Tuesday, May 13, 2008

Surfing, Ultrasound, Subclavian Placement, and "Del.icio.us for Docs"

One of the major goals in placing a subclavian central line is to avoid pneumothorax and other complications.

To avoid pneumothorax, time the entry of your needle with respirations, much as a surfer would time a wave to catch it at the right time.

Basically, you identify the clavicle with your first probe with the big needle, then redirect, aim towards the sternal notch, and sit, right under the skin, getting in the flow of the respiratory cycle. As the chest rises and falls, time entry of the needle into the vein with the falling of the chest. This will avoid hitting the lung. If you do not obtain access, pull back and wait until the next wave of exhaled air and chest fall.

This diagram from the AHRQ's web Morbidity and Mortality on central line complications shows approximately where you would sit, like a surfer in the outside break, waiting for the chest to come into position for an attempt.

There appears to be consensus that for an IJ, it is the standard of care to use ultrasound guidance for access, this does not apply to all patient contexts, particularly the emergent setting.

A question that could be posed is whether it is useful to use ultrasound to avoid a pneumothorax in subclavian placement, not for the purposes of directing the needle to the vein, but to AVOID directing the needle into the lung. Here is one group that has looked at the question of avoiding pneuomothorax generally. An older review of ultrasound guidance by Skolnick suggests that the axillary vein is the preferred site in comparison to the subclavian for avoidance of pneumothorax due to the lateral position of the axillary vein in relation to the lung. In a complicated series of surgical patients, using predominantly the subclavian approach, Fry, Clagett and O'Rourke et al used ultrasound and specifically address the issue that the plane of the ultrasound image is parabolic (see their figure), thus making it very important to keep the needle in the middle of the image in dynamic access.

The New England Journal of Medicine has a video on some of the other complications that can happen with subclavians, here . A better example of things that can go wrong is here, where a case is presented

It seems obvious that a fracture of the clavicle or ribs in the area would be a relative contraindication to placement of a subclavian, carefully inspect the chest x ray before and after placement to make sure there are no broken bones, particularly in elderly patients who may have fallen and have rib fractures. I have seen a case of a 97 year old lady who had fallen, and a right posterolateral rib fracture was identified only on the post-IJ line placement film (the initial portable film was poor quality). To avoid this, carefully palpate the ribs, clavicles, and chest wall prior to access.

The NEJM video does not mention what to do when the line goes up instead of down. There is some debate about what causes this, some say it is the orientation of the bevel and some say it is the direction of the j tip on the guidewire, other factors may include the anatomy of junction of the IJ and the subclavian at the inominate. The J tip was introduced by Blitt primarily to advance catheters through the external jugular into central veins.

One group (Le, Jin, and Guldner) at Loma Linda replicated this and found it was the guidewire direction that determined the direction of the subclavian, a j tip pointing up led to the placement of the wire going up 100% of the time in a simulation model.

In this case, if access is needed, it may be wise to advance the line not as far as you usually would so that the line does not show up in the brain, and continue to use the line if necessary using non irritant solutions until other access can be obtained, eg avoid solutions like concentrated D50 to avoid thrombophlebitis.

Speaking of surfing and the upper chest, surfers who do laybacks are prone to surfer's rib , an isolated fracture of the first rib. To see why this can happen, check this out!

The "metadata" for this post is that it is my first attempt to use Connotea, which is like del.icio.us for doctors, cool ways of organizing articles based on tags!

Blitt CD et al (1982) J- Wire versus Straight Wire for Central Venous System: Cannulation via the External Jugular Vein. Anesthesia and Analgesia 61(6): 536-37.
Braner DAV et al (2007) Videos in Clinical Medicine. Central Venous Catheterization: Subclavian Vein. NEJM 357: e26.
Fry WR, Claggett GC, O'Rourke PT(1999) Ultrasound Guided Central Venous Access Archives of Surgery 134:738-741
Giacomini M, Iapichino G, Armani S, Cozzolino M, Brancaccio D, Gallieni M. (2006) How to avoid and manage a pneumothorax. J Vasc Access. 7(1):7-14.
Le J, Jin P, Guldner G(2008) Subclavian Central Line Misplacement: Is it Needle Bevel or Guidewire Direction that Influences Line Placement? Western Journal of Emergency Medicine 9(1), Article 39.
Skolnick ML (1994) The role of sonography in the placement and management of jugular and subclavian venous catheters. AJR 163:291-295.
Tripathi, Dubey, Ambesh. (2005) Direction of the J-Tip of the Guidewire, in Seldinger Technique, Is a Significant Factor in Misplacement of Subclavian Vein Catheter: A Randomized, Controlled Study. Anesthesia Analgesia 100:21-24

No comments: