Role of Phase change materials in Blood Storage and Transportation

Blood Transport

A person may need a blood transfusion in case of loss of excess blood, due to injury, during surgery or deteriorating health conditions like anaemia (low level of red blood cells).

Components of  blood and their functions:

Red Blood Cells (RBC): They carry oxygen and carbon dioxide to and from tissues and nutrition to body tissues.

White Blood Cells (WBC): They protect the body against infections.

Platelets: These are small fractions of cells that in help in blood clotting (coagulation) by accumulating in places of injury, sticking to the lining of an injured blood vessel and forming a base on which blood coagulation would occur.

Plasma: Plasma is the liquid part of blood holding cellular components in suspension. The function of plasma is to transport blood cells along with nutrition, antibodies, clotting proteins and hormones throughout the body.

Blood collection  and extraction of blood components:

Whole blood: The blood from the donor (body temperature at  +37 Deg C)  is collected into pre-cooled, internally sterilised hermetically sealable plastic bag containing anticoagulants to prevent clotting and nutrients. The transportation of whole blood could withstand a temperature of +20 to +24 Deg C for a maximum of 6 hrs.  At mobile collection centres, blood is placed is directly placed into a well insulated Cold chain shipper with sufficient Cryophase Phase Change Materials that is capable of cooling blood below +10 Dec C  in under 6  hrs and thereafter maintain the temperature below +10 Deg C for a maximum transportation time of 24 hrs. It is hence very important to ensure the Quality of the Cold chain shipper or Icebox and the Appropriate refrigerant Ice pack be used in storing and transporting blood samples.

Extraction and storage of  blood components:

Whole blood should be maintained at +20 to 24 Deg C (in controlled room environment) until processed into components within 6 hrs. Centrifugation of whole blood results in red blood cells being deposited at the bottom of the blood bag. The white blood cells and platelets remain suspended above red blood cells while plasma remains as a thin film on the surface. The white blood cells that may be contaminated with viruses/ bacteria can cause complications to the recipient.  Hence, white blood cells are filtered out by custom designed special filters. The plasma with platelets is then extracted into a separate bag. Platelets are then extracted from the plasma through centrifuging.

Red blood cells concentrate: The red blood cells have to be stored at +2 to 6 Deg C with a shelf life of 35 days. Most of the anticoagulants and nutrients in whole blood are removed during centrifugation. Hence, the red cells are suspended in a saline fluid by the use of additive solutions for enhancing storage /shelf life. If red cells freeze, cell membranes rupture releasing haemoglobin. This blood could be fatal for the recipient on transfusion.  Hence, a lower limit of +2 Deg C is fixed to avoid freezing. If blood is stored beyond + 6 Deg C, any bacteria that might have entered during collection may grow and this blood again could be fatal to the blood recipient. Therefore the right Cryophase Phase Change Material must be used with the right Shipper in order to ensure the Specimens are not cooled below 2Degree C.

Platelet concentrates: These should be stored at room temperature + 20 to 24 Deg C with continuous agitation to retain viability. Storage at room temperature poses a risk of bacterial growth. The shelf life of platelets is 7 days. However, it is limited to 5 days to minimise bacterial growth.

Fast Frozen Plasma( FFP): FFP is obtained by separating plasma from whole blood within 6 - 8 hours of collection and maintained at +2 to +6 Deg C and then freezing within 30 minutes.  FFP is  maintained at <= -20 Deg C, optimally <= -30 Deg C with shelf life of 3 years.  FFP can be stored even up to 7 years in temperature at <= - 65 Deg C.

Crypto precipitate:  This is the insoluble part of plasma after FFP has been extracted for correcting some coagulation defects of patients. The storage temperature requirement is <=- 25 Deg C with a shelf life of 36 months.

Plasma derivatives:  Derivatives like albumin, immunoglobulin are concentrated specific proteins obtained from plasma fractionation and used to treat patients with specific deficiencies. They are to be stored at +2  to 8 Deg C without freezing.

