Blood waste and conservation

 

An issue that has always concerned blood banks has been that of blood waste. The economic implications of this problem are obvious, since the greater the amount of waste, the less blood there is available for transfusion, and the greater must be the ensuing effort spent in trying to make up for the blood shortages that are likely to occur. Now, while there are still unresolved issues on this topic, as there is still no absolute agreement as to what constitutes the medically justifiable use of blood and what constitutes waste, we can state that the different conceivable forms of blood waste can be classified into four broad categories. 

 

The first category is “technical waste” [1], which occurs when blood products are haemolysed, or contaminated by destructive foreign agents such as bacteria. Due to safety concerns, these products are not considered fit for any clinical use and therefore end up being destroyed. Usually, this form of waste applies to only a few units of blood at a time, but there have been incidents where hundreds of units of blood, representing a significant share of available inventories, were disposed of when identical defects in batches of product were noticed at the same time. Despite this, the improved clinical safety procedures and quality control standards that are constantly implemented mean that this form of waste, expressed as a fraction of total blood waste, is likely to become ever less important over time.

 

The second form of waste that must be considered is known as “administrative waste” [2], since it arises mainly as a result of inadequate institutional policies relating to the ordering and handling of blood products. Substandard ordering policies are caused by inadequate planning and administration by medical personnel, who may use faulty estimates and thus over-order blood supplies, request supplies of the wrong blood group, or fail to account for a range of other factors that result in medical institutions first hoarding and subsequently disposing of blood products that cannot safely be reissued. Handling failures arise either in the laboratory or, later on, in an operating theatre or hospital ward, when blood products can, amongst other things, be mislaid, accidentally mislabelled, or incorrectly transfused into a patient. One example (of many) that demonstrates poor handling concerns the manner in which blood is stored, with guidelines stating that if a unit of blood is taken out of a refrigerator for a set period of time (about 30 minutes), but is not utilized, then it cannot be taken back by the blood bank. Instead, it must automatically be discarded due to the possibility that it may have deteriorated in quality or suffered from contamination. According to one American blood bank, over 18,000 units of blood are discarded annually because of this problem alone, even though it is believed that patient safety is not likely to be compromised if unused blood that has thawed for up to 2 hours outside of a fridge is stored immediately for later use [3].

 

The third, most contentious, type of blood waste is attributable to a procedure that Titmuss called “defensive medical practise” [4]. This occurs when medical practitioners are said to transfuse more than the necessary volume of blood products into their patients. Whether this should actually be classified as a form of waste is debatable, since there may be considerable differences in opinion as to what the appropriate level of blood use for any given medical activity should be. While guidelines based on objective data such as actual blood loss may provide approximate values of how much blood should be used, the ultimate decision lies in the hands of the medical practitioner, who has the responsibility of safeguarding the patient’s well being. As such, so long as “excessive” transfusion does not do the patient harm, and is not too far from the normal range of provision, then this practise cannot really be considered an exercise in blood waste. If anything, this issue may actually be overrated, for as many doctors are aware of the scarcity of blood, they may tend to resort to transfusion only when there is a real need for it, with blood being transfused only if the volume in a patient falls below a pre-determined “threshold” level. As they become more adept and confident at working on patients, doctors are likely to transfuse blood at ever-lower threshold levels, thereby resulting in lower, not greater levels of such blood “waste”.

 

Finally, we have waste that arises when blood reaches its expiry date and is no longer suitable for consumption in its present state, even though parts of it, such as the red cells and plasma, may be salvaged for reuse in other products. While such processing ensures that part of the expired blood is still put to good use, it is not an entirely perfect approach, as blood components with short life spans whose use could have been most beneficial immediately after collection will have perished. Of the different forms of waste that exist, this is arguably the most prevalent one, with estimates indicating that for the USA at least, up to 10% of all blood reaches its expiry date before it can be used in its original form [5].

