COLLECTION OF BLOOD, Blood Containers, Method of Collecting Blood, Anticoagulants and Preservatives Used for Blood Collection

COLLECTION OF BLOOD

Blood Containers

Method of Collecting Blood

Anticoagulants and Preservatives 

Used for Blood Collection

COLLECTION OF BLOOD:- Blood for transfusion must be collected and handled under strictly sterile conditions to prevent contamination. Plastic blood collection bags are used which contain an anticoagulant sufficient for the amount of blood to be collected. Generally, a combination of citrate and dextrose is used as an anticoagulant. Citrate binds with calcium and prevents activation of the coagulation cascade. Dextrose provides energy for the red blood cells. 

The anticoagulant also contains inorganic phosphate buffer to increase the production of energy-rich adenosine triphosphate (ATP) which increases red cell viability. If adenine is added, it increases the survival period of red cells. The two commonly used anticoagulants are citrate phosphate dextrose (CPD) and citrate phosphate dextrose adenine-1 (CPDA-1). When stored at 16°C, CPD anticoagulated blood is approved for 21 days storage while with CPDA-1, blood can be stored for up to 35 days.

Blood Containers:- Plastic containers of blood have replaced the glass bottles. The plastic bags are more compact and lighter in storage. They are more flexible and can avoid the hazard of air embolism. Two or three bags can be connected to each other aseptically so that components can be separated without contaminating the primary container.

Method of Collecting Blood:- While collecting blood, the donor should lie down, and a blood pressure cuff should be used on the arm above the venepuncture site. Under aseptic conditions, make a venepuncture using an 18 gauge needle to obtain a faster flow. 

The collection bag with anticoagulant should be kept below the level of the arm for gravity flow. Swirl the bag intermittently to bring about mixing of blood with the anticoagulant. 

The donor should gently flex the fingers or clench and unclench the fist to assist the flow of blood from the vein. About 420-450 ml of blood can be collected from a donor at a time. When the full amount of blood has been collected, collect the blood into 2 tubes in 5 ml amounts for various screening tests. 

Seal the venepuncture site on the donor's arm with a plaster to stop the flow of blood. The donor should be allowed to rest for a while and offered a nourishing drink to adjust for the loss of blood.

Proper labelling of the collecting container is of utmost importance

The label should contain the following information:-

1.Donor identification number

2.ABO and Rh type

3.The type and volume of anticoagulant.

4.Volume and name of the product (e.g.,whole blood, red cells.)

5.Temperature for storage

6. Date of expiry.

The blood must be stored in a refrigerator with a constant temperature of 1-6°C. An alarm should sound if the temperature exceeds the limit. The stored blood should be inspected daily for colour, turbidity, haemolysis and clot formation, and should be discarded if there is any evidence of bacterial contamination.

Anticoagulants and Preservatives Used for Blood Collection:-The most important factor that affects recovery of red cells after blood storage is the anticoagulant solution used. The changes in blood on storage are directly related to the storage time and the type of anticoagulant used. The solutions commonly in use are both anticoagulants and red cell preservatives, but are referred to as anticoagulants.

Anticoagulant Citrate Dextrose (ACD):- This solution has been in use and modified for a number of years since 1918. The anticoagulant contains 100 ml of 2% sodium citrate and 20 ml of 15% glucose for the preservation of 420 ml of blood. This anticoagulant is now replaced by CPD and CPDA-1.

Citrate Phosphate Dextrose (CPD):-This anticoagulant has a pH higher than that of ACD and is more isotonic. With CPD, the survival rate of red cells is as good or better than that of ACD, but there is a remarkable improvement in the red cell function. Therefore, CPD has replaced ACD as the anticoagulant of choice.

Citrate Phosphate Dextrose Adenine-1 (CPDA-1) Because the red cell needs ATP as a source of energy, addition of adenine to CPD helps in the maintenance of high ATP levels. Adenine is non-toxic and well tolerated by recipients.

The composition of CPD and CPDA-1 is shown in Table 9.1.

Other Additives and Anticoagulants:- Synthetic enzyme inhibitors are sometimes added to the anticoagulant to inhibit some enzymes produced by leucocytes which may cause haemolysis. Ion exchange resins are sometimes used to remove all cations, including calcium from blood, thus preventing coagulation. Such blood is useful for plasma production and sometimes for research. 

Copostion of CPD and CPDA  and CPDA-1 solution (for 450 ml of blood)
Ingredient	CPD	CPDA-1
Trisodium Citrate(G)	1.66	1.66
Citric Acid (Mg)	206	206
Dextrose(G)	1.61	2.01
Manobasic Sodium Phosphate	140	140
Adenine	-	17.3