The quality and safety of blood used for transfusions depend entirely on maintaining precise storage temperatures. Blood is a living product with different components—red cells, platelets, and plasma—each requiring a specific thermal environment to preserve its function and viability. Temperature acts as the primary control mechanism, slowing metabolism or preventing degradation, which dictates how long a blood product remains safe and effective. Incorrect temperatures can render the product useless or harmful, making strict thermal control a fundamental requirement in blood banking.
Storing Red Blood Cells and Whole Blood
Red blood cells (RBCs) and whole blood must be stored within a narrow, refrigerated temperature range, typically between 1°C and 6°C (33.8°F to 42.8°F). This cold temperature is necessary because it dramatically slows the metabolic rate of the red cells, which are still biologically active and consuming energy in storage. By reducing this activity, the cells conserve their adenosine triphosphate (ATP) levels and maintain the integrity of their cell membranes, which is directly linked to their oxygen-carrying capacity after transfusion.
Storage below 1°C must be avoided, as freezing the component causes ice crystals to form, leading to the rupture of the red cell membranes, a process called hemolysis. Conversely, temperatures exceeding 6°C increase the metabolic rate and, more significantly, promote the rapid growth of any potential bacterial contaminants. Standard refrigerated storage using an anticoagulant-preservative solution allows red cells to be stored for up to 42 days, a duration that is entirely dependent on continuous adherence to this specific temperature window.
Maintaining Platelet Viability
Platelets, which are responsible for clotting, have completely different storage requirements than red blood cells and must be kept at a controlled room temperature, usually between 20°C and 24°C. Refrigeration is detrimental to platelets because cold temperatures can cause them to become activated and clump together, irreversibly compromising their function before transfusion. Storing them at room temperature allows them to remain in a functional, non-activated state, ready to participate in clot formation.
The room temperature storage environment presents a higher risk of bacterial proliferation, resulting in a much shorter shelf life of typically five to seven days. To ensure their survival and function, platelets require continuous, gentle agitation during storage. This movement prevents clumping and facilitates gas exchange, ensuring the platelets are continuously supplied with oxygen and excess carbon dioxide is expelled.
Freezing Plasma and Cryoprecipitate
Plasma and cryoprecipitate are stored using deep freezing to preserve the delicate clotting factors and proteins they contain for long periods. Fresh frozen plasma (FFP) must be frozen quickly, typically within eight hours of collection, to ensure the labile coagulation factors remain active. The required storage temperature is typically at or below -18°C, which allows for a shelf life of up to one year.
For extended storage, plasma may be kept in ultra-low temperature freezers at -30°C or even below -65°C, which can preserve its quality for several years. Cryoprecipitate, which is concentrated from plasma and rich in factors like fibrinogen and Factor VIII, follows similar deep-freezing requirements, also being stored at -18°C or colder. This ultra-low temperature halts all metabolic and enzymatic activity, maintaining the integrity of these proteins until the component is thawed for patient use.
Shelf Life and Monitoring Requirements
The stated shelf life of any blood product is a function of continuous temperature maintenance; any deviation from the established range immediately reduces its expiration time. For example, if a refrigerated red cell unit is removed and not transfused immediately, it is often assigned a maximum out-of-refrigerator time, such as 30 minutes, before it must be returned or discarded.
Robust monitoring systems are mandatory in blood banking facilities. Specialized refrigerators and freezers must be equipped with continuous temperature recording devices that log data and feature alarm systems set to trigger immediately if the temperature drifts outside the acceptable range. Standard operating procedures require that any unit subjected to a temperature excursion must be quarantined immediately. Its fate—whether it is usable, requires testing, or must be discarded—is determined by careful review of the temperature records.