Blood collected from a patient for re-transfusion at a later time into the same individual is called "autologous blood". The patient who receives his or her own blood gets the safest possible blood because no foreign antigens infused, no infectious diseases other than the patient may already have are transmitted. Its use has increased with the awareness of infections particularly human immuno-defficiency virus (HIV) transmitted through allogenic (homologous) tranfusion.
The general categories of autologous transfusions are:
(1) Preoperative donation of blood - 2 or more units blood are drawn and stored prior to anticipated need.
(2) Intra-operative blood collection - blood is collected in operation theatre prior to surgery or during surgery and include:
a) Perioperative hemodilution - 1 or 2 units of blood is drawn before
(acute normo volemic surgery and concomitantly replaced with
hemodilution) crystalloid or colloid solution.
b) Intraoperative blood - blood is collected (salvage) from the surgical field, then processed and returned.
(3) Post operative blood collection
General advantages and disadvantages of autologous transfusions are summarized below:
• Prevents the possibility of transfusion-transmitted infections like HIV, HBsAg, HCV and Treponema Pallidum (syphilis).
• Prevents alloiminimization to red cells, leukocytes, platelets , and plasma proteins.
• Supplements blood supply - adds to blood inventory.
• Prevents adverse transfusion reactions especially allergic and febrile reactions.
• Provide blood to patients having antibodies against common antigens.
• Provides blood to patients who refuse homologous blood transfusion because of religious belief.
• Preoperative autologous donation stimulates the bone marrow to increase cells production.
• Preoperative autologous blood donation subjects to patient to anemia and hypovolemia.
• Consequences of transfusing incorrect unit due to the clerical error.
• Careful management of labeling, storing, and reinfusion of blood/its products is necessary.
• Increase complexity of providing transfusion.
• Preoperative autologous blood donation is inconvenient to patient-donor.
• There may be unnecessary loss of blood if operation is postponed or transfusion is not needed.
• More costly than allogenic blood.
• Risk of adverse reactions during donation.
PREOPERATIVE AUTOLOGOUS DONATIONS
Preoperative autologous blood donations is most feasible for patients likely to require transfusion during elective surgery scheduled to take place with in 35 - 42 days (the shelf life of blood stored in liquid state). Long time storage in frozen state is expensive and ineffective. Each patient for preoperative autologous donation must be carefully evaluated by his or her physician and the blood bank consultant. Autologous donation requires the written advice of patient's physician. Patients are required to sign a consent acknowledging that they have been informed and understand the risks and advantages of autologous donation. See Annexure in the end of the chapter.
Each unit drawn from the patient is assigned a number that is placed on the bag and donors- patients' records in the blood bank. This allows the unit to be tracked to its final disposition. A label stating "For Autologous Use Only" must be placed on the bag. Autologous blood units should be stored in a separate shelf of the blood bank refrigerator.
Indications for Predeposit Autologous Donations :
Predeposit autologous donation is indicated in elective surgical procedures with reasonable probability for transfusion and for which there is sufficient time to obtain one or more units of blood with minimum risk and without creating significant hemoglobin deficit in patient-donor. Examples are orthopedic surgery (joint replacement), plastic and reconstructive surgery, cardio- vascular surgery, major abdominal surgery (splenectomy), and in obstetrics & gynaecological conditions - particularly women having multiple antibodies or antibodies to high frequency antigens.
Contraindications for Predeposit Autologous Donations:
1. Bacteremia and acute localized infection
2. Myocardial infarction in the past 6 months
3. Unstable angina
4. Aortic stenosis
5. Congestive heart failure
6. Significant ventricular arrythmias
7. Marked uncontrolled hypertension
8. Cerebrovascular accident with in 6 months
Eligibility of predeposit autologous donation
Patient-donor, for autologous donation need not meet all the criteria of homologous blood donation. Whenever requirements for donor selection or blood collection of homologous blood donations can not be applied, suitable guidelines for the individual patient-donor should be established in consultation with patient-donor's physician/surgeon and must be recorded. Major guidelines are:
Hemoglobin: Acceptable at 11 gm/dl or 33 per cent (0.33) hematocrit or higher. Below this level phlebotomy should not be done, except in special circumstances with the approval of patient's physician but it should not be done if hemoglobin is less than 10 g/dl.
