Portal de Periódicos da CAPES

Blood storage and transportation

2008; Wiley; Volume: 3; Issue: 2 Linguagem: Inglês

10.1111/j.1751-2824.2008.00196.x

1751-2824

Joel Hardwick,

Trauma, Hemostasis, Coagulopathy, Resuscitation

In terms of blood processing, quality may be defined as a series of processes to prepare components that will improve the haematological status of the patient. Blood components may be collected and prepared correctly, but if anticoagulant and preservative solutions are not suitable, or storage conditions are not well managed, then the components transfused will not achieve this quality goal. Anticoagulants and preservatives initially prevent clotting and thereafter maintain cell viability and function during storage. Storage conditions relate largely to the maintenance of temperature from the time of collection, through processing, testing and labelling and transportation, up to the point of issue for transfusion into a patient. This is known as 'cold chain management'. Blood is of a fragile nature and components should be handled with due care; mechanical trauma is detrimental to their viability and functionality and rough handling may also damage collection bags. As components are usually administered in hospital wards or operating theatres – areas that must be kept clean – it is important to store and transport blood and components under stringently hygienic conditions to ensure that when they reach the patient, they are visually presentable and free of any sign of soiling. By the end of this section the student should be able to describe the concepts of blood anticoagulation and preservation, as well as storage and transportation requirements, under the following headings: Anticoagulant-preservatives composition of anticoagulant-preservatives adenosine triphosphate 2,3 biphosphoglycerate red cell additive solutions storage lesion Storage temperatures shelf life of whole blood components storage temperature specifications Storage equipment blood storage refrigerators plasma storage freezers room temperature storage facilities design features of blood storage refrigerators and plasma storage freezers design features of cold rooms and freezer rooms Blood and component transport containers features of a blood/component transport container latent heat of melting and selection of suitable coolants design features of blood/component transport containers transportation of fresh blood from collection area to processing centre transportation of stored blood from one storage venue to another transportation of stored platelet concentrates from one storage venue to another transportation of frozen plasma from one storage venue to another container and coolant validation Temperature monitoring responsibility temperature measuring points temperature monitoring devices alarms Installation and maintenance installation regular maintenance repairs contingency measures Links in the blood cold chain collection processing storage transport transfusion Inventory management and control baseline usage figures daily stock count. Anticoagulant-preservatives used for blood collection vary in composition; their main aim is to prevent clotting and then to provide nutrients to maintain red cell viability and functionality throughout storage. Sodium citrate is a calcium-chelating (binding) agent that interferes with the calcium-dependent steps in the clotting cascade and prevents coagulation. Dextrose supports the generation of adenosine triphosphate (ATP) – see explanation below – by glycolysis and in this way provides nutrients that are required by the red cells. Citric acid is used in conjunction with sodium citrate and dextrose to make the anticoagulant solution called acid citrate dextrose (ACD). This was one of the earliest anticoagulants used for blood collection and storage. The acidic pH does not maintain 2,3 BPG levels (see explanation below) and it is no longer commonly used, as better solutions are now available. Sodium phosphate, when used in conjunction with citric acid, sodium citrate and dextrose, comprise the anticoagulant citrate phosphate dextrose (CPD), which is in common use in conjunction with red cell additive systems (see explanation in succeeding discussions). CPD has a more alkaline pH and maintains 2,3 BPG levels better than ACD. CPD to which adenine (A) is added, becomes CPDA-1 (the '1' signifies the formula used) and improves the synthesis of ATP. CPDA-1 is usually used when the collected donation is to be stored as whole blood. The volume of anticoagulant required to prevent clotting and preserve red cells is dependent on the volume of blood taken from the donor. Some collection bags are designed for the collection of 500 mL blood and contain 70 mL anticoagulant; others are designed for 450 mL collections and contain 63 mL anticoagulant. If smaller quantities of blood are to be drawn, then the volume of anticoagulant is reduced proportionately. Metabolism of ATP provides energy for red cells. Energy-rich compounds (such as glucose or dextrose) are absorbed into the cells, and are metabolized by enzymes to release their potential energy by a process called glycolysis. This energy is stored in a form that the cells can utilize, known as ATP. During component shelf life, ATP levels drop, but when ATP-reduced red cells are transfused, ATP is regenerated and normal energy metabolism restored. 2,3 BPG affects the ability of haemoglobin to release bound oxygen. When 2,3 BPG levels drop during storage (they fall to zero in about 2 weeks), the affinity of haemoglobin for oxygen increases proportionately. Therefore, when transfused, these cells cannot readily release oxygen to the tissues where it is required. However, once in circulation, stored red cells regenerate 2,3 BPG and normal function is restored within 24 hours. Red cell concentrates that are prepared from whole blood donations collected into CPD are suspended in additive solution for improved storage and shelf life. See Section 11: Blood processing: red cell concentrate, buffy coat removed, in additive solution, for more detail. When plasma is removed after the centrifugation of whole blood donations, most of the anticoagulant and nutrients in CPD are removed along with it. At this stage, blood has been effectively anticoagulated so the presence of CPD is no longer required by the red cell concentrate remaining in the primary collection bag. However, the red cells need nutrients to survive, and should also be suspended in sufficient fluid to allow for normal flow characteristics. This is achieved by the use of additive solutions. Additive solutions (AS) vary in composition depending on the supplier. They are sometimes referred to by their brand names or simply as SAGM (saline, adenine, glucose and mannitol) or AS-1, AS-3, AS-5 and so on. The typical composition of an additive solution is as follows: Saline is the fluid in which the red cells are suspended to provide the desired flow rate conditions. Glucose (or dextrose) provides the basic nutrients for glycolysis. Adenine and mannitol assist in the process of ATP generation. When an additive system is used then the blood donation is collected in CPD, which has no adenine. The unit is processed within 24 hours of collection and the adenine is added with the red cell additive solution. The volume of additive solution required to preserve red cells during storage varies according to the volume of the whole blood donation. Red cells from a donation of 500 mL require about 111 mL of additive solution, whereas 450 mL donations need 100 mL. Changes that alter the physiological properties occur in collected blood over time, and this is known as storage lesion. Coagulation factor activity (including factor VIII) deteriorates very rapidly in whole blood, particularly after the first 24 hours of storage and is not a suitable product to treat haemostatic disorders. Platelets in whole blood lose viability and functionality very quickly and are not a suitable source for treatment of patients requiring platelet therapy. The red cells increase their affinity for oxygen and lose some viability. Leucocytes deteriorate with the release of leucocyte proteases. Microaggregates form. Potassium is released from the red cells. Collection of blood into anticoagulant-preservatives maintains component function and viability only if storage is within the correct temperature range. Low temperature storage slows glycolytic activity and allows the shelf life of the component to be extended. Low temperatures also retard bacterial proliferation, should bacteria have gained access during the time of donation; either from the venepuncture site, the donor's circulation or other source. The same storage principles that apply to the effective storage of blood components are seen to be applied in everyday life; products such as milk and meat are kept at low temperatures so that they last longer. Preservatives are sometimes added to food products (such as fruit juice) to extend shelf life – provided that low temperature is maintained. Just as everyday products need a clean storage environment and careful handling to avoid physical damage, so too, do blood components. Shelf life is the maximum allowable storage time that a blood product may be stored, provided that the requirements of temperature, preservative solutions and physical environment are met. For red cells, shelf life varies at +4°C ± 2°C according to anticoagulant/preservative and additive solution used. The requirement that determines shelf life is that at least 75% of red cells transfused at the end of the proposed storage period must still be in circulation 24 hours after transfusion. This interprets as a shelf life of 21 days for ACD, 28 days for CPD, 35 days for CPDA-1 and 42 days for CPD replaced with a suitable additive solution. For platelet concentrates, shelf life at +22°C ± 2°C is determined by its efficacy when transfused. This may be related to platelet viability and function during storage in the correct conditions of