Placement of subclavian venous catheters

INTRODUCTION — Central catheters provide dependable intravenous access and enable hemodynamic monitoring and blood sampling [1-3]. The subclavian veins are an often favored site for central venous access, including emergency and acute care access, and tunneled catheters and subcutaneous ports for chemotherapy, prolonged antimicrobial therapy, and parenteral nutrition. However, antecedent subclavian access has been associated with subsequent complications, particularly among those with chronic kidney disease who subsequently require hemodialysis arteriovenous access.

The initial selection of central venous access site and type of device are reviewed separately. (See "Central venous access: Device and site selection in adults" and "Central venous access in adults: General principles", section on 'Device and site selection'.)

Once a subclavian access site has been selected as the best appropriate site, this topic guides the placement.

Other considerations, complications of venous access, and issues related to other access sites are discussed elsewhere. (See "Central venous access in adults: General principles" and "Central venous catheters: Overview of complications and prevention in adults" and "Placement of jugular venous catheters" and "Placement of femoral venous catheters".)

SUBCLAVIAN VEIN ANATOMY — The clavicle is the primary surface landmark for subclavian cannulation (picture 1). Moving laterally from the suprasternal notch, the bulky sternal head takes an elongated S-shape (a double curve in the horizontal plane); the medial two-thirds are convex anteriorly, and the lateral third is concave anteriorly. The anterior convexity at the junction of the medial and middle thirds is known as the "bend" or "break" in the clavicle and serves as an important palpable landmark. (See 'Subclavian vein cannulation' below.)

The subclavian vein is the direct continuation of the axillary vein beginning at the lateral border of the first rib (figure 1 and picture 1). The vein arches cephalad behind the medial clavicle and then slopes caudally to join the internal jugular vein, forming the brachiocephalic (innominate) vein posterior to the sternoclavicular joint. The vein is accompanied by the subclavian artery located superior and posterior to the vein and separated from the vein by the anterior scalene muscle.

The neck is a complex area with multiple structures traversing the thoracic outlet. Injury is avoided by knowing the location of these structures relative to the subclavian cannulation sites.

●The lung lies deep and inferior to the medial portion of the subclavian vein. The dome of the left lung often extends above the level of the first rib on the left, but rarely on the right.

●The phrenic nerve passes inferiorly along the anterior aspect of the anterior scalene muscle and posterior to the origin of the brachiocephalic vein.

●The brachial plexus is superior and deep to the medial portion of the subclavian artery.

●The left-sided thoracic duct and right-sided lymphatic duct course posterior to the subclavian vein and enter the vessel near the confluence of the subclavian and internal jugular veins.

GENERAL PREPARATION — General considerations for patient preparation, including catheter and access site selection, monitoring and sedation, measures to control infection, and consent, are discussed elsewhere. (See "Central venous access in adults: General principles", section on 'General preparation'.)

Equipment — Subclavian venous catheters and other venous devices are usually placed via the Seldinger or modified Seldinger technique in a series of defined steps. Prefabricated kits containing all necessary materials are available for most devices. Typical supplies are described in (table 1) [4]. For nontunneled catheters, the steps for central venous catheterization are detailed in the table (table 2). For tunneled catheters and other devices, the steps are similar except that a sheath is placed over the guidewire and the catheter (or other device such as pacemaker leads, filter) is placed through the sheath, which is then removed.

Prior to the placement of subclavian venous catheters, assemble the following equipment:

●Ultrasound machine (see "Basic principles of ultrasound-guided venous access", section on 'Ultrasound machine')

●Sterile ultrasound transducer gel

●Central venous access kit with appropriate venous catheter or sheath

●Sterile drapes, gloves, gown, surgical mask, and cap

●Topical antiseptic (eg, chlorhexidine, povidone iodine) (see "Overview of control measures for prevention of surgical site infection in adults", section on 'Skin antisepsis')

●Local anesthetic (see "Clinical use of topical anesthetics in children" and "Subcutaneous infiltration of local anesthetics")

●Isotonic saline and/or heparin to flush the catheter lumens

●Transparent adhesive dressing, tape

●Intravenous tubing and connectors (eg, needleless Luer connector, three-way stopcock)

Proper functioning of any required fluoroscopic equipment should be verified. Fluoroscopy is rarely required for subclavian venous access but is routine when implanting catheters or devices (eg, pacemaker, defibrillator, vena cava filter).

