VEnous air embolism

[sevoflurane]

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What Is the correct location of central venous catheter tip for a VAE?

 

[Planktonmd]

What Is the correct location of central venous catheter tip for a VAE?

It doesn't matter because you will never be able to aspirate air.
For the boards I would say: a multi orifice catheter with the tip in the right ventricle then pull the catheter gradually through the right heart to the SVC while aspirating.
But really there is no strong evidence supporting any specific position.

Look at this too:
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=1344183

 

[sevoflurane]

I hear you. Unfortunately I've seen this topic on my last 4 intraining examinations. I bet I'll see it next week.

I think what they are getting at is if you have an "air lock" and consequently acute right heart failure. So IVC is incorrect. Junction of IVC and RA is also incorrect as it will do nothing. Now other options would be

1. RV
2. RV outflow tract
3. PA

I'm wanting to say RVOT, but I'm not sure and I have not read this anywhere.

 

[IN2B8R]

What Is the correct location of central venous catheter tip for a VAE?

Take your TEE probe and look to see where the air lock is. Most likely, if the patient's right side is not up, it will probably be distal to the RVOT. Slide your TEE probe in and see if you can spot the air, then direct your Swans Ganz catheter toward the air and aspirate away (from the closest port to the air, you can actually visiualize this with the TEE). Be mindful that the left main bronchus will overshadow the left main PA, possibly preventing you from seeing an air embolus down the left main pulm artery.... but you should be able to see the common pulmonary artery, right pulm artery, as well as your Swan Ganz from an upper esoph, SAX view, just above the aortic valve. Also look at your ME RVOT view. I would start there and see what I can find. Nothing as helpful as a TEE in these scenarios, but as mentioned above, it is approx. only 80% sensitive (and probably 100% specific), secondary to the inability to fully view the left main pulm artery. Hope this helps. Regards.

 

[usnavdoc]

I hear you. Unfortunately I've seen this topic on my last 4 intraining examinations. I bet I'll see it next week.

I think what they are getting at is if you have an "air lock" and consequently acute right heart failure. So IVC is incorrect. Junction of IVC and RA is also incorrect as it will do nothing. Now other options would be

1. RV
2. RV outflow tract
3. PA

I'm wanting to say RVOT, but I'm not sure and I have not read this anywhere.

Miller states that if it is a multi orifice it should be placed 2cm below the junction and if single orifice it should be 3cm above the junction. pg 1908

Although it also states that if it is a massive vloume then anywhere in the RV is acceptable.

had a practice question on this the other day and looked it up.

 

[Duane E]

When a pump fails due to air-lock, it is because it has lost its prime (or suction) due to air in the pump. If the right ventricle has blood, it will pump it on out because of it being an incompressible fluid. If there is air in the atrium, it will be drawn into the pump and then you will have a lock. The valves will not perform properly because they were designed to close with the help of fluid and since air is compressible, the ventricular volume will continue to oscillate except with less flow due to the compression of air. It's like squeezing a syringe full of air compared to one full of water.
I guess what I'm trying to say is there has to be air inside the ventricle for an air-lock scenario to happen.

This is only from a previous life as an engineer so....grain of salt...

BTW, I assume the air would be in the RVOT just due to anatomy and since the ventricles squeeze from apex to base. Or perhaps it would be in the apex if the patient was supine...If the air is in the PA, it has already left the pump and that voids the definition of air-lock.

EDIT: I think it will be in the RV for a supine patient, that would be consistent with air-locking too.

 

[lvspro]

I was going to jump in and write that u need to be at the tip of the SVC, but decided to look it up in longnecker.

JUST ABOVE THE RT ATRIUM as per Longnecker.

3.0 cm ABOVE THE SVC AND THE RT ATRIAL JXN as per Barash

HIGH IN THE ATRIUM AT ITS JXN WITH THE SVC as per morgan/mikhail

MULTIORIFICE CATH GOES 2 CM BELOW SVC RA JXN as per miller

SINGLE ORIFICE CATH GOES 3 CM ABOVE SVC RA JXN as per miller


So if I had an exam question on it w/o indicating the # of orifices (orifi?) i would assume a single orifice cath, and drop it 3 cm above the svc ra jxn.