Blood Storage Equipment, Temperature Monitoring/ Control:

Room Temperature Storage facilities:

The requirement of bulk storage of blood specimens from Blood banks/ hospitals  +20 to +24 Dec C   is met by controlled cold rooms with a sterile environment to avoid contamination during handling. The temperature should be controlled to be maintained within the specified range irrespective of external temperature conditions. Standby electrical power supply has to be made available for control equipment to handle the failure of normal power supply. Entry/ exit doors for these areas should be provided with automatic closing feature along with alarm system to indicate door open conditions. The alarm system should have should be employed to warn the out of range temperature requirement. The setting temperature for Low /High temp limits should be slightly within the limits so that enough time allowance is provided to the operational staff to take any emergency action as required in time. Refrigerators with double doors have to be employed in blood processing areas. Large single door refrigerators for hospital blood banks and small emergency refrigerators inwards is recommended.

For temperature requirement of +2 to 6 Deg C, large size refrigerators with double doors have to be made use of.  Data loggers capable of logging inside temperature at set intervals with the capability to download the data to the external computer and analysis through software have to be made use of. The data loggers should be battery powered.

Plasma storage freezers: These freezers should maintain the plasma content at <= -25 Deg C. During defrost cycle, inside temperature rises by about 5 Deg C. Hence, temperature setting should be kept below - 30 Deg C.  CFC-free refrigerators should be employed.

All these facilities should be handled by trained personnel with assigned responsibilities and also should have substitute personnel to handle the task in case of any requirement.

 Transport of Blood and Blood Components:

The temperature requirement applicable for transport is generally same that of storage requirements. Transport of blood/components could arise from blood bank to hospital or between blood banks. The transport could be by road, by air or ship as the case may be.

The transport containers are of two types, namely, reusable and disposable. Reusable containers are made of formed plastic or fibreglass filled with High-Density Polyurethane. They should be easy to clean and store. They should be tamper proof. They should have been evaluated for the intended application. The disposable containers are made of moisture resistant cardboard boxes with polyurethane foam inside.

The containers employed should be an insulated box built and tested for the intended. The coolant material is kept inside the box along with blood /components (payload). The requirement of coolant should be estimated to maintain the payload within specified limits for the duration of transit under extreme external temperatures forecast. Battery powered Data loggers should be employed to record inside temperature with temperature probes at pre-set periodic intervals. At the end of the transit, the temperature recordings available could be the basis for deciding the suitability of the product for transfusion.

The Refrigerant material for transportation of Blood components:

The passive Cryophase Phase Change Materials (PCMs) are employed inside the insulated Container to keep the payload/ blood component at a predetermined temperature as per requirement within a narrow range for long periods during transit. The principle of operation of Cryophase PCMs is as follows:

In case of blood/ components, the temperature required for various components are as follows;

Whole blood                         :  + 20 to 24 Deg C 

Red Blood Cells (RBCs)    :   + 2 to 6 Deg C

Platelets                                :   + 20 to 24 Deg C

Fast Frozen Plasma            :    <= - 30 Deg C

Crypto precipitate                :   <= - 30 Deg C

In practice, the product/payload temperature in insulated containers are generally warmer by a few degrees.

For example, Dry Ice (frozen Carbon dioxide) has the potential to reduce the temperature to < - 6o Deg C if an excess amount of dry ice is used. However, dry ice is expensive and hazardous. Hence Cryophase phase change materials after being conditioned to the right temperature with quality insulated coolers are able to bring down the payload temperature

Cryolux has developed various types of PCMs ( Phase Change Materials ) PCM Gel packs and ice packs for use in positive and negative temperature ranges. For the blood chain requirement, appropriate Cryophase PCM could be selected and employed for effective and cost considerations.

Effective Maintenance of temperature from the time of collection, through testing, processing, labelling and transportation up to the point of issue for transfusion to the recipient makes it a successful Cold Chain Project.