Depending on the protocol in your particular situation, you may be involved in blood testing procedures with patients. To be effective, you’ll need to know how to go about different parts of this process in a safe manner that protects the integrity of the samples and the results. Here is an outline of what you’ll need to know about this area of medicine for a medical assistant test.
Patient care is the most important thing in medicine. Ultimately, it is why we as healthcare providers do what we do, so we should always strive for excellence. Excellence in patient care includes not only being efficient in our skill set, but also having outstanding bedside manner.
When approaching a patient to perform a procedure, such as a blood draw, you must first identify yourself. Then, using 2 patient identifiers, identify the patient. Finally, explain the procedure to the patient. An appropriate example of these procedures would be, “Hello, Mr. Smith. My name is Samantha. I will need to do a small needle stick to get a blood sample for some lab testing. Is that okay?”
Prior to collecting a specimen, you will need inquire whether the patient is fasting, or has recently taken certain medications. For example, if you are drawing PT/INR, it would be appropriate to ask the patient if he has been administered heparin or is on a continuous heparin infusion. Monitor for specific patient needs, as well. Some areas may not be used for IV sticks. Look for an identifying arm band that indicates a “do not use” area. A different approach may be needed for a patient who is confused and another staff member may be needed to assist in the blood draw. Be aware of other possible special needs, such as burns or bleeding disorders.
When providing direct patient care, patient safety is a priority. Adhere to established standards, including hand hygiene and appropriate aseptic techniques for procedures. For blood draws, equipment should be clean and in good working condition. Prepare the patient for venipuncture by cleansing the skin thoroughly around the area where the blood will be drawn. When performing the procedure, monitor the patient closely for negative response. Potential problems include syncope, fainting, nausea, and diaphoresis. Know how to respond to complications and emergencies of any sort.
After obtaining a lab specimen that includes venipuncture, be sure bleeding has stopped. Bandage the site appropriately with gauze or tape, being mindful of the patient’s allergies, including tape and certain skin cleansers. Age should be considered when selecting an appropriate method of bandaging. For example, elderly people may have very thin or fragile skin, so certain types of tape may be contraindicated because it may cause a skin tear.
Equipment should always be in good working order. Reusable equipment should be appropriately cleaned with approved cleansers between each patient.
Before performing a venipuncture, gather all equipment needed. This includes the type and number of collection tubes, needles, attachments, cleaning swabs, tape, and gauze. Depending on the type of test ordered, other equipment may be needed. Different tests require different amounts of blood to be collected. Know what additives may be needed for certain tubes.
Evacuated tubes contain a vacuum that makes drawing blood easier. They are used along with a double-pointed needle and a plastic adapter.
With the exception of a red-stoppered tube, all tubes contain an additive. Additives include clot activators, thrombin, and anti-coagulants. Review which colored tubes contain each additive.
Needles come in different sizes. They are typically referred to by their thickness or diameter size, which is known as their gauge. Smaller gauge numbers have a larger diameter, so a 20 gauge needle is bigger than a size 26. In addition to standard straight needles, there are winged needles that are frequently used when drawing multiple tubes of blood from one access site. Know which size needle may be recommended for each patient. For example, an elderly patient with small veins would need a smaller needle, such as a size 22 or 24, whereas someone with “heartier” veins might be able to tolerate a 22 or 20 gauge.
A capillary puncture requires a specific tube and a lancet. In adults, the fingers are usually used for capillary puncture. In infants, the heels can be used.
Even if you are not the one doing the blood draw, you will be better able to assist that person if you know the procedure steps, the reasons behind each one, and the terminology involved. This way, you can anticipate the needs of the person you are assisting and make sure you do not do anything that would compromise safety or test result accuracy.
Blood samples are drawn in a specific order to reduce risk of coagulation. Tubes should be drawn in the following order: yellow, red, red/gray, blue, lavender, green, pink, and gray. Evacuated tubes contain a vacuum that will draw blood to a designated fill line. If drawing blood using a different method, be sure tubes are filled to the marked line.
Venipuncture is used on people of all ages. Special considerations should be made for different age groups. For example, a smaller needle size should be used for small children or the elderly. When performing venipuncture on an infant, the biggest vessels should be used. These are oftentimes located in the head, arm, or leg.
Proper Insertion and Removal
Demonstrate proper insertion and removal techniques for venipuncture. Needles should be inserted at a shallow angle, parallel to the vein. The vein should be stabilized before performing venipuncture. Monitor for bleeding when needle is removed and apply pressure as necessary.
Order of Steps
Review venipuncture steps for evacuated tube system, syringe method, and winged set blood collection methods. While many aspects are similar, each method has different nuances. For example, an evacuated tube system requires use of a double-pointed needle and a plastic tube adapter that may be used to collect several tubes of blood at one time.
Some considerations when drawing labs include skin integrity (how thick/thin a patient’s skin is), venous insufficiency (some vessels may not allow for blood draw due to collapse, etc.), and contraindications, such as “do not stick” areas (like mastectomy or DVT.).
Review capillary puncture procedure in order: site selection, aseptic technique, equipment required, risks of capillary puncture, etc.
When drawing blood, blood cultures are to be drawn first. When drawing multiple sets of cultures, different sites must be used for each set. You may be responsible for assisting in blood culture collection. Know what type of additive is required for blood cultures.
Initial blood samples needed for an IEM (inborn areas of metabolism) include CBC, serum electrolytes, BUN, and creatinine. Review what other labs may be appropriate. Examples of IEMs are PKU and galactosemia.
Complications during a venipuncture can include hematoma, excessive bleeding, missed vein, and blown or collapsed vein. When a vein is missed, or doesn’t provide blood return, remove the needle and bandage appropriately. Try again in a different area. If excessive bleeding occurs, an appropriate response would be to apply direct pressure with bandages. Alert the nurse or physician, if necessary. Know how to respond to other complications.