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The Journal of Emergency Medicine, Vol. 37, No. 4, pp. 403–408, 2009Copyright © 2009 Elsevier Inc.

Printed in the USA. All rights reserved0736-4679/09 $–see front matter

doi:10.1016/j.jemermed.2008.02.061

Ultrasound inEmergency Medicine

THE OBLIQUE VIEW: AN ALTERNATIVE APPROACH FORULTRASOUND-GUIDED CENTRAL LINE PLACEMENT

Michael Phelan, MD* and Daniel Hagerty, MD†

*Department of Emergency Medicine, The Cleveland Clinic Foundation, Cleveland, Ohio, and †Department of Emergency Medicine,MetroHealth Medical Center, Cleveland, Ohio

Reprint Address: Michael Phelan, MD, Department of Emergency Medicine/E19, The Cleveland Clinic Foundation, 9500 Euclid Ave.,

Cleveland, OH 44195

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Abstract—Background: Numerous studies have shownignificant benefits of using real-time ultrasonography forentral line intravenous access. Traditionally, the ultra-ound probe is placed along the short axis of the vein toisualize and direct needle placement. This view has someimitations, particularly being able to visualize the needleip. Some practitioners place the ultrasound probe in theong axis of the vessel to direct needle placement, allow-ng better visualization of the needle entering the vein,ut this does not allow visualization of relevant anatomictructures. Objectives: We describe an alternative meanso obtain ultrasound-guided vascular access using anblique axis rather than the traditional short-axis ap-roach. Discussion: This view allows better visualizationf the needle shaft and tip but also offers the safety ofeing able to visualize all relevant anatomically signifi-ant structures at the same time and in the same plane.his orientation is halfway between the short and longxis of the vessel, allowing visualization of the needle ast enters the vessel. This capitalizes on the strengths ofhe long axis while optimizing short-axis visualization ofmportant structures during intravenous line placement.onclusion: Ultrasound-guided vascular access can bebtained in a variety of ways. We describe a techniquehat is used by some experienced ultrasound users buthat has never been fully described in the literature. Thisechnique for obtaining ultrasound-guided vascular ac-ess offers another option for attempting ultrasound-uided vascular access that has the potential to improveuccess rates and minimize complications associated withntravenous access. © 2009 Elsevier Inc.

ECEIVED: 1 December 2007; FINAL SUBMISSION RECEIVED:

CCEPTED: 28 February 2008

403

Keywords—ultrasound-guided vascular access; emer-ency medicine; axis; oblique; central line

INTRODUCTION

btaining vascular access is a vital component of patientare. When peripheral intravenous access is unable to bebtained, an intravenous catheter may be blindly placedercutaneously into the internal jugular vein using sur-ace landmarks for guidance. Unfortunately, the perfor-ance of a landmark-guided procedure can be associatedith significant complications, particularly in the obese,ypotensive, or anticoagulated patient, and in those withraumatic or congenital abnormalities.

Ultrasound-assisted vascular access can provide a safernd more efficient means of obtaining both peripheral andentral venous access, reducing morbidity and the timeequired to place the catheter (1–4). Meta-analyses haveeported that ultrasound guidance significantly increases therobability of successful cannulation while reducing bothhe number of attempts and the complication rate (5,6). Thegency for Healthcare Quality Research has recommended

hat ultrasound guidance be used for central line placementue to an improved margin of patient safety (7). Likewise,ome authors suggest using ultrasound-guided vascular ac-ess in all central line attempts, and recommend that ithould become the standard of practice for central linelacement (8,9).

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404 M. Phelan and D. Hagerty

Several techniques for the performance of internalugular vein central line placement have been described.hese include the central, anterior, and posterior ap-roaches (10). All are performed blindly, guided only bynatomic landmark of the sternocleidomastoid musclehere it overlies the internal jugular vein in the neck, ando not consider anatomic variation or abnormality.

Our purpose was to describe the use of an obliqueiew for direct visualization of the vein and artery duringlacement of ultrasound-guided venous catheter.

DISCUSSION

ULTRASOUND PROBE ORIENTATION

hen using ultrasound to directly visualize placement of aenous catheter, there are two traditional ultrasonic views:hort (transverse) and long (longitudinal) (11). The termi-ology “short” and “long” refer to the probe axis along thetructures visualized on the ultrasound screen. Each viewas its strengths and weaknesses. The short axis view al-ows a broad image of the lateral surrounding tissue andtructures (especially the carotid artery during internal jug-lar line placement), making co-localization of the needle toessel (artery vs. vein) much easier. However, it is difficulto keep the needle tip within the plane of the ultrasoundeam, and frequent adjustments (fanning) of the probe areeeded to maintain needle visibility.

