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The Speed of Sound

The Speed of Sound

Avoid Errors Using Oblique Approach for Central Line Placement

Butts, Christine MD

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doi: 10.1097/01.EEM.0000471524.01259.f4
    Image 1. Placement of the transducer for the lateral-to-medial oblique approach. The needle enters as shown, from the long end of the transducer, so that it can be seen in its entirety.

    Complications can occur while placing central lines under ultrasound guidance, as I noted last month. The transverse, or short axis, approach is often used successfully, but it can result in inadvertent arterial puncture and cause potentially disastrous consequences in the hands of inexperienced practitioners.

    The transverse approach, described in last month's article, is possibly the most popular and most frequently taught approach to those learning to place lines under ultrasound guidance. I have become very partial, however, to the oblique technique. It combines the familiar and reassuring view of the transverse approach with the ability to visualize the needle tip at all times, as with the longitudinal approach.

    The oblique approach was first described some time ago, but it has possibly taken some time to catch on with those who have become familiar and comfortable with the transverse approach.

    The transducer is rotated approximately 45 degrees from the traditional transverse placement in this technique. The earliest descriptions describe a clockwise rotation, so that the lateral aspect of the transducer is angled cephalad, compared with the medial aspect. (Image 1.) Once the internal jugular vein (IJ) and carotid artery are identified, the needle is introduced from the long end of the transducer in a lateral-to-medial approach. (Image 2.) Using this technique, the entire needle, including the needle tip, can be visualized at all times as it nears the IJ.

    Physicians who learned to place central lines blindly may recognize this approach as similar to the posterior blind approach because the needle will enter posterior to the sternocleidomastoid muscle. Once the needle tip enters the vein and a flash of blood is obtained, the procedure then continues like all other access methods.

    Image 2. Ultrasound image of an oblique approach. The vessels are seen similar as in the transverse approach, but the needle (arrow) can be visualized throughout the procedure. The needle tip can be seen just piercing the wall of the IJ.

    Although the lateral-to-medial approach has been extensively described (and used), some have made an argument for a medial-to-lateral approach. In this case, the transducer is rotated counterclockwise instead of clockwise, so that the medial end of the transducer is more cephalad. (Image 3.) The needle is then introduced from the medial aspect and follows a medial-to-lateral trajectory. Advocates of this technique argue that this directs the needle away from the vital structures of the neck and closely mimics the traditional “ipsilateral nipple” trajectory that was taught with the blind approach. The jury is still out on head-to-head comparisons of these techniques, but we have used the lateral-to-medial and medial-to-lateral approaches with success at our institution.

    Image 3. Placement of the transducer for the medial-to-lateral oblique approach. In this case, the needle would enter from the medial aspect of the transducer and travel laterally, toward the ipsilateral nipple.

    Next month: Making central lines safer using ultrasound.

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