Cell salvage

a common intervention to avoid

permissive anaemia,
hazards of allogenic blood transfusions
blood storage lesions

The process involves harvesting blood from the intra-operative site and from wound swabs via a specialized suction device
This device has two lumens:

one removes blood from the surgical site
one adds a pre-determined volume of anticoagulant at the point of blood collection
- & avoids adding it to the surgical field.

Heparin or citrate can be used as anticoagulant and, once added, the mixture is filtered to remove large debris (e.g. bone and clots) and collected in a reservoir

Red blood cells (RBCs) are separated from the substrate by various techniques, the most common being centrifugation, leaving RBCs with a high haematocrit.
The red cells are then washed with, and stored in, a suspension of 0.9% saline. The product is then re-infused into the patient within 6 h of collection

The reinfusion bag contains only RBCs as all other blood products are removed during processing. This means in large volume blood loss transfusions of clotting factors, cryoprecipitate and platelets will also be required

A standard 200-µm blood administration filter is sufficient in most clinical scenarios

Leukocyte depletion filters (LDFs) have a charged surface, attracting negatively charged leukocytes and are used in cancer surgery to reduce the presence of tumour cells. One must be aware of the much-reduced flow rate of these filters as well as the maximum volume that can be used before the charge is eliminated
There has also been a UK Medicines and Healthcare products Regulatory Agency (MHRA) safety alert reporting several episodes of hypotension with use of LDFs

Lipid reduction filters can be used to reduce the reinfusion of lipid material, which may be of particular concern in orthopaedic and spinal surgery

Indication

Surgery where blood loss is expected to be 500 ml or 10% of circulating volume
Major haemorrhage
Patients who will not accept allogenic blood
- (careful consent must be taken in this circumstance)
Blood cross-matching difficulties where donor blood may not be readily available

Absolute C/I

Patient refusal
Aspiration of toxic materials,
- e.g. non-set cement, topical antibiotics, iodine.
Aspiration from matallosis contaminated tissue

Aspiration of frank pus or faecal material may result in high concentrations of viable bacteria and should be avoided

ICS produce consistently contains skin bacteria; however, the incidence of sepsis or wound infection is not increased. The use of prophylactic antibiotics may have a protective effect on infection rates

ICS in malignancy surgery may offer benefit by reducing the need for allogenic transfusion, hence reducing transfusion related immunomodulation (TRIM)

Sickle cell disease (SCD): the washing of red cells has the potential to cause sickling or lysis of salvaged cells in SCD and trait.
There are no trials in this setting, but a number of case reports have reported successful use. However, in others, testing of product revealed significant sickling and the blood was rejected prior to administration.
Exchange transfusion in SCD is used to reduce the risk of crisis, hence in this situation, allogenic transfusion may have specific benefits.

β-Thalassaemia trait: increased red cell fragility is associated with extracorporeal haemolysis; this has led to cautions in its use, though ICS has been used without complications.

Obstetrics: UK guidelines1 recommend consideration of ICS in women who are anaemic or in unanticipated bleeding during surgery but not for routine use in elective caesarean section.
There remains concern regarding the theoretical risk of contamination with neonatal red cells and amniotic fluid. As such RhD negative mothers should have an estimation of fetal maternal haemorrhage performed. Amniotic fluid embolus remains a theoretical risk which is difficult to diagnose.
LDFs are almost always used and are effective in reducing neonatal squame load which may reduce the risk.

Jehovah witness
Haemodilution and intra-operative cell salvage may be acceptable when the circuit is in continuity with the patient's own body and in a continuous flow system. This may be achieved by priming the circuit with saline, commencing a slow infusion to ensure cannula patency and attaching a three-way tap between salvaged product and the patient's cannula. The three-way tap will allow the introduction of a new LDF filter, once its maximum volume has been reached, without breaking the circuit.

References

Strategies to Avoid Intra-Operative Blood Transfusion - A&ICM