PINNED - Cushions

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Re: PINNED - Cushions

Postby Burgerman » 23 Feb 2021, 09:45

Its worse... Most cushions are 1024 sensors. Rohos one is 1380 sensors. And costs 10s of thousands of dollars.
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Re: PINNED - Cushions

Postby ex-Gooserider » 02 Mar 2021, 04:16

Burgerman wrote:Its worse... Most cushions are 1024 sensors. Rohos one is 1380 sensors. And costs 10s of thousands of dollars.


I was guessing conservatively at the number of sensors... But not all that far off really...

Given your numbers, and assuming a square mat, that would be 32^2 sensors on most, and 37+^2 sensors on the Roho... In approximate numbers, if sticking with the assumption of a 20"^2 mat, then it would be about 1/2 to 3/4" between sensors (probably some metric equivalent...) or a bit wider if the mat was bigger....

Either way, my guess is that nearly all the cost is in the mat, as the electronics in the rest of the unit looked to be mostly off the shelf hardware and some relatively standard software.... I would also guess that the software is doing at least some level of interpolation between adjacent sensors in order to get more 'virtual' points on the pretty butt pictures.

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Re: PINNED - Cushions

Postby Tomkilmore » 11 Mar 2021, 21:54

https://www.otstores.co.uk/p/systam_pol ... tegory/463

Hayley moved from a roho to the above cushion approx 3 months ago, after many years of a recurring pressure injury on her ischium, it looks like this cushion has sorted it. Very similar to the roho but with much thinner membrane. No more sweating in pain or limiting time up to 3 or 4 hours a day...amazing.
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Re: PINNED - Cushions

Postby Irving » 11 Mar 2021, 23:03

ex-Gooserider wrote:
Burgerman wrote:Its worse... Most cushions are 1024 sensors. Rohos one is 1380 sensors. And costs 10s of thousands of dollars.


I was guessing conservatively at the number of sensors... But not all that far off really...

Given your numbers, and assuming a square mat, that would be 32^2 sensors on most, and 37+^2 sensors on the Roho... In approximate numbers, if sticking with the assumption of a 20"^2 mat, then it would be about 1/2 to 3/4" between sensors (probably some metric equivalent...) or a bit wider if the mat was bigger....

Either way, my guess is that nearly all the cost is in the mat, as the electronics in the rest of the unit looked to be mostly off the shelf hardware and some relatively standard software.... I would also guess that the software is doing at least some level of interpolation between adjacent sensors in order to get more 'virtual' points on the pretty butt pictures.

ex-Gooserider

A colleague of mine is researching printable 3D pressure sensors (both normal and shear force) using graphene compounds and conductive elements embedded in 3D printed deformable silicon rubber structures. He reckons it should be possible to 'print' a pressure sensor mat approx 50cm x 50cm x 1.5cm containing sense elements on, say, a 4mm grid, giving a 128 x 128 array (16384 points). Since they are simply resistive devices a simple analog multiplexer and differential A2D converter 8-channel setup could easily scan the array several times a second.

Maybe sometime later this year or early next...
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Re: PINNED - Cushions

Postby ex-Gooserider » 16 Mar 2021, 03:20

Sounds like a good item if it makes it from the lab to the production floor (the problem with a lot of research is that it doesn't) However it seems unlikely to be something one can print on a typical hobby level printer due to the mix of materials....

Hope his research works!

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Re: PINNED - Cushions

Postby Chairman » 03 Apr 2021, 17:20

Varilite Evolution for me. Sat on most cushions over the 38 years of chairdom and can't get on with the Jay variants. I have a couple here to use temporarily on other chairs and the gel does nothing for me in terms of comfort. The Varilite is great and can be adjusted simply by a valve. If you're sitting on it too high just let out the air until you're satisfied, if you want the air back in, lift up and have someone to open the valve and it re-inflates. I've never had a Varilite puncture and they last years, in fact I can still sit on my cushion of 10 years and not notice it's age.

I wouldn't entertain a Roho based on the fact it's like jelly under your rump and transferring is unnecessarily difficult. Adjusting your position is made way more difficult if you can move. Rohos were always meant for those that can't move or lift themselves.
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Re: PINNED - Cushions

Postby Seajays » 03 Apr 2021, 18:26

I have sat on a Roho for 22 years with np problems , You must only get a Roho Quadro so the cells are locked . I am a double above the knee amp and have no problem to transfer
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Re: PINNED - Cushions

Postby Burgerman » 03 Apr 2021, 19:18

You must be better at it than me! I cannot transfer without a fight on the two quadros I have here. I always knew they offered the best pressure ulcer prevention based on looking at both the way they work and on hundreds of others pressure maps at my spinal injuries unit.

