标题: 澳纽专科考题2005年A [打印本页] 作者: shenxiu2 时间: 2009-12-16 13:06 标题: 澳纽专科考题2005年A 2005A15: Discuss the advantages and disadvantages of intra-operative blood salvage
Definition:
A technique that is used to return washed or unwashed autologous blood to the
patient ·
Commonly in cardiac, vascular, orthopedic surgery, & liver transplants
·
Considered where significant blood loss is anticipated ·
Blood is collected by a suction technique which anticoagulates the blood
immediately with heparin or Na citrate or both, as it is retrieved. These red
cells then are washed and packed by centrifugation. The effluent that contains
heparin and cellular and tissue debris is removed as part of the washing and
centrifugation process, and the packed red cells then can be reinfused into the
patient either intraoperatively or postoperatively. ·
Washing and haemoconcentration creates a product with an average haematocrit
of 50% that carries normal erythrocyte survival, with minimal coagulation
factors or platelets. ·
The necessity of washing collected blood before autotransfusion has
been questioned in the literature.
Advantages ·
Intraoperative blood salvage can allow as much as 60 per cent of the
red blood cells that are lost during the operative procedure to be recovered for
subsequent autotransfusion.
· More cost effective as the amount of blood collected increases.
·
Cost effective: once initial machinery bought disposable kit has
similar cost to 1 unit of leucocyte depleted cells and can process limitless
units of packed cells ·
Especially useful in high-volume blood loss situations (AA repair,
major orthopedic, cardiac)
· Reduced the risk of allogeneic blood exposure by up to 40% and reduced the
mean transfusion requirement per patient ·
If the blood is not transfused intraoperatively, it can be stored for
up to 24 hours at 1°C to 6°C, and it should be handled like any other autologous
unit ·
In orthopaedics many studies show it is safe and efficacious: advantageous
in major orthopaedic surgery because most contaminants including
methylmethacrylate monomer, antibiotic from the irrigation fluid, free
hemoglobin, fat, and bacteria are removed from the suctioned fluid from the
operative site.
· There are no published adverse reactions to washed autologous red
cells in patients undergoing THR. ·
2,3 diphosphoglycerate is preserved, thereby enhanced the ability of red
blood cells to deliver O2 to tissues ·
May be beneficial for patients who are unwilling to accept allogeneic
transfusions for religious reasons, such as Jehovah's Witnesses ·
It is possible to process a unit of salvaged erythrocytes in less than
5 minutes when the patient is bleeding rapidly ·
When bleeding is slower, blood can be held in the collection reservoir until
there is enough to process ·
Can be of particular benefit to patients who are unable to donate before
surgery ·
Salvaged blood does not need to be tested for compatibility or disease
markers if it never leaves the OR. ·
There are different types of instruments available for IBS, ranging
from simple canister collection systems to table-top cell salvage instruments
and "high-speed" cell salvage instruments. Some of the instruments also can be
programmed to allow sequestration of platelet-rich plasma if desired ·
Cells are equal or superior to bank blood in red cell survival, pH, 2,3 DPG
levels, potassium levels ·
Eliminates risks of homologous blood (clerical errors and infection)
Disadvantages: ·
There is controversy surrounding the merits of washed versus unwashed
salvaged blood. It appears that unwashed blood can be transfused in small
amounts (2 L or less) with minimal adverse effects. Washing blood removes much
of the debris, anticoagulants, and free hemoglobin from the red cell product.
Red cell survival is comparable with that of allogeneic erythrocytes ·
To be effective, a minimum of 400 ml of drainage is required. ·
May only be cost effective when expected blood loss is 1000ml or
greater. ·
Significant loss of clotting factors and platelets from salvaged blood can
be anticipated.
· Particulate debris may be concentrated during processing warranting
microaggregate filters before or during reinfusion to the patient. ·
Cost-effectiveness of returning washed autologous blood to patients has been
questioned because the technique requires an expensive device and technical
expertise to operate it. Ideally, unwashed autologous blood should be filtered
and transfused within four hours after collection to avoid potential febrile
reactions. ·
Blood collected perioperatively cannot be transfused to other patients
·
Possibility of air embolism. However, many of the newer cell salvage
instruments contain an in-line "bubble detector," which will stop the pump once
air is detected in the reinfusion line. Another way to prevent air embolism is
to avoid direct connection between the reinfusion bag and the patient. air
embolism is almost unheard of with current devices ·
Haemolysis can occur if operative suction pressures are high (> 100mmHg)
or centrifugation rates excessive. ·
Coagulopathy ranging from mild to severe DIC is a complex multifactorial
problem that rarely occurs after autologous transfusion, especially if cell
washing is performed. Exposure to foreign surfaces, haemodilution of coagulation
factors, hypothermia, heparinisation, and other factors may be contributory.
·
Instruments need dedicated trained operators.
· Relative contraindications: obvious blood contamination (although this
reportedly has been successful in some desperate trauma cases), sickle cell
disease, and cancer surgery, based on concerns of dissemination ·
Pregnancy is a contraindication because of the concern that final post
transfused RBC may be contaminated with amniotic fluid elements that can cause
amniotic fluid embolism syndrome. Despite a lack of proven safety in obstetrics,
there are numerous anecdotal reports of its use in massive obstetric haemorrhage
during caesarean section, with no adverse sequelae.
· Can precipitate sickling in pts with sickle cell disease ·
Cost: centrifuge/cell washing device is costly.
Free haemoglobin can be nephrotoxic in pts with impaired renal fxn
(recommend suction < 150 torr) ·