temperature and motion, and is considered to be up to 7 days. Most blood services allocate a 5-day shelf life to limit the increased risk of bacterial growth resulting from the room temperature storage requirement. For plasma, the levels of stable clotting factors (FII, FVII, FIX, FX and fibrinogen) are quite well maintained at +4°C ± 2°C. Labile clotting factors (FV, FVIII) deteriorate to levels that are not useful if not frozen within 24 hours of collection. Shelf life of labile coagulation factors is up to 3 years if frozen (colder than –25°C). However, a storage temperature that does not reach –25°C but is colder than –18°C reduces shelf life to 3 months. Control of temperature is vital to the successful shelf life of blood and components. Because of the great diversity in collection containers and anticoagulant preservatives, as well as storage capabilities within different blood services, the shelf life of different components varies considerably. Shelf life specifications must comply with local standards. For information and benchmarking, international standards should be consulted. The specifications may be broadly interpreted as follows: Whole blood may be stored immediately after collection at the refrigeration temperature of +4°C ± 2°C. Alternately, it may be placed in a controlled room temperature environment of +22°C ± 2°C, using a facility validated to maintain this temperature range. The option of +22°C ± 2°C storage for up to the first 24 hours after collection is a prerequisite for the production of platelet concentrates, and discussed in succeeding sections. Whatever option is used, after the first 24 hours all whole blood donations must be maintained at +4°C ± 2°C. Red cell concentrates prepared from whole blood refrigerated immediately after collection should be replaced at +4°C ± 2°C as quickly as possible after processing, and in total no longer than 1 hour from the time the whole blood was removed from the refrigerator for processing. The centrifuge used to spin the whole blood for separation of the red cell concentrate should be set at +4°C. Red cell concentrates prepared from whole blood stored at ±22°C ± 2°C for up to 24 hours after collection, should be stored at +4°C ± 2°C immediately after processing. The centrifuge used should be set at +22°C when processing blood stored at +22°C ± 2°C. Platelet concentrates derived from whole blood donations (single or pooled), or by apheresis are stored at +22°C ± 2°C. Plasma separated within 24 hours of collection, and stored at temperatures colder than –25°C for the maximum preservation of all its contents, has a storage period of up to 3 years. Plasma for labile clotting factor replacement that is stored at temperatures between –18°C and –25°C is acceptable, but results in a reduction of shelf life to only 3 months. Liquid storage of plasma at +4°C ± 2°C is acceptable but not commonly utilized as a result of the rapid deterioration of clotting factors and availability of more suitable volume expanders. Studies have shown that whole blood may be stored at controlled room temperature (+22°C ± 2°C) for up to 24 hours after collection without deleterious effects on factor VIII yield, or on the properties of red cells and platelets: When whole blood is rapidly cooled after donation, to +22°C ± 2°C and stored within this range for more than 16 hours (overnight holding time) before centrifugation and buffy coat (BC) preparation, the yield of platelets is higher and more consistent than if processing was carried out within 3 hours of donation. The average factor VIII yield in plasma after 24 hours storage of whole blood at +22°C ± 2°C from donation, is considerably higher (approximately 15%) than the yield from whole blood stored at +4°C. The decline in 2,3 BPG levels in red cell concentrates stored for up to 24 hours from donation at +22°C ± 2°C is limited by rapid cooling to this temperature. In most clinical situations 2,3 BPG levels are restored within a few hours of transfusion. The drop in 2,3 BPG is balanced by the improved platelet yield/function and better factor VIII yield. Extended hold has little or no deleterious effect on ATP concentration, especially when the cooling to +22°C ± 2°C after donation is rapidly carried out. A holding time ('hold') at +22°C ± 2°C allows for the natural immunological activities to take place in the blood donation, such as the phagocytosis of contaminating bacteria. Immediate storage at +4°C ± 2°C prevented this. Rapid cooling of whole blood immediately after collection should result in its temperature reduction to +22°C ± 2°C in less than 4 hours. Continued storage at +22°C ± 2°C for up to 24 hours from donation allows more time for better scheduling of blood processing workload. The purpose of a blood storage refrigerator is to maintain whole blood, red cell concentrates and other components at +4°C ± 2°C. As correct storage is critical to the quality and functionality of blood components, a custom-built blood storage refrigerator is a basic