Downside to a VAMP

[bryanboling5]

I'm an RN in a community Med/Surg/Cardiac ICU and I've got a question about a-lines. I work at night, so our PulmCCM doc is never here to ask.

We don't get many a-lines, but when we do, they almost never use the VAMP (by Edwards) even though that's what we stock. I work in a CTICU at a sister hospital and all my a-lines have the VAMP. I've been told that our PulmCCM doc "doesn't like them" but I don't know why and never get the chance to ask him. I think they're great because I don't have to waste 10mls of blood with every draw. It seems that they make more sense than the traditional line. Anyone know what the downside might be? Why our PulmCCM doc doesn't like them?

Not trying to second guess, just trying to learn.
Thanks!
Bryan

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[emergiQ]

I'm an RN in a community Med/Surg/Cardiac ICU and I've got a question about a-lines. I work at night, so our PulmCCM doc is never here to ask.

We don't get many a-lines, but when we do, they almost never use the VAMP (by Edwards) even though that's what we stock. I work in a CTICU at a sister hospital and all my a-lines have the VAMP. I've been told that our PulmCCM doc "doesn't like them" but I don't know why and never get the chance to ask him. I think they're great because I don't have to waste 10mls of blood with every draw. It seems that they make more sense than the traditional line. Anyone know what the downside might be? Why our PulmCCM doc doesn't like them?

Not trying to second guess, just trying to learn.
Thanks!
Bryan

Not sure what a VAMP is. Is it the same as a "rosebud"? We use those at one of my institutions, mainly to keep the tracing stable so it doesn't have to always be re-zeroed due to damping, over-damped, etc.

I think the main downside is just cost. The rosebuds are overpriced for a little piece of damn plastic if you ask me...

Maybe your pulm doc thinks the cost of 10ml of blood is less. (shrug)

 

[proman]

I think the VAMP is a self contained in-line syringe that allows to draw back 10cc of blood then sample from the a-line with a needle-less device, then return what was formerly wasted. We have something called Safe-T set (or something like that).

I think they kill a lines. No evidence, just experience (and many 3 am a line re-do).

 

[bryanboling5]

I think the VAMP is a self contained in-line syringe that allows to draw back 10cc of blood then sample from the a-line with a needle-less device, then return what was formerly wasted. We have something called Safe-T set (or something like that).

I think they kill a lines. No evidence, just experience (and many 3 am a line re-do).

That's what the VAMP does. So, WHY do they kill a-lines? What about them? Is it returning the blood?

 

[proman]

I think it's the negative pressure generated by the syringe.

 

[bryanboling5]

I think it's the negative pressure generated by the syringe.

If that's the case, wouldn't using a regular 10ml syringe (which is what we do when we don't have a VAMP) cause the same problems?

 

[proman]

If that's the case, wouldn't using a regular 10ml syringe (which is what we do when we don't have a VAMP) cause the same problems?

The times I've watched a nurse draw on one of those syringes they pulled it back all the way quickly. That's not how I draw back, it usually takes me about 4-5 seconds to aspirate back. That produces much less negative pressure.

I also don't throw away the aspirate, but will give it back, usually through the a line or through a venous line (sometimes). I know most nurses won't do that. If you do give back through the a line, it should be at a rate that's slower than 1ml per second. Anything faster and you can have retrograde bolus to the cerebral circulation (bad if there's air or clot).

Does any of this make a difference? I can't say. My experience is that the units that use the systems have much shorter duration of a lines (sometimes <12 hours). Our cardiac SICU does not routinely use the system and routinely has a lines last several weeks. All of this is just anecdote though.

 

[The right Path]

Can only speak from my hospital regarding vamps.

I know there are different varieties, but the kind we stock are the inline syringe pull back system.

Personally, I've never come across any physicians prefering that we don't use them for specimens.

If you want to know an individual's rationale for preference, you really have to go straight to the source.

I can throw out some options of why they may prefer the a-line not be used for blood draws.

1. The rapid return of the "waste" and the flush can cause arterial spasm which can interfere with accuracy of measurement and cause a fling in the waveform, not to mention potentially compromising perfusion.

2. With the set-up that we use, it is possible to get retrograde blood flow into the transducer which can impair accuracy.

The points that proman already made are interesting and may be contributing factors. Interesting topic.

Also, granted, in our units (ICU/NSICU) we typically don't rely heavily on A-lines. Most frequently they are placed by the anesthesiologist during surgery for their own monitoring purposes and they usually don't bother to suture them- which doesn't help it's lifespan.

 

[proman]

1. The rapid return of the "waste" and the flush can cause arterial spasm which can interfere with accuracy of measurement and cause a fling in the waveform, not to mention potentially compromising perfusion.

I've not heard of this. Why would this happen?

Also, granted, in our units (ICU/NSICU) we typically don't rely heavily on A-lines. Most frequently they are placed by the anesthesiologist during surgery for their own monitoring purposes and they usually don't bother to suture them- which doesn't help it's lifespan.

You seem to think that suturing the line in out prolong the catheter's lifespan. I don't agree. I've had sutured and non-sutured a lines both fail, relatively quickly. I don't see how suture is any better than quality dressing and tape. One thing that does appear to matter is looping the extension tubing around the thumb. Our PICCs are never sutured either.

Unfortunately none of this stuff has ever been studied, so we don't have more than experience and opinion.

 

[cowboy71]

To keep a-lines patent there is a continuous flow through the catheter based on the pressure head against the transducer. I believe it is around 1ml/hr for each 100mmHg. I don't remember all the details, but there was a presentation at the ASA this year suggesting that failure rates are much lower with at least 3ml/hr flowing through the catheter. The surprising part was that the people presenting this had studied the difference between the pressure on the gauge of the pressure bag and the actual pressure on the transducer and there was a huge variation. Sometimes the gauge would read 400mmHg and there still wasn't 300mmHg on the transducer. This would suggest that keeping a sufficient pressure on the transducer would lower failure rate. I know in many a-lines I replace the pressure bag isn't holding that much pressure constantly and the nurses are too busy to constantly keep watching it.

The VAMP system may place enough of a resistance in the system to further reduce the flow through the catheter causing increased failure rates.

Just something to think about and for this reason I suggest putting even more than 300mmHg on the pressure bag.

 

[The right Path]

I've not heard of this. Why would this happen?]

I can't verify if it is theory, or actually proven, but the pressure and/or temperature of the flush causes irritation which results in spasm. According to this theory, when you use the rapid flush, it is supposed to be done in brief interrupted bursts and you are supposed to check the distal circulation for blanching. When I have downtime at work this weekend, I can do some searching to see if there is any research to back it up.

You seem to think that suturing the line in out prolong the catheter's lifespan. I don't agree. I've had sutured and non-sutured a lines both fail, relatively quickly. I don't see how suture is any better than quality dressing and tape. One thing that does appear to matter is looping the extension tubing around the thumb. Our PICCs are never sutured either.

Unfortunately none of this stuff has ever been studied, so we don't have more than experience and opinion.

True, my preference is only based on what I experience. And that may be because the patients that have sutured lines are usually placed by a pulm/intensivist for our nontrauma shocky patients, whereas our unsutured A lines are placed by the anesthesiologist in OR (and they are usually fresh traumas). These patients have more agitation type behavior than our 90 y old UTI sepsis patient, so it's not surprising that their A lines don't last very long. Maybe it wouldn't even help if they were sutured. I'd have to look around to see if there is any literature on that.