Chapter 21. Vascular Access

Establishing reliable vascular access in an emergency situation is of critical importance. Many factors, including body habitus, volume depletion, shock, history of injection drug use, congenital deformity, and cardiac arrest, can make obtaining vascular access in the critically ill or injured patient extremely difficult. The introduction of point-of-care ultrasound into emergency and acute care settings has been an important advance for facilitating rapid and successful vascular access.

For central access, the use of an anatomic landmark-guided approach has been the traditional practice. Internal jugular vein location traditionally relies on the sternocleidomastoid muscle and clavicular landmarks; the femoral vein relies on the inguinal ligament and femoral artery pulsation landmarks; and the subclavian vein relies on clavicular landmarks. In many patients, however, these landmarks may be distorted, obscured, or nonexistent. In addition, normal variations in the anatomic relationship of the internal jugular vein may make cannulation difficult.1 In the emergent situation, attempting central vascular access with poor external landmarks is frequently approached using a “best guess” estimate of the vessel location. This may lead to multiple needle passes to locate the vessel. Excessive bleeding, inadvertent arterial puncture, vessel laceration, pneumothorax, and hemothorax are some of the potential complications of central vascular access. The incidence of complications increases when multiple attempts are required for cannulation.2–5 In patients with an underlying coagulopathy (pathologic or therapeutic), multiple attempts can carry significant morbidity due to hemorrhage.6,7

The introduction of point-of-care ultrasound has been very effective in assisting with the placement of central venous access catheters. For internal jugular vein cannulation, ultrasound use has been described by numerous disciplines, including emergency medicine, critical care medicine, anesthesiology, obstetrics/gynecology, nephrology, surgery, and radiology.2,3,8–10 When compared to the external landmark approach, ultrasound-guided internal jugular vein cannulation results in fewer complications and is more effective in time-to-cannulation and first-attempt success.2,6,11–15 For femoral vein cannulation, the ultrasound-guided approach was found to be more successful than the landmark approach in patients presenting in cardiac arrest.16

Peripheral venous access is less invasive and is used more commonly in the emergency and acute care settings than central access. The inability to find an adequate peripheral vein generally requires that the clinician consider central venous access. Traditionally, successful peripheral venous cannulation requires that a vein first be visualized or palpated. Some peripheral veins that are not readily apparent on the skin surface can be clearly visualized with the use of ultrasound, which may obviate the need for central access.16,17 The basilic and cephalic veins of the arm are superficial veins that are not generally visible but are readily cannulated using ultrasound guidance. Basilic vein cannulation has been shown to be very successful in the ED setting in patients in whom it was difficult to obtain other peripheral vascular access.18 Basilic vein cannulation is readily learned by novice users.19 In addition, basilic veins have been cannulated using ultrasound in patients requiring prolonged outpatient IV access.20

Evidence supporting the use of ultrasound for vascular access has become overwhelming. In 2001, a report published by the Agency for Healthcare Research and Quality (AHRQ) on patient safety in health care included a chapter strongly advocating the use of ultrasound in central venous catheterization.21 The resulting scientific and policy positions favor the use of ultrasound for central venous access stronger than any other point-of-care ultrasound application. The National Institute for Clinical Excellence (NICE) has also recommended that central venous catheters be inserted under ultrasound guidance.22

Indications for ultrasound guidance for vascular access are as follows:

• To confirm vessel location prior to landmark-based approach. This is termed as the static approach with ultrasound for IV access. The patient is positioned and the ultrasound transducer is placed on the patient to confirm the predicted landmark-based anatomy. The transducer is then removed, and the patient is prepped for vascular access via the standard landmark-based technique. This can be performed by a single operator and does not require additional adjunctive equipment such as a sterile transducer sleeve. This approach is particularly useful when the patient is unable to assume the standard position for cannulation, when time is of the essence, or when the target vessel is discovered to be large and superficial during the pre-scan phase. One randomized trial demonstrated that the static technique is superior to the traditional landmark technique for central venous cannulation.14
• To assist in real-time cannulation under direct ultrasound visualization. This is termed as the dynamic approach. The ultrasound transducer is inserted into a sterile sleeve and placed on the patient after the sterile prep. The operator can then watch the needle entering the vessel under real-time ultrasound guidance. This technique can involve one or two operators.23 With two operators, real-time vessel visualization can be maintained throughout the entire procedure. With a single operator, ultrasound guidance stops prior to guidewire insertion in order to free up the nondominant hand. The dynamic technique takes full advantage of the benefits of ultrasound-assisted vascular access, and is the approach advocated in the AHRQ report. It should be emphasized that the fine motor skills required for this procedure are not automatic. Practice on models and/or phantoms is recommended in order to achieve steady control of the transducer (with the nondominant hand) while aligning the needle and target within the narrow imaging sector of the probe. Although this method may require more training and patient preparation time, it can save precious minutes when routine landmarks are not evident in the critically ill or injured patient.
• To minimize the number of vascular access attempts. In certain clinical situations, definitive access is needed in patients at risk for significant complications from multiple vascular attempts. Patients with therapeutic anticoagulation, disseminated intravascular coagulation, thrombocytopenia, hemophilia, or any condition that adds significant risk to vascular access attempts can benefit from the higher first-attempt success rate afforded by ultrasound.
• To assist in alternative peripheral access. Alternative peripheral vascular access is important in many patients. Either static or dynamic ultrasound techniques can be used to locate and facilitate cannulation of peripheral vessels. Saphenous, basilic, and cephalic veins are all easily located with ultrasound but difficult to locate with surface visualization. External jugular veins may also be located with ultrasound when anatomic limitations make surface visualization difficult. Some clinical situations require vascular access but choosing a central approach may add unwarranted risk. Ultrasound-guided approach to peripheral veins allows for reliable access without the need for central venous access. This has been shown to be helpful in both adults and children.16,24
• To facilitate arterial puncture or cannulation. Ultrasound can be used to locate arteries for puncture or cannulation. Radial, brachial, and femoral arteries are easily located with ultrasound. Both dynamic and static techniques can be used to facilitate arterial puncture.

At times it may not be easy to distinguish veins from arteries with B-mode ultrasound. Recognition of key sonographic characteristics can help distinguish veins from arteries. In comparison to arteries, veins have several distinct sonographic features: (1) they are more easily compressed, (2) have thinner walls, and (3) have no arterial pulsation. In addition, central veins possess characteristic triphasic venous pulsations that can be distinguished from arteries. The addition of color flow is a useful adjunct on ultrasound units used for vascular access.

Cannulation of the Internal Jugular Vein

Ultrasound allows for easy localization of the internal jugular vein (Videos 21-1: Central Vascular Access Tips and 21-2: Central Vascular Access Examples). In addition, the carotid artery can be distinguished from the adjacent internal jugular vein. The internal jugular vein lies deep to the sternocleidomastoid muscle and is lateral and superficial to the carotid artery. Using the sternocleidomastoid muscle as the external landmark, the internal jugular vein sits below the bifurcation of the sternal and clavicular heads of the muscle (Figures 21-1 and 21-2). It is important to note that the relative relationship of the carotid artery with the internal jugular vein may change with head position. Specific technical details of internal jugular vein cannulation are provided below.

Cannulation of the Subclavian Vein Using a Supraclavicular Approach

Placement of a central venous catheter into the subclavian vein at the junction with the internal jugular vein is possible using ultrasound guidance (Figure 21-3A,B). The use of ultrasound for the traditional infraclavicular approach to subclavian vein catheter placement is limited by the large acoustic shadow created by the clavicle in some patients. In contrast, the supraclavicular approach allows for adequate sonographic visualization of the proximal subclavian vein anatomy, and the internal jugular/innominate vein confluence.

Cannulation of the Subclavian/Axillary Vein Using an Infraclavicular Approach

For this approach, place the ultrasound transducer initially just below and in contact with the clavicle. Orient the transducer in long axis over the proximal axillary vein, which travels parallel to the deltopectoral groove. Approach the axillary vein from a more peripheral location near the anterior axillary line if the vein is prominent. Alternately, a more central approach (at the mid-clavicular line area) will allow the needle/catheter to enter the vein just before it courses below the clavicle to become the subclavian vein. The later approach often requires that the transducer be placed partially over the clavicle so that needle entry for longitudinal (in-plane) visualization is closer to the clavicle (Figure 21-4).