requirement for the blood bank. Upright freestanding units that combine all the ideal design features as listed later in this section are most widely used. They vary in size according to workload and application. Large, double-door units are required for managing large numbers of components, such as in processing areas. Hospital blood banks use single-door units with storage capacity appropriate for the number of units handled. Emergency blood refrigerators are small and are based in the hospital ward. Freestanding chest type refrigerators are not commonly used. The feature of a top-opening lid rather than a door, allows for better retention of cold air when the lid is opened, and models with better insulation can be useful in areas where power supply is intermittent, as they are able to hold temperature for longer periods during outages. Cold rooms are fixtures built into major blood transfusion centres. They vary in size and design, and are usually constructed at the same time as the facility is built so that their features may be carefully planned. Cold rooms are set to the required temperature range for bulk storage of blood and components. Solar and gas powered storage devices: Although in most applications blood storage refrigerators are electrically powered, and this is a basic assumption in describing available refrigerators, it must be acknowledged that in some areas, gas or solar powered units may be the only way to store blood under controlled conditions. Such units are available from some suppliers and will meet basic requirements for blood storage. Generally they are expected to hold fewer units and have very thick insulation to limit heat loss. They do not have blower fans to circulate air in the storage chamber. The purpose of a plasma storage freezer is to store plasma for therapeutic use and bulk plasma for transfer to a fractionation facility at temperatures consistently colder than –25°C. Freezers require a 'defrost cycle' to clear ice from the fan (blower) unit. During the defrost cycle the temperature in the freezer may rise approximately 5°C, so in order to maintain a temperature consistently colder than –25°C, the operating temperature of the freezer should be set at –30°C or colder. Freezer units used in issue areas to store FFP for short periods may only be required to maintain temperatures colder than –18°C. Upright freestanding freezers are convenient to use because the front-opening door allows easy access to stored plasma. This feature makes them popular in issue areas, and for holding quarantine units for sorting and checking before long term storage. Freestanding chest type freezers are commonly used for both small quantity and bulk plasma storage applications. As cold air is heavier than warm, it remains at the bottom of a chest freezer when the top-opening lid is raised, and it is this feature that makes chest type freezers most suitable. Freezer rooms are fixtures built into a blood transfusion centre. They vary in size and design, and are usually constructed at the same time as the facility is built so that their features may be carefully planned. Freezer rooms are best suited to bulk storage of plasma that is destined for fractionation or large scale quarantine of plasma in a 'donor retest' programme or, if properly segregated and labelled, general storage of all these types of plasma. Certain areas within the freezer may be made lockable to limit access, i.e. for plasma in quarantine. The purpose of creating a room temperature storage facility is to provide a controlled environment, validated to maintain temperature at +22°C ± 2°C, under all ambient conditions (extreme heat or cold). Such an environment is required for: Storage of platelet concentrates on a platelet agitator housed in an incubator Storage of fresh blood between receipt and processing, if a 24 hours hold at +22°C ± 2°C is used, in a temperature controlled room Providing an area that complies with good laboratory practice (GLP) where units of blood are processed or handled in bulk (i.e. sorting of incoming fresh blood, labelling, preparing deliveries and so on), in a temperature controlled working environment. A platelet agitator can be housed in an incubator capable of maintaining a temperature of +22°C ± 2°C. Several suppliers are able to provide this agitator/incubator combination, in various sizes depending on the number and type of platelet concentrates (PCs) requiring storage. Features specific to these units are: Preset alarm points at +20°C (low) and +24°C (high) with audiovisual alarms when temperature is out of range Temperature display in 0·1°C graduations. Continuous recording of this temperature by computer or thermograph chart is desirable. The device should be manually monitored and all parameters recorded at least twice per day (even with continuous monitoring) A battery-powered alarm to notify personnel if the power supply to the unit is cut Contents of the incubator are visible through a glass door that should be opened for