Age: There is no upper or lower limit of age. Pediatric patients undergoing elective surgery can benefit from autlogous blood.
Weight and Volume of blood withdrawn: Donors weighing 60 kg or more can donate 450 ml of blood and donors weighing less than 60 kg may donate proportionately smaller volume of blood but no more than 8-9 ml/kg body weight. In pediatric patient of 8 years of age the weight should be 27 kg and no more than 10% of the patients blood volume should be drawn at each phlebotomy.
Frequency of donation: Donations are often scheduled weekly or even at 4 days intervals with the last phlebotomy performed 72 hours or more before the operation. This allows patient-donor plasma to return to normal before surgery. Oral iron (325 mgm of ferrous sulfate three times a day) is given to accelerate the restoration of hemoglobin to predonation levels. Use of erythropoietins along with iron is the most effective way to enhance the chances of successful predonation program, but it is expensive.
Use of Autologous Donation for Homologous use
A policy must be made for the final disposition of predeposit autologous donations and allowing it to crossover for allogenic (homologous) use. The unused unit of pre-operative autologous blood donation may be transferred (cross over) for allogeneic (homologous) use only if it meets all standard criteria of blood donors like Hb 12.5 g/dl and negative for various transmissible - infections like HIV 1 &2, Hepatitis B & C and treponema pallidum. Hower, the policy of allowing autologous blood to cross over for allogeneic use is controlversial and now it is not permissible becuase of doner - Patient's associated medical illness, medication, and intermittent bacteremia
and other conditions.
Minimum laboratory testing requirements, for the autologous unit are ABO group and Rh typing.Testing of autologous blood donations for infectious diseases markers is controversial. The rational for testing markers of diseases is to protect the hospital staff rather than the intended recipient. Some advocate that the first unit of autologous blood should be tested for the markers of the transfusion-transmitted diseases. If any infection disease test is positive, a biohazard label must be applied to the unit(s) and the patient's physician must be informed.
PERIOPERATIVE AUTOLOGOUS BLOOD DONATION
Acute normovolemic or isovolemic hemodilution entails the removal of predetermined volume of blood from the patient, either immediately before or shortly after the induction of anesthesia in operation theatre, and its simultaneous replacement with blood volume expanders (colloid 1 ml or crystalloid 3 ml for every 1 ml of blood collected). The patient's hematocrit is lowered to about 20% (1-3 g/dl).
The volume of blood to be collected for a given hematocrit can be determined by the following formula:
Estimated blood volume = Body weight(kgs) × 70 in adults
= Body weight (kgs) × 80 in children
Weight of patient - 70kg
Estimated blood vol . - 5000 ml approx.
Initial Hct-45%; desired Hct-30%
Vol. of blood may be removed = 5000x([0.45-0.30]) / 0.0375
= 2000 ml
The total volume of blood collected should not exceed 40% of the patient estimated blood volume.
The advantages of the procedure include:
1. Surgical bleeding occurs at lower Hct., and therefore the loss of RBCs is less.
2. The blood flow through microcirculation is improved because of the reduced Hct.
3. The donated blood that can be used during or immediately after surgery is very fresh and contains viable platelets, adequate protein levels and good levels of all plasma clotting factors.
The collected blood usually does not leave the operation theatre. It can be stored at conditioned temperature in operation theatre or in the refrigerator at 2-6°C for upto 24 hours. All procedures and policies must ensure proper collection, handling, storage, identification, and transfusion or disposition.
Indications for Peri-operative Hemodilution
Surgical procedures where expected loss of blood is more than 1 L.
1. Cardiovascular surgery
2. Vascular surgery
3. Spinal surgery for scoliosis
4. Total hip or knee joint replacement
Contraindications for Peri-operative Hemodilution
1. It is usually inappropriate to do hemodilution when the hemoglobin is less than 11 g/dl as it decrease immediately 1 g/dl for each unit of blood removed.
2. Patients with impaired renal function who can not excrete the large volume of infused fluid.
3. Patients who have preoperative deficiencies of coagulation factors as hemodilution further reduces them.
4. Sever obstructive and/or restrictive pulmonary disease is a contraindication as near-normal oxygen transport is essential. Pulmonary function should be carefully evaluated.