Therefore, the practitioner, using careful coordination ofeedle, ultrasound probe, and hands, must advance botheedle and probe in a continuous fashion to maintain visu-lization of the vein and needle tip within the beam of theltrasound. In contrast, the long axis view shows orientationf the needle along its long axis and the long axis of theessel, allowing direct visualization of the needle throughhe tissue and into the vein. However, this technique re-uires additional skill to maintain the needle directly in theidline axis for visualization and to keep all the necessary

tructures, especially the needle, within the very narrowidth of the ultrasound beam. It is difficult to discern if theeedle is overlying the artery or vein using the long axisechnique alone and nearby structures cannot be visualized.

oreover, the long axis technique is anatomically limited toocations where the needle insertion angle is sufficientlyhallow to accomplish this goal. Additionally, the long axisechnique may be limited by anatomic considerations suchs room on the neck with the probe in vertical orientation.hus, the long axis view is used much less frequently tolace central lines.

During central line placement with ultrasound guid-nce, direct visualization of key vascular structures isecessary to prevent arterial puncture, and most experi-

nced ultrasonographers will use the short axis for cen- t

ral vein cannulation (11). This preference may be due tobias in training or the inability to visualize both the

rtery and vein with the more technically challengingong axis-guided procedure.

OBLIQUE VIEW

he oblique approach for ultrasound probe orientation mayrovide easier needle visualization during ultrasound-uided vascular access. Because the needle tip acts as aeflector dispersing the ultrasound beam, poor visualizationf the tip in the short axis is one of the most commonifficulties encountered during ultrasound-guided vascularccess. Axis and approach angle affect needle visualization.hen the needle is visualized in the short axis, only a small

art acts as a reflector and it appears as only an echogenicot. In contrast, positioned in the long axis, the wholeeedle acts as a reflector and it appears as a bright line.ngle of insertion determines appearance, where a steep

ngle provides a smaller reflector. A shallow angle ofpproach allows the best visualization, where there isore surface area for the ultrasound beam to reflect

ack to the probe. In this article, we describe the usef an oblique view for direct visualization of the veinnd artery while visualizing the needle in the long axisuring placement of ultrasound-guided venous access.

The oblique view is obtained by initially locating theessel in the short axis, followed by rotation of the probe tolmost midway between the short axis and long axis views.ith this technique, both vessels are still visualized on the

creen but in a slightly elongated view. The main advantagef this approach is that the needle will enter along the longxis of the probe, thus providing a long axis view of theeedle as it enters the vessel, while providing the short axisdvantage of simultaneously localizing both the internalugular and carotid artery. This view both capitalizes on thetrengths and minimizes the weaknesses of the short andong axis approaches to yield an optimized venous cannu-ation approach. Although we describe the oblique viewsing the internal jugular vein as a reference vessel, thisechnique can be applied to any vessel that allows anblique approach.

INTERNAL JUGULAR VEINULTRASOUND-GUIDED ACCESS, POSTERIOR

APPROACH USING OBLIQUE VIEW

he technique is as follows. Place and drape the patientn the usual sterile fashion using the head-down positiono optimize distention of the vein. Locate a triangularegion on the base of the neck, with the clavicle forming

he inferior/base and the edges of the sternal and clavic-

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The Oblique View for US-Guided Central Line Placement 405

lar heads of the sternocleidomastoid muscle (SCM)orming the sides of the triangle. Place sterile conductiveedium, such as sterile lubricating gel available in com-ercial ultrasound cover kits, in the triangle, just ceph-

lad to the clavicle. Cover the high-frequency linearrobe and place it on the patient’s neck between the twoeads of the SCM oriented in the short axis of the vesselstransverse plane) (Figure 1), similar to the short axis orentral approach. The ultrasound probe indicator is fac-ng the patient’s left side, regardless of whether one isttempting the right or left internal jugular central veinccess, to preserve proper orientation of the ultrasoundmage. On the image, identify the vascular structures; thenternal jugular vein is more superficial, usually larger,hin-walled, and easily compressible, compared to theeeper, thicker, and smaller carotid artery. To assureorrect probe position, gently indent the skin along oneide of the probe, watching the ultrasound screen foreformation of the image. Depression of the skin beneathhe left side of the probe should yield deformity of theltrasound image on the left side of the screen.

