In selecting a venipuncture site, how can you tell a vein from an artery?
The antecubital area of the arm is usually the first choice for routine venipuncture. This area contains the three vessels primarily used by the phlebotomist to obtain venous blood specimens: the median cubital, the cephalic and the basilic veins. Show
Although the veins located in the antecubital area should be considered first for vein selection, there are alternate sites available for venipuncture such as the veins on the top of the hand (Table 2). These sites should only be considered after determining that the veins of the antecubital area cannot be accessed or cannot be used. Table 2. Choosing the Best Vein.VeinLocationReason for ChoicePlacementDirectionMedian CubitalMid antecubital fossaVertical to diagonalMusculature assists in stabilizing vein; very often largest; ease of accessCephalicThumb side of antecubital fossaVerticalEase of access; few nerves and tendons in areaBasilicBody side of antecubital fossaVertical to diagonalMore difficult to access; proximity of artery, nerves and tendons. Use this vein only as the final alternative. Eiting E, Kim HT. Arterial puncture and cannulation. In: Roberts JR, Custalow CB, Thomsen TW, eds. Roberts and Hedges' Clinical Procedures in Emergency Medicine and Acute Care. 7th ed. Philadelphia, PA: Elsevier; 2019:chap 20. Smith SF, Duell DJ, Martin BC, Gonzalez L, Aebersold M. Specimen collection. In: Smith SF, Duell DJ, Martin BC, Gonzalez L, Aebersold M, eds. Clinical Nursing Skills: Basic to Advanced Skills. 9th ed. New York, NY: Pearson; 2016:chap 20. Last reviewed on: 1/17/2021 Reviewed by: David C. Dugdale, III, MD, Professor of Medicine, Division of General Medicine, Department of Medicine, University of Washington School of Medicine, Seattle, WA. Also reviewed by David Zieve, MD, MHA, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team. This chapter covers all the steps recommended for safe phlebotomy and reiterates the accepted principles for blood drawing and blood collection (31). The chapter includes background information (Section 2.1), practical guidance (Section 2.2) and illustrations (Section 2.3) relevant to best practices in phlebotomy. The information given in this section underpins that given in the remainder of Part II for specific situations. Chapter 4 also provides information relevant to the procedure for drawing blood given below in Section 2.2, but focuses on blood collection from donors. Institutions can use these guidelines to establish standard operating procedures. Such procedures should clearly state the risks to patients and health workers, as well as the means to reduce those risks – discussed below in Sections 2.1.4 and 2.2. 2.1. Background information on best practices in phlebotomyBest practices in phlebotomy involve the following factors:
2.1.1. Planning aheadThis is the most important part of carrying out any procedure, and is usually done at the start of a phlebotomy session. 2.1.2. Using an appropriate locationThe phlebotomist should work in a quiet, clean, well-lit area, whether working with outpatients or inpatients. 2.1.3. Quality controlQuality assurance is an essential part of best practice in infection prevention and control (1). In phlebotomy, it helps to minimize the chance of a mishap. lists the main components of quality assurance, and explains why they are important. Table 2.1Elements of quality assurance in phlebotomy. 2.1.4. Quality care for patients and health workersSeveral factors can improve safety standards and quality of care for both patients and health workers, and laboratory tests. These factors, discussed below, include: Availability of appropriate supplies and protective equipmentProcurement of supplies is the direct responsibility of the administrative (management) structures responsible for setting up phlebotomy services. Management should:
Several safety-engineered devices are available on the market; such devices reduce exposure to blood and injuries. However, the use of such devices should be accompanied by other infection prevention and control practices, and training in their use. Not all safety devices are applicable to phlebotomy. Before selecting a safety-engineered device, users should thoroughly investigate available devices to determine their appropriate use, compatibility with existing phlebotomy practices, and efficacy in protecting staff and patients (12, 33). Annex B provides further information on infection prevention and control, safety equipment and best practice; Annex C provides a comprehensive guide to devices available for drawing blood, including safety-engineered equipment. For settings with low resources, cost is a driving factor in procurement of safety-engineered devices. Where safety-engineered devices are not available, skilled use of a needle and syringe is acceptable. Availability of post-exposure prophylaxisAccidental exposure and specific information about an incident should be recorded in a register. Support services should be promoted for those who undergo accidental exposure. PEP can help to avert HIV and hepatitis B infections (13, 27). Hepatitis B immunization should be provided to all health workers (including cleaners and waste handlers), either upon entry into health-care services or as part of PEP (34). Annex D has details of PEP for hepatitis B and HIV. Avoidance of contaminated phlebotomy equipmentTourniquets are a potential source of methicillin-resistant Staphylococcus aureus (MRSA), with up to 25% of tourniquets contaminated through lack of hand hygiene on the part of the phlebotomist or reuse of contaminated tourniquets (35). In addition, reusable finger-prick devices and related point-of-care testing devices (e.g. glucometers) contaminated with blood have been implicated in outbreaks of hepatitis B (4, 5, 36). To avoid contamination, any common-use items, such as glucometers, should be visibly clean before use on a patient, and single-use items should not be reused. Training in phlebotomyAll staff should be trained in phlebotomy, to prevent unnecessary risk of exposure to blood and to reduce adverse events for patients.
