RCP 100 - Arterial Puncture: Locations and Complications

Anatomical Locations for Arterial Puncture

• The radial artery is located in the wrist on the radial side
• A key advantage of using the radial artery is the safety in puncturing, which is due to the presence of collateral circulation
• A disadvantage of using the radial artery is the small size of the artery
• The brachial artery has the advantage of large size
• Disadvantages of using the brachial artery include the proximity to a large vein and a nerve and the lack of collateral circulation
• The femoral artery has advantages that include a large size, easy palpation, and presentation of a large target
• Disadvantages of using the femoral artery include proximity to a major vein with a lack of collateral circulation
• Other disadvantages of using the femoral artery are that it may be deep and difficult to locate, and atherosclerotic plaques commonly form in the artery

Complications of Arterial Puncture

• Potential complications from arterial puncture include vessel spasm, formation of thrombi or emboli, infection, loss of blood flow, and loss of circulation
• Techniques to minimize potential complications are the use of the Modified Allen's Test, pulse oximetry, and sampling syringes
• The Modified Allen's Test is performed before arterial puncture to determine the adequacy of circulation from the ulnar artery
• Pulse oximetry is used to assess collateral circulation of the hand
• Specialized plastic syringes are used for arterial blood sampling

Blood Gas Sampling Errors

• Air bubbles must be expelled immediately upon collection in arterial blood gas sampling
• Carbon dioxide in the blood diffuses into air bubbles potentially lowering the measured carbon dioxide tension
• Samples held longer than ten minutes may show lower PaO2, higher PaCO2, or a pH less than the patient’s actual Ph
• Anticoagulants can cause acidosis in the blood sample
• Sodium heparin is the best anticoagulant to use in arterial blood sampling
• If a sample is drawn from a hypoxemic patient, it is difficult to distinguish arterial blood from venous blood
• Patient anxiety may lead to hyperventilation and alter the PaCO2

Capillary Blood Gas Sampling

• Capillary blood gas sampling is commonly obtained from an infant’s heel, which is referred to as a heel stick, or it’s taken from the finger
• Arterialization is done before capillary blood gas sampling
• A lancet is used to puncture the skin surface

Capillary Sampling Errors

• Potential capillary sampling errors include poor blood flow, introduction of air into the sample, and inadequate mixing of heparin

Puncture Techniques

• Standard precautions must be followed, including wearing personal protective equipment, exercise caution when using sharps, and properly dispose of sharps into an approved biohazard sharps container
• Patient-related considerations include checking for a required physician’s order, putting pressure on the site for up to 15 minutes, and using ABG analysis to judge adequacy of oxygen therapy
• Patient-related considerations also include re-assessing the patient 20-30 minutes following arterial puncture
• Puncture preparation includes a use of an anesthetic, performing the modified Allen’s test, palpating the puncture site, and cleansing the site with an iodine-based prep pad
• Once the site is cleansed with an iodine-based prep pad, repeat the action with an alcohol prep pad

Obtaining the Specimen

• When using a radial site, hold the syringe like a pencil, palpate the pulse, and visualize artery location
• With a radial site, puncture the skin at a 45° angle with the needle bevel up
• When visualizing the artery location, slowly advance the needle toward the artery
• When the artery is punctured, blood will quickly appear in the needle hub; do not move and allow the syringe to fill
• When using a brachial site, puncture the skin when the needle bevel is up at a 45° to 90° angle
• When using a brachial site, visualize the artery location and slowly advance the needle toward the artery, watching for the flash and allowing the syringe to fill
• When using a femoral site, the procedure may require a longer needle
• With the femoral site, keep the bevel of the needle facing the patient’s head and perpendicular to the skin’s surface; puncture the skin and watch for the flash, then allow the syringe to fill

Post-Puncture Care

• After the sample is collected, withdraw the needle and apply firm pressure with a gauze pad
• Expel air and insert the needle into the rubber stopper
• While applying pressure to the puncture site, mix the sample in the syringe
• Ice the sample and check the puncture site
• Label and transport the sample

Indwelling Arterial Catheter Sampling

• Indwelling Arterial Catheter Sampling supplies moment-by-moment pressure monitoring
• Indwelling Arterial Catheter Sampling allows repeated arterial sampling with minimal trauma to the patient
• To reduce clotting, a continuous drip of sodium heparin is used in Indwelling Arterial Catheter Sampling
• The line must be flushed before drawing a sample when using Indwelling Arterial Catheter Sampling