For right-sided internal jugular vein cannulation, rotatehe ultrasound probe approximately 45° so that the medialnd of the ultrasound probe (and the marker on the probe)ligns with the patient’s contralateral nipple or shoulderFigure 2). The probe should remain perpendicular to theurface of the skin. This position, the oblique view, nowhows the same vascular structures but they are now seen asvals (more elongated circles than when in the short axis)ith black, hypoechoic centers (Figures 3, 4).The SCM should be visualized overlying the vessels.

or the anatomic landmark technique, the most lateralspect of the SCM is the location of needle entry for the

igure 1. Proper placement of linear ultrasound probe forhort axis (transverse) orientation over the right neck ves-els. The ultrasound probe indicator is on the patient’s leftide.

osterior approach. The needle should traverse the skin,op

oing beneath (or attempting to) or posterior to the SCMhence the “posterior” anatomic or landmark approach).or the ultrasound-guided oblique approach, place theeedle at the end of the long axis or lateral edge (thepposite end of where the marker is located for right-ided internal jugular vein cannulation) of the probe inpproximately the same location used for the posteriornatomic approach. The key to the oblique view is toaximize the amount of skin the footprint (length) of the

robe is in contact with and allow a generous amount ofoom for the needle to traverse the screen. This willequire positioning the ultrasound probe so that the ves-els are as far laterally on the screen as possible, andaving as much contact with the patient’s skin as rea-onable before needle entry. Anesthetize the overlyingubcutaneous skin at the most lateral aspect of the probevery close to the posterior aspect of the SCM muscle)ith lidocaine (Figure 2). Observe the changes to the

ubcutaneous tissue over the vessels.Using the introducer needle and a syringe, puncture the

atient’s skin immediately beneath the cephalad/lateraldge (end) of the linear ultrasound probe, at the site ofidocaine injection (Figure 2). The closer the puncture site iso the probe, the easier it will be to visualize the needle justs it enters the skin and subcutaneous tissues. When theuncture is well-centered beneath the probe, the white/yperechoic needle is visualized in a long axis format as aright line. Advance the needle, keeping it centered beneathhe ultrasound probe, allowing direct, continual visualiza-ion of the needle as it approaches the vein. Adjust theeedle depth and angle of insertion according to the locationf the needle tip during this process. This may requireemoving the needle and reinserting it if the angle is too

igure 2. Proper placement of linear ultrasound probe for

blique orientation over right neck vessels. The ultrasoundrobe indicator is pointed toward the patient’s left.

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406 M. Phelan and D. Hagerty

teep. When the needle touches this anterior wall of theessel, the vessel is momentarily indented (Figure 5). Anal, small thrust allows the needle tip to enter the veinnder continuous visualization and prevent puncturing ofhe posterior wall. Once the needle enters the vein, the walleturns to its previous distended position. Remove the ul-rasound probe and place the central line according totandard Seldinger technique.

One of the most common visualization techniques whensing ultrasound for vascular access is the standard shortxis view: the vein, artery, and needle are visualized in theirhort axis. Figure 6 shows a single vessel vascular phantomith different approaches. For the short axis, the tip of theeedle is visualized only as a small echoic dot when itrosses the narrow ultrasound beam (Figure 6a). As a result,he physician placing the needle estimates its location byatching for changes in the soft tissue or vessel during

nsertion. This technique is limited by its inability to visu-

igure 3. Ultrasound image of the right neck vessels shown tausing vessels to appear more oval. There is anatomy distopplied with the ultrasound probe (c).

igure 4. Ultrasound image of right neck vessels shown in

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blique orientation. Notice the slight oval shape of the inter-al jugular vein.

lize and follow the needle. Although the long axis seems toe a better approach due to improved visualization of theeedle itself (much more of the needle is available to act asreflector), absence of landmarks to verify vessel identity

vein or artery) make the long technique less than optimalFigure 6b).

CONCLUSIONS

he oblique view is a potentially superior technique be-ause it optimizes the capabilities of dynamic ultrasound-uided vascular access. The oblique view uses the supe-iority of the short axis view by visualizing all of themportant surrounding structures (artery and vein) in anblong view while allowing continuous real-time visu-lization of the long axis of the needle, therefore provid-ng a larger, more easily visible target with a brighter,

igure 5. Ultrasound image of the right internal jugular veinhown in oblique orientation with the needle in long axis, and

ning from short axis orientation (a) to oblique orientation (b),f vessels in oblique orientation when downward pressure is

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The Oblique View for US-Guided Central Line Placement 407

ore easily recognized needle (Figure 6c). This may beeneficial, especially for novice ultrasound users, ashere is a steep learning curve to ultrasound-guided pro-edures. As a result, central venous cannulation suc-ess rates may be improved while decreasing compli-ations and damage to adjacent structures. Furthertudies are needed to evaluate the efficacy of thisariation of ultrasound-guided vascular access.

