INTRODUCTION TO VACUTAINER TUBES
Vacutainer tubes were invented by Joe Kleiner and BD (Becton, Dickinson & Co.) in 1949. These tubes are the registered trademark of Becton, Dickinson & Co. and today vacutainer tubes are manufactured and sold by them.
A Vacutainer blood collection tube is a sterile glass or plastic tube with a closure that is evacuated to create a vacuum inside the tube facilitating the draw of a predetermined volume of liquid. Most commonly used to draw the blood samples directly from the vein. These tubes can also be used sometimes for the collection of urine samples.
Vacutainer tubes may contain additives, mostly the anticoagulants, designed to stabilize and preserve the blood specimen prior to analytical testing. These tubes are available with or without a safety-engineered closure (the rubber stopper inside the plastic cap), with a variety of labeling option and closure colors as well as a range of draw volumes.
PRINCIPLE OF VACUTAINER TUBES
Vacutainer tubes work on the pressure difference that is created between the blood vessel and the vacuum in the tubes which forces the blood through the needle into the tube.
Vacutainer needle is double-ended, with one side being encased in a thin rubber coating for safety and the other side for the insertion into the vein. When the needle is screwed into the translucent plastic vacutainer needle holder, the rubber needle is inside the holder, and the exposed needle will be inserted into the vein.
When a Vacutainer tube is inserted into the holder, its rubber cap is punctured by the inner needle and the vacuum in the tube pulls blood through the needle into the tube. The filled tube is then removed and another can be inserted and filled the same way which aid in the blood collection. The amount of air evacuated from the tube predetermines how much blood will fill the tube before blood stops flowing.
Moreover, the exact volume that should be drawn in a specific vacutainer tube is mentioned on the label of every tube which is to minimizes the errors that may occur if more or less amount of blood is taken in the tube because every tube contains an anticoagulant or an additive or Clot activator in some and the ratio of the blood to the Additive must be maintained in order to get the accurate values of the tests.
It is important to remove the tube before withdrawing the needle from the vein, as there may still be some suction left in the tube that may cause the pain or discomfort to the patient upon withdrawal.
Vacutainer tubes are covered with a Color-coded plastic cap that indicates which additives the tube contains. These color indicators help the phlebotomist to easily select the tubes in which the blood should be drawn as per the tests that have to be performed. The additives present in the vacutainer tubes plays the most important role as every additive has a unique function and these are selected as per the tests to be performed.
Here is the list of Color codes of the tube, the Additives present in them and their common uses –
S.No. COLOR CODES ADDITIVE COMMONLY USED FOR
1.) Purple / Lavender EDTA (Ethylene diamine tetra-acetic acid) CBC, BLOOD TYPING (Rh Factor & ABO Screening), Cross match, Hb, Red cell Indices, ESR by Wintrobe's method etc.
2.) Light blue Tri-Sodium Citrate (Blood:Anticoagulant ratio is 9:1) Prothrombin time (PT), Activated Partial Thromboplastin Time (APTT), Fibrinogen thrombin time and other blood Coagulation tests.
3.) Light green Lithium Heparin Basic Metabolic Panel (BMP), Comprehensive metabolic Panel (CMP) and other plasma determination tests.
4.) Royal Blue None/ Di-sodium EDTA Trace Elements like Cu, Zn, etc, Toxicology and Nutrient determination etc.
5.) Gold (commonly known as Serum Separator tube) Polymer Gel and Powdered Glass Clot activator BMP, CMP, LFT, KFT, Lipid Profile and other biochemistry assays, Serological tests etc.
6.) Red Powdered glass Clot Activator BMP, CMP, Lipid Profile, Serology tests, Therapeutic drug monitoring, blood bank procedures etc.
7.) Dark green Sodium Heparin Arterial blood gas analysis, alpha-TNF, Lymphocyte Immunotherapy etc.
8.) Gray Sodium Fluoride Blood Sugar testing, Toxicology tests etc.
9.) Black Tri-Sodium Citrate (Blood:Anticoagulant ratio is 4:1) ESR by Westergren method
10.) Yellow ACD (Acid-Citrate Dextrose) Blood Bank studies, HLA Phenotyping, Paternity testing, Tissue typing etc.
11.) Pink Dried EDTA Rh factor, ABO typing, CBC, Blood banking procedures etc.