Step 1: Suction

As the surgeon makes the incision, blood oozes from the dissected tissues and begins to pool. The blood is sucked away via a dual lumen tube, which mixes the blood immediately with an anticoagulant. Both are then sucked into a reservoir connected to a vacuum pump. The anticoagulant is either heparin or citrate.

Step 2: Collection and filtration

The blood and anticoagulant collect in the reservoir, and filtered to remove large clots and debris.

Step 3: Preparation

Blood and anticoagulant are drawn from the reservoir into a centrifuge to be processed.

Step 4: Separation

A sterile isotonic saline solution is pumped into the centrifuge bowl. The force supplied by the centrifuge holds the more dense red blood cells against the outer wall of the bowl. The less dense white blood cells, platelets, plasma, clotting factors and anticoagulant, move toward the centre of the bowl, where they spill over into a waste bag.

Step 5: Waste disposal

Waste products, including white blood cells, platelets, plasma, anticoagulant, fat, clotting factors, and free plasma haemoglobin, are collected in a bag and are disposed of in harmony with procedures for clinical waste.

Step 6: Red cell salvage

Packed red blood cells are separated from waste products, and collected in a separate bag. The quality of the collected red cells depends upon the volume of wash solution used, the degree of concentration achieved, the quality of the blood prior to washing, the type of surgery, and the presence of various substances which remain in the red cell pack.

Step 7: Re-infusion

Red blood cells can then be sent to a transfusion bag. If a patient requests that the circuit be continuous, the blood can be re-infused immediately. Otherwise, it can be taken to the recovery area to be re-infused later. There is, however, a limit of 6 hours during which re-infusion can take place.

Note:

During an operation, blood which is lost on swabs and sponges can be collected and given back to the patient. These swabs and sponges are carefully weighed to calculate the amount of blood contained in them, before placing into a bowl of anticoagulant. The blood from the bowl is then taken to the reservoir and processed in the same way as blood collected from the surgical field. (Step 3). This ensures that all available blood is salvaged. Considerable volumes of blood can be collected on swabs and sponges.