Cannulation of the Femoral Vein

Place the transducer in a transverse position just below the mid-portion of the inguinal ligament. Identification of the key vascular structures begins just below the inguinal ligament and medial to the femoral arterial pulsation. Use the compression technique to distinguish the readily compressible vein from the less compressible artery (Figure 21-5). In addition, appreciating the variable relationships of the vascular structures with respect to limb position is important. Utilize either the static or dynamic technique for femoral vein cannulation. Limit the use of the femoral vein for central venous access in adults to emergency situations because of higher complication rates.21

Peripheral Venous Cannulation

Ultrasound will permit localization of veins that often do not have consistent anatomic relationships or are too deep to be readily palpable (Video 21-3: Peripheral Vascular Access). Of note, the superficial venous structures are easily collapsed with even slight pressure of the transducer on the skin. This feature of collapsibility is useful for distinguishing between veins and arteries. Superficial veins may not be identified, however, if they are collapsed by inadvertent excessive pressure on the transducer. Placing a tourniquet on the extremity to maximize vein dilation is also advisable. Once a suitable vein is identified, the process of IV catheter placement is largely unchanged from standard practice using routinely available venous catheters. With respect to ultrasound guidance in peripheral venous access, either the static or dynamic technique may be successfully utilized. Ultrasound use for peripheral IV access has been shown to decrease the number of needle sticks and time to successful cannulation, and can be readily employed by novice users.16,17

Cannulation of the External Jugular Vein

Since the external jugular vein is superficial, it is often readily identified by visualization and palpation without ultrasound assistance (Figure 21-6). However, limited range of motion (i.e., cervical spine precautions) or adiposity may make this vessel difficult to cannulate without ultrasound guidance.

Cannulation of the Brachial and Cephalic Veins of the Upper Extremity

The antecubital veins of the arms are commonly used for venous access in the emergency setting, as are the more proximal cephalic and brachial veins (Figure 21-7A). The cephalic and brachial veins lie deeper in the structures of the upper arm and are not readily palpable; consequently, these veins are not generally used for IV catheter placement in the absence of ultrasound guidance. Be cautious with the more proximal brachial vein since it lies immediately adjacent to the ulnar and median nerves. In most patients, the depth of these vessels and angle required for cannulation mandates that a longer catheter (2.5 inches) be used. An example of transducer placement and vessel visualization for proximal vein cannulation is demonstrated in Figure 21-7.

Arterial Cannulation

In the absence of color flow Doppler, real-time arterial pulsation, thickness of arterial wall, and lack of arterial compressibility are all sonographic features that help distinguish arterial from venous anatomy. The mechanics of placing an arterial catheter or simple arterial puncture can proceed along traditional technical guidelines once the pertinent anatomy has been recognized.

The dynamic technique can be summarized by the Four Ps: Pre-scan, Preparation, Poke, and Path. Use a 7.5 or 10 MHz linear array transducer.

The purpose of the pre-scan is to survey the underlying vessels, confirm the target vessel appropriately, and optimize patient and machine positions and settings in advance of the actual procedure (Figure 21-8). For internal jugular vein cannulation, observe for three structures during the pre-scan: thyroid gland, internal jugular vein, and carotid artery. Visualize all three structures before proceeding. The internal jugular vein can be easily compressed, especially in volume-depleted patients; confirming its presence in relationship to the other structures will ensure verification of the proper target vessel. When standing at the head of the bed, point the transducer position marker toward the patient's left side and the monitor located at the patient's hip and facing you. This will ensure the proper relationship of the underlying anatomy with the ultrasound image anatomy. For example, when cannulating the patient's right internal jugular vein, the thyroid, carotid artery, and internal jugular vein will be from left to right anatomically as well as on the ultrasound monitor. Thus, when moving the needle more medially, or to the left, it will move left on the monitor. When moving the needle more lateral, or to the right, it will move to the right on the monitor.

