Venipuncture
[2] Venipuncture is one of the most routinely performed invasive procedures and is carried out for any of five reasons: Blood analysis is an important diagnostic tool available to clinicians within healthcare.
[4] Minute quantities of blood may be taken by fingerstick sampling and collected from infants by means of a heelprick or from scalp veins with a winged infusion needle.
[1][6] There are many ways in which blood can be drawn from a vein, and the method used depends on the person's age, the equipment available, and the type of tests required.
[citation needed] Greiner Bio-One manufactured the first ever plastic evacuated blood collection tube in 1985 under the VACUETTE brand name.
When a needle from a hub or transfer device is inserted into the stopper, the tube's vacuum automatically pulls in the required volume of blood.
This keeps blood from freely draining out of the back of the needle inserted in the vein, as each test tube is removed and the next impaled.
The majority of chemistry and immunology tests are performed on serum, which is produced by clotting and then separating the blood specimen via centrifuge.
Below in the order of draw generally required for the Evacuated Tube System (ETS) collection method are the most common tubes, listing additive and color:[10][11] ("light blue") (weak calcium chelator/anticoagulant) Plasma separator gel ("navy") Fluoride Oxalate Grey, Green, Yellow, Purple 1.
Purple (mitogen) tube Use of lidocaine iontophoresis is effective for reducing pain and alleviating distress during venipuncture in children.
[19] A needle-free powder lignocaine delivery system has been shown to decrease the pain of venipuncture in children.
[20][21] Rapid dermal anesthesia can be achieved by local anesthetic infiltration, but it may evoke anxiety in children frightened by needles or distort the skin, making vascular access more difficult and increasing the risk of needle exposure to health care workers.
By contrast, noninvasive dermal anesthesia can be established in 5–15 min without distorting underlying tissues by lidocaine iontophoresis, where a direct electric current facilitates dermal penetration of positively charged lidocaine molecules when placed under the positive electrode.
[citation needed] One study concluded that the iontophoretic administration of lidocaine was safe and effective in providing dermal anesthesia for venipuncture in children 6–17 years old.
Other interventions have not been found to be effective and these are suggestion, blowing out air, and distraction with parent coaching did not differ from control for pain and distress.
It is vital that the procedure is performed in as sterile a manner as possible as the persistent presence of skin commensals in blood cultures could indicate endocarditis but they are most often found as contaminants.
[25] Povidone-iodine has traditionally been used but in the UK a 2% chlorhexidine in 70% ethanol or isopropyl alcohol solution is preferred and time must be allowed for it to dry.
[citation needed] The blood is collected into special transport bottles, which are like vacuum tubes but shaped differently.
These specially designed bottles have long necks that fit into the evacuated tubes holders that are use for regular venipuncture collection.
If too much blood is collected, there is the risk of a hospital-induced anemia and the ratio of blood-to-nutrient broth will tilt in the opposite direction, which also is not conductive to optimal growth.
[citation needed] The bottles are then incubated in specialized units for 24 hours before a lab technician studies and/or tests it.
This step allows the very small numbers of bacteria (potentially 1 or 2 organisms) to multiply to a level which is sufficient for identification +/-antibiotic resistance testing.
Modern blood culture bottles have an indicator in the base which changes color in the presence of bacterial growth and can be read automatically by machine.
Lactated Ringer's solution (LRS) is recommended as the best fluid replacement by National Institutes of Health (NIH).