5. Impaired myocardial infarction as a result of previous infarction or therapy with calcium channel or B-adrenergic blocking agents may limit the ability of the heart to respond to hemodilution with usual increase in out put. The same is applicable in severe aortic stenosis.
7. Pregnancy with anemia
INTRAOPERATIVE BLOOD COLLECTION (Salvage)
Intraoperative blood salvage is the collection of sheded blood from a closed wound or body cavity during surgery and its subsequent transfusion into the same patient. Surgical indications for intraoperative blood salvage include any surgical procedure in which blood loss more than IL is anticipated and if there is no contamination (sepsis or penetrating wound) of surgical site or contamination with malignant tumor cells. Intaoperative autotransfusion can decrease the need for homologous transfusions.
The procedure can be used in many surgical procedures:
• Orthopedic procedures (especially total hip replacement and spinal surgery)
• Liver transplant
• Ruptured ectopic pregnancy
Contraindications of Intraoperative Blood Salvage
• Infection - reinfusion of contaminated, even washed, blood may lead to bacteremia.
• Malignancy (malignant cells) - reinfusion of malignant cells may lead to metastatic spread.
• Fecal contamination.
Many intraoperative autotransfusion devices are available. The basic principles involved are suction driven aspirator, which collects sheded blood from wound or body cavity during surgery, anticoagulation; filtration to remove debris, and fibrin; centrifugation and washing the red cells with normal saline and transfer into a separate pack for reinfusion.
Newer devices (e.g. Sorenson Autotransfusion Systems, Haemonetic's Cell Saver) that transfuse salvaged whole blood or washed red cells have proved to be safer and no major complications develop. Air embolism has never been reported with a newer autotransfusion device. The devices are costly and the process is cost effective.
All intaoperative salvage techniques must confirm to the safety requirements. Salvaged blood must be clearly labeled having name of the patient, identifying number, date and time of collection. Blood should be reinfused within six hours from the start of collection and should remain with the patient until reinfused.
Blood salvaged from a serosal cavity is frequently deficient in fibrinogen and platelets and will not clot. It is feasible to transfuse such blood with minimal or no added anticoagulant. For most surgical situations, however the patient is either systemically anticoagulated (for example, in cardiac surgery), or anticoagulant is added to the salvaged blood. In the later case, citrate anticoagulants are preferable to heparin, which at low doses, can cause paradoxical platelet activation and clotting.
Complications from the use of intraoperative salvaged blood are:
• Disseminated intravascular coagulation (DIC)
• Air embolism
POSTOPERATIVE BLOOD SALVAGE
Techniques available for collecting the postoperative drainage are usually of value within 24 to 48 hours after surgery in patients actively bleeding into a closed site (e.g. after cardiopulmonary bypass, blood from the chest following traumatic hemothorax, joint cavity drainage). This procedure is also contraindicated where there is evidence of infection or malignant tumor cells in the site from which blood is being salvaged or when the rate of blood loss is less than 50 ml per hour. The blood collected from postoperative drainage is sterile and defibrinogenated. It will not clot.
It utilizes the same devices for collecting and processing blood that are used in intraoperative autotransfusion. It must be filtered (washing is optional) before it is returned to the patient. The blood must be reinfused with in six hours from the start of collection in order to minimize the proliferation of bacteria. The blood bag should be labeled having patient's name and an identifying number.
Autologous blood is generally accepted to be the safest type of blood for transfusion. It decreases the demand of banked blood. Logistical problems can be minimized by protocols developed in hospitals for successful autologous transfusion programs.
CONSENT FOR PREDEPOSIT AUTOLOGOUS BLOOD DONATION
1. .... I, Mr./Mrs./Miss………….…son/daughter/wife of………………………….have been explained fully the purpose and the procedure of the autologous transfusion, and the possibility and the nature of its complications.
2. I consent for withdrawl of my blood by an authorized member of the staff of the blood bank for autologous transfusion. If I do not require transfusion of the blood withdrawn for autologous transfusion, it may disposed off as per the hospital policy.
Date: Patient- Donor signature
(if patient is minor)