Platelets
have been documented to pay a vital role in blood coagulation (Mustard
et al, 1966; Guyton and Hall, 1996). To adequately play this role, it
is important that the quantity of these platelets in blood be maintained
regularly within a narrow range of 150-400x109 cells per liter of
blood (Caucasians) (Dacie and Lewis; 1994) and 100-400x109 cells per
liter of blood (Nigerian) (Miller and Weller; 1971). The
lifespan of a platelet is 7-10days, once they are released from the bone marrow;
young platelets are trapped in the spleen for 36 hours before
entering the
circulation, where they have a primary haemostatic role. (www.bioline.org.br/request). Quantitative
abnormalities of platelets have been reported to result in many disease
conditions e.g. hemorrhage, thrombosis and atherosclerosis (Bloom and Thomas 1981, Sheldon
1988).
An anticoagulant is a substance that
prevents coagulation, that is, it stops blood. Chemical can be added to stop
blood clotting. Apart from heparin, most of these chemicals work by binding
calcium ions, preventing the coagulation proteins from using them (Buller
et al; 2005). Heparin work by binding to antithrombin (Lewis
et al; 2008). The commonly used anticoagulants are
ethylemediaminetetra-acetic acid (EDTA), oxalate, heparin, sodium citreate, and
sodium fluoride/potassium oxalate (Coles 2007). Some authors also
include Citrate Phosphate Dextrose and Adenine (CPDA), fluoride oxalate, Acid
Citrate Dextrose (ACD) (Chessbrough; 2006).
The change in blood on storage are
directly related to the storage time and the type of anticoagulant used (Ochei
and Kolhatka; 2008). Haematologic sample must be analyzed as soon as
possible to prevent artifacts created by exposure to anticoagulants and cell
deterioration due to storage (Willard at al, 1999). Haematology
samples should be analyzed within 3 hours or to be refrigerated at 4oC
to avoid artificial increased haematocirt, increased mean corpuscular volume
and decreased mean corpuscular haemoglobin concentration. Platelet counts should
be performed no later than 1 hour after collection. www.vetal/tranquerancom.ar/pages/wild/smallanimal.ss.htm.) Abnormalities
blood stored in anticoagulatnt include tetany of muscles, decreased packed cell
volume (PCV), count. (Gossens et al; 1991, Date and Lewis 1994).
Erythrocyte creation, neutrophil hypersegmentation and lymphocytic nuclear
distortion may occur in aged samples. In addition, monocyte vacuolization monocyte
pseudopod formation and platelet aggregation are some of the more common
artifacts encountered in stored samples (Willard at al; 1999). Despite all
this documented abnormalities observed in blood stored in anticoagulants, the
use of anticoagulants to store blood at 4oC still remain the most
available, widely accepted and most reliable method of blood storage in the
Tropics (Nwafia et al; 2003). But the changes in environmental factors
especially the fluctuating electric power supply and local availability of
substandard blood anticoagulant bags.
There is need, therefore to constantly
monitor the procedural effect in blood storage.
Aims and
Objectives
To
determine the effect of storage in different anticoagulants and storage
time
on platelets.
Justification of
the Study
Platelets
are vital in blood coagulation and their quantity in the body is essential.
Some disease conditions may require blood transfusion and oftentimes, it is
difficult to obtain fresh whole blood in that immediate environment, hence, the
only available choice are blood stored in anticoagulant. It then becomes very
vital that the components of these stored blood especially platelets are
maintained relatively constant to prevent post transfusion complications
especially with blood coagulation. This study/research is to determine the best
anticoagulant that can preserve blood components especially platelets in stored
blood.