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Bloodless Surgery

As the drive to avoid unnecessary exposure to donated blood and promote alternatives gathers momentum, transfusion scientist Barry Hill examines the background and latest developments in this area.

BLOOD has been famously described as "a precious gift" to the NHS, it was certainly no understatement by the Chief Medical Officer Professor Sir Liam Donaldson. As a resource, blood is vital both to allow elective surgery to proceed and to treat anaemia, but safety fears and escalating processing costs over recent years have dictated that it must always be used conservatively. Approximately 2.5 million blood donations are collected annually in the UK by the National Blood Service (NBS) and great efforts are expended to reduce the infection risks to every donation. In terms of safety fears to the blood supply, it is the emergence of vCJD has probably had the greatest single impact, as Dr Patricia Hewitt, current Chair UKBTS/NTSBC Standing Advisory Committee on Transfusion Transmitted Infection outlined when speaking in Manchester recently. "Donated blood has never been safer, a combination of careful donor selection and sophisticated screening testing have reduced the risk of transmissible agents such as HIV, HCV and HBV to the blood supply to miniscule proportions, the risk of HCV for instance being as low as 1 in 30 million donations."

Although bacterial contamination is still a significant risk, particularly in platelet components, it is the long term threat of vCJD that is causing the greatest challenge to the NBS. With no blood screening or diagnostic test available yet and the prevalence of vCJD in the population as of yet unknown, Dr Hewitt believes that vCJD poses a real risk of uncertain magnitude. "Improved vCJD surveillance, further donor exclusion and pathogen reduction techniques such as prion filters are possible answers but vCJD will inevitably cause increasing pressure to the blood supply over the coming years."

In a bid to both save blood, promote its appropriate usage and to reduce any unnecessary exposure towards it, several 'blood sparing' techniques and alternatives are now available to limit the amount of donated blood used during surgery. These 'bloodless surgery' techniques include options such as 'intra-operative cell salvage' (ICS), which recovers the patient blood that would have been otherwise lost during surgery, thereby dramatically reducing blood requirements. ICS is growing in popularity now that it is becoming financially more viable, and it is seen very much as a green technique since it re-cycles blood that would have previously been wasted. Cell salvage systems used in the operating theatre recover, filter and then re-infuse lost blood back to the patient in one continuous process. But not only is ICS enjoying a reputation as the optimum blood conservation system of choice in elective surgery, it is beginning to enjoy a growing use in trauma surgery and virtually any situation where there is a clean operative field present. ICS can therefore make a major contribution in saving patient lives in extreme situations involving major blood loss such as liver trauma, crush injuries and stabbings, providing a vital bridge to keep blood circulating in the patient until allogeneic blood itself becomes available. Latest figures show that around 170 NHS Trusts now perform ICS which is making a major contribution in saving valuable resources and improving patient outcomes.

Other blood sparing weapons may include the use of surgical adhesives or fibrin glues which are can reduce blood leakage from sutures. Even the simple re-positioning of the patient during the surgery itself has been shown to have a marked impact on reducing blood loss. Pharmacological interventions can also play a vital role in reducing blood requirements. Aprotinin for instance can be given during surgery to slow down bleeding, and erythropoietin can be prescribed pre-surgery to increase the body's own red cell production. Conversely, drugs which may encourage or prolong bleeding such, as aspirin should be discontinued. This approach is now being actively explored in the careful pre-operative assessment (POA) of the patient prior to elective surgery, where the optimisation of haemostatic function or even a simple course of iron therapy, for instance, to correct any anaemia discovered can have a major impact on the amount of blood required during subsequent surgery. One final alternative to donated blood is to transfuse artificial blood substitutes instead. Phase III clinical trials of synthetic haemoglobin solutions and perfluorocarbons are now in progress and some are proving useful temporary oxygen carriers during surgery. However the risk of hypertensive side effects and the relatively short half-lives of these recombinants may limit their overall effectiveness.