If possible, elevate the exam table to a comfortable height and tilt to allow venous distention. Lower the room lights and adjust the monitor gain (brightness) and image depth before any sterile preparation is begun.

The second P stands for preparation (Figure 21-9). Prepare the patient's skin for a sterile procedure in the standard fashion. For dynamic cannulation, prepare the transducer with a sterile sleeve and gel. Several types of sleeves are available for ultrasound transducers. Sleeves that cover the transducer and cable are preferred since they can be placed on the sterile field and easily located for single operator use. Careful application of coupling gel to the transducer prior to placement in a sterile sleeve is necessary to avoid entrapment of air bubbles. Secure the sterile sleeve with elastic bands and apply sterile coupling gel to the outside of the transducer sleeve prior to further imaging. With the sterile barrier in place, the transducer is ready for use.

The poke refers to the initial skin puncture (prior to actual venipuncture), which places the needle in the SC tissues where it is identified before further advancement. The initial insertion of the needle and its subsequent localization is an important step. Advancing the needle prior to localization can result in a misdirected path. Figure 21-10 demonstrates proper needle position for the initial insertion. Note how close the needle is to the transducer. Use a thick pool of sterile gel to prevent interference from air as the skin is pushed downward.

Following the path of the needle and adjusting the course are keys to successful placement. Tissue motion during initial real-time imaging of the procedure can help localize the area of the needle prior to visualization of the needle itself. The needle will be detected as a bright spot echo and ring-down artifact (short axis) or a reflection from the shaft and shadowing or reverberation artifact (long axis) (Figure 21-11A,B). Direct the needle toward the vessel while using the monitor display to locate the needle tip. Ensure that the needle tip has been located prior to each advancement of the needle. A common error involves mistaking the needle shaft for the needle tip and thereby misjudging the actual tip location. Figure 21-12 illustrates scanning with different needle vectors and imaging planes. Note the convergence of the shafts of all three needle paths in the transverse plane. However, each needle tip is in a different location in relation to the vessel. Accurate needle guidance in the transverse plane requires a sweeping motion of the scan plane to localize the needle tip as it is advanced. The long-axis view of the needle has the potential advantage of visualization of the entire shaft of the needle from skin to vein; however, if the transducer is angled slightly during the procedure, the clinician risks guiding the needle to an adjacent incorrect target (such as the carotid artery).

Prior to successful cannulation, the vein will be seen to deform with the pressure of the advancing needle (Figure 21-13). Confirmation of successful venipuncture proceeds as usual with a flash of venous blood into the syringe. With either static or dynamic technique, the mechanics of catheter placement (i.e., using the Seldinger technique) proceeds unchanged from standard technique.

Transducer and Needle Orientation: Longitudinal versus Transverse versus Oblique

Figure 21-12 illustrates the most common approaches to needle guidance where the scan plan is longitudinal or transverse to both the structure of interest and to the shaft of the needle. Certain approaches, however, require a combination of views. For example, the imaging plane for the vessel could be primarily transverse, while the needle shaft is directed within the longitudinal axis of the imaging plane (or vice versa). As this terminology can be confusing, some have begun to describe a long-axis needle approach as an “In-Plane” view, while a short-axis needle view is considered an “Out-of-Plane” view. Variations in transducer positioning will yield different information relative to vessel and needle placement. Transverse transducer positioning gives information related to lateral orientation. The longitudinal transducer position gives depth and slope information (Figure 21-14). The authors generally rely primarily on transverse short-axis imaging to assist with venous cannulation. The transverse short-axis orientation is most helpful in demonstrating relationships with other adjacent anatomy (Figure 21-8). Novice operators should use the transverse short-axis approach since time for vascular access is shorter when compared to the longitudinal axis approach.25 The longitudinal orientation will help with needle orientation in the long axis of the vessel of interest (Figure 21-15). A potential danger with the short-axis approach is unseen penetration of the deep wall of the vein and any structure that lies deep to it. There is preliminary evidence that long access may be effective in decreasing vessel penetration through the deep wall in novice users26 Long-axis orientation can be helpful when difficulty is encountered with the guidewire. The long-axis view may demonstrate the location of resistance and allow for subtle readjustments.

