Source: Sharon Bord, MD, Department of Emergency Medicine, The Johns Hopkins University School of Medicine, Maryland, USA
When monitoring patients, it is important to obtain values that are accurate and reliable. Blood pressure monitoring is one of the essential vital signs, and for a majority of patients, measuring it utilizing non-invasive techniques provides accurate values. However, there are situations in which the blood pressure requires more exact, specific, and reliable measurements. This can be achieved by intra-arterial blood pressure monitoring and requires arterial line placement. Arterial line placement refers to the insertion of a catheter, which is able to transduce blood pressure, into one of the major arteries (e.g., radial or femoral artery). Patients who potentially need arterial line placement include those with extreme low (such as in sepsis or cardiogenic shock) or high (as in cerebrovascular accident or hypertensive emergency) blood pressure measurements. Many of these patients are placed on vasoactive medications to either increase or decrease blood pressure. When the goal is to decrease a patient's blood pressure, it must be done gradually, which further necessitates close blood pressure monitoring. Arterial line placement is also ideal for patients who require frequent arterial blood gas monitoring.
Placement of an arterial line is a core procedure when caring for critically ill patients. It is important to note that the procedure might not be successful on the initial attempt. If multiple attempts are made for placement in the same vessel, spasm may develop. In this situation, an alternative site should be identified for arterial access. Arterial line placement provides accurate and timely blood pressure monitoring and affords a clinician with the ability to closely titrate medications and pressors.
Arterial line placement refers to the insertion of a catheter, which is able to transduce blood pressure, into one of the major arteries, like radial or femoral.
Blood pressure monitoring is one of the essential vital signs and, for a majority of patients, measuring it utilizing non-invasive techniques-discussed in a video in the Essential of Physical Examinations 1 collection-provides accurate values.nHowever, there are situations in which the blood pressure requires more exact, specific, and reliable measurements. In such cases, one can perform arterial line placement, or ALP, which allows intra-arterial blood pressure monitoring in real time.
Here, we will demonstrate the essential steps required to successfully place an arterial line in a patient’s radial artery.
Now let’s review the steps for performing a successful arterial line placement in the radial artery.
The necessary supplies include: antiseptic skin prep pads, such as chlorhexidine pads; a 1% lidocaine syringe with a needle attached-this is optional; an arterial line introducer kit-there are two different types: over-the-needle and with a guide wire; proper suture material-which is generally zero silk-with a needle driver, pickups, and iris scissors; tape for patient positioning, gauze, sterile dressing to further secure the line and, lastly, an arm board-only necessary for some patients.
Don personal protective equipment, this includes appropriately sized sterile gloves and a mask with an attached face shield. It is imperative to keep the eyes shielded from possible exposure.
Upon entering the room, verify that the arterial line setup is attached to the monitor correctly. Before starting the procedure, assess the patient for procedure contraindications. Inspect the insertion site for cellulitis or severe burns, would be a contraindication to the procedure. Assess for adequate collateral blood flow to the hand, by using the Modified Allen’s test.
Ask the patient make a fist, and then occlude their ulnar and radial artery. Next, have the patient releases their fist. The hand should be pale. Release the pressure on the ulnar artery. The patient’s hand should turn pink in the next 1-3 seconds. This indicates the ulnar artery is functioning properly, and one can proceed with the arterial line placement in the radial artery of that arm. After confirming the absence of any contraindication, place the patient’s arm on a flat surface in supine position, with the wrist adequately exposed. Then place the patient’s hand in dorsiflexion and support it in this position with a gauze roll under the dorsal aspect. Placing the patient’s hand in this position brings the radial artery closer to the skin’s surface and aids in cannulation. To maintain the hand in this position, tape it with the gauze roll, and once properly secured, one can begin with line placement can begin.
Now let’s discus the two different techniques commonly utilized for line placement – the over-the-wire technique and the over-the-needle technique.
First, prep the insertion area with a chlorhexidine swab. Be sure to allow the area to dry prior to the line insertion. Locate the radial artery by feeling for the pulse with your non-dominant hand, approximately 1-2 cm proximal to the wrist.
To prevent discomfort from the procedure, anesthetize the insertion site with an intradermal injection of 1-2 milliliters of lidocaine 1%.
At the location of the pulse, using your dominant hand, insert the needle at a 30 – 45° angle and when advancing the needle, look at the hub for a flash of blood. It is important to identify the first flash of patient’s blood, as the radial vessel is small and the flash can be easily missed. Failure in identifying this first flash may lead to a vessel puncture. Note, that the initial blood flash is bright red in appearance, as opposed to the darker colored blood from a vein. Once the flash is observed, advance the needle a few more millimeters.
For the “over-the-wire technique”, advance the wire gently into the vessel, while removing the needle. It should not meet much resistance and should easily thread. If experiencing difficulty, gradually rotate the needle tip and attempt the wire placement again. After the wire is inserted, advance the catheter over the wire and remove the wire. Be sure to never let go of the wire during the procedure.
If the over-the-needle technique is being utilized, advance the needle a few millimeters more when the initial flash of blood is observed, and then gradually advance the catheter as the needle angle is reduced to approximately 10°. The catheter should advance easily into the vessel. When removing either the needle or the wire, be careful to hold pressure on the proximal portion of the catheter. You will know the catheter is in the correct location if there is pulsatile blood flow from the catheter.
Promptly connect the hub of the catheter to the arterial line setup. At this time, blood pressure monitoring can begin. Secure the line with sutures, usually zero silk, and place a sterile dressing over the line. Be sure to discard the sharps appropriately. Lastly, assess perfusion by performing the capillary refill in the patient’s hand. Capillary refill should be normal- fingers should turn pink in 1-3 seconds.
You have just watched a JoVE video detailing the steps for arterial line placement. This is a core procedure when caring for critically ill patients, as it provides accurate and timely blood pressure monitoring, which in turn allows the clinician to closely titrate medications and pressors. As always, thanks for watching!
