Chapter 31: Vascular Access

Multiple factors determine the route and site for vascular access, and knowing the basic anatomy, techniques, indications, and contraindications is essential to emergency care.

Infusion rate is key in the resuscitation of those with severe hypovolemia or hemorrhage.¹ Infusion rates through a medical catheter behave according to Poiseuille's law:

The rate of flow is directly proportional to the catheter radius and the pressure gradient, and inversely proportional to the dynamic fluid viscosity and catheter length. Flow rates increase with larger catheter radius, use of more pressure (gravity, manual push-pull devices, pressure bag application, or commercial rapid infusing devices), decreasing viscosity (co-administration of crystalloid with viscous blood products), or decreasing catheter length (peripheral angiocatheter vs triple-lumen catheter). Flow rates are maximized by using the largest internal diameter catheter possible.

PERIPHERAL VENOUS ANATOMY OF THE UPPER EXTREMITY

The most commonly accessed veins for peripheral catheterization of the upper extremity are the dorsal hand veins and the veins of the antecubital fossa (Figure 31-1).

Peripheral catheterization of the superficial veins of the lower extremity can require cutdown of the great and small saphenous veins. The femoral vein is the primary deep vein of the lower extremity. It is located medial to the femoral artery.

TECHNIQUE FOR PERIPHERAL VENOUS ACCESS

Gather all equipment before beginning the procedure (Table 31-1). Observe universal precautions. The procedure for peripheral IV line insertion is summarized in Table 31-2.

Avoid venous access through or distal to areas of infection, injury, or sites of potential vascular disruption (e.g., injury to the inferior vena cava from abdominal trauma). Also avoid using extremities with arteriovenous fistulas or grafts or those in which there have been previous lymph node dissections. If possible, avoid IV access of the lower extremity in diabetics due to an increased risk of infection and phlebitis. Do not use peripheral venous access to administer vasopressors for infusion, sclerosing solutions, concentrated electrolyte or glucose solutions, or cytotoxic chemotherapeutic agents.

POSTPROCEDURE CARE

Flush peripheral catheters with normal saline every 8 hours; change dressings that are damp or soiled, and change the catheter site every 72 to 96 hours.² Risk of infection and thrombophlebitis increases with time. Assess the skin for signs of infection (erythema) or infiltration (induration, edema). Reassess catheter function and neurovascular status of the distal extremity frequently.

Complications

The complications of peripheral venous access are listed in Table 31-3. The first step in treating all complications is catheter removal.

US-GUIDED PERIPHERAL ACCESS

US can localize veins with inconsistent anatomic relationships or those too deep to palpate. US-guided peripheral IV placement results in high success rates, few complications, and a decreased need for central vein cannulation.^5,6 The cephalic and brachial veins, which are not readily palpable, are easily located and cannulated using US guidance.

When inserting an IV using US guidance, use a high-frequency linear transducer. Vascular structures are anechoic (black) in US imaging. Key sonographic characteristics help distinguish veins from arteries. Veins are more easily compressed, have thinner walls, and have no arterial pulsation. Color flow may also help differentiate between the two structures. A centimeter scale on the US monitor indicates the depth of the vessel.

To locate a vessel, view it in short axis (transverse plane) and long axis (sagittal plane), then center the vessel on the screen. The midpoint of the screen correlates with the midpoint of the transducer. Introduce the catheter into the skin at the transducer's midpoint and direct it toward the vessel lumen. Use a longer catheter (2.5 in. or 6.4 cm) for deeper vessels. Watch the screen as the catheter enters the vessel lumen. Secure the catheter and apply a sterile dressing to the IV line.

The indications for central venous catheterization are listed in Table 31-4. The indication for direct central venous access in the setting of resuscitation of cardiac arrest is debated.

CENTRAL VENOUS ANATOMY

The most frequent sites used for central venous access are the internal jugular, subclavian, and femoral veins (Figures 31-3 and 31-4). The external jugular vein, a superficial structure, also provides a route to the central circulation but is technically a peripheral site.

The clavicles, first ribs, sternum, sternocleidomastoid, platysma, and other strap muscles of the neck overlie the internal jugular and subclavian veins (Figure 31-3). The internal jugular vein lies lateral to the internal carotid artery inside the carotid sheath. The internal jugular vein joins the subclavian vein to form the brachiocephalic vein.

