Antecubital Information and Courses from MediaLab, Inc.
These are the MediaLab courses that cover Antecubital and links to relevant pages within the course.
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|Venous, Arterial, and Capillary Blood Specimens|
Venous BloodVenous blood is deoxygenated blood that flows from tiny capillary blood vessels within the tissues into progressively larger veins to the right side of the heart. Venous blood is the specimen of choice for most routine laboratory tests. The blood is obtained by direct puncture to a vein, most often located in the antecubital area of the arm or the back (top) of the hand. At times, venous blood may be obtained using a vascular access device (VAD) such as a central venous pressure line or Hickmann Catheter or an IV start. Most laboratory reference ranges for blood analytes are based on venous blood.Arterial BloodDeoxygenated blood is pumped from the right side of the heart to the lungs where it takes up oxygen. The now oxygenated blood is pumped through the left side of the heart via arteries.The most common reason for collection of arterial blood is the evaluation of arterial blood gases. Arterial blood may be obtained directly from the artery (most commonly, the radial artery) by personnel who are trained to perform this procedure and are knowledgeable about the complications that could occur as a result of this procedure. Arterial blood may also be obtained from a vascular access device (VAD) inserted in an artery such as a femoral arterial line or Swan-Gantz catheter. Capillary BloodCapillary blood is obtained from capillary beds that consist of the smallest veins (venules) and arteries (arterioles) of the circulatory system. The venules and arterioles join together in capillary beds forming a mixture of venous and arterial blood. The specimen from a dermal puncture will therefore be a mixture of arterial and venous blood along with interstitial and intracellular fluids.Capillary blood is often the specimen of choice for infants, very young children, elderly patients with fragile veins, and severely burned patients. Point-of-care testing is often performed using a capillary blood specimen. Specimen Type Method of Collection Common Use Venous Direct puncture of vein by venipuncture; vascular access device Routine laboratory tests Arterial Direct puncture of artery; vascular access device Arterial blood gases Capillary Dermal puncture of fingertip or heel Infants and young children Elderly patients with fragile veins Severly burned patients Point-of-care testing
|Choosing a site|
The median cubital vein is most commonly used. It is the middle of the bend of the arm (antecubital region).
|Positioning the patient|
Position the patient's arm in a comfortable position.Turn the arm so that the wrist and palm face upward, and the antecubital area is accessible.
|Explore the Possibilities!|
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.Although the veins located in the antecubital area should be considered first for vein selection, there are alternate sites available for venipuncture. These include the top of the hand, the side of the wrist, and the forearm. These sites should only be considered after determining that the veins of the antecubital area cannot be accessed or cannot be used. Vein Location Reason for Choice Placement Direction Median Cubital Mid antecubital fossa Vertical to diagonal Musculature assists in stabilizing vein; very often largest; ease of access Cephalic Thumb side of antecubital fossa Vertical Ease of access; few nerves and tendons in area Basilic Body side of antecubital fossa Vertical to diagonal More difficult to access; proximity of artery, nerves and tendons. Use this vein only as the final alternative.
|Which of the veins in the antecubital area should be considered only as a final alternative due to its proximity to an artery, nerves, and tendons?||View Page|
|Unacceptable Sites for Venous Blood Collection|
If the antecubital area of the patient's arm is compromised or inaccessible, an alternate site must be chosen for venipuncture such as the top of the hand or the thumb-side of the wrist. However, some sites must be avoided due to the risk of complications and/or unnecessary pain to the patient.
|If a vein cannot be located in the antecubital area of the arm, the next best alternative for venipuncture is a vein in the ankle.||View Page|
|When to Use Hand Veins to Obtain Blood|
Sometimes the phlebotomist may decide that the antecubital area is not the best site for venipuncture. Reasons for this decision may include: Extensive bruising (hematomas) in the antecubital area Inability to "feel" a vein suitable for puncture Presence of an intravascular line (IV) or vascular access device Physical condition of the patientWhen the veins in the antecubital area cannot be used, the phlebotomist may choose to use a vein on the top of a hand. The veins in the hand are very near the surface and often very small and thin so the procedure must be performed carefully and cautiously. .
|Handle With Care|
Equipment: To successfully enter a hand vein, the phlebotomist must choose equipment that will allow needle entry at a very small angle. A winged device with a small gauged needle of 3/4 inch length is most often used to obtain blood from a hand vein. A syringe is usually attached to the end of the tubing of this device. By using a syringe, the phlebotomist can control the amount of pressure on the vein and avoid vein collapse. Evacuated tubes may collapse a vein by exerting too much pressure on the delicate vein. If available, smaller tubes containing less vacuum may be used.Insertion angle: The angle at which the needle is inserted into a hand vein is smaller compared to the angle of needle insertion into veins of the antecubital area. When drawing from a hand, the needle should be inserted into the vein at approximately a 15 degree angle to allow easier access of the surface hand veins. By inserting the needle at this angle, the risk of the needle going "through" the vein and puncturing the bony structures underneath is reduced.
|Where should the tourniquet be placed when assessing a vein in the hand as a venipuncture site?||View Page|
|Bobby Jones, a phlebotomist at Community Hospital, enters the room of Mrs. Mary Grayson with a physician's order for blood tests. After greeting Mrs. Grayson, identifying himself, and properly identifying the patient, using two methods of identification, Bobby prepares for the venipuncture.As he approaches the patient's bed, he notices a sign posted above the bed that reads: "Restricted left arm use. Do not use left arm for venipuncture." Bobby prepares to use the patient's right arm and notices an intravenous (IV) line in Mrs. Grayson's right arm positioned in a vein slightly above her wrist on the dorsum (top) of her forearm.Which site should Bobby choose for the venipuncture?||View Page|