In a move that could reduce pressure on precious donated blood resources, a major international study has found it is safest for older heart patients to have less rather than more blood transfused.

The study, involving 5200 older cardiac surgery patients in 19 countries including 560 in five New Zealand hospitals, was published today in the New England Journal of Medicine.

Auckland Hospital Intensive Care Specialist Dr Shay McGuinness, one of the study’s lead investigators, said the findings go against what was international accepted best practice for surgical teams operating on older patients having open heart surgery.

“Prior to this study it was accepted wisdom that older patients need to be transfused to a higher haemoglobin level because it was thought their body’s physiology and ability to cope with the stresses of surgery made them less able to tolerate lower levels than younger patients” says Dr McGuinness.

“The results from this new study, which follows patients six months after their surgery, clearly show that using less transfused blood during and after heart surgery actually lowers the patient’s subsequent risk of heart attack, stroke, kidney failure and death” he says.

The study supported the evidence-based ‘Why use two, when one will do?’ project

initiated by Auckland District Health Board in 2010  – and now used in a number of New Zealand hospitals – to promote the use of single unit transfusion of red blood cells (RBC) rather than the formerly routine two units (apart from critical or trauma patients).  The research indicates that the risk of adverse effects – like infections or reactions – increased with every unit of blood transfused.

Under the just-published international randomised study – the world’s largest ever transfusion trial in cardiac surgery – some of the moderate-to-high risk heart surgery patients were treated using a liberal blood transfusion strategy while others were given a less, more restrictive transfusion strategy. It found that for every 28 patients aged 75 years or older on the restricted blood transfusion strategy that one patient was prevented from experiencing a major complication up to six months post-surgery.

“Not giving a blood transfusion until an older patient’s haemoglobin measurement is as low as 65% of normal, while once considered risky, now appears to be just as safe if not safer than giving blood more liberally,” said study co-author Dr Paul Young from Wellington’s Medical Research Institute of New Zealand (MRINZ). “This means many who would have been transfused in the past will no longer require it at all, and patients who previously required several units of blood may now only require one”.

Researchers say the findings will change cardiac surgery clinical practice on blood transfusions around the world and also had the potential to reduce the use of the precious and expensive resource that was donated blood.

“If these research findings are adopted into every day practice then not only will they result in better health outcomes for older patients but also major savings for health systems in the use of less donated blood for transfusion” says Dr McGuinness. “This is important as cardiac surgery uses significant amounts of donated blood in theatre”.   New Zealand Blood Service statistics indicated that heart disease treatments use about 8 per cent of the country’s blood products annually.

NZ Blood Service spokesperson and Transfusion Medicine Specialist Dr Richard Charlewood agreed that a change in clinical practice for older people’s cardiac surgery may help the pressure on both donors and the blood service because as the population ages there would be more and more older people receiving heart surgery.

The Health Research Council-backed study is the very first completed by the New Zealand Improving Outcomes After Cardiac Surgery Network – a new programme within the Medical Research Institute of New Zealand (MRINZ) which brings together cardiac surgeons, anaesthetists, Intensive Care Specialists, nursing and support staff.

“The next step now is to develop robust guidelines to determine exactly when we should use transfusions for older people having cardiac surgery” says Dr McGuinness.


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