as short a time as possible when loading or unloading PCs. A controlled room temperature environment of +22°C ± 2°C can be created in a dedicated room of suitable size. The room should be large enough for several platelet agitators and/or, the storage of crates/trays of fresh blood (less than 24 hours from donation), that are to be processed. Features specific to a room of this type are: Moderately insulated walls Automatically closing door Sealed viewing window (no opening windows) Good lighting A top quality air conditioning unit that is able to cool the room in a hot environment and warm the room in a cold environment Preset alarm points at +20°C (low) and +24°C (high) with audiovisual alarms when temperature is out of range A battery powered alarm to notify personnel if the power supply to the air conditioning unit is cut Temperature display in 0·1°C graduations. Continuous recording of this temperature by computer or thermograph chart is desirable. The device should be manually monitored and all parameters recorded at least twice per day (even with continuous monitoring). To be GLP compliant, a well controlled room temperature environment of +22°C ± 2°C is desirable in areas where units of blood are processed or handled in bulk. This is to avoid the need to unload blood from an insulated transport container, and handle it in a room that that has no temperature control. Likewise, taking cooled blood from a refrigerator for labelling, or for despatch preparation, changes its temperature rapidly to that of the environment, which could be unfavourable (either too hot or too cold). Handling of stock blood is best performed in a room with a controlled temperature, and even then, steps should be taken to ensure that as few units as possible are removed from their controlled storage facility at one time. Features specific to the provision of a controlled working environment of +22°C ± 2°C are not as rigid as those for platelet incubators or dedicated rooms. They include: An efficient and well maintained air conditioning system. Work areas with sealed windows and self-closing doors, air curtains and other features to assist air conditioners in performing efficiently. Two temperature displays in 1°C graduations placed in separate locations to detect variation in temperature within the work area. These temperatures should be manually monitored and all parameters recorded at least twice per day. Personnel should have clear instructions on action required if the temperature moves out of range. Audible alarms and continuous monitoring of the work area temperature are not essential but could be useful in achieving high-level quality ratings. It is very important that there is prompt service for repair when problems are experienced. Very good insulation is required, which minimizes heat transfer from the environment to the contents of the refrigerator/freezer interior. Insulation used for freezers may consist of denser and thicker insulating material than that used for blood refrigerators. Good insulation reduces the workload placed on the equipment's compressor, making its operation much more efficient and also improving 'hold-over' time. Hold-over time may be defined as the time period that a fully loaded piece of equipment is able to hold its temperature – as the door remains closed – when there is a loss of power. A longer hold-over time is particularly useful in areas where electricity supply is unreliable, and ambient temperatures are usually high. To protect the environment from harmful compounds, the compressor should use chlorofluorocarbon (CFC)-free gas. The motor should have sufficient reserve capacity to cool the refrigeration/freezing compartment efficiently. The motor/compressor should be controlled by a sensitive thermostat capable of holding the temperature within the required range for blood, or maintaining a sufficiently low temperature for frozen plasma. A fan is used to efficiently circulate cold air within the refrigerator/freezer to ensure that uniform temperature is maintained in all parts of the interior. Shelving within the unit should be designed to fit blood trays/crates and may be of a roll-out design for ease of accessibility. The shelving should also be perforated and not made of solid sheeting, and should be positioned to allow the free flow of circulating air. A visual temperature display and an audible alarm should be fitted to notify personnel when temperature is out of range, or when the electricity supply is cut. There should be an automatic temperature recording facility and an interface for attachment to an electronic recording device linked to a computer database. The interior and exterior of the refrigerator/freezer should be made of material that is easy to clean, and that will withstand strong detergents and regular cleaning. Stainless steel and aluminium are commonly used but other corrosion resistant metals are also acceptable. The storage area inside the refrigerator should be well lit to enable easy identification