Chapter 19. Vascular Access

Establishing reliable vascular access in an emergency situation is of critical importance. Many factors, including body habitus, volume depletion, shock, history of intravenous drug abuse, congenital deformity, and cardiac arrest can make obtaining vascular access in the critically ill or injured patient extremely difficult. The introduction of real-time bedside 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 portable bedside 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, 11–14 For femoral vein cannulation, the ultrasound-guided approach was found to be more successful than the landmark approach in patients presenting in cardiac arrest.15

Peripheral venous access is less invasive and is used more commonly in the emergency department 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.15, 16 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 emergency department setting in patients in whom it was difficult to obtain other peripheral vascular access.17 Basilic vein cannulation is readily learned by novice users.18 In addition, basilic veins have been cannulated using ultrasound in patients requiring prolonged outpatient intravenous access.19

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.20 The resulting scientific and policy positions favor the use of ultrasound for central venous access stronger than any other emergency ultrasound application. The National Institute for Clinical Excellence (NICE) has also recommended that central venous catheters be inserted under ultrasound guidance.21

Indications for ultrasound guidance for vascular access are:

• To confirm vessel location prior to landmark-based approach. This is termed the static approach with ultrasound for intravenous 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 and the operator wishes to confirm vessel location. One randomized trial demonstrated that the static technique is superior to traditional landmark technique for central venous cannulation.13
• To assist in real-time cannulation under direct ultrasound visualization. This is termed 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 enter the vessel under real-time ultrasound guidance. This technique can involve one or two operators.22 With two operators, real-time vessel visualization can be maintained throughout the entire procedure. With a single operator, the transducer must be put down prior to guidewire insertion to free up the nondominant hand. This technique takes full advantage of the benefits of ultrasound-assisted vascular access. The dynamic technique is the approach advocated in the AHRQ report. Although this method may require more 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. 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.15, 23
• 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. 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 19-1 and 19-2). It is important to note that the relative relationship of the carotid artery to 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 take-off of the internal jugular vein is possible using ultrasound guidance (Figure 19-3). 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 contrast, the supraclavicular approach allows for adequate sonographic visualization of the proximal subclavian vein anatomy.

Cannulation of the Subclavian/Axillary Vein Using an Infraclavicular Approach

For this approach, the ultrasound transducer should be placed inferior and lateral to the clavicle. It is oriented in long axis over the proximal axillary vein. Although this is a more lateral approach than the traditional blind infraclavicular technique, it allows for excellent visualization of the axillary vein just before it technically changes name to the subclavian vein (Figure 19-4).

Cannulation of the Femoral Vein

The initial vascular survey is initiated by placing 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. The compression technique may be used to distinguish the readily compressible vein from the less compressible artery (Figure 19-5). In addition, appreciating the variable relationships of the vascular structures with respect to limb position is important. Either the static or dynamic technique can be utilized for femoral vein cannulation. Recent evidence has indicated that the routine use of the femoral vein for central venous access should be limited in adults because of higher complication rates.20

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. 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 intravenous 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 used by novice users.15, 16

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 19-6). 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 19-7a). 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 intravenous catheter placement in the absence of ultrasound guidance. Caution should be taken 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 probe placement and vessel visualization for proximal vein cannulation is demonstrated in Figure 19-7.

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.

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

The purpose of the Pre-scan is to survey the underlying vessels and confirm the target vessel appropriately (Figure 19-8). For internal jugular vein cannulation, three structures should be seen during the pre-scan: thyroid gland, internal jugular vein, and carotid artery. Generally, all three structures should be visualized 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, the position marker should be pointed toward the patient's left side. This will ensure the proper relationship of the underlying anatomy to 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.

The second P stands for Preparation. The patient's skin is prepared for a sterile procedure in the usual fashion. For dynamic cannulation, the transducer is prepared 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 (Figure 19-9). Careful application of coupling gel to the transducer prior to placement in a sterile sleeve is necessary to avoid entrapment of air bubbles. The sterile sleeve is placed and generally secured with elastic bands. Sterile coupling gel will then be applied to the outside of the transducer sleeve prior to further imaging. With the sterile barrier in place, the transducer is ready for use. The use of a sterile glove is an alternative to using a specialized sterile sleeve. The transducer cable will not be sterile and care is required to avoid contaminating the field.

The poke refers to the initial skin puncture (prior to actual venipuncture), which places the needle in the subcutaneous 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 19-10 demonstrates proper needle position for the initial insertion. It should be noted how close the needle is to the transducer.

Following the path of the needle and adjusting the course are keys to successful placement. Tissue motion during real-time imaging of the procedure can help direct the advancing needle prior to visualization of the needle itself. The needle will subsequently be detectable through ring-down artifact (Figure 19-11). The needle is directed toward the vessel while using the monitor display to locate the needle tip. Care must be taken to ensure that the needle tip has been located prior to advancement of the needle. A common error involves mistaking the needle shaft for the needle tip and thereby misjudging the actual tip location. Figure 19-12 illustrates scanning with three different needle vectors. Note the convergence of all three needle paths in the transverse plane. However, each needle tip is in a different location in relation to the vessel. Prior to successful cannulation, the vein will be seen to deform with the pressure of the advancing needle (Figure 19-13). 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 routine technique.

Transducer Orientation: Longitudinal versus Transverse

Variations of probe positioning will yield different information relative to vessel and needle placement. Transverse probe positioning gives information related to lateral orientation. The longitudinal probe position gives depth and slope information (Figure 19-14). The authors generally rely primarily on transverse short-axis imaging to assist with venous cannulation. The transverse short-axis orientation is most helpful with demonstrating relationships to other adjacent anatomy (Figure 19-8). Recent evidence supports the transverse short-axis approach for novice users.24 The longitudinal orientation will help with needle orientation in the long axis of the vessel of interest (Figures 19-15). 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. 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.

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.13

Sterile Technique

There are several different options for maintaining sterile technique. The best option is to use prepackaged sterile probe sleeves that are manufactured solely for the purpose of handling the probe and transducer cord in a sterile fashion (Figure 19-16). Alternatively, the use of a large sterile glove while positioning the probe and adequate amounts of conductive gel into the thumb of the glove can also be effective (Figure 19-17). 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.25 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 (non–ultrasound-assisted) technique, given certain patient positioning, may result in arterial injury or failed venous cannulation (Figure 19-5c).

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, the vessel should be confirmed that it 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 sonologist 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. The vessel should be located 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-dimentional image, the beam should be angled toward the needle where it will enter the vessel. Occasionally, fanning the transducer beam may be required to identify the optimal location. Figure 19-12 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 intravenous 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 intravenous drug use presented for drainage of a deltoid abscess. It was determined that the abscess cauld 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 has a large right basilic vein easily visualized with ultrasound. A 2-inch 18-gauge catheter is inserted without difficulty. The patient's abscess is successfully drained after receiving adequate intravenous 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.