 

Due to the difficulties in accurately defining the meaning of waste, the statistics that measure this phenomenon are often vague and contradictory. As such, all data presented on this topic must be viewed with caution. During the 1960s, Titmuss argued that the total amount of blood waste, in all forms, ran from a low of about 1-2% in the UK [6], to a much greater figure of 15-30% in the USA [7]. For the 1990s, a more accurate assessment would suggest that the real proportion of blood waste lies somewhere between these two figures, with about 10-15% of all collected blood being wasted in most systems. This estimate arises from noting that for every 1,000 people in the UK who presented themselves at a collection centre for the purpose of making a donation, only the blood obtained from about 800 donors would actually be transfused [8]. Of the remaining 200 donors, about 100 would be unable to donate due to medical restrictions, while the other half would give blood, but this would be lost going down the collection, processing and distribution chain due to a variety of reasons (including a small portion dedicated to research and development purposes). Effectively then, 1 in every 9 units, or approximately 11% of all blood collected in the UK is “wasted” by blood banks before transfusion takes place, without even taking into consideration factors such as defensive practices, which arise after blood has left the custody of the blood banks.

 

To overcome this waste, a range of proposals have been put forward to counter this problem, with one of the most popular approaches being the implementation of blood management programmes that attempt to use accounting techniques to ensure that all blood use is strictly monitored. While some of these programmes have been tested on a trial basis, with some success, they have a major fault in that they are often undertaken in strictly controlled settings, where the behaviour of all participants is aimed at limiting waste [9]. While they may therefore be able to provide dazzling results in the short run, in the longer term they may not be able to give such sustainable figures, largely due to the fact that habitual slackness occurs due to a loss of discipline amongst staff in working according to operating protocols. Nevertheless, while it may be a long time before any failsafe methods of controlling blood waste are introduced, a variety of innovative approaches have been adopted to ensure that where possible, new ways of collecting and using blood with greater care are implemented, with two very different approaches being highlighted below.

 

i) Autologous blood transfusion

When we speak of blood transfusion, what we are usually referring to is the technique of allogeneic transfusion, where blood donated by one person is transfused into another. There is, however, an alternative option available known as autologous transfusion, which involves the transfusion into recipients of the blood that they themselves have donated at an earlier date. While such a technique may have a limited field of applications, as it is centred mainly on elective surgery that can be scheduled in advance, it is nonetheless worth examining in greater detail due to the substantial blood savings that it offers. This is borne out by the fact that while this procedure has only recently been introduced to South Africa, in the USA, where it is widely respected and practised, over 600,000 units of such blood were collected in 1999 alone [10]. As such, autologous blood is a partial substitute for allogeneic blood, for while it has only an indirect impact on the total quantity of blood donated, it has a very direct impact on how such normally collected blood can be used by freeing these supplies up for use on other recipients.

 

While patients may have a variety of reasons for choosing autologous transfusion over allogeneic transfusion, it appears that a desire to be altruistic by helping blood banks ease their supply problems is not foremost among them. In a unique study which asked autologous donors why they had chosen to follow this course of action, about two-thirds of respondents said they were acting on the recommendations of their physicians [11]. Thereafter, about one-fifth said they donated because they feared infection by a disease transmitted via allogeneic blood, with the remaining donors citing various personal reasons for doing so [12]. In no way were any of these donors acting in the interest of others – rather, they were acting according to their own self-interest, as is clearly demonstrated by the fact that their “donations” were made solely for their own use, not for the benefit of others [13].

 

There are numerous benefits from engaging in autologous transfusion. First, while patients who belong to a rare blood group might acquire blood of their particular type in advance of a scheduled operation, this is not guaranteed, since there may not be sufficient time to gather it from the relevant donor, screen it, and then transport it to the appropriate medical facility. To forestall such a problem, the most viable course of action is often for the patient to pre-donate blood beforehand. Second, people with certain medical conditions, such as those who are HIV positive or of an advanced age, may find autologous transfusion to be useful if receiving blood from another person could affect the stability of their fragile immune systems. As they are using their own blood, the possibility of suffering from adverse medical reactions is greatly diminished. Finally, the most important advantage is that the risk of being exposed to a disease that may be present in the blood of another person is completely avoided. This applies not only to known diseases such as HIV, but also to any unidentified infectious agents with long incubation periods that may be present among the general population, but whose transmission via blood has not been confirmed and for which no effective screening test is yet in place. While this scenario may, at first sight, appear to be far fetched, it was precisely what occurred when HIV first appeared, where nobody knew that it was present in or transmittable via blood. It may be a scenario that could, unfortunately, be repeated again in the future with diseases such as CJD, where it has taken a number of years for scientists to even begin understanding the features of this disease. Thus, autologous transfusion is desirable for those who have doubts about the current safety of the blood transfusion system, or who do not wish to be too complacent about the transmission of any as yet unrecognised viruses.

