Autologous transfusion means collection and reinfusion of the patient’s own red blood cells. This is in contrast to allogenic blood transfusion where blood from unrelated/anonymous donors is transfused to the recipient.
Need for Autologous Blood Transfusion
Transfusion is important part of modern medical practice. However, the safety of the procedure is a great concern. Allogeneic transfusion always carries a risk of transfusion reaction and transmission of infection associated with allogenic blood transfusion. Moreover, in rare types of blood groups the donor blood may not always be available for the patient.
Autologous transfusion reduces the need for allogenic transfusion. Repeated studies have shown autologous transfusion to be more cost-effective than allogeneic transfusion and that clinical outcomes are improved.
Types of Autologous Blood Transfusion
The three main techniques are
- Predeposit transfusion
- Intraoperative haemodilution
- Intraoperative and postoperative salvage
Predeposit Autologous Blood Transfusion
For predeposit autologous transfusion, blood collection begins three to five weeks before elective surgery, and last donation should take place at least 48-72 hours before surgery [to allow for re-equilibration of the blood volume].
On each occasion, about half a litre of the patient’s own blood is taken and put into sterile plastic bags along with citrated glucose anticoagulant solution. The blood is stored until the time of surgery.
Patients may be given iron supplements, sometimes with erythropoietin, to prevent anaemia or allow more donations to be collected.
The donations must be processed and tested in the same way as allogenic donor blood.
Indications for Predeposit autologous transfusion are
- Rare blood groups
- Patients with or multiple blood group antibodies where compatible allogeneic blood is difficult to obtain.
- Patients disproportionate anxiety about exposure to donor blood.
As blood collection before preoperative autologous transfusion begins several weeks before surgery, and phlebotomy may be carried out several times
Before collection, the patient’s ability to donate safely must be assessed.
Predeposit autologous transfusion virtually eliminates the risks of viral transmission and immunologically mediated haemolytic, febrile, or allergic reactions.
But predeposit autologous donation is practical only for elective surgery.
Intraoperative Acute Normovolemic Hemodilution
Acute normovolaemic hemodilution hemodilution) is a type of autologous donation that is performed preoperatively in the operating theatre or anaesthetic area. It is usually restricted to patients in whom substantial blood loss is predicted (>1 litre or 20% of blood volume).
The procedure involves removal of patient’s blood preoperatively and diluting the remaining blood in circulation by crystalloids and /or colloids.
Because the blood is now diluted, it means lesser number of RBCs lost per ml of the blood loss during surgery. The anticoagulated blood is then reinfused in the operating theatre during or shortly after surgical blood loss has stopped.
For hemodilution, whole blood (1.0-1.5 litres) is removed, and simultaneously intravascular volume is replaced with crystalloid or colloid, or both, to maintain blood volumeReduced red cell mass lost during surgical bleeding.
As blood is stored at room temperature for a short time, deterioration of clotting factors and cells is minimal. Additional advantages include a lower cost than for predeposit transfusion.
Hemodilution has a disadvantage that circulating red cell mass is lowered appreciably and acutely. Many patients may not tolerate that well. Patient’s ability to tolerate a low volume of red blood cells is a limiting factor. Patients with severe anemia are usually poor candidates.
Hemodilution may be used before any type of surgical procedure. Elective operations with typical blood losses of 1-2 litres are particularly suitable for haemodilution. Examples are
- Cardiac valve replacement
- Revision of hip arthroplasty
- Spinal reconstruction
The principle behind this technique is to salvage the lost blood during surgery and can be performed intra-operative cell salvage (ICS), postoperative cell salvage (PoCS), or by both ways. The process involves a collection of shed blood from the surgical field.
The salvaged blood is then either filtered or washed and processed prior to retransfusion back to the patient in the immediate postoperative period. The blood generated is labelled and kept with the patient at
all times and is not refrigerated.
Devices are available for cell collection broadly fit into three categories:
- Surgical suction into reservoir canisters. It is then processed in batches producing units of packed red blood cells for reinfusion.
- A semi-continuous system – Blood is simultaneously scavenged, anticoagulated and washed ready for reinfusion.
- Simple single use reservoir bags, which are attached to surgical drains to collect blood lost after the operation.
Indications for intra-operative cell salvage in adults and children
- Anticipated blood loss is >20% of the patient’s estimated blood volume.
- Elective or emergency surgery in patients with risk factors for bleeding
- High-risk Caesarean section
- Low preoperative Hb concentration.
- Major hemorrhage.
- Patients with rare blood groups
- Patients with multiple blood group antibodies
- Some patients who do not accept donor blood transfusions but do accept, and consent to, intraoperative cell salvage.
Many litres of blood can be salvaged intraoperatively during extensive bleeding, far more than with other autologous techniques.
Salvaged blood is not haemostatically intact as coagulation in the wound leads to consumption of coagulation factors and platelets.
Complications of extensive intraoperative salvage include
- Disturbances to pH and electrolytes
- Systemic dissemination
- Infectious agents
- Malignant cells
- Air or fluid embolism
- Dilutional coagulopathy.
- Salvaged blood syndrome
- Multiorgan failure and consumption coagulopathy
Intraoperative salvage is used extensively in cardiac surgery, trauma surgery, and liver transplantation.
Bacterial infection or malignant cells in the operative field are contraindication of the procedure.
Cell salvage is a costly procedure.
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