When to remove tourniquet during blood draw
Phlebotomy, the practice of drawing blood from a vein, is a proficiency that all nurses should learn in their career. While not commonly taught in nursing school programs, many recommend that nursing students take extra courses in how to take blood to hone this skill. Show
Obtaining blood samples, either via a venous stick or from a central line, is a critical nursing skill. Phlebotomy is essential for a variety of medical diagnoses, procedures, and tests. Without proper specimens, unhelpful or even harmful medical treatment could happen. Nursing schools do not teach this skill due to legality issues. Students should study venipuncture in books and watch licensed nurses in clinical settings perform this task. In doing so, this will enable students to learn basics prior to graduation. Even though most hospitals do have phlebotomy teams, it is still critical for nurses to learn these skills in order to provide the best patient care. In fact, the majority of intensive care units require their nurses to possess these skills. Phlebotomy teams generally only make rounds at specific times in hospital settings, therefore, if a lab test is ordered immediately it could be the responsibility of the nursing staff to draw the specimen. How to Learn How to Draw BloodThe practice of phlebotomy is not something that can strictly be learned from watching videos or reading a how-to guide but something that must be practiced repeatedly in a controlled environment with other trained professionals. It’s important to speak to your supervisor to learn the steps in order to become certified in your hospital. Each healthcare system has its own requirements prior to nurses performing blood draws. The World Health Organization's Blood Draw GuidelinesThe World Health Organization’s (WHO) best practice guidelines for blood draws include the following:
The overall purpose of establishing the guidelines is to,
The WHO has set forth the following standards of patient care for hospitals to adhere by:
They also identify dangerous and unsafe practices for blood draws including,
>> Related: Arterial Blood Gases (ABGs) Explained How to Draw BloodDrawing blood from a patient can be a daunting task but it also is a necessity for nurses. Here are the basic steps to drawing blood:
Step 1: Identify The VeinThe first step in drawing blood correctly is to identify the appropriate veins to puncture. For adult patients, the most common and first choice is the median cubital vein in the antecubital fossa. Commonly referred to as the antecubital or the AC it can be found in the crevice of the elbow between the median cephalic and the median basilic vein. This is an extremely large vessel and if stuck properly can yield excellent blood results. Some health care settings may insert blood drawing peripheral intravenous catheters into this vessel for frequent blood draws. For novice phlebotomists, this vein is the first choice because it is close to the skin’s surface and tends not to roll when punctured. Furthermore, it has a low risk of damaging surrounding nerves, arteries, and tendons versus other veins in the hands. Learning the anatomy of the main veins and arteries in the body is essential to becoming competent in phlebotomy. If the antecub has already been accessed there are great options for venipuncture. Other commonly used veins include:
Avoid Puncturing These AreasWhile it is important to know the best veins to access it’s also important to know which areas to avoid. These areas include:
Step 2: Gather SuppliesAfter identifying the site for the blood draw, gather the appropriate supplies needed. Some institutions have kits with all of the needed supplies while others will require the nurses to gather them individually. An important tip - take extra supplies into the patient’s room in case you need to attempt a second venipuncture. These supplies include:
Step 3: VenipunctureAfter assembling the appropriate equipment, follow the next steps to perform a proper venipuncture. Once again, please be aware that these are only guidelines for blood draws and nurses should consult with the appropriate hospital personnel regarding performing this procedure on patients. Additionally, these steps only apply to the adult and pediatric population and not neonates.
Don’t be discouraged if at first, you don’t access the vein. Venipuncture is a skill that takes time and practice to master. Always remember to ask for help from seasoned nurses and seize opportunities to practice your skills. Things Nurses Should Know About Drawing BloodIn order for the nurses to be successful when drawing blood, there are several key things they must know including,
Blood Draw Best PracticesThe WHO has best practices that are key to preventing infection and being successful during blood draws. Furthermore, they protect the nurse or healthcare professional from a potential needle stick. Best practices in phlebotomy involve the following factors:
Drawing Blood FAQs:*This website is provided for educational and informational purposes only and does not constitute providing medical advice or professional services. The information provided should not be used for diagnosing or treating a health problem or disease. How long should you leave a tourniquet on when drawing blood?A tourniquet is used to increase venous filling and makes the veins more prominent and easier to enter. Never leave the tourniquet on for longer than one (1) minute. To do so may result in either hemoconcentration or a variation in blood test values.
What happens if you don't Take the tourniquet off when drawing blood?A prolonged tourniquet time may lead to blood pooling at the venipuncture site, a condition called hemoconcentration. Hemoconcentration can cause falsely elevated results for glucose, potassium, and protein-based analytes such as cholesterol.
Why do you release the tourniquet when drawing blood?The phlebotomist should not leave the tourniquet on the patient's arm for longer than a minute. This increased pressure against the vessel walls allows plasma and small molecules to flow through capillary walls and into the tissue.
Why is tourniquet removed first before the needle?To prevent a hematoma:
Remove the tourniquet before removing the needle. Use the major superficial veins. Make sure the needle fully penetrates the upper most wall of the vein. (Partial penetration may allow blood to leak into the soft tissue surrounding the vein by way of the needle bevel)
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