Vol. 16 Issue 8
Percutaneous Arterial Puncture
Insertion Site, Positioning and Technique
Percutaneous arterial puncture is often used in the acute care setting to determine acid-base balance. Use an indwelling arterial catheter when a patient requires ongoing acid-base determinations, continuous blood pressure monitoring or frequent blood sampling. Arterial catheterization is the second most frequently performed invasive procedure in the intensive care unit.1
The most common site for arterial cannulation is the radial artery.2This artery is superficially located, relatively immobile and can be easily accessed. Additionally, the site is relatively easy to care for and maintain in an intensive care setting. The femoral artery is the second most commonly accessed site, used when the radial site is inappropriate or unable to be cannulated.1Other sites for cannulation include the brachial, axillary or dorsalis pedis arteries.
When evaluating potential sites, first palpate arterial flow. When considering placement of a radial line, collateral circulation distal to the proposed insertion site may also be evaluated.
The Allen test has historically been the preferred method to evaluate collateral circulation before radial artery puncture. It is performed by applying fingertip pressure to simultaneously occlude the radial and ulnar arteries. To facilitate venous outflow while the arteries are occluded, have the patient clench and unclench his or her fist several times. Consider forearm elevation. In unconscious or anesthetized patients, an Esmarch bandage may be used to facilitate venous outflow from the hand. In such cases, release the ulnar artery with the hand in extension.
Evaluate collateral flow by noticing the return of color into the hand; this identifies superficial palmar arch patency. A sluggish response of greater than 10 seconds may be indicative of impaired collateral circulation that puts the patient at risk for an ischemic complication. False-positive results may be obtained if the hand is hyperextended with the fingers widely spaced.2
Recently, the accuracy of the Allen test has come into question. Some sources consider the test a poor predictor of collateral flow.1-4Numerous studies have reported ischemic complications after radial artery cannulation following a normal Allen test. Other studies have documented no ischemic complications after an abnormal Allen test.2
No absolute contraindications to arterial line cannulation have been documented. All contraindications should be assessed using a risk:benefit ratio. Relative contraindications to arterial line insertion include the presence of a coagulopathy, prior surgery or trauma at the proposed site, recent systemic anticoagulation, the presence of a skin infection, inadequate collateral flow to the distal extremity, impaired circulatory support or the presence of thermal injury.
Once the preferred site has been determined, obtain the necessary equipment (see table). Many supplies are included in commercially prepared kits. Shorter-length catheters are preferred for cannulating peripheral arteries such as the radial or dorsalis pedis arteries, and longer catheters are the typical choice for cannulating the femoral, brachial or axillary sites.
Palpate the radial artery between the distal radius and the flexor carpi radialis tendon with the wrist in extension. The artery is palpable medially on the ventral (palmar) surface of the wrist. To access the artery, position the wrist in dorsiflexion at an approximately 60-degree angle. Place a towel under the wrist, and immobilize it by securing it to an arm board. This position immobilizes and fixates the artery for easier cannulation. The brachial and axillary arteries are more difficult to access and are not routinely used.
The femoral artery is relatively easy to cannulate because its diameter is greater than the radial artery, and the pulse is easily palpable. The artery lies medial to the femoral nerve and lateral to the femoral vein. Puncture distal to the inguinal ligament to prevent hemorrhage into the pelvis or peritoneum. Position the patient recumbently with the leg in extension for cannulation.
The dorsalis pedis artery is located over the anterior midfoot, and in 16% of patients, it provides the main blood supply to the toes.5The pulse is palpable lateral to the extensor hallucis longus tendon. This artery may be more mobile, which increases cannulation difficulty. While the site may be useful for frequent blood draws due to its peripheral location, the transduced pressure waveforms are somewhat distorted and delayed.2
Once the site has been selected, direct the setup of the transducer or manometer system specific to your facility. It should be readily available for immediate connection once the arterial site has been cannulated and the catheter is in place.
After positioning the patient, palpate the pulse again to ensure that it remains readily identifiable and easily accessed. A Doppler ultrasound unit may facilitate cannulation in patients with weak pulses and minimize the number of punctures needed for placement.
Prepare the site using aseptic technique. Anesthetize the site with a small wheal of 1% lidocaine without epinephrine, making sure not to inject intra-arterially. The lidocaine may assist in reducing vessel spasm at the time of puncture. Ensure that any noninvasive blood pressure cuffs are located on the contralateral arm so that the artery you are attempting to cannulate is not obscured during insertion attempts.
