The use of vacuum extraction tube systems as closed systems for blood collecting
reduces the risk of direct exposure to blood and has made it easier to take multiple samples from a single venepuncture
.
What is the purpose of the vacuum in evacuated tubes?
The air between the two glass tubes is removed (or evacuated) to form a vacuum, which
reduces conductive and convective heat loss
.
Why is venous blood collected?
Venous blood is the specimen of choice for most routine laboratory tests. The blood is
obtained by direct puncture to a vein
, most often located in the antecubital area of the arm or the back (top) of the hand.
What are the advantages of vacutainer tube?
Vacutainers have the advantage of
being prepared with additives
, allowing easy multi-tube draws, and having a lower chance of hemolysis. In developing countries, it is still common to draw blood using a syringe or syringes.
What is a venous blood sample used for?
Venous sampling is a diagnostic procedure that uses
imaging guidance to insert a catheter into a specific vein and remove blood samples for laboratory analysis
. Abnormal levels of certain substances in the blood may indicate the presence of disease in the organ or tissue that produces them.
How efficient are evacuated tubes?
The evacuated tube solar collectors are the most expensive, but importantly they are also the most efficient with a
conversion efficiency of over 90%
.
How does the evacuated system work?
The absorber plate is bonded to a copper pipe, and fluid passed through the pipe collects the
heat
for transfer to a hot water system. The whole assembly is sealed within a glass tube containing a high vacuum, virtually eliminating heat losses by convection or conduction.
Which is the best vein for venous blood collection?
Relevant Anatomy.
The median cubital and cephalic veins
are preferred for blood sampling, but other arm and hand veins may be used. The cephalic vein is located on the lateral (radial) side of the arm, and the basilic vein is located on the medial (ulnar) side.
What happens when venous return increases?
Increased pulmonary venous return to the left atrium leads
to increased filling (preload) of the left ventricle
, which in turn increases left ventricular stroke volume by the Frank-Starling mechanism.
What are the requirements for venous blood collection?
- Skin-cleansing materials: Alcohol, chlorhexidine, or povidone-iodine swabs or wipes.
- Nonsterile gloves (sterile gloves if blood cultures are being obtained)
- Tourniquet, single-use.
Why is EDTA tube used for CBC?
Historically, EDTA has been recommended as
the anticoagulant of choice for hematological testing
because it allows the best preservation of cellular components and morphology of blood cells.
What is the purpose of additives in blood collection tubes?
Most blood collection tubes contain an additive that either
accelerates clotting of the blood (clot activator) or prevents the blood from clotting (anticoagulant)
.
What is EDTA tube used for?
EDTA is the anticoagulant used for
most hematology procedures
. Its primary use is for the CBC and individual components of the CBC. The larger 6 mL tube is used for blood bank procedures. This tube has no anticoagulant and is used for many chemistry tests, drug levels, and blood bank procedures.
Why is venous blood used in most Test?
Venous blood is
a good indicator of the physiological conditions throughout the body
. It is also relatively easy to obtain. Therefore, venous blood is used most frequently for testing. Be sure to collect the specimen in the correct blood tube.
What does a venous blood gas tell you?
A blood gas test measures
the amount of oxygen and carbon dioxide in the blood
. It may also be used to determine the pH of the blood, or how acidic it is.
What is the difference between capillary and venous blood?
The differences between capillary and venous blood in
most cases are minimal
. However, there are some discrepancies in hemoglobin and hematocrit values and in platelet counts. It is well known that capillary blood has higher hemoglobin and hematocrit values than venous blood.
