- Education and Science
Phlebotomy: How to Draw Blood With Venipuncture
Venipuncture is performed by doing a small incision in a specific site where blood vessels are available and fit enough to be punctured by a needle safely.
Phlebotomy is the most common and routinely performed invasive medical process of obtaining blood sample for test and in some cases also for treating certain type of hematologic diseases. The most common procedure involving drawing of blood is termed venipuncture however, the term phlebotomy is somewhat a broad definition covering all type of medical and non-medical procedures serving the purpose of obtaining venous blood from different regions of the human body or inside veterinary practice in case of animals.
When Is Venipuncture Performed?
The procedure of venipuncture - or phlebotomy - can be considered as the initial process of a blood transfusion, blood sugar level measurement and venous cannulation. Basically any kind of invasive interventions involving administration of drugs, blood collection for tests or other treatment scopes have venipuncture as the core technique to access a body's venous circulation.
How is Phlebotomy Performed?
Phlebotomy is usually done by doctors, medical practinioners, nurses, EMTs if needed and technicians commonly known as phlebotomists. The process is performed under sterile conditions almost always inside a medical facility or environment including hospitals, ambulances if it carries urgent priorities and even hospice and ordinary medical offices.
Ensure that the patient is inside a sterile, clean environment. If you are working inside a hospital especially in an emergency room, be sure to exclude factors that would make the intervention hard to perform. If the patient is conscious and the medical condition requires urgent treatment, be sure to use curtains to avoid psychological discomfort. Also consider bed and floor cleanness. Never start the intervention if the coverlid is not clean and body fluids are present on the floor from previous emergency cases. If all of the factors listed above are present, there is a high chance of patient side complaint and unpleasantness.
How To Draw Blood Step By Step
Be sure that you wear appropriate clothes for doing the procedure: work clothing is usually suggested, sterile gloves and a previously disinfected armboard is crucial for avoidance of possible complications mainly involving infections and psychological patient-side discomfort.
Be sure that the patient's mental status is expectable, usually people are afraid from venipuncure. Normally needle insertion causes minimal pain, however fear of needles can exacerbate pain and anticipated malaise sometimes resulting in near-syncope states. If this happens, avoid this complication by placing the patient in a supine or orthostatic position.
You may also ensure that the mental status is clear and unaltered. Usually inside an ER environment, people with altered mental states caused by intoxication from alcohol, drugs cannot respond to the worker's instructions. By this fact there is a tendency that immobilization of arm can be annoying and sudden body movements can cause unwanted damage of the poked vessel resulting in local bleeding and subcutaneous hemorrhage causing hematomas.
Prepare the appropriate equipment before inserting the needle. Sterile latex or non-latex gloves have to be worn depending on latex allergy. An alcoholic disinfectant is also crucial for safe puncture. Iodine solutions for further disinfection and complication treatment are also suggested. Of course it has to be remarked that some percentage of the population is allergic to iodine preparations, in this case obtaining information on previous allergic reactions is strongly advised. To slow down venous flow prepare a torniquet and and arm board where the patient's selected limb will be placed. Additionally, prepare the appropriate tubes accordingly to the kind of required blood parameters.
Which Is The Best Vein For Venipuncture?
The median cubital vein lies inside the cubital fossa anterior to the elbow and is the most common and easiest site of incision:
- It is not surrounded by large innervation meaning that the pain is minimal,
- It lies very close to skin surface allowing optimal visibility and less complications.
Before needle insertion, check the patient's skin status. Possible injection spots may show up on people using intravenous drugs thus having compromised veins. Usually the preferred injection site is the median cubital vein. If you encounter troubles visualizing a good one, apply a towel humidified with warm water to cause vasodilation.
Place and stretch the torniquet just above 2-3 centimeters from the selected puncture site, this will narrow the diameter of targeted vein for venipuncture.
Visualization of Vein
If the vein is hardly visible, gently slap the selected area with one of your hand, this will usually make the vein more visible and temporarly swollen.
Disinfect the site where you will apply the puncture.
Gently and carefully insert the needle inside the vein until a third of its length is inside the vessel. Note, the needle have to be inserted with an angle of 30 degrees related to the skin surface.
Flash Tip Check For Correct Needle Placement
After the needle is inserted, check the flash tip on the needle, it is a good sign if this become coloured with red because it means that the end of the needle is inside the vein and did not go into surrounding tissue.
Attach the predetermined tube to the eclipse whereinto the blood sample will be collected.
Keep in mind that is not important to fill it completely, two third of its capacity is enough for the laboratory tests.
Tube, Needle and Tourniquet Removal
Remove the tube with your free hand while keeping the needle in place to avoid follow-up displacement of the needle with your other hand.
Gently remove the torniquet with your free hand, then pick a gauze and press it to the puncture site while the needle is still inside the vein. Remember, you don't need to disinfect is since the site has been already cleaned.
Remove the needle with one hand, while with the other gradually press the gauze to the puncture site.
Fix the gauze with an adhesive tape. You can optionally instruct the patient to keep it pressed with his or her hand until the possibility of further bleeding is completely disclosed, this phase usually last up 2-3 minutes.
Be careful to label the patient's tube appropriately. Remember to write down:
- Full name of patient ID,
- Date of birth