Skin preparation — For subclavian venous access, a wide skin preparation that includes the neck and chest above the nipple line allows the operator to attempt cannulation at an alternative ipsilateral target (eg, jugular vein), if the initial site fails. If difficult access is anticipated, the neck and chest can be prepared bilaterally.

Positioning — For subclavian venous access, the clinician should position the patient's bed or procedure table at a comfortable height. The position of the operator depends upon the vein cannulation technique chosen. We prefer to stand at the patient's shoulder for infraclavicular access. Standing at the head of the bed is an alternative for the supraclavicular approach. (See 'Approaches to the subclavian vein' below.)

Unlike the jugular vein, Trendelenburg positioning does not significantly affect subclavian diameter, but Trendelenburg positioning may help prevent air embolus [5-9]. Most patients can be safely positioned supine or in Trendelenburg position. However, critically ill and patients with obesity may develop respiratory compromise, and close monitoring is required. Successful supraclavicular subclavian cannulation has been performed in upright and prone positions under extenuating circumstances [10]. Some patients may require anesthesia with a controlled airway for safe placement of central venous catheters and devices. (See "Anesthesia for the patient with obesity", section on 'Patient positioning'.)

Various anatomic studies have shown that the relationship between the subclavian vein and clavicle changes with head, arm, and shoulder positioning [6,7,11-14]. Shoulder elevation shifts the point of intersection of the vein with the clavicle more medially, and the length of overlap is reduced. Thus, to facilitate subclavian cannulation, we generally place the patient's arm along the torso (adducted) and use a neutral-to-lower shoulder positioning, which increases the area of contact between the subclavian vein and the undersurface of the clavicle, providing a consistent landmark. A shoulder position 5 cm below neutral shoulder position appears to provide maximal amount of overlap and can be facilitated by placing a small sandbag or rolled towel between the scapulae, if necessary [13]. However, retraction of the shoulders was shown in one small trial to be unnecessary [15]. The natural tendency for the shoulders to assume a cephalad orientation with Trendelenburg position can be countered by gentle caudal traction on the arm performed by a bedside assistant. One small clinical trial demonstrated improved cannulation with caudal arm traction [13].

●For infraclavicular subclavian access (figure 2 and picture 1), shoulder retraction facilitates needle insertion by reducing the deltoid prominence [16] and also positions the vein closer to the clavicle for a more consistent landmark [7,12]. Avoid excessive retraction because this reduces the anterior-posterior dimension of the vein, flattening it [17]. Recommendations to turn the head toward the side of the cannulation are based on anatomic studies and reduced catheter malposition in a single pediatric study, but such positioning had no effect in trials on adult patients [17-19].

●In contrast to the classic arm adducted position, arm abduction 90 degrees to the torso was demonstrated to increase vessel diameter in more than half of patients [20]. One small trial also demonstrated a reduced incidence of catheter misplacement when the arm was abducted 90 degrees from the trunk during infraclavicular cannulation.

●For supraclavicular subclavian access (figure 3A-B), the lateral border of the clavicular head of the sternocleidomastoid muscle is an important landmark. Contralateral rotation of the head away from the site of access provides unobstructed access [21]. Resisted head turn toward the cannulation site activates the sternocleidomastoid muscle to accentuate recognition of the landmark.

SUBCLAVIAN SITE SELECTION — Right-handed operators often prefer right-sided subclavian access procedures. Right subclavian anatomy carries the theoretical advantage of lower risk of complications due to the lower pleural apex and absence of the thoracic duct. However, right-sided subclavian access is associated with higher rates of catheter malposition and vessel trauma compared with left-sided access [22]. As such, left subclavian access may be preferred when immediate cardiac access is needed (eg, temporary transvenous pacer placement, pulmonary artery catheter) since the guidewire and catheter are more consistently directed into the superior vena cava and right heart.

