Blood is a thick and bright red coloured fluid. It is alkaline (pH is 7.3 -7.45),
salty, viscous, and heavier than water (specific gravity is 1.03-1.05).
Blood is made up of a liquid portion (plasma) and a cellular portion containing red blood cells (erythrocytes), white blood cells (leukocytes), and platelets (thrombocytes). The plasma contains water, electrolytes, different proteins such as clotting (coagulation) factors and immunoglobulins, and numerous metabolic substances. Blood plays various important roles in the human body, like transport of oxygen, nutrients and ions and serving as a buffer between the cells and environment. The major whole blood
components are enlisted in table 10.1:
Components of Whole Blood
Plasma Cells
Water (97%) Red blood cells
Ions White blood cells
Organics Platelets
Sugars
Amino acids
Lipids
Trace elements
Dissolved gases
Blood transfusion is a lifesaving intervention with well-known benefits and risks.
It includes some infectious and non -infectious complications. Blood transfusion technique is used:
1) For maintaining adequate circulating blood volume,
2) For replacing specific blood components (erythrocytes, leukocytes, platelets, plasma, etc.), and
3) For removing harmful substances (such as bilirubin or excess red cells) by
using various techniques of exchange transfusion.
Whole Human Blood
Whole blood is the simplest and most common type of blood donation. It can be transfused in its original form, or it can be separated into its specific components of red cells, white cells, plasma and platelets to be used in multiple patients.
Whole human blood is transfused for replacing the red blood cells, clotting
factors, or other normal constituents missing from the patient’s blood (either
partially or wholly), or for restoring blood volume after acute haemorrhage. It is also utilised in various research applications, like drug target discovery, analysis of immune responses, and identification/validation or biomarkers.
Collection Blood can be collected by the following steps:
1) An area of the donor’s arm over the antecubital vein is cleaned and swabbed
with an antiseptic solution.
2) A local anaesthetic is injected, and the sterile needle of a blood donor set is inserted in the vein.
3) The needle is connected to a bottle or plastic bag containing Acid -Citrate-
Dextrose or ACD anti coagulant [disodium hydrogen citrate (2.0 -2.5gm),
dextrose (3gm) and water (120ml)] via the tubing of the blood donor set.
4) The citrate binds to the calcium ions present in the blood and prevents clotting which would have occurred otherwise within a few minutes of colection.
5) Dextrose preserves the red cells, increase their life during storage from 4-7 days (in citrate alone) to 21 days (in ACD).
6) Volumes of 420ml of blood are collected and mixed appropriately with the solution in the container.
7) Two samples are withdrawn from the collected blood before being issued,
one is checked for syphilis and blood group tests, and the other is checked for compatibility test made before the blood is given to a particular patient.
8) On standing, the cells settle down and form a dark red layer occupying about
half the fluid volume, with a yellowish layer of plasma above.
9) The above layer of plasma is either clear or cloudy, which depends on the
amount of lipid ingested by the donor in his meals before donating blood.
10) Blood which is contaminated or haemolysed through improper storage appear abnormal and should be carefully inspected before the blood is given to a patient
Storage
Given below are the storage requirements for whole human blood:
1) Soon after the blood is collected from the donor, it should be cooled to 4-6ï‚°C
temperature and maintained at the same temperature for 21 days, except for short periods of 30 minutes (necessary during transportation or testing).
2) The concentration of haemoglobin in the blood -anticoagulant mixture should
be not less than 9.7gm/dl.
3) The blood cells and th e serum should be examined to determine the ABO
blood group, and the cells alone should be examined for the Rh group.
4) The blood sterility should be checked before it is used for transfusion by
testing a proportion of containers of blood older than 21 days as a check on
the technique of collection and storage.
5) The label should bear the ABO and Rh groups, volumes of blood and
anticoagulant solution present, date of collecting blood, expiry date, required
storage conditions, a warning that the contents should not be used if any visible sign of deterioration is seen, and a number or code by which the history of the preparation can be traced back to the original donor.