But as an active user the stability and ease of transfers on the Jay gel cushions mattered. As did the zero maintainance. And worry about bottoming out, or pnctures. So now I have decided that I am sick of being on a bed with pressure ulcers reccuring and so have no choice but to use roho, and a patient lift which is a royal pain in the backside (not literally). Note that NON of this has anything to do with comfort but pressure ulcer prevention or healing. So if you dont NEED a roho, esp if active, then a Jay2 or a jay fusion etc are better and almost as good with pressure. But if you have no choice, a roho it has to be...

Also, Varilite Evolution maps for pressure on most users slightly worse than jay2 and considerably worse than roho for peak pressure on the ischeals. It might well be more comfortable. But its almost garanteed worse for ulcer prevention than a roho. I know that from looking at dozens of comparisons as above. So I never tried one.

I might add that the least comfortable cushion for those that were testing it (spinal injuries unit plus others) that could actually feel it (I cant) was the best one for low pressure on the ischeal tuberosities. It was similar to this: https://www.permobil.com/en-us/products ... ct-cushion
Only more extreme. So comfort and peak pressure on the important bits do not always align.

The advantage of the deep roho's is that they can get you due to high levels of air immersion, to below 27mmHg across your backside. With no peaks above 32mmHg. Since its air infated the pressure is the same everywhere. Its not higher where immersed deeper. Not many other cushions can achieve this. This is the pressure that closes the blood flow in capilliaries. Hence my fancy pressure gauge/pump on the previous page. It allows me to be 100% sure that it is at the lowest pressure possible daily or weekly without bottoming out safely without doing further difficult hand tests. Remember that the barometer changes over a day or so. And so does the pressure in that cushion. The difference between capilliary closed and open can be 1mmhg variation.

If you are not struggling with ulcers this isnt important.
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Re: PINNED - Cushions

Postby Chairman » 03 Apr 2021, 20:52

Burgerman wrote:
Also, Varilite Evolution maps for pressure on most users slightly worse than jay2 and considerably worse than roho for peak pressure on the ischeals. It might well be more comfortable. But its almost garanteed worse for ulcer prevention than a roho. I know that from looking at dozens of comparisons as above. So I never tried one.

We are all built differently so maps to me are just that, maps. As far as I am concerned I have never had a pressure sore nor once needed to resort to bedrest in 38 years. There are many variables to this of course and I got out of a manual 'static' sitting chair full time enough years ago to give my body a rest and allow for weight relocation via tilt and recline which I believe has helped no end. Age dictates too that we cannot sit in one position most of the day except for the occasional lift without extreme pressure on one area, eventually something has to give.

Rohos are not for active paras or tetras, they might well help AFTER the sore but will also reduce activity which is equally important to recovery and loss of movement prevention. The object is to prevent sores in the first place and your Jay2 clearly failed you, mapping or no mapping which I am not surprised at having tried them.

Compatibility cannot be decided either comparing different injuries/conditions. A paraplegic transfers differently to a tetraplegic (if they transfer at all independently) to a double above the knee amputee.
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Re: PINNED - Cushions

Postby snaker » 04 Apr 2021, 04:00

I am fighting a sore. I bought a Vicair and it did not help, then I bought a Roho. After ordering, I recognized that Roho cushion was not quadro and I thought I wasted my money. It arrived 2 months ago and I tried it. It is really good in preventing pressure sore. I only use it when going outdoors, the sitting time is usually 5-6 hours but the sore only get wet a little. After the sore occurs, I always sweat a lot. But sitting on that Roho, I do not sweat. Although it is not a quadro but sitting is fairly comfortable and stable.
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Re: PINNED - Cushions

Postby Burgerman » 04 Apr 2021, 07:49

They work. Because they are one of the only cushions that allow a less than 27mmHg pressure across the most submerged (and all) bits. If sized and set correctly. This is critical. And cant be reached by any other type of cushion.

The problem with any types of foam is that they increase pressure the deeper your backside pushes into them. With all air, and no foam at all, the pressure on the bits of your backside that are submerged is exactly the same on the bits that are not. And in getting all of your backside below 27mmHg this is critical.

That pressure in the air cushion, is equal everywhere. So if you are sunk deeply into the cushion so that only