Another option that some GPs and surgeons may be asked about by patients being referred for elective surgery is the possibility of using their own blood instead. Autologous blood transfusion or ABT is the process of transfusing a patient's own blood back to them during a planned surgical procedure. Assuming clinical suitability, a patient undergoing certain types of elective surgery may pre-donate from 1 to 4 units of their own blood up to 3-4 weeks in advance of their operation. This blood is stored optimally and then can be transfused back to the patient during the operation itself, thus hopefully removing the need to provide any donated or allogeneic blood at all. Not only does ABT help to conserve existing blood stocks, there is no risk of exposure to transmissible viruses and also a greatly reduced chance of any procedural mix-ups occurring, as highlighted regularly by the findings of the Serious Hazards Of Transfusion (SHOT) Annual Reports. These reports have consistently shown that the biggest risk involved in the transfusion process is that of receiving an incorrect component due to human error. Any patient undergoing an elective surgical procedure such as hip or knee replacements that have a high probability of needing blood, providing they are fit enough to pre-donate should be offered the option of ABT. With over 100,000 of these operations carried out each year it is estimated that ABT could save the NHS around 200,000 units of blood annually.

For one particular group of patients avoiding blood transfusions is not a new concept, in fact they have been practising this for many decades on religious grounds alone. According to Ken Bate, a Jehovah's Witness Hospital Liaison Committee member for the Manchester regions, Jehovah's Witnesses are now amongst the most medically well informed of all patient groups in terms of blood safety issues. "There are over 129,000 Jehovah's Witnesses in Britain, and although we are not opposed to surgery or medicine and decline allogeneic blood transfusions, we do request alternative non-blood medical and surgical management instead. Many Witnesses will accept procedures such as ICS, post-operative blood collection for example from wound drains, plus certain pharmacological approaches including haemostatic agents and recombinant coagulation factors. All these are a matter of patient choice, but ABT however is not acceptable to us. In an effort to broaden potential treatment options for Jehovah's Witness patients it is important for the clinical team to discuss with each individual whether or not these procedures and products are acceptable to them. As a result of the latest techniques available, there have now been a number of successful examples of complex surgery involving Jehovah's Witness patients that has taken place without the need for blood transfusion such as revision and replacement hip and knee surgery, and even major cardiac surgery." Ken is aware of the changing relationship between the medical profession and Jehovah's Witnesses and believes this has lead to a better understanding of the issues involved regarding blood transfusion. "We have in recent years for instance joined in helpful discussions with the NBS and we have also enjoyed a very helpful relationship with the British Blood Transfusion Society. On a local level our Hospital Liaison Committee has been welcomed as a helpful, free resource for Hospital Transfusion Committees and Specialist Practitioners of Transfusion. Additionally some local Jehovah's Witnesses groups have also donated funds to purchase hospital equipment such as cell salvage machines and other blood conservation equipment out of appreciation for the excellent clinical care that we receive and for the skill and dedication of the clinical teams that have cared for our patients."

Ensuring we continue to have a safe, long-term supply of blood in the wake of problems such as vCJD is the huge challenge now facing the NBS. Because of this, biomedical scientists, nursing staff, clinicians and surgeons can all play a pivotal role in ensuring that the limited blood stocks are used both conservatively and wisely. In surgical cases doctors should follow the maximum surgical blood order schedule (MSBOS) if one is in use at their Trust, which is a pre-agreed system that specifies set amounts of blood for each procedure. If the hospital blood bank also is using electronic crossmatching, then they should be aware that blood can be provided very quickly and in many cases they may no longer need to be reserved in advance at all, a pre-operative blood group and antibody screen only being sufficient. Wherever appropriate, transfusion alternatives such as ICS, ABT and other blood sparing techniques should be implemented to reduce allogeneic blood usage. A lower post-operative haemoglobin level should also be considered, as should the use of the transfusion trigger during unavoidable bleeding episodes. For medical cases especially anaemia, blood should only be prescribed if appropriate, the underlying cause should always be investigated and treatment using iron or folate considered as an alternative. Finally from a safety perspective, the risk verses benefit to the patient from a possible transfusion of blood components must always be carefully considered and then only prescribed if absolutely essential.