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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.
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CENTRAL VENOUS ANATOMY
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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.
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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.
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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.
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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.
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TECHNIQUE FOR CENTRAL VENOUS ACCESS
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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.
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The technique for all approaches is summarized in Table 31-6 and depicted in Figure 31-5.
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Complications of central venous catheterization are listed in Table 31-7.
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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.
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US-GUIDED CENTRAL VENOUS ACCESS
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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.
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TECHNIQUES OF COMMONLY USED APPROACHES
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External Jugular Vein
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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.
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Internal Jugular Vein
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The internal jugular vein is easily located with US guidance.
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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.
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Traditional Approaches
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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.
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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.
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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.
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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.
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See Table 31-8 for a summary of traditional approaches to internal jugular vein catheterization.
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The location of the subclavian vein allows patient mobility and is an excellent choice for longer-term use.
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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).
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Traditional Approaches
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The two traditional approaches to the catheterization of the subclavian vein are the infraclavicular and supraclavicular (Figure 31-11).
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Infraclavicular Approach
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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.
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Supraclavicular Approach
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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.
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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).
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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.
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The femoral vein is the most accessible central access site during critical illness, notably cardiac arrest.
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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).
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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.
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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.
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Always insert the needle below the inguinal ligament, because vascular injury above the inguinal ligament may cause severe hidden hemorrhage into the retroperitoneal space.
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Limit femoral vein cannulation because of the higher complication rates (notably infection and thrombosis) and the limits it places on patient mobility.