الفهرس 
Complications of Blood TranfusionOnly 14 pages are availabe for public view
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Abstract
.’-\l1csthesio!ogists are frequently met with many patients tl t are in need
for blood transfusion during their anesthetic practice. The prim y reason for
blood transfusion is to maintain the oxygen carrying capacity of blood. A
hematocrit less than 30 percent (or hemoglobin less than lOgic ) indicated a
need for blood transfusion. However the fear in recent years, ’transfusion
induced diseases especially acquired immune deficiency syndrom (AIDS) has
caused a reexamination of this indication. Messmer suggests hat oxygen
transport can be sustained with a hematocrit as low as 20 percent.
Blood transfusion, though life savmg, always carries the iotential for
producing complications e.g. transmission of infectious diseases SI .h as AIDS,
viral hepatitis and non infectious risks of blood transfusion includii \ hemolytic
reactions which may lead to acute renal failure and death and ru Ihemolytic
reactions as allergic reactions.
Because of the above mentioned complications, there are IT ny ways to
avoid homologous blood transfusion, that are:
TOLERA TING A LOWER HEMATOCRIT:
Although 02 carrying capacity decreases linearly with hema icrit (Hct),
physiologically 02 transport may be optimal at a Hct in the low 30: because of
the decreased blood viscosity and the increased cardiac output.
Normovolemic anemia IS well tolerated when there is adeqi ue cardiac
reserve to compensate by increasing the blood flow. The primary co .pensation
involves increased stroke volume down to a Hct of 20% and incr ased heart
rate at lower Hcts. If cardiac reserve is limited anemia would be less ilerated,
MI~IMIZI’iG BLOOD LOSS:
Although the surgical blood loss is not under the primary ontrol of the
anesthesiologist there are methods that may be used to reduce rtraoperative
blood loss: Induced hypotension and treatment with drut; that effect
coagulation.
Induced hvpotension:
The benefits of induced hypctension for rrururmzmg bl xl loss have
been demonstrated most dramatically In major orthopedic rrgery. The
majority of studies have demonstrated at least a 50% decrease I blood loss.
The target mean arterial pressure is between 50-65mmHg measur j relative to
the surgical site. This pressure is the lower limit of cerebral autorej dation.
A variety of methods are utilized to induce hypotensic , including
infusion of sodium nitroprusside, nitroglycerin, trimethaphan, adet ’sine, a and
13blockade, calcium channel blockade, inhalational anesthetic, ents, spinal
and epidural anesthesia, or combination of these methods.
Although induced hypotension may be appropriate
undergoing procedures with anticipated blood loss, the techi
recommended for patients with cerebral or coronary artery
relatively contraindicated in anemic patients.
ir patients
que is not
sease, and
Drug therapy:
Fibrinolytic system acts in balance with the coagulation sys .m through
a series of activators and inhibitors. The key substance in the lbrinolytic
system is plasminogen which when activated releases plasmin w ch cleaves
the fibrin producing fibrinolysis. There are substances which inhibit the
fibrinolytic system. Synthetic substances are the epsilon-amino- iproic acid
and transexamic acid. A naturally occurring substance is the aprotin I.
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Epsilon-amino caproic acid (EACA) and Tranexamic cid bind to
plasminogen and exert their inhibitory effect These drug: have been
demonstrated to reduce blood loss. Aprotinin, acts similarly anc in addition,
have a platelet protective effect.
Desmopressin acetate (DDA VP) IS a synthetic anak ~ue of the
antidiuretic hormone and has been demonstrated to increase the v nwillebrand
factor (y\\T) and increase factor VIII activity, and have some ion-specific
enhancement of platelet function. It has been reported to decrease I ood loss.
Human recombinant erythropoietin (rhuEPO), which is identical to
human erythropoietin produced in the kidneys 111 respons: to anemia,
stimulates the bone maITOWto produce red cells.
