Marco Gerges, MD Emergency Medicine, PGY-3

Allyson Hansen, DO EM Ultrasound Residency Director

Question:

Is the rate of complications for US-guided supraclavicular subclavian vein central lines noninferior to US- guided infraclavicular lines?

It’s not like we do these every day in the ED but when you need vascular access and there has been multiple failed attempts or restrictions to other approaches, you want to know this! It’s baked into some of us that the infraclavicular approach is technically more challenging due to the traditional thought that this be performed blind. Also, many of us have never even seen or heard that there is a supraclavicular technique to cannulate the subclavian vein! But alas, it has been shown that you can actually do both approaches via ultrasound guidance. There also has been evidence comparing the two approaches. Recently a study focused on the safety of either style. Let’s look at a prospective randomized non-inferiority trial to help us answer the question, are both approaches equally safe?

Source: ultrasoundgel.org

Methods

Prospective randomized non-inferiority trial for patients undergoing elective neurosurgery needing central line placement with ultrasound guidance. Performed at Seoul National University Hospital in Seoul, S. Korea by anesthesiologists.

- Supraclavicular lines are in-plane

- Infraclavicular lines are out-of plane

Total of 401 patients:

- Mean age in early 60s, BMI 24-25 and most ASA class 2

- Minimal difference between allocated groups

Excluded patients that had infection, certain medical devices such as chemo port or pacer at the puncture site, had a right subclavian vein thrombosis, hemophilia, current anticoagulant use or previous surgery that may alter anatomy of right subclavian vein.

Primary outcome: Catheter misplacement or mechanical complications including arterial puncture, hematoma formation, pneumothorax and hemothorax

Secondary outcome: Timing and first pass success and overall success

Non-inferiority design - used a non-inferiority margin of 5.9% based on a prior RCT by this same author group. Power analysis required 198 patients in each group.

Patient population (not your typical ED patient unfortunately):

- Age 20-79 - Elective neurosurgical procedures

- All intubated and under general anesthesia

- All patients flat on the table

- Right sided subclavian only

- Mechanical ventilation paused for cannulation. Because we all do this, don’t we? *hint hint, sarcasm*

What defines failure of the procedure?

- Required rescue ventilation for desaturation < 92%

- Not successful in 3 minutes

- After three failed attempts, a second anesthesiologist attempts. If 2nd anesthesiologist fails three times, an IJ line would be inserted.

Infraclavicular Approach: this was done OUT OF PLANE. Why?

They stated:

“In a previous RCT comparing the two ultrasound techniques during the infraclavicular approach for subclavian catheterization, the incidence of complications, including all catheterization-related complications assessed in this study, was significantly lower when using the short-axis out-of-plane technique than the long-axis in-plane technique (3% vs. 13%).”

Source: EMRA

Image 1: In the above image, note that the operator identifies the SCV (subclavian vein) in the infraclavicular region. Using an out of plane technique to cannulate the SCV.

Supraclavicular Approach

Image 2. Source: aneskey.com

Image 2: The approach for a right sided supraclavicular subclavian venous cannulation. Note the probe is used in plane above the clavicle angled into the thorax.

Image: 3,4,5

The above images 3 through 5 are from a great Youtube Video by SonoSite. Watch 4:40 through 7:20 for live ultrasound guided cannulation of the supraclavicular subclavian vein.

Essentially, here’s what you gotta do:

- Follow IJ down neck with linear probe. Note where your probe marker is!

- Visualize SCV as it joins with IJ at the confluence of brachiocephalic vein, may need to angle into thorax

- Vein is anterior to artery

- Long access orientation at supraclavicular fossa

- Aim needle for subclavian vein near confluence to braciocephalic vein

Results of the Trial

Primary outcomes: Complications (catheter misplacement + mechanical complications)

- Supraclavicular 3%

- Infraclavicular 13.4%

- Difference 10.4%, w/ CI 15.7- 5.1

The difference was allowed to be up to 5.9% predetermined from the authors experience performing a RCT looking at subclavian catheterization complications. In this study the difference in complications was 10.4%, in favor of supraclavicular approach. Thus, this meets the criteria for saying supraclavicular is non-inferior to infraclavicular approach.

Catheter misplacement made up 2 of 6 complications in supra and 21 of 27 complications in infraclavicular approach. Most of the misplacements were into the ipsilateral IJ they theorized was secondary to direction/aim of catheter between the two approaches. There was no significant difference in mechanical complications between groups.

Secondary outcomes: time to cannulation

-Supraclavicular approach 9 seconds (CI 6-20)

-Infraclavicular approach 13 seconds (CI 8-20)

No difference in overall success, first-pass success, time required for catheterization overall. These, remember, are skilled and experienced anesthetists performing these with at least 10 Subclavian Iines placed via both approaches.

Also solidifying this as a safe procedure, mechanical complications were few:

- Only 1 hematoma

- Only 2 pneumothoraces during out of plane infraclav approach

- Overall 1.5 to 2% rate of arterial puncture What does all that mean? Well, it looks like the supraclavicular ultrasound guided approach is actually relatively safe and is perhaps something we should try to integrate into our skillset.

Limitations

There are obvious massive limitations when comparing to the ED vs. elective neurosurgery patients:

- 8.8% of these patients had BMI over 30, which is small compared to our population seen in the emergency department.

- Based on rarity of mechanical complications (arterial puncture, hematoma, pneumothorax), study may have been too small to find significant difference between groups. Also, as Ultrasound Gel Podcast who reviewed this article stated, lumping these outcomes together (pneumothorax is not the same as a misplaced line) makes it more challenging to interpret the true important differences between these approaches. It would be nice to compare in plane to in plane with subclav and infraclav approach as this is preferred for needle visualization and anecdotally quite possible with the infraclavicular approach.

- Stopping ventilation to cannulate, we usually do not do this. So overall incidence of pneumothorax may be lower than reality.

- Performed by skilled anesthetists with significant experience in these techniques

- There is no clear reason why this had not been applied to left sided venous cannulations, but one may hypothesize that anatomically speaking for most right handed medical professionals, the right sided approach would be easier as the practitioner doesn’t have to adjust his already baked-in technique of right sided venous central cannulation versus attempting to take a more awkward approach on the left side of the patient. This is why we are predominately taught this in our training. Albeit, the left subclavian vein does enters the brachiocephalic at a less acute angle. Overall success seems to not be much different between either side. Yet, there seems to be a higher degree of malpositioned lines on the right side (1) . Checking with a post procedural X-ray is essential before using your central line!

Conclusion

So then again, maybe if a similar trial were performed in the ED, we would all feel better about actually honing this skill and adding it to our skillset, wouldn’t we? Consider practicing obtaining these ultrasound views while on your next shift. You will no doubt find yourself at some point with a difficult to cannulate patient or someone with poor vascular access requiring an alternative approach and you will need to pull out something like this from your toolbox. Consider the ultrasound guided supraclavicular approach for your next line!

References:

1. Tarbiat M, Manafi B, Davoudi M, Totonchi Z. Comparison of the Complications between Left Side and Right Side Subclavian Vein Catheter Placement in Patients Undergoing Coronary Artery Bypass Graft Surgery. J Cardiovasc Thorac Res. 2014;6(3):147-51. doi: 10.15171/jcvtr.2014.003. Epub 2014 Sep 30. PMID: 25320661; PMCID: PMC4195964.