Washing machine for blood that turns you into your own donor

SINCE the early 20th century, using one person’s blood to replace another’s lost blood has been a routine part of surgical life.

But donated blood is a precious resource. With 400 new donors a day needed to meet demand in the UK, shortages can occur, and it can be a race against time to find donations for those with rare blood types.

At around £150 a unit (just less than a pint), donated blood is also relatively expensive and transfusions are not without risk. Although all donated blood is tested for viruses including HiV and hepatitis c, there is still a very low risk of infection. Potentially fatal reactions to donated blood can also occur.

So it is perhaps no surprise that hospitals are being urged to consider an alternative: turning patients into their own donors. in a process known as cell salvage, blood lost by a patient during surgery is washed, cleaned and put back into their body while they are still on the operating table.

This cuts the risk of infections and reactions and conserves valuable blood stocks. it also speeds up recovery time — the months of adjustment required after a transplant from another source are not necessary here, since it is a patient’s own blood.

Blood washing has been available for the past 20 years, but the initial outlay on equipment and a lack of staff trained in the technique have stopped it being used as widely as it might.

now, anaesthetists say this must change. Guidance published last year by the Association of Anaesthetists said that all nHS hospitals performing major surgery should use cell salvage for operations likely to cause significant blood loss.

The guidelines, detailed in the journal Anaesthesia, state that cell salvage is a ‘relatively simple and effective blood conservation technique’ and should be ‘integral to surgical practice’.

Dr Andrew Klein, a consultant anaesthetist from the Royal Papworth Hospital in cambridge, chaired the group that devised the new guidance after examining recent trials of the technology.

He explains the process: ‘Blood is sucked from a wound, put into a canister, then mixed with heparin to stop clotting. Once a pint or so is collected, the blood is quickly spun in a centrifuge, so that only the red cells are collected, and the rest — plasma and debris such as fat and bone — is washed away with saline. The red cells are kept in a bag, ready to be infused back into the patient via their drip.’

WHETHER a normal transfusion or one via cell salvage, only red cells — which ferry vital oxygen around the body — are ever transfused into a patient.

‘if you lose too much blood, and therefore too many red cells, during surgery, you could end up not having enough to carry oxygen around,’ says Dr Klein. ‘it could

lead to anaemia and even death if there is not enough oxygen to reach vital organs.

‘Problems can arise if you have to wash a lot of blood. You have around ten pints of blood in your body and, if you lose more than half into a cell salvage machine, for example, then you are losing a lot of plasma.

‘We test the blood throughout the operation to make sure it’s OK and to find out whether we need to infuse more plasma or platelets from the blood bank.’

Plasma carries salts and enzymes and transports nutrients, proteins and hormones to the parts of the body that need them. it is also vital for blood clotting. not all operations lead to enough blood loss for the cell salvage machine to be of use. But cell salvage should be routinely used in hip replacements and revisions, caesareans, spinal surgery, cardiac procedures and other operations where the loss of more than a pint of blood is expected, says the Association of Anaesthetists.

While some 90 per cent of trusts are thought to have blood-washing equipment, not all have trained staff to use it, often due to training costs and staff shortages.

However, with a unit from a blood bank costing up to £150, plus administration and delivery fees, donated blood is expensive.

Blood washing can be cheaper in the long term, but the £20,000 initial outlay for the salvage machine has put some off, while the £100 charge per patient for the disposable equipment used in the procedure has left others reluctant to use the technology — even if they have the machine.

James cook University Hospital in Middlesbrough has embraced cell salvage. its seven machines are used every weekday and on many weekends in its 27 theatres.

‘We use cell salvage machines 20 to 25 times per week — and sometimes more,’ says chris elliott, a transfusion scientist at South Tees Hospitals NHS Foundation Trust. ‘As a proportion of transfusions, cell salvage blood represents just 2 to 3 per cent.

‘The majority of surgical cases do not bleed sufficiently in theatre to allow blood to be salvaged.’

Despite cell salvage being used in a relatively low proportion of cases, the savings are huge.

Over the past decade, it has saved James cook University Hospital more than £3 million — a healthy return for what could be seen as just a wash and spin.