Catheter insertion may be performed using one of three techniques. In the direct puncture technique, the nondominant hand palpates the artery without occluding the vessel. Using the dominant hand, insert the intravascular catheter at a 30- to 45-degree angle from the skin, and advance the catheter until a "flashback" of blood appears in the catheter hub.
Once observed, advance the catheter slightly further, approximately 1 mm to 2 mm, to ensure it has advanced into the arterial lumen. The initial flash identifies entry of the introducer needle into the vessel, and the needle extends slightly beyond the catheter itself.
Once in the arterial lumen, use the nondominant hand to advance the catheter into the lumen while the dominant hand stabilizes the needle. After the catheter is fully inserted, use the nondominant hand to stabilize the catheter and the dominant hand to remove the introducer needle from the intravascular catheter. Note pulsatile arterial flow from the catheter hub.
To minimize blood loss, apply gentle external pressure at the site of the arterial pulse. After ascertaining blood flow, cover the hub of the catheter with your fingertip to prevent a potential air embolism. Connect the pressure tubing to the end of the catheter.
A second technique is a modification of the Seldinger technique. This technique uses a guidewire to cannulate the vessel. While the direct puncture technique is often used for radial punctures, the Seldinger technique is recommended for cannulation of a femoral site. Once the vessel is cannulated and flashback appears, advance a guidewire through the hollow needle into the arterial lumen. Do not force the guidewire.
Without releasing the guidewire, remove the needle. As in cannulation of a central vein, the tract may be dilated to facilitate catheter placement; be sure to dilate the tract and not the arterial vessel, since arterial injury may create excessive blood loss. After dilation, thread the intravascular catheter over the wire, pull the wire out, and confirm pulsatile blood flow. Connect the pressure tubing to the catheter hub.
The third technique uses an integral guidewire approach. An integral guidewire is an over-the-needle catheter preattached to a spring wire guide. It is contained in a clear "feed" tube.
In this technique, the artery is cannulated with an over-the-needle catheter. After flashback into the hub of the introducer needle, advance the catheter an additional 1 mm to 2 mm into the artery. While holding the needle hub steady, use the nondominant hand to advance the spring-wire guide (via an actuating lever) to cannulate the artery (see figure).
A reference mark on the clear feed tube indicates when the spring-wire guide coincides with the tip of the introducer needle. Gently slide the actuating lever down the entire distance of the feed tube. Do not force the catheter into the vessel if resistance occurs. Feed the catheter down the length of the spring-wire guide to cannulate the arterial vessel.
Hold this catheter in place with the nondominant hand, and using the opposing hand, remove the introducer needle, spring-wire guide and feed tube assembly all at once from the catheter hub. Pulsatile blood return indicates successful arterial cannulation. Attach the catheter hub to the pressure tubing.
Secure the catheter, and cover the site with a sterile dressing.
Assess peripheral circulation by noting color and warmth of the extremity, presence and fullness of pulse distal to the cannulated site, capillary refill and, when appropriate, motor function. Evaluate the site daily for signs of infection. Evaluate the arterial waveform, noting its configuration.
After arterial line placement, document a procedure note, and include the following components: insertion date and time, procedure, indication, consent, location, blood return and any complications.
To bill for this procedure, the following current procedural terminology code may be used: 36620 arterial catheterization or cannulation for sampling, monitoring or transfusion (separate procedure); percutaneous.
1. Seneff MG. Arterial line placement and care. In: Irwin RS, Rippe JM, eds. Irwin and Rippe's Intensive Care Medicine. 5thed. Philadelphia, Pa.: Lippincott Williams & Wilkins; 2003:36-45.
2. Milzma D, Janchar T. Arterial puncture and cannulation. In: Roberts JR, Hedges JR, eds. Clinical Procedures in Emergency Medicine. 4thed. Philadelphia, Pa.: Saunders; 2004:384-400.
3. Cousins TR, O'Donnell JM. Arterial cannulation: a critical review. ANNA J. 2004;72(4):267-271.
4. Williams DJ, et al. A survey of venous and arterial cannulation techniques used for routine adult coronary artery bypass grafting. The Internet J Anesthesiol. 2003:6(2). Available at: http://www.ispub.com/ostia/index.php?xmlFilePath=journals/ija/vol6n2/iv.xml. Accessed Feb. 27, 2008.
5. Spoerel WE, et al. Direct arterial pressure monitoring from the dorsalis pedis artery. Can Anaesth Soc J. 1975;22(1):91-99.
Shannon Billingsley is an acute care nurse practitioner who practices in the emergency department at The University Medical Center at Brackenridge in Austin, Texas. She is a member of the ADVANCE for Nurse Practitioners editorial advisory board.