The subclavian vein crosses under the clavicle at the medial to proximal third of the clavicle. The subclavian artery lies posterior and superior to the brachiocephalic vein. The thoracic duct joins the left subclavian vein at its junction with the left internal jugular vein. The domes of the pleura lie posterior and inferior to the subclavian veins and medial to the anterior scalene muscles.

The femoral vein is the most accessible central vein below the waist. It travels in the femoral sheath with the femoral artery, nerve, and lymphatics deep to the medial third of the inguinal ligament. A mnemonic for the anatomy of the femoral structures from lateral to medial is NAVEL: nerve, artery, vein, empty space, and lymphatics.

TECHNIQUE FOR CENTRAL VENOUS ACCESS

After gaining consent if possible, identify the access site and approach and position the patient. Prepare all materials before the procedure (Table 31-5). Use a procedure checklist to optimize infection prevention practices.

The technique for all approaches is summarized in Table 31-6 and depicted in Figure 31-5.

COMPLICATIONS

Complications of central venous catheterization are listed in Table 31-7.

Complication rates increase with each additional attempt or percutaneous puncture. Accidental arterial puncture during internal jugular cannulation can lead to hematoma formation and airway compromise. Carotid arterial puncture may result in acute plaque rupture and stroke in patients with known carotid artery stenosis or atherosclerosis. Femoral lines often become infected and thrombose (nearly 20% each in some studies) and so are avoided for longer use. Do not use the subclavian approach in patients with coagulopathy because accidental subclavian arterial puncture or injury is not amenable to direct vascular compression.

US-GUIDED CENTRAL VENOUS ACCESS

US-guided central venous access increases first attempt success rates and decreases the number of attempts needed for success when compared to the unassisted standard method. Complication rates are similar in both techniques. The technique of US-guided central venous access is similar to peripheral venous access described previously.

TECHNIQUES OF COMMONLY USED APPROACHES

External Jugular Vein

The external jugular vein is readily available due to its superficial location in the subcutaneous tissue overlying the sternocleidomastoid muscle. Place the patient in the head-down position or use Valsalva maneuvers to distend the vein and improve visualization. Entering a central vein via the external jugular vein is difficult and rarely successful without using a J wire; it is often not required because the site accommodates large-volume flow. Puncture the skin at a 10-degree angle. Placement is aided by tilting the head to the contralateral side, applying skin traction to "straighten" the course of the vein, and by rotating the guidewire 180 degrees before re-advancement if the first pass fails.

Internal Jugular Vein

US-Guided Approach

The internal jugular vein is easily located with US guidance.

Place the probe on the sternocleidomastoid muscle (Figure 31-6). Identify the thyroid gland and carotid artery in addition to the internal jugular vein. Do not attempt needle insertion before visualizing all three structures.

Traditional Approaches

The three traditional approaches to internal jugular vein catheterization are central, posterior, and anterior. The right internal jugular has a shorter, straighter course to the superior vena cava and avoids injury to the thoracic duct on the left; use this site unless contraindications exist.

Central Approach

Place the patient in Trendelenburg position, head slightly tilted to the contralateral side. The landmark for the central approach is the triangle created by the clavicle and the sternal and clavicular heads of the sternocleidomastoid. The internal jugular vein lies just deep to this triangle. Insert the needle at a 30- to 45-degree angle to the skin, 1 cm below the apex of the triangle, parallel to the carotid artery located medially, and directed toward the ipsilateral nipple (Figure 31-7). Successful venous return typically occurs within 1 to 3 cm of needle advancement.

Posterior Approach

The landmark for the posterior approach is the lateral aspect of the clavicular portion of the sternocleidomastoid, one third of the distance from the clavicle to the mastoid process. The needle is directed toward the sternal notch (Figure 31-8). Successful venous return typically occurs within 3 to 5 cm of needle advancement.

Anterior Approach

Identify the pulse and course of the carotid artery, which lies just medial to the site of entry for the anterior approach. Hold the carotid artery with fingers of the nondominant hand. Hold the needle and syringe in the dominant hand at an angle of 30 to 45 degrees and enter at the midpoint of the medial aspect of the sternal portion of the sternocleidomastoid muscle. Aim the needle toward the ipsilateral nipple (Figure 31-9). Successful venous return typically occurs within 3 to 5 cm of needle advancement.

See Table 31-8 for a summary of traditional approaches to internal jugular vein catheterization.