We recommend access ipsilateral to the compromised lung in patients with significant unilateral lung disease to avoid respiratory compromise in the event of a procedure-related pneumothorax.

In patients with prior catheter placement in the subclavian or internal jugular veins, or a history of upper extremity deep venous thrombosis, consider ultrasound to assess venous patency prior to attempting subclavian access. (See "Catheter-related upper extremity venous thrombosis in adults", section on 'Duplex ultrasonography'.)

SUBCLAVIAN VEIN CANNULATION — The subclavian vein is generally cannulated using one of three anatomic approaches, with a large-bore access needle using landmark techniques. Following cannulation, subclavian catheters are placed using an orderly sequence of steps (table 2).

Vein access — Although ultrasound-guided subclavian venous access has been described, landmark techniques remain the standard approach.

Role of ultrasound guidance for subclavian access — Ultrasound guidance is commonly used and recommended for internal jugular and femoral venous access sites. Acoustic shadowing from the overlying clavicle and rib can obscure the underlying vascular structures, making an ultrasound-guided approach technically challenging during subclavian access. Nevertheless, real-time ultrasound guidance for both infra- and supraclavicular approaches to the subclavian vein have been described [23-25]. A 2015 systematic review of 10 randomized trials demonstrated that ultrasound-guided subclavian catheterization reduced overall complications compared with the landmark technique (odds ratio 0.53, 95% CI 0.41-0.69) but did not alter success rates [26]. The principles of ultrasound in guiding venous access are discussed in detail elsewhere. (See "Central venous access in adults: General principles", section on 'Infraclavicular venous access'.)

Access techniques — Typically, the subclavian vein is accessed using a thin-walled introducer needle. A micropuncture kit (picture 2) or seeker needle may, at times, be useful, although this is less commonly used compared with internal jugular vein cannulation. An angiocatheter over needle assembly is less commonly used to access the subclavian vein. The general technique for each of these is described below. Isolated arterial needle puncture is one of the most common complications of venous access but is typically uneventful if recognized prior to vessel dilation [27]. Clinical confirmation that the access needle is in the vein is essential prior to dilating the vessel. (See 'Venous confirmation' below.)

There is a learning curve for central venous access procedures [28]. Experienced operators enjoy greater success rates with fewer complications. Among experienced or inexperienced operators, complication rates increase with the number of introducer needle passes and are significantly higher after two unsuccessful passes [2,29,30]. If two unsuccessful attempts have been performed, we recommend needle removal and reassessment of surface landmarks with reconsideration of the approach and assistance from an experienced proceduralist [2,16,31].

Introducer needle — To access the subclavian vein with an 18-gauge, thin-walled standard introducer needle:

●Insert the introducer needle into the skin and apply continuous negative pressure by pulling back on the plunger of the syringe. Vein penetration will not be recognized unless negative pressure is applied, but only a small amount of continuous negative pressure is needed (approximately 1 cc of a 10-cc syringe) during advancement of the needle.

●Traditionally, the bevel is directed anteriorly (bevel up) during insertion; however, orienting the bevel of the needle posteriorly (bevel down) may decrease the risk of needle tip penetration of the posterior vein wall (ie, "past-pointing") [32].

●Always advance and withdraw the needle in the same vector. Lateral movement of an inserted needle can lacerate vessels and should not be done. Prior to any redirection of the needle, it should be withdrawn to the skin surface.

●Anticipate that venous backflow into the introducer needle will be sudden, and steady the position of your hand to avoid dislodgement from the vein when this occurs.

●Failure to aspirate blood during needle advancement is common. In this circumstance, withdraw the needle slowly while maintaining continuous negative pressure. Venous puncture may only be recognized during needle withdrawal as the compliant vein may not be punctured during initial needle advancement in up to one-third of cases [23]. Once access is achieved, stabilize the hub of the needle and carefully remove the syringe to avoid dislodging the introducer needle from the vessel.