Patient cooperationOne of the essential markers of quality of care in phlebotomy is the involvement and cooperation of the patient; this is mutually beneficial to both the health worker and the patient. Clear information – either written or verbal – should be available to each patient who undergoes phlebotomy. Annex F provides sample text for explaining the blood-sampling procedure to a patient. 2.1.5. Quality of laboratory samplingFactors that influence the outcome of laboratory results during collection and transportation include:
2.2. Practical guidance on best practices in phlebotomy2.2.1. Provision of an appropriate location
2.2.2. Provision of clear instructionsEnsure that the indications for blood sampling are clearly defined, either in a written protocol or in documented instructions (e.g. in a laboratory form). 2.2.3. Procedure for drawing bloodAt all times, follow the strategies for infection prevention and control listed in . Table 2.2Infection prevention and control practices. Step 1. Assemble equipmentCollect all the equipment needed for the procedure and place it within safe and easy reach on a tray or trolley, ensuring that all the items are clearly visible. The equipment required includes:
Ensure that the rack containing the sample tubes is close to you, the health worker, but away from the patient, to avoid it being accidentally tipped over. Step 2. Identify and prepare the patientWhere the patient is adult and conscious, follow the steps outlined below.
For paediatric or neonatal patients, see Chapter 6. Step 3. Select the siteGeneral
Hospitalized patientsIn hospitalized patients, do not take blood from an existing peripheral venous access site because this may give false results. Haemolysis, contamination and presence of intravenous fluid and medication can all alter the results (39). Nursing staff and physicians may access central venous lines for specimens following protocols. However, specimens from central lines carry a risk of contamination or erroneous laboratory test results. It is acceptable, but not ideal, to draw blood specimens when first introducing an in-dwelling venous device, before connecting the cannula to the intravenous fluids. Step 4. Perform hand hygiene and put on gloves
Step 5. Disinfect the entry site
Step 6. Take bloodVenepuncturePerform venepuncture as follows.
Step 7. Fill the laboratory sample tubes
Step 8. Draw samples in the correct orderDraw blood collection tubes in the correct order, to avoid cross-contamination of additives between tubes. As colour coding and tube additives may vary, verify recommendations with local laboratories. For illustration purposes, shows the revised, simplified recommended order of draw for vacuum tubes or syringe and needle, based on United States National Committee Clinical Laboratory Standards consensus in 2003 (43). Table 2.3Recommended order of draw for plastic vacuum tubes. Step 9. Clean contaminated surfaces and complete patient procedure
Step 10. Prepare samples for transportation
Step 11. Clean up spills of blood or body fluidsIf blood spillage has occurred (e.g. because of a laboratory sample breaking in the phlebotomy area or during transportation, or excessive bleeding during the procedure), clean it up. An example of a safe procedure is given below.
If a person was exposed to blood through nonintact skin, mucous membranes or a puncture wound, complete an incident report, as described in WHO best practices for injections and related procedures toolkit. For transportation of blood samples outside a hospital, equip the transportation vehicle with a blood spillage kit. Annex H has further information on dealing with a blood spillage. How can you tell if a vein is an artery or phlebotomy?Look, feel for the paths of the veins. Arteries are more elastic than veins and have a thick, rough wall. Veins do not pulsate; arteries do. Venous blood is dark, arterial blood is bright red.
What should you consider when selecting a vein for venipuncture?The optimal sites for venepuncture are the veins in the antecubital fossa – the cephalic, basilic and median cubital veins. A suitable vein will be 'bouncy' to the touch, have no pulse and refill when depressed.
How is arterial puncture different from venipuncture?Puncture of an artery may be more uncomfortable than puncture of a vein. This is because arteries are deeper than veins. Arteries also have thicker walls and have more nerves. When the needle is inserted, there may be some discomfort or pain.
How can you tell that you are in a vein when using a needle and a syringe?Pull back the plunger and a little dark red blood should appear. This means you're into a vein. If no blood appears in the barrel: you're not in the vein – pull the needle out, take the tourniquet off (if you're using one) and apply pressure with a clean tissue or cotton wool. Then try injecting somewhere else.
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