Subclavian Vein

The location of the subclavian vein allows patient mobility and is an excellent choice for longer-term use.

US-Guided Approach

The supraclavicular approach allows good sonographic visualization of the proximal subclavian vein anatomy. The infraclavicular approach to US-guided subclavian vein catheter placement is limited by the large acoustic shadow created by the clavicle (Figure 31-10).

Traditional Approaches

The two traditional approaches to the catheterization of the subclavian vein are the infraclavicular and supraclavicular (Figure 31-11).

Infraclavicular Approach

Place the patient head down and in a neutral position with a small towel under the thoracic spine to help identify the clavicle. The landmark for the site of entry is the junction of the middle and medial thirds of the clavicle. Orient the bevel of the needle inferomedially to direct the guidewire to the brachiocephalic trunk rather than the internal jugular vein. Align the numbered markings on the syringe with the bevel of the needle to guide the orientation of the bevel once the needle has breached the skin. Place the index finger of the nondominant hand at the suprasternal notch and the thumb at the midpoint of the clavicle. Direct the needle toward the suprasternal notch at a 10-degree angle parallel to the surface of the chest (Figure 31-12). If the clavicle is encountered, "walk" the needle down the clavicle until the needle is posterior to it. Successful venous return occurs typically at a depth of 3 to 5 cm.

Supraclavicular Approach

The supraclavicular approach is often referred to as the "pocket-shot." The supraclavicular approach has fewer failures, fewer catheter malpositions, and less interference with CPR than the infraclavicular approach. It may also be performed in the upright position in patients unable to lay supine in the setting of severe orthopnea.

The landmark for entry is 1 cm lateral to the clavicular head of the sternocleidomastoid and 1 cm posterior to the clavicle. Enter at an angle of 10 degrees above horizontal. Orient the bevel of the needle medially, bisecting the angle formed by the clavicle and sternocleidomastoid toward the contralateral nipple. Successful venous return typically occurs at a depth of 2 to 3 cm (Figure 31-13).

COMPLICATIONS

The risk of pneumothorax is higher when cannulating the subclavian vein. If attempts at subclavian venous access fail on one side, assess for pneumothorax using chest x-ray or US before attempting cannulation on the contralateral side.

Femoral Vein

The femoral vein is the most accessible central access site during critical illness, notably cardiac arrest.

US-Guided Approach

Place the transducer in a transverse position just below the midportion of the inguinal ligament. Identify the femoral vein just below the inguinal ligament and medial to the femoral arterial pulsation. The vein is more easily compressed than the artery. The relationship among the vessels varies depending on limb position (Figure 31-14).

Traditional Approach

Place the patient supine in reverse Trendelenburg position with the hip slightly abducted and leg slightly externally rotated.^7,8 Palpate the femoral artery, if possible. Classically, the femoral vein is just medial to the femoral artery and 1 to 2 cm below the inguinal ligament, although US often demonstrates an anomalous position, which is one reason why landmark-based insertions are less successful (Figure 31-15). Use a 45-degree angle of approach.

In pulseless arrest, locate the femoral vein using the "V" technique. Place the thumb on the pubic tubercle and the index finger on the anterior superior iliac spine. The femoral vein is typically located at the interdigital space (the "V" of the finger and thumb) just inferior to the inguinal ligament.

Always insert the needle below the inguinal ligament, because vascular injury above the inguinal ligament may cause severe hidden hemorrhage into the retroperitoneal space.

Limit femoral vein cannulation because of the higher complication rates (notably infection and thrombosis) and the limits it places on patient mobility.

Venous cutdown is typically performed on the saphenous vein, anterior and superior to the medial malleolus.

IO vascular access is used in patients of all ages when venous access cannot be quickly and reliably established during circulatory collapse.⁸ The commercial EZ-IO^® (Vidacare Corp., San Antonio, TX) eases procedure performance (Figure 31-16). Contraindications to IO access include proximal ipsilateral fracture, ipsilateral vascular injury, and severe osteoporosis or osteogenesis imperfecta.

TECHNIQUE FOR IO ACCESS

Use either a standard bone marrow aspiration needle or specialized IO infusion needle. In children, the site of entry is two finger-widths (2 cm) below the tibial tuberosity on the medial, flat surface of the proximal tibia (Figure 31-17). Use other sites, such as the medial malleolus, distal femur, sternum, humerus, and ileum, in adults, because the tibia is thick and difficult to penetrate.