●Cover the hub of the needle between manipulations and coordinate hub exposure with the patient's exhalation to avoid air entry during the subclavian access. Encourage the patient to hum or perform Valsalva maneuvers to augment central venous pressure.

Micropuncture needle — Although more commonly used for internal jugular vein localization, a 3.5-cm small-caliber (21- to 22-gauge) micropuncture (picture 2) or exploratory (seeker or finder) needle may help locate the subclavian vein (picture 3) [31,33,34]. This technique minimizes injury in the event of inadvertent arterial puncture. However, with the infraclavicular subclavian vein approach, a standard micropuncture needle may not be long enough to reach the vessel in some patients.

To use a micropuncture needle to aid introducer needle placement:

●As described above for large-bore needle access, insert the micropuncture needle while applying negative suction on the plunger of the syringe; more suction will be required (approximately 2 to 3 cc of a 10-cc syringe). Steady, unimpeded blood return confirms intraluminal venous placement.

●Once the needle enters the vein, withdraw the micropuncture needle, noting the angle and depth needed to reach the vein. Alternatively, remove the syringe, leaving the micropuncture needle in place to anchor the vessel and provide a guide for venous access by the introducer needle. While applying negative pressure to the syringe, advance the needle in the same vector, or alongside the preceding micropuncture needle, into the vein.

Angiocatheter — The catheter-over-needle technique uses an 18-gauge plastic angiocatheter mounted over a 20-gauge access needle. It is more commonly used for supraclavicular subclavian vein access compared with the infraclavicular approach. Stable venous access via the flexible angiocatheter during manometry for venous confirmation prior to guidewire placement is a perceived benefit of the angiocatheter technique. A single randomized trial comparing the traditional introducer needle technique with the catheter-over-needle technique for right infraclavicular subclavian cannulation demonstrated lower complications and improved first pass and overall success with the introducer needle [35]. The technique for using an angiocatheter to access deep veins is described separately. (See "Placement of jugular venous catheters", section on 'Angiocatheter' and "Placement of femoral venous catheters", section on 'Angiocatheter'.)

Approaches to the subclavian vein — The subclavian vein can be approached from above or below the clavicle. The landmarks and needle placement for each of these approaches are presented below.

Infraclavicular approach — Three insertion points are described for the infraclavicular approach to the subclavian vein. The midpoint approach is the most commonly used technique [3,12].

●For the midpoint approach, the needle is inserted 2 to 3 cm inferior to the midpoint of the clavicle (approximately 1 to 2 cm lateral to the bend of the clavicle) and directed just posterior to the suprasternal notch (figure 2 and picture 4).

●A lateral needle insertion (lateral to the midclavicular line) takes advantage of the thin anterior convexity of the clavicle to facilitate a level coronal approach, which may improve safety if the vessel can be reached by the cannulating needle [12,13,36].

●The medial insertion point is along the inner third of the clavicle. The needle is directed cephalad toward the suprasternal notch to penetrate the vessel at the broad confluence of the great veins. The downside of this method is that medial positioning requires a steep approach beneath the thick medial clavicle and passage through intervening soft tissue, including the costoclavicular ligament.

After the needle has penetrated the skin, the clavicle may be initially contacted. Take care not to push the needle into the periosteum, as bone plug can occlude the lumen of the needle. The needle should be gently "walked" deeper to reach the underside of the clavicle. The needle should remain parallel to the clavicle (in the coronal plane) to allow it to pass cleanly beneath the bone and minimize the risk of pleural puncture. As the needle passes beneath the junction of the middle and medial thirds of clavicle, it should enter the vein. If the first needle pass is unsuccessful, orient the needle more cephalad on subsequent attempts.

An observational study at a large trauma center evaluated common errors during infraclavicular subclavian venous acces [37]. The most frequently observed errors during videotaped assessment of venous cannulation in 86 patients included improper or inadequate identification of anatomic landmarks, improper needle insertion site, too shallow a needle trajectory, and insertion of the needle through the periosteum of the clavicle.

Supraclavicular approach — The supraclavicular approach aims to puncture the subclavian vein near its junction with the internal jugular vein. The insertion of the clavicular head of the sternocleidomastoid is the access landmark for this approach (figure 3A and figure 3B).

