Safe and innovative PVC blood bags
Blood is central to the great advances in healthcare that have happened in the last century. More than 110 million blood transfusions are performed each year for a range of medical procedures, whether it is to treat anemia, sickle cell diseases, severe bleeding, or in cancer treatments. Blood components are also key to many treatments, for instance bleeding disorders such as haemophilia which can be treated with plasma-derived medicines. In medical research, blood serve a range of useful purposes, for instance to study blood-borne diseases. All this could not be made possible without the many million donors around the world and the fine-meshed network of blood banks. Since the 1950s, blood systems have depended on the polyvinyl chloride plastic bag, which provide a remarkable storage time of up to 49 days. Now, the next generation PVC blood bags are imminent.
Robust and safe plastic bag
PVC is the material of choice for blood bags and has been so for over 60 years. In 1950, two American doctors invented a plastic bag for blood. Prior to that, fragile glass containers were used. The new robust plastic bag enabled a revolution in blood collection and preparation. Now, safe and easy preparation of multiple blood components from a single unit of whole blood was made possible. The plastic bag could simply withstand the high g-force it is exposed to when blood is separated into plasma, red blood cells and platelet concentrates in the refrigerated centrifuge.
The new plastic blood bag first showed its worth during the Korean War. As it could withstand being dropped from the air without shattering it helped save thousands of soldiers’ lives. Robustness continues to be a key advantage. In various parts of Africa, drones deliver blood much faster than would be possible with land transport. Instead of a 5-hour round-trip drive to a hospital, average time for a drone delivery is 30 minutes. See for yourself in the video below.
Strict material requirements
Attempts have been made to replace PVC with alternative materials. While PVCMed welcomes innovation, it must be done without compromising patient safety. The European Blood Alliance, which organises the European blood banks, only accepts blood bags that meet the strict requirements set by ISO 3826 and the European Pharmacopeia.
- Compatibility with existing sterilisation techniques
- Thermal stability
- Resistance to leakage
- Oxygen permeability for platelet survival
- Minimum 42 days of storage for red blood cells
Why is a storage period for up to 49 days necessary?
PVC blood bags allow a long shelf life for the blood. Under refrigeration, the blood can last for up to 49 days. While much blood is used within a few weeks, there are several reasons why a storage period of up to 49 days is crucial:
- The warehousing and distribution of the national blood supplies in Europe are based on up to 49 days shelf life. Patients’ safety depends on this stability of supply of blood components stored in blood bags, especially of Red Blood Cells (RBCs) that have to meet the criteria of a low hemolysis rate without visible hemolysis in the supernatant.
- A shorter storage period would have dramatic consequences in the national supply chain for RBCs. A reduced storage time could only be compensated by an increase amount of RBC´s including an extension of warehouse capacity and furthermore in increase of donations. To increase the number of donations will be very difficult as the motivation of the population to donate blood is typically low and is thus a challenge in many of the European countries already today. This would increase the risk of blood shortages, an increase in discarding outdate RBCs and pose a threat to patients. Last but not least, an increase in discards of voluntarily donationed blood is also an ethical problem for the public.
- Rare blood types are often in low stock. Thus, the shelf life of the blood must be as long as possible to have enough supply.
- Unforeseen events, big social events, seasonal volatilities such as holiday periods, distribution of blood groups, and compatibility of blood groups are some of the factors that can impact blood supplies. Typically holiday period do already today pose a supply risk, this would dramatically increase in case the storage period is reduced to only 28 days. A shorter shelf life would heighten the risk of shortages.
Next generation of blood bags
Currently, blood bags are made flexible with the plasticiser DEHP, which stabilises the red blood cells and thereby ensures the long storage time. However, the substance has come under scrutiny by authorities and regulators. The PVC medical device value chain is working hard to replace this substance with the new generation of plasticisers that have been developed in recent years and are included in the updated European Pharmacopeia.