold chain, regardless of the income of the country where a donation or transfusion occurs, and can increase the effectiveness of blood transfusions across the world. The WHO is working to enable this by helping countries better monitor the cold chain, acquire the necessary equipment, and increase transparency and visibility in their cold chains.