 

Regardless of such attractions, several weaknesses mitigate against the widespread utilization of autologous blood. Firstly, while screening and cross matching tests do not need to be carried out on such blood (as it is returned to the same person who donated it), there exists a need for special safety procedures to ensure that such blood is not misplaced or mishandled. As a result, the economies of scale that exist from handling large volumes of allogeneic blood are nullified, so that on a unit cost basis, autologous blood is substantially more expensive than allogeneic blood. Whether such a price premium is worthwhile to either society or the individual patient is a value judgment open to debate, but if it is the patient or a private insurer that pays for this procedure, then no real objections can be raised against it. Secondly, since it has only a limited lifespan, the quantity of blood that a patient can safely pre-donate without endangering his health is limited to a maximum of 3 units of whole blood [14]. Should more blood be required if something goes wrong during the operation, then the operating surgeon may have no option but to resort to the use of allogeneic blood – in such an event, the entire rationale behind the use of autologous blood, namely the avoidance of allogeneic blood, will have been defeated. Finally, even if the donor does not require his own blood, it may be of no use to other people, as the standard operating procedure for dealing with unused blood of this type involves destroying it immediately after the scheduled operation has taken place, when no further need for it is deemed to exist. While this course of action may appear to represent a waste of precious blood resources that could be used on other people, it is usually a prudent move, since not only does such blood have to still undergo the process of being tested, but as it is provided by sick people who require surgery, it is often of negligible value to other sick people [15].

 

ii) Blood recycling

A related technique that has been developed in order to ensure that the blood of a patient is available for reuse involves the salvaging of blood during the performance of a surgical procedure or in the post-operative recovery period. With this technique, blood lost from surgical wounds, which is usually destroyed, is instead drained into a reservoir, where it may then be directly re-infused back into the patient during surgery, or recycled for later use in the recovery period.

 

There are two main techniques of collecting and reusing blood in this manner. The first, simpler method, involves the use of a relatively basic machine that collects discarded blood and then intravenously pumps it directly back into the patient. While this machine is both cheap and easy to use, the flaw with the process is that the salvaged product is unwashed, which means that the blood that is collected may be mixed with materials that could contaminate the blood stream, such as bowel contents, fat particles, malignant cells and other undesirable fluids. The second, more advanced technique is that of automated cell salvage, where discarded blood undergoes a filtration process before being placed in a centrifuge that extracts mainly the red cells, which are then sterilized and returned to the patient. While this more hygienic process does ensure that the patient is replenished with the oxygen carrying red cells that are most needed in an operation, it does suffer from the major disadvantage of functioning properly only when large volumes of blood are reprocessed, plus the machines are expensive to own and operate.

 

Finally, a passing mention should be made of scientific investigations that were carried out in the mid-twentieth century to determine the feasibility of acquiring blood from cadavers. With this process, most of the blood in a recently deceased human could be drained from the body before coagulation took place, whereupon it could then be used to produce blood products. While the technique was only considered as a theoretical exercise in the USA, it was actually performed several times in various parts of the then USSR, although the practise was discontinued due to what were then deemed to be insurmountable technical difficulties [16]. Given the many technical advances that have been made in recent years, it would not be implausible to assume that this technique may be revived sometime in the future (especially if performed in conjunction with the removal of organs for transplantation).

 

Despite the improvements that have taken place in recent years to ensure that blood is not wasted, we persist with the basic fact that the blood supply system remains entirely dependent on the willingness and ability of the individual human to come forward and donate. With this fundamental defect in mind, we move on to look at how scientists have started work on developing a range of innovative substitutes for blood that may, one day in the future, help us to minimize or overcome the current problems that so bedevil blood services around the world. 

 

Link to:  <Contents>  <Previous Section>  <Following Section>