AUTOLOGOUS TRANSFUSION:
There are three ways of acquiring autologous blood for tram USlOn:
Preoperative donation and storage:
In this method the blood is collected from the patient preo .ratively, in
collection bags which are clearly labeled with the patient’s name uid hospital
number and stored until they are used at the time of the operation. ’his method
has the advantage of avoiding transmission of diseases ane transfusion
reactions. It also stimulates endogenous erythropoietin producti n and it is
useful in patients having rare blood typing. As it requires appn cimately 72
hours to normalize plasma proteins, so the last donation should be nnpleted at
least 3 days prior to surgery. Also, the period between each tw successive
donation should not be less than 3 days. All, the patients should ecerve Iron
supplements 325mg t.i.d, High risk patient are not necessarily unab ~to donate.
It is currently not recommended to transfuse even an ; itologously
donated unit of blood to a patient if he does not require the transfi ion. This is
becaue the most likely cause of a lethal hemolytic transfusion react )J1 is due to
clerical errors and this may occur with autologous as well as omologous
blood.
Acute preoperative phlebotomy and isovolemic hemodilution:
When a patient with a hematocrit (Hct) of 45% loses one ler of blood,
he in essence loses 450 cc of RBCs. If the Hct were 25%, he we lid have lost
250cc of red cells if he lost a liter of blood. This method is ace nplished by
removal of blood and simultaneous resuscitation with crystallc I or colloid.
The purpose is to lower the Hct but not the vascular volume pri r to surgical
blood loss and then have the ability to transfuse several units 0 the patient’s
fresh whole blood. It is easy and inexpensive but has the obvious mitations of
providing limited number of units with decreasing Hct in each.
It is contraindicated in previously anemic patients, vascular liseases and
patients with coagulopathy because the clotting factors are dilu ed. It is also
contraindicated in patients with significant renal disease, becaus the method
involves diuresis of the hemodilution fluid. The hemodilution luid may be
either crystalloid with a 3: I volume replacement or colloid with 1:1 volume
replacement.
When reinfusing blood this is done in the reverse order of c lection that
IS the first unit which has the highest Hct is the last to be re fused. This
method is the only one to provide whole fresh blood.
Perioperative blood salvage from the surgical site:
Intraoperative salvage:
In this method blood is retrieved from the surgical fiel during the
operation and processed and then returned again to the patient. Tl re are three
basic techniques: semi-continuous flow centrifugation, canister co ection with
disposable liner and single use self-contained salvage and reir usion. The
commonest type is the first one which results in washed cell: with Hct of
”,60~o. None of the transfused products will have functioning olatelets or
coagulation factors. This method is relatively cotrtraindicated whe : there may
be bacterial or malignant cell contamination.
Postoperative blood salvage and reinfusion:
In this method blood collected in a drain from a surgi al wound is
washed and reinfused. It is useful in operations where the ble ling mostly
occurs postoperatively like operations performed under toumique as the total
knee arthroplasty. Also it can be used after cardiothoracic s .gery. It is
contraindicated if the wound is contaminated.
RED CELL SUBSTITUTES:
Two types of artificial oxygen transporting fluids (red eel substitutes)
have been under investigation:
Pertluorochemicals:
They are inert immiscible liquids which have an oxygen olubility of
approximately 20 times that of normal plasma. This inert fh d must be
cmuslified into aqueous electrolyte solution forming a suspensi n of small
particles (0.1f.lIIl). These emulsions are very temperature unstable nd must be
stored at -20°C. Fluosol DA20, which is now commercially availal e, contains
20% perfluorochemical on weight basis (13.4% on volume basis), nd since it
transports oxygen by direct solubility, so to be effective it requir ; very high
PaO, values.
Hemoglobin solutions:
When hemoglobin IS removed from the red blood cells anc s purified,
ItS Pso is reduced to the range of 12-l4mmHg (the normal 27mmHi I so, it will
pick up oxygen and ,,,i11 not readily release it. Also, due to the s iall size of
hemoglobin tetramer it will be quickly diuresed. More recent ’ purified,
pyridoxilared. polymerized form of hemoglobin has been found to I ve Pso’s in
the normal range and not diuresed, so it has a longer intravascul r retention
nme. Hemoglobin solutions have the advantage of transporting .ubstantial
oxygen at normal Pa02 values, but they may be nephrotoxic.
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