The subclavian vein is 1 to 1.5 cm deep to the skin and easily reached using a micropuncture needle if this is preferred [38]. The micropuncture needle, large-bore cannulation needle, or angiocatheter is inserted 1 cm posterior to the sternocleidomastoid and 1 cm cephalad to the clavicle. The needle is depressed 10 to 15 degrees below the coronal plane and oriented to bisect the angle formed at the base of clavicle and sternocleidomastoid (picture 5). Advance the needle toward the venous confluence behind the medial clavicle along a trajectory aimed just inferior to the contralateral nipple.

Axillary approach — This approach, which accesses the vessel at the junction of the subclavian and axillary veins, typically uses an ultrasound-guided infraclavicular technique.

Venous confirmation — An intraluminal position of the needle can be confirmed by observation of the needle entering the vein with ultrasound-guided access when used. Otherwise, steady return of dark-colored venous-blood into the syringe is a first confirmation of venous access. Bright red and high-pressure pulsatile bleeding are important clues to arterial puncture [39]. The absence of these signs is not perfectly reliable for excluding inadvertent arterial puncture. Dark, nonpulsatile backflow of blood may be seen with arterial puncture in the face of oxygen desaturation, shock, or needle malposition. If there is doubt, the needle location can be confirmed by pressure transduction. As an alternative, a blood gas can be drawn from the accessed venous site and compared with an arterial sample; however, blood gas analysis is more time consuming.

To transduce the blood pressure:

●Attach the needle directly to the pressure tubing system.

●Alternatively, replace the needle over a guidewire with an appropriate-length angiocatheter or 18-gauge single-lumen transduction catheter (without any intervening dilation). Connect the transduction catheter to a pressure line and transducer and evaluate the pressure and waveform tracings on the monitor. Typical venous waveforms should be seen (figure 4).

●If a pressure transduction system is not available, attach a short length of saline-filled intravenous tubing to the needle and hold it vertically to measure the pressure, which should approximate anticipated venous pressure and demonstrate respiratory variation.

Steady, unimpeded blood return confirms intraluminal placement. The hub of the needle should be stabilized and the syringe carefully removed to avoid dislodgement from the vessel. The needle hub should be covered between manipulations to avoid the entry of air. The patients can be encouraged to hum or perform Valsalva maneuvers to augment central venous pressure, and hub exposure can be coordinated with spontaneous exhalation to avoid aspiration of air.

If the subclavian artery is inadvertently punctured, the needle can be withdrawn and pressure applied over the site for 5 to 10 minutes. Elevating the ipsilateral arm overhead may help to compress the artery. If subclavian artery catheterization is confirmed, the catheter should be left in place and vascular consultation obtained.

CATHETER PLACEMENT — Most catheters and other central venous devices are placed using the Seldinger method, which refers to the use of a guidewire placed into a vessel to provide a conduit for intravascular device placement [4]. Seldinger first described the guidewire technique for arterial cannulation in 1953, and it was subsequently adopted for venous access procedures [4].

Guidewire handling — Once the subclavian vein has been successfully accessed, a guidewire should be advanced through the needle or angiocatheter. Multiple types of wires are available to assist with venous access procedures. The most commonly used wire for initial subclavian venous access is a flexible J-tip guidewire, favored because it negotiates curvatures and minimizes vessel trauma during passage (picture 6).

The subclavian approach (particularly from the right side) has the highest rate of catheter malposition compared with other access sites (jugular, femoral), which is due to errant positioning of the guidewire [1]. Head position alters the relationship of the subclavian vein and may affect guidewire placement. (See 'Positioning' above.)

The J-tip guidewire passage is influenced by the needle bevel and J-tip orientation. Orienting of the needle bevel caudally for infraclavicular access and medially for supraclavicular access facilitates guidewire passage from the subclavian vein into the superior vena cava [21]. Similarly, passage of guidewire with the J-tip directed caudally improves correct placement [40].

