Walking without a pulse

[cscboulder11]

http://www.popsci.com/science/article/2012-02/no-pulse-how-doctors-reinvented-human-heart?page=all

Thought this was interesting.

[DwayneEMTP]

That site is blocked for me, but is that the guy with the mechanical hear that has continuous blood flow, instead of pulsating circulation?

If so, it's a pretty amazing story. I wonder though if the circulatory pulsations serve purposes other than being an expression of the heart filling/emptying? Could there be side effects from it's absence?

[cscboulder11]

That site is blocked for me, but is that the guy with the mechanical hear that has continuous blood flow, instead of pulsating circulation?

I PM'd the text of the story to you. It is continuous.

[paramedicmike]

I worked in an area that had several ventricular assist device (VAD) patients several of whom did not have a pulse. Yet they were quite alive.

Science is pretty amazing, isn't it?

[Asysin2leads]

Dick Cheney has one of those continual flow models. Cue Darth Vader theme.

Edited March 1, 2012 by Asysin2leads

[DwayneEMTP]

Not wondering so much about short term failure, as they seem to work, at least in the reported patients, pretty well.

I just wonder if over time the body's mechanism come to count on the pulse for some reason.

If it changes the bodies natural compensation mechanisms?

I wonder how the pump manages compensation?

Any idea where it get's it's rate from?

[island emt]

We had a regular summer visitor that has an LVAD. It is quite disturbing the first time you feel for the pulse and don't feel one while the Pt is answering your questions

the only thing was the whirring of the pump and the wires from the battery pack into the chest.

I think the rate is set by the controller to get the desired perfusion flow.

Our Pt had about 1 year on the pump while letting his heart rest & recuperate.

Last I knew he was doing fine running on his own heart muscle.

[mikemedic999]

How about i nip to the specialist hospital and ask.....ive been to papworth hospital where they do amazing shit like this!

[fiznat]

I just wonder if over time the body's mechanism come to count on the pulse for some reason.

Hi Dwayne!

Just learned this a few months ago in school. The body actually works really heard to diminish that pulsing effect. Having peaks and toughs (a diastolic and systolic) in vascular pressure is actually bad for exchange of nutrients at the capillary level. It would actually be completely ideal if the blood flow were slow and constant (like a gently passing stream) rather than the pulsating flow that comes out of the heart. Turns out, this is why arteries are so elastic: because the way they stretch helps to buffer the high and low pressures to even things out. This works so well, that normal healthy people by the time you get to the capillary level (where exchange actually happens), blood flow is smooth and the pulsating is effectively gone.

We've done a whole lot of systems by this point, and I haven't yet run across any sort of autoregulatory or otherwise physiologic mechanism (outside of the heart itself) that relies on a pulsating flow of blood. Doesn't mean there isn't one haha, but just my brief experience in medical school so far tells me that a "pulse" might not be all that important or necessary.

Edited March 3, 2012 by fiznat

[DwayneEMTP]

Hey Fiz! Man, have I been missing you around here!!

Thanks for your comments. That's exactly what I was wondering, and it makes perfect sense the way that you describe it.

Have you come across any descriptions about how these types of devices deal with compensation/decompensation? Or changes in demand say, secondary to catecholamine release? I'm not sure why this suddenly grabbed my interest, but it has.

And most important of all....any chance that we'll ever have access to your blog again? I've probably spent 25hrs reading it, and miss it still, and I know that many here would benefit from it. It's truly one of the most amazing EMS related things that I've read, at least where my experience base is concerned. It not only matched the things I thought and felt from memory, but often predicted the things that I hadn't thought or felt yet...it was like a friggin' drug!

Anyway, it seems, if I remember right and I probably don't, that you took it down secondary to legal concerns? Whatever is best for you Brother, but if there's the possibility of opening it back up as a resource for the City, that would be awesome.

I hope all is well with you Fiz...The City is certainly less when you're not here.