The procedure for manual insertion of IO venous needles is summarized in Table 31-9 and illustrated in Figure 31-18.

COMPLICATIONS

Complications of IO access include cellulitis, osteomyelitis, iatrogenic fracture or physeal plate injury, and fat embolism (rare).

A number of medications can be administered via the endotracheal tube in the critical minutes of resuscitation before IV access is obtained. These medications include lidocaine, epinephrine, atropine, and naloxone (mnemonic LEAN). The most commonly administered medication is epinephrine, given as a high-concentration preparation of 1 milligram/mL (1:1000) with a recommended dose of 2 to 2.5 milligrams in adults.⁹

Dosage recommendations are empirical and usually double or triple the standard IV dose⁹ diluted in 3 to 5 mL of normal saline. After injecting the medication down the tube, administer several positive-pressure ventilations with a bag-to-tube device.

Outcomes after endotracheal drug administration during cardiac arrest are inferior to IV administration.¹⁰ With other access techniques possible, notably IO, this route has little utility even in cardiac arrest.

The indications for arterial line placement are listed in Table 31-10.

RADIAL ARTERY ANATOMY

The most common site for arterial line placement is the radial artery due to the ease of identifying its location and its accessibility at the wrist. The collateral artery blood supply provided by the arterial artery lowers the risk of complications (Figure 31-19). The anatomic landmarks for the radial artery are medial to the radial styloid process and lateral to the flexor carpi radialis tendon at the proximal flexor crease of the wrist. A palpable radial pulse should be felt, and radial and ulnar artery compression tests (release of latter to assess collateral circulation, looking for hand to "pink up" rapidly—called the Allen test) are done prior to any puncture, although the latter test has a limited ability to predict later ischemic complications.

FEMORAL ARTERY ANATOMY

As discussed in the section on femoral central venous access, the femoral artery lies in the femoral triangle inferior to the inguinal ligament, midway between the pubic symphysis and the anterior superior iliac spine (Figure 31-4). A longer catheter is typically needed to cannulate the deeper femoral artery compared to the radial artery.

ALTERNATIVE ARTERIAL SITES

Other sites for arterial catheter placement include the dorsalis pedis artery and the brachial artery. Similar to the radial artery, the dorsalis pedis artery is superficial and easy to identify, and the foot has collateral circulation similar to the hand. The brachial artery is located just medial to the biceps brachii muscle in the antecubital fossa adjacent to the medial nerve. The lack of collateral blood flow at the level of the brachial artery increases the risk of upper extremity ischemia and is avoided for this reason.

TECHNIQUE FOR ARTERIAL ACCESS

After explaining the procedure and gaining consent, identify the access site and approach and position the patient with all materials at the bedside (Table 31-11).

The technique for all approaches is summarized in Table 31-12 and Figures 31-20, 31-21, and 31-22. The direct puncture approach is less likely successful, takes longer, and requires more puncture attempts than the integral wire approach.

POSTPROCEDURE CARE

Secure the arterial catheter to the skin either by suture or adhesive catheter locking device with a sterile transparent protective dressing placed over the site. An arm board or wrist splint may aid securing a radial artery line. Monitor the site regularly for dislodgment, hematoma, bleeding, infection, or distal ischemia. The dressing should be changed regularly, and the necessity for the line should be determined daily.

COMPLICATIONS

The complications of peripheral venous access are listed in Table 31-13. The first step in treating all complications is catheter removal. Direct pressure should be applied a minimum of 3 to 5 minutes after removal at all peripheral sites and 10 minutes for a femoral site.

Air embolization from an arterial catheter is more likely to have adverse sequelae than from venous catheterization because of no pulmonary filtration. Infection rates increase with poor aseptic technique and duration of catheter use. Thrombosis occurs in up to 25% of patients who have an arterial catheter, although clinical morbidity occurs in less than 1%. Femoral artery catheterization can lead to concealed retroperitoneal hematoma and major hemorrhage. Neuropathies can occur from direct nerve injury from cannulation attempts or hematoma formation causing nerve compression. Brachial artery sites can lead to median nerve neuropathy, and an axillary artery site complication can result in brachial plexopathy.

US-GUIDED ARTERIAL ACCESS

US-guided arterial puncture aids cannulation, especially when a palpable pulse is difficult to identify.¹¹ Key sonographic characteristics to identify arteries include round, pulsatile, thick-walled vessels that are difficult to compress.