The oblique view is an alternative approach that has been developed to capitalize on the advantages of both the short- and long-axis techniques27 This view allows better visualization of the needle shaft and tip but also offers the safety of being able to visualize all relevant anatomically significant structures at the same time and in the same plane (Figure 21-16). The transducer orientation is halfway between the short and the long axis of the vessel, and the transducer is placed over the portion of the vessel that is most superficial and/or accessible. This often requires a slightly more coronal position of the transducer (side of the neck). By aligning the edge of the transducer close to the posterior border of the sternocleidomastoid, the needle can enter and track just below the muscle. Avoiding muscle puncture is advantageous for patient comfort, and it avoids bleeding complications. An in-plane approach for the needle is used to direct the tip into the oval shaped internal jugular vein, while keeping the carotid artery in view (Figure 21-17). The oblique approach has great potential for infants or other patients where neck access is limited and where increased distance from the lung pleura is needed for safety (COPD patients).

Static versus Dynamic Placement Technique

Techniques utilizing ultrasound-assisted venous cannulation may vary depending on the clinical scenario and the availability of assistance as well as the necessity for strict sterile technique. The advantage of the dynamic technique is that it allows for real-time observation of the needle position and target vascular structures. The logistical simplicity of the static technique may be advantageous in the case where the landmark-based anatomy is straightforward. The static technique allows a brief inspection and confirmation of the vessel location without the reliance on a second operator. Both static and dynamic approaches have been found to be superior to the traditional landmark-based approach.14

Needle Visualization

As clinicians gain experience with ultrasound needle guidance, it becomes more evident that accuracy for these techniques requires that the position of the needle tip is clearly visible on the monitor during the entire procedure. There are specific adjustments in the image that can improve needle visualization. Adjust the ultrasound frequency, focus, and gain to optimize resolution in the near field. If possible, tilt the transducer to align the beam more perpendicular to the needle, which results in a stronger echo (brighter needle tip or shaft). Manufacturers have recognized this need with echo-enhanced needles. Although one study did not find improved efficiency with echo-enhanced needles for novice users, 28 anecdotal information from experienced users suggests these may be helpful. Newer machines are adding enhanced needle visualization options and some transducers are designed for use with needle guides that ensure the needle is steady and will advance only within the plane of the image.

Whatever method is used, the importance of accurately visualizing the needle from skin to target vessel cannot be stressed enough.

Sterile Technique

There are several different options for maintaining sterile technique. The best option is to use prepackaged sterile transducer sleeves that are manufactured solely for the purpose of handling the transducer and transducer cord in a sterile fashion (Figure 21-18). Alternatively, the use of a large sterile glove, positioning the transducer and adequate amounts of conductive gel into the thumb of the glove, can also be effective (Figure 21-19). If using the glove option, care must be taken to avoid compromising sterility by puncturing one of the “extra” fingers of the glove during the process of venipuncture. Sterile lubricant is sufficient as a conductive medium between the sleeve and the skin.

Variability of Normal Venous Anatomy

The large central venous structures of the body have fairly constant anatomy, whereas the peripheral veins are extremely variable in their position. It is helpful, however, to keep in mind the typical course of the veins and the important adjacent structures while using ultrasound to assist in vessel identification and cannulation.

Effect of Patient Positioning

The usual considerations apply for patient preparation for central or peripheral venous cannulation. The Trendelenburg position is useful to provide slight venous distention in the veins of the head and neck. Furthermore, the use of ultrasound may help determine optimal patient position with respect to surrounding arterial anatomy.29 It is apparent in individual patients that rotation or abduction of a limb will significantly alter the relationship of the vein and artery with respect to the skin. It merits emphasizing that in certain individuals leg position alone can cause the femoral artery to directly overlie the femoral vein. Hence, the use of a standard (nonultrasound-assisted) technique, given certain patient positioning, may result in arterial injury or failed venous cannulation (Figure 21-5C).