 

[periopdoc]

I think this is the article that led to all this "where do you position the catheter" stuff

Positioning the right atrial catheter: a model for reappraisal.

A flexible Silastic casting of the human right atrium was developed to correspond to some in vivo human right atrium hemodynamic characteristics including chamber pressures, pulsatility, fluid output, and flow velocity. Using an infusion pump, air was introduced (10 ml in 30 s) into the superior vena cava of the model and aspirated via a catheter from different positions within the model atrial chamber. The tests were carried out at atrial inclinations of 60 degrees, 80 degrees, and 90 degrees from the horizontal and compared the aspiration efficiency of a single-orificed 16-gauge catheter to a 16-gauge multiorified (5 aperatures) catheter. Optimal air aspiration occurred with the multiorificed catheter tip positioned within the area 2.0 cm below the junction of the superior vena cava (SVC) and the atrial chamber at an inclination of 80 degrees. As much as 80 per cent of the incoming air could be aspirated under these conditions. At its optimal position the single-orificed catheter gave a maximal yield of 45 to 50 per cent aspiration when the tip was positioned 3.0 cm above the SVC and atrial chamber junction. Aspiration of air from mid right atrium (4.5 cm below the SVC-atrial junction) was poor regardless of the type of catheter used or atrial inclination. These data suggest a need for reappraisal of catheter design and placement.

Then there was this one

In vitro comparison of central venous catheters for aspiration of venous air embolism: effect of catheter type, catheter tip position, and cardiac inclination. - Hanna PG - J Clin Anesth - 01-JUL-1991; 3(4): 290-4

STUDY OBJECTIVE: To test the relative efficiency of balloon-tipped and plain catheters for aspiration of venous air embolism.

DESIGN: The following four single-lumen central venous catheters were studied in a silastic model of the right atrium, tricuspid valve, and vena cavae: (1) the 16-gauge single-orifice catheter; (2) the 14-gauge Bunegin-Albin multiorifice catheter; (3) the 7-Fr pulmonary angiography catheter with balloon distal to orifices; (4) the 7-Fr pulmonary angiography catheter with balloon proximal to orifices. A 10% glycerol-water solution was circulated at 3.7 to 4.0 L/min. Catheter tips were positioned at 1 cm increments from -3 to +3 cm around the superior vena cava-right atrial junction with cardiac inclinations of 65 degrees and 80 degrees. Air (10 ml) was infused over 30 seconds; aspiration from the test catheter began 5 seconds later at 40 ml/min for 75 seconds. The balloon catheters were evaluated with the balloons inflated and deflated.

MEASUREMENTS AND MAIN RESULTS: Amounts of air aspirated were compared by analysis of variance and Tukey's multiple comparison, p less than 0.05, for all combinations. The 16-gauge single-orifice catheter tested best at a 65 degrees cardiac inclination with 86% of the venous air embolism recovered, while the 14-gauge Bunegin-Albin multiorifice catheter tested best at an 80 degrees cardiac inclination with 62% of the venous air embolism recovered. Both catheters functioned most efficiently at or above the superior vena cava-right atrial junction.

CONCLUSIONS: This study demonstrated that efficacy of air recovery depends on catheter type, catheter tip position, and cardiac inclination. No benefit was derived from positioning the catheter tip inside the atrium or from using balloon-tipped catheters.

Personally, I think that if you have an air embolism you should advance the catheter as far as is reasonable and suction on the way out. Stop when you find a pocket of air and suction until you only get blood back. Repeat.

For the purposes of the test I am sure the answer will be at the tip of the SVC/ RA.

For real fun think like the fat man and follow The ICU books advice

In dire circumstances, a needle can be inserted through the anterior chest wall and into the right ventricle to aspirate the air. (This can be accomplished by inserting a long needle in the 4th intercostal space just to the right of the sternum and advancing the needle under the sternum at a 45 degree angle until there is blood return.)

Damn.

- pod

 

[proman]

According to Faust (pg 390), the proper placement is high right atrium. A multiorifice catheter ECG tracing is from the middle orifice, which should be positioned just above the cavo-atrial junction (so that the tip is high atrial). A single orifice catheter would be place just beyond the CA junction.