All About Vacutainer Tubes
Historically, Vacutainer tubes in glass were invented by Joseph Kleiner in 1947. They are being manufactured and marketed by BD (Becton, Dickinson and Company) since 1949. Vacutainer is a registered trademark of Becton, Dickinson and Company. The plastic version, known as Vacutainer PLUS, was developed at Becton Dickinson Research Center, RTP, NC during 1991-1993, by co-inventors E. Vogler, D. Montgomery and G. Harper.
The first evacuated tube invented by Joseph Kleiner was called Evacutainer. BD hired Kleiner as a consultant for the product and changed the name of his tube to Vacutainer®.
Prior to the invention of an evacuated tube system, before collecting blood, solutions for the additive tubes like EDTA and citrate were prepared and dispensed into test tubes for blood anticoagulation. Then, to identify the proper draw volume, the laboratory used to etch lines in the borosilicate glass tubes. The phlebotomist would collect blood specimens with needles and glass syringes. After collection, the blood would be transferred into a series of test tubes and sealed the tubes with black rubber stoppers for transportation of the specimens to the laboratory. For electrolyte measurements, mineral oil was added to the tubes to prevent loss of CO2. For serum specimens, wooden applicator sticks were used to loosen the clot from the tube walls (Franklin Lakes, 1996).
The shortcomings of these techniques were numerous. The patients were subjected to the ordeal of multiple needle entries to the vein. The errors during the collection and transfer process and the safety risks were unavoidable (Franklin Lakes, 1996). Red Line Tube
The introduction of vacuum blood collection systems marked an era of greater safety, easy handling, speed, and accuracy in blood-to-additive ratios. During blood collection with evacuated tubes, one end of the needle entered the patient’s vein; the other end penetrated the rubber stopper as the tube was pushed into the open end of the holder. The vacuum enabled the tube to fill with the appropriate volume of blood.
Initially vacutainer tubes were packaged and shipped in vacuum tins similar to coffee cans. This was a breakthrough at the time because previously, a heavy clamp was used to prevent the stoppers from popping off during autoclaving (Franklin Lakes, 1996). However, now there are regulatory agencies and guidelines that ensure the consistency in the design and manufacture of blood collection systems like Food and Drug Administration (FDA); International Standardization Organization (ISO); and Clinical Laboratory Standards Institute (CLSI); The Medical Device Amendment (1976) and the Safe Medical Devices Act (1990).
A Vacutainer tube and the apparatus consists of a plastic hub, a hypodermic needle and a vacuum tube. Vacutainer tubes also contain additives to stabilize and preserve the blood specimens prior to analysis. Vacutainers are available with a wide range of labeling options and closure colors. They are also available with a range of draw volumes with or without a safety-engineered closure.
Vacutainer tubes have found wide recognition due to their functional ease. The venipuncture protocol employing a syringe requires elaborate preparations for blood sample analysis in terms of addition of appropriate additives into the tubes that carries more risks of sampling and analytical errors.
Vacutainer tubes have a color-coded plastic cap. The color code of the caps indicates the blood additives the tube contains. Additives are chemical substances that preserve the blood for processing in the laboratory.
The additives include anticoagulants like EDTA, Sodium citrate and Heparin. Some vacutainer tubes have a gel that has an intermediate density between blood cells and the serum. During centrifugation of these gel containing tubes, the blood cells sink to the bottom of the tube and are covered by a layer of the gel leaving the serum on top. When plasma containing blood platelets is required for analysis a vacutainer that does not contain gel or a clotting agent is used and centrifuged. The color code has a standard protocol and hence, finds universal application across the medical domain.
The Order of Draw:
As mentioned earlier, vacutainer tubes facilitate multiple blood suctions and the needle that pierces multiple tubes may carry additives from one tube into the next that hamper the blood analysis. Hence, there is need for a standardized sequence for such multiple suctions to avoid cross-contamination of additives. The Order of Draw is a term that refers to a standard protocol that has been developed for the sequence in which these tubes should be filled.
Recent Trends and Recommendations:
Recent trends in vacutainers include tubes made up of polyethylene terephthalate and use of various types of blood collection needles. Vacutainer tubes of recent introduction are made of a special formulation of the plastic, polyethylene terephthalate that is extremely strong, dimensionally stable, and resistant to chemicals and breakage. The manufacturers specify that all non-gel blood collection tubes, including those that contain heparin, EDTA and non-gel serum tubes can be centrifuged at ≤1300 RCF for 10 minutes. There are also tubes that should be spun at room temperature at a speed of 1000 to 1300 RCF for 10 minutes in a swinging bucket centrifuge and 15 minutes in a fixed-angle centrifuge.
These recent tubes are coated with silicone and micronized silica particles to accelerate clotting. A silicone coating reduces adherence of red cells to tube walls. The silica coating can sometimes cause the inner tube wall to appear cloudy and/or filmy. This cloudy appearance does not make the tubes unacceptable for use. Most Tubes are packaged 100 tubes/box and 1,000 tubes/case (10 boxes). The expiration date on the tube label is stated as a month and year. The tubes expire at the end of the month that is stated on the label. Vacutainer blood collection tubes have a sterile interior. Tubes are sterilized by gamma radiation (Wayman, 1994).
These tubes are under a specific negative pressure. During the re-sterilization cycle this negative pressure may be disrupted and therefore the tubes may not draw the proper blood volume. Thus, these tubes are sterile on the interior only. The manufacturer does not recommend re-sterilizing the tubes with ethylene oxide or autoclaving, due to pressure changes that take place during the re-sterilization cycle. Some manufacturers do offer a sterile peel-apart pouch that contains a 10 mL glass red top serum tube and 7 mL glass lavender top EDTA tube. 3mL and 6mL plain tubes with no added additives used as discard tubes are also available and find utility when drawing blood directly from an indwelling line or catheter. The tubes should be stored at 4-25’C (39-77’F) and requires inversions after a draw. An inversion is one complete turn of the wrist, 180 degrees, and back.