There are no absolute contraindications to the use of ultrasound for vascular access; however, there are a few common pitfalls.

1. Failure to identify the needle in tissue. When using ultrasound for dynamic venous access, it is important to accurately view the needle ring-down artifact or venous tenting to confirm position. Whether using the transverse or longitudinal approach, it is important to identify the needle with ultrasound visualization before advancing into deeper structures. This is important to ensure successful cannulation while minimizing complications. Transverse orientation allows for better lateral positioning of the needle, while longitudinal orientation provides better depth and needle slope positioning.

2. Failure to distinguish between vein and artery through compression testing or color flow Doppler. Since arterial pulsations at times may be subtle, veins and arteries may initially appear very similar (especially in the hypotensive patient). In the absence of color flow Doppler capability, confirm that the vessel is a vein by using compression maneuvers. A vein will easily collapse with gentle external pressure. While color or power Doppler may be of some use, pulse wave Doppler will enable the clinician to actually interrogate the vessel of choice and determine if venous or arterial flow is present.

3. Locating the vessel with the static approach prior to the patient being in proper position. Locate the vessel after the clinician has the patient properly positioned for the cannulation attempt. As emphasized earlier, many vessels will move slightly and change relationship depending on the patient's position.

4. Failure to angle the transducer beam into the needle puncture area. Since ultrasound provides a two-dimensional image, angle the beam toward the needle tip as the needle is advanced. Figure 21-12 demonstrates how in the short axis the needle can appear over the vessel while the tip is not within the vessel. Note how three different needle vectors intersect over the vessel although the ultimate needle tip may be in a very different location.

Case 1

Patient Presentation

A 50-year-old man who was morbidly obese presented complaining of chest pain. On examination, he was hypotensive and diaphoretic. A 12-lead EKG revealed him to be in complete heart block. Multiple attempts at peripheral access failed. The transcutaneous pacemaker was intermittently capturing but had little effect on the patient's hemodynamic status. There were no good external anatomic landmarks due to his adiposity.

Management Course

The patient's right internal jugular vein was easily visualized under ultrasound guidance using a 7.5 MHz linear transducer. A dynamic real-time ultrasound-guided cannulation of the right internal jugular vein was successful on the first attempt. An IV pacemaker wire was then successfully placed (also under ultrasound visualization). Upon improved ventricular capture, the patient's blood pressure normalized.

Case 2

Patient Presentation

An 18-year-old woman who was severely scarred and contractured from old burns to the neck, chest, arms, and legs, presented after ingesting a lethal quantity of a tricyclic antidepressant in a suicide attempt. On examination, the patient was hypotensive and lethargic. Numerous attempts at peripheral access failed. There were no appreciable anatomic landmarks for central access due to her old scars.

Management Course

Although a femoral arterial pulsation was difficult to palpate for the landmark-based approach, the femoral vein was easily visualized under ultrasound guidance. An ultrasound-guided femoral vein catheter was inserted on the first attempt. The patient was then administered induction agents for orotracheal intubation and successfully resuscitated.

Case 3

Patient Presentation

A 40-year-old man with a long history of injection drug use presented for drainage of a deltoid abscess. It was determined that the abscess could be drained as an outpatient with the use of systemic sedation and analgesia. Numerous attempts at routine peripheral venous access failed. The patient was refusing a central venous line.

Management Course

The patient had a large right basilic vein easily visualized with ultrasound. A 2-inch 18-gauge catheter was inserted without difficulty. The patient's abscess was successfully drained after receiving adequate IV sedation and analgesia.

Commentary

Anatomic landmarks in patients may be distorted, obscured, or nonexistent. In the three cases, each patient presented with anatomic variations that made it difficult to obtain rapid peripheral venous access or landmark-based central venous access. Venous access was facilitated by the use of ultrasound in each case, thereby expediting patient resuscitation and care. Ultrasound use allowed the clinicians to obtain venous access on the first attempt and helped prevent complications associated with delays in obtaining venous access or multiple attempts to obtain central venous access.