Complaints of facial pain following guidewire placement often indicate passage into the internal jugular vein. Manual occlusion of the ipsilateral jugular vein during guidewire placement may decrease malposition into it [41].

The guidewire should always pass smoothly and easily thorough the needle, dilator, or catheter without resistance. Methods to address resistance to guidewire advancement or withdrawal are discussed below.

To place the guidewire:

●Position the tapered plastic introducer to straighten the distal J-tip (picture 7). The orientation of the introducer needle bevel tip and the J-tip of the guidewire can help facilitate the direction of wire passage.

●Maintain the residual length of guidewire (50-cm standard length) under constant manual control to maintain sterility and avoid its loss off the operating field.

●Advance the guidewire only as far as needed to allow passage of the catheter over the wire. Guidewires (and catheters) rarely require positioning more than 20 cm deep [42,43]. The atriocaval junction averages 18 cm for right subclavian access and 21 cm from the left subclavian [42]. These average values vary depending upon stature. In an Asian study, average distances were slightly shorter at 14 cm for the right subclavian vein and 17 cm for the left subclavian vein [44]. Advancing the guidewire deeper risks intracardiac or inferior vena cava (IVC) wire placement with the potential for cardiac arrhythmia, perforation, and snaring of other intravascular devices [45].

●Never forcefully advance the guidewire, as this can kink and permanently deform the wire and risks vessel injury. The guidewire should always pass smoothly and easily thorough the needle, dilator, or catheter without resistance. Resistance to guidewire passage can be due to needle dislodgement, compression of the guidewire against the vessel wall, or anatomic obstruction. Rotating the needle and/or guidewire to reorient the bevel or J-tip may relieve impingement of the guidewire on the posterior vessel wall.

●If resistance persists, remove the guidewire and aspirate blood to confirm intraluminal needle position. Reducing the angle of the needle against the skin may facilitate guidewire passage. Once the guidewire is positioned, hold it firmly in place and remove the needle.

●Resistance during guidewire withdrawal can be managed by simultaneous removal of the needle and indwelling wire. Continued resistance may indicate entrapment and warrants diagnostic radiography to evaluate the wire appearance and position [46]. Withdrawing a kinked guidewire through the needle can shear off the wire, allowing it to embolize [47].

Tract dilation — Central venous catheters are substantially larger caliber than the needle and guidewire used for venous access. Dilation of the subcutaneous tissue tract is required for catheter insertion and is accomplished by threading a single stiff tapered dilator or series of dilators over the wire to expand the subcutaneous tissue and vein. The skin and fascia catheter tract should be dilated carefully with gentle pressure. Only the soft tissue and vein wall need to be dilated. Overzealous efforts and guidewire kinking (especially with stiff dilators) risk traumatic vein injury.

The dilator-sheath combination for large-bore tunneled catheters is stiff, and placement is facilitated with fluoroscopy, which allows imaging of the tip of the dilator and sheath, ensuring that it is placed no further into the vein than is necessary. (See 'Equipment' above.)

To place the dilator:

●Once the guidewire is in place, making a controlled 3-mm stab incision (#11 blade) in the skin at the guidewire entry site will prevent the dilator from catching.

●Thread the stiff tapered dilator over the wire, making certain the guidewire does not advance and is not pulled out at the skin exit site. The guidewire and dilator should never be advanced as a single unit, to avoid venous injury. The wire should serve as an immobile monorail over which the dilator (or catheter) is passed. Lateral traction of the skin helps to apply tension and avoid kinking the wire as the dilator traverses tissue planes.

●Hold the wire just above the dilator hub, grasp the dilator just above its tip, and push it over the guidewire with a firm corkscrew motion (picture 8). Mild resistance is normal. Excessive resistance may represent an inadequate skin incision, a malpositioned guidewire, or guidewire or dilator deformation. Kinking of the guidewire against the dilator is associated with vessel trauma and puncture [48].

●As described above with needle placement, the opening of the dilator (or dilator/sheath combination) should be covered and the patient encouraged to Valsalva to prevent entry of air.

●Advance the dilator only to the anticipated depth of the subclavian vein, not the entire length of the dilator. For the subclavian site, the dilator need only be advanced 3 to 5 cm into the vein depending upon the thickness of the patient's neck.

●Withdraw the dilator while maintaining the guidewire position within the vessel. Apply direct pressure to the exit site to maintain hemostasis prior to catheter insertion.

●Steady traction on the skin during soft tissue dilatation helps prevent wire kinking. Rotating the dilator during advancement often facilitates tract dilatation (round dilators only). If resistance is met, it may be related to a kink in the wire, which can be remedied by advancing the wire deeper or withdrawing the kink into the dilator. Overzealous efforts and guidewire kinking (especially with stiff dilators) risk traumatic vein injury.

Many indwelling tunneled subclavian catheters are placed through a peel-away sheath. To place these devices, a dilator-sheath combination is placed over the wire after the tract has been dilated. The dilator and guidewire are removed, and the catheter is placed through the sheath. Once the catheter is in place, the sheath is peeled away from the catheter and discarded.

Positioning the catheter — After the subcutaneous tissues and vein have been dilated, the catheter is placed over the wire and positioned (picture 9).

To place and position the catheter:

●Thread the guidewire back through the end-hole of the catheter until it emerges from the distal port, and advance the catheter over the wire into the vessel (picture 10).

●Resistance to catheter advancement through the soft tissue tract can be overcome by simultaneously advancing the catheter and wire together for the first 2 to 3 cm. Advancing further risks subclavian vein injury if the wire is inadvertently kinked. Withdrawal of the catheter and redilation of the tract is preferred.

●Following catheter insertion, we recommend placement of the used guidewire on the procedural field after removal as a verification step to avoid a retained guidewire.

Ideal insertion distance varies by patient size and anatomic site. To minimize intracardiac placement, do not insert catheters more than 20 cm from any upper body access site [42,43]. Initial insertion depth for most adults should be 16 cm for right-sided subclavian catheters and 20 cm for left-sided subclavian vein catheters [31]. Height-based formulas to determine insertion depth exist, but there are no well-controlled studies supporting their use [49,50]. Rare case reports implicate intracardiac catheter tip placement as a possible cause of cardiac tamponade [51,52].

In contrast to right-sided catheters, catheters inserted from the left negotiate the angulation of the brachiocephalic vein to enter the superior vena cava. For large-bore catheters used for hemodialysis or oncology, advancement under fluoroscopic guidance helps minimize the risk of central venous laceration. The risk of complications is related to the angle of catheter impingement on the superior vena cava [31]. From the left, catheters positioned above the pericardial reflection often abut the weak lateral wall of the superior vena cava and risk erosion and perforation [53-56]. As such, left-sided catheters should be inserted to an appropriate length to lie parallel in the long axis of the superior vena cava, when possible. This may require catheter tip placement in the upper right atrium [57-59]. It is also important to realize that catheter tips are not fixed and migrate 2 to 3 cm with head and arm movement and change in body position [60].

Catheter flushing and fixation — Once the catheter is in place, the proper function of the catheter should be confirmed by aspirating blood and subsequently flushing each port with saline (picture 11) [31,61].

The catheter can be secured into place by suturing (2-0 or 3-0 nylon or silk) it to the skin (picture 12). If more than 2 cm of catheter remain exposed, it can be sutured to the skin or to a separate catheter anchor that is often included in the catheter kit. A transparent dressing should be placed over the catheter exit site to protect it from contamination.

CONFIRMATION OF SUBCLAVIAN CATHETER POSITION — Confirmation of subclavian catheter tip location can use one or more of the following methods: chest radiography, fluoroscopy, and transesophageal echocardiography (typically intraoperative setting) [62-68]. Chest radiography and fluoroscopy are the most commonly used methods. In general, catheters function well with the tip situated in any major vein. However, suboptimal tip position may be related to delayed complications.

Following subclavian access, the position and course of the catheter and tip should generally be confirmed prior to its use. When using fluoroscopy for placement, a routine chest radiograph is unnecessary unless clinical suspicion of pneumothorax/hemothorax is high. If fluoroscopy has not been used, we obtain a postprocedure chest radiograph in non-life-threatening situations. If immediate catheter use is needed, venous positioning (but not tip position) can be confirmed with transduction of the central venous pressure, display of the central venous waveform, or via ultrasound. Bedside ultrasound is under investigation as an alternative modality to confirm catheter placement and detect pneumothorax [69].

The optimal catheter tip position is controversial, and controlled studies are lacking. The distal tip of jugular catheters should lie in the lower superior vena cava [2,43]. To minimize the likelihood of cardiac complications, some guidelines recommend catheter tip position outside the right atrium and above the pericardial reflection. The right superior heart border on chest radiography is not a reliable determinant of right atrial position [70]. The carina and right tracheobronchial angle represent reliable landmarks for the pericardial reflection, and right-sided catheters should generally be positioned above this point [70-72].

Malposition is common with subclavian access and is often related to an initially misplaced guidewire [1]. If a catheter is malpositioned within the venous system, it can be used under emergency circumstances but should be repositioned as soon as feasible. In contrast, inadvertent placement of a catheter into the subclavian artery mandates surgical consultation [27].

●If a subclavian catheter tip is positioned too deeply, it can be repositioned at the bedside using sterile technique. Remove the sutures, withdraw the catheter, and re-suture the catheter into place.

●If a catheter is not in far enough or is misplaced into the contralateral subclavian or internal jugular vein, it will need to be replaced over a guidewire under sterile conditions. The portion of a catheter left out of the body is unsterile and should never be advanced into the patient, not even if it is under a sterile dressing.

CATHETER MANAGEMENT — The management of central catheters is discussed elsewhere. (See "Routine care and maintenance of intravenous devices".)

COMPLICATIONS — The complications related to subclavian venous access are discussed separately. (See "Central venous catheters: Overview of complications and prevention in adults".)

SOCIETY GUIDELINE LINKS — Links to society and government-sponsored guidelines from selected countries and regions around the world are provided separately. (See "Society guideline links: Venous access".)

SUMMARY AND RECOMMENDATIONS

●Central catheters provide dependable intravenous access and enable hemodynamic monitoring and blood sampling. The subclavian veins are reliable access points for temporary and permanent cannulation and device introduction. Several anatomical approaches to the subclavian vein are described, and the method should be individualized to the patient's clinical circumstances. (See 'Introduction' above.)

●For subclavian access, the patient is typically placed supine or in Trendelenburg position with the arms placed to the side (adducted) with a neutral-to-lower shoulder positioning. The natural tendency for the shoulders to assume a cephalad orientation during Trendelenburg tilt should be countered by gentle caudal arm traction performed by a bedside assistant. (See 'Positioning' above.)

●Left-sided subclavian access is associated with lower rates of catheter malposition and vessel trauma. It is preferred when immediate cardiac access is needed (eg, temporary transvenous pacer and pulmonary artery catheter insertion) since the guidewire and catheter are more easily directed into the superior vena cava and right heart.

●Subclavian artery puncture during vein localization is not uncommon and can be managed by withdrawing the needle and applying pressure over the site for 5 to 10 minutes. Elevation of the ipsilateral arm overhead may help to compress the vein. If arterial catheterization is confirmed, the catheter should be left in place and a general or vascular surgery consult obtained. (See 'Venous confirmation' above.)

●A postprocedure chest radiograph is typically performed to confirm catheter position and exclude pneumothorax. If immediate catheter use is needed, venous positioning (but not tip position) can be confirmed with transduction of the central venous pressure, display of the central venous waveform, or via ultrasound. Bedside ultrasound is under investigation as an alternative modality to confirm catheter placement and detect pneumothorax. (See 'Confirmation of subclavian catheter position' above.)

●If a subclavian catheter is placed too deeply, it can be withdrawn at the bedside using sterile techniques. If the catheter is not placed deeply enough or is malpositioned, the catheter should be replaced over a guidewire under sterile conditions. The portion of a catheter left out of the body is unsterile and should never be advanced into the patient. (See 'Confirmation of subclavian catheter position' above.)