In practice, we continue to utilize this oblique ap-roach during ultrasound-guided internal jugular central-ine placement with excellent success. Our combinedumbers at present are limited (about 25–30) and noignificant complications have been reported. We teachhis technique to residents and interested staff, who haveeported it to be an easier method with superior needleisualization. Although not a replacement for currentpproaches to ultrasound-guided vascular access, theblique view should give the physician an additionalpproach when needed. Moreover, this approach cane applied to any vessel (including the femoral vein);he technique was easiest to describe with the internalugular vein. Evaluation of this technique comparedo other ultrasound-guided approaches has yet to beonducted.

cknowledgement—We gratefully acknowledge the skilled

igure 6. Photographs of ultrasound probe position with neeltrasound images. (a) Short axis orientation, needle in short a

f vessel is artery or vein, but needle and vessel are viewedrientation and needle visualized in long axis, allows excelle

ontributions of illustrator Bill Garriott.

REFERENCES

1. Hrics P, Wilber S, Blanda MP, Gallo U. Ultrasound-assisted in-ternal jugular vein catheterization in the ED. Am J Emerg Med1998;16:401–3.

2. Fry WR, Clagett GC, O’Rourke PT. Ultrasound-guided centralvenous access. Arch Surg 1999;134:738–40; discussion 741.

3. Keyes LE, Frazee BW, Snoey ER, Simon BC, Christy D.Ultrasound-guided brachial and basilic vein cannulation inemergency department patients with difficult intravenous ac-cess. see comment. Ann Emerg Med 1999;34:711– 4.

4. Miller AH, Roth BA, Mills TJ, Woody JR, Longmoor CE, FosterB. Ultrasound guidance versus the landmark technique for theplacement of central venous catheters in the emergency depart-ment. Acad Emerg Med 2002;9:800–5.

5. Randolph AG, Cook DJ, Gonzales CA, Pribble CG. Ultrasoundguidance for placement of central venous catheters: a meta-analysis of the literature. Crit Care Med 1996;24:2053–8.

6. Hind D, Calvert N, McWilliams R, et al. Ultrasonic locatingdevices for central venous cannulation: meta-analysis. BMJ 2003;327:361.

7. Shojania KG, Duncan BW, McDonald KM, Wachter RM,Markowitz AJ. Making health care safer: a critical analysis ofpatient safety practices. Evid Rep Technol Assess (Summ) 2001;(43):i–x, 1–668.

8. Scott DH. ‘In the country of the blind, the one-eyed man is king’,Erasmus (1466–1536) see comment. Br J Anaesth 1999;82:820–1.

9. Leung J, Duffy M, Finckh A. Real-time ultrasonographically-guided internal jugular vein catheterization in the emergency de-partment increases success rates and reduces complications: arandomized, prospective study. Ann Emerg Med 2006;48:540–7.

0. Roberts JR, Hedges J. Clinical procedures in emergency medicine,4th edn. Philadelphia, PA: Saunders; 2003.

1. Rose JS, Bair AE. Vascular access. In: Ma OJ, Mateer JR, eds.Emergency ultrasound, 1st edn. New York: McGraw-Hill Profes-

acement over a single-vessel phantom with correspondingpoorly visualized; (b) long axis orientation, cannot determine

long axis; (c) oblique orientation vessel viewed in obliquedle visualization and preserves vascular alignment.

dle plxis is

sional; 2002:349–60.

408 M. Phelan and D. Hagerty

ARTICLE SUMMARY1. Why is this topic important?Because emergency medicine physicians are increasinglyusing ultrasound to obtain vascular access; there aretechniques that may improve visualization of the needletip itself.

2. What does this study attempt to show?The traditional way of teaching ultrasound-guided vas-cular access in the short access has some shortcomings,especially the ability to visualize the needle tip. Wedescribe an alternative means of trying ultrasound-guidedvascular access using an oblique axis, which is abouthalfway between the long and short axis.

3. What are the key findings?This technique of using the oblique axis of the vessel, butlong axis of the needle offers the advantage of the longaxis visualization of the needle tip but continues to keeprelevant anatomic structure within the view.

4. How is patient care impacted?By being able to visualize the needle tip itself this couldpotentially increase comfort level of ultrasound users andpossibly increase success rates and decrease complicationrates.