of contents, numbers and labels. Some models have double-glazed glass doors to enable viewing of the contents without opening the door. The product temperature is better maintained, and the compressor works more efficiently when the door is opened less frequently. The room must have well insulated walls. The insulation can be built into the brickwork, but it is more common to use interlinking pre-built panels to construct the room. The door could be either a conventional hinged type or sliding. The entrance should be wide enough to allow easy access by personnel (and wheeled trolleys if required). It is advisable to have either a strip plastic curtain, or a blower unit mounted above the door which turns on when the door is opened and creates an air curtain across the doorway to prevent massive loss of cold air when the door is opened. For safety reasons, the door locking mechanism must be designed so that an individual inside the room is able to open it. many installations have a 'panic' alarm button located inside the room that can be activated by an individual unable to get out. some units have alarms that are automatically activated when the door is opened, and sound after a preset period of time if the operator has not manually reset the alarm on exiting again. If the alarm sounds, other personnel are alerted to check the cold room for trapped or injured personnel. Freezer rooms should ideally not open directly into a warm environment (i.e. open air or room temperature) as it is difficult for the cooling plant to compensate for the rush of warm air entering the room each time the door is opened (even with a strip plastic or air curtain fitted). To avoid temperature fluctuation and frosting up of the blower fan motor, a freezer room is often built off a +4°C cold room. Personnel entering the freezer room therefore enter the +4°C cold room first, and this forms an 'airlock' between the freezer and the external environment. Cold room and freezer room floors should be non-slip, and at the same level, and have no step or ramp from the outside adjoining room. With no steps or ramps it is easy to wheel bulk components, placed on a trolley, in and out of storage. One of the biggest advantages of a cold/freezer room over freestanding refrigerators or freezers is that the operating plant (motor, compressor, control gear and so on) is located outside the work area. Therefore noise, heat and dust accumulation are absent from the blood handling area, and refrigeration maintenance personnel are able to work on the motor without disruption to the work area. Cold/freezer rooms are frequently built with two cooling units that work in tandem. If one is out of operation, the other unit is able to provide back-up and maintain cold room or freezer room temperatures on its own for quite long periods of time, while the other is undergoing repair. Installation of cold/freezer rooms should only be considered if the motors can be linked to a reliable emergency power supply (i.e. generator) capable of providing sufficient power during power outages. It may be very difficult to find alternate storage for large amounts of blood and plasma in the event of an extended power failure. An assured power supply capable of maintaining the correct temperature is therefore critical, as these rooms usually hold the bulk supply of valuable blood or plasma that would be extremely difficult to replace. Continuous temperature monitoring should be carried out in at least two separate locations in the room to confirm that the correct temperature is evenly distributed throughout. The room should be well lit to enable easy identification of product labels and numbers but should not generate too much heat within the room. Shelving should be sturdy enough to support the weight of fully loaded blood trays or crates. They should also cater for separate storage and restricted access of different categories of blood in clearly demarcated areas (e.g. units for issue, units awaiting completion of testing, and quarantine plasma). Personnel who work in cold/freezer room environments for extended periods must be provided with appropriate protective clothing. Figure 12·1 is a diagram to show the ideal design for a freezer room, with a cold room airlock. Ideal design of freezer room. The purpose of a transport container is to provide a secure controlled temperature environment for blood and components in transit from one location to another. A transport container consists of an insulated box that, when sealed, provides a space that is isolated from the external (ambient) environment. Efficient insulating material is able to control temperature inside the box and prevent it from changing as a result of ambient temperature. No matter how good the insulation, isolation from external temperature is never absolute, and gradually, over time, the temperature within the container will equilibrate to the external temperature. Placing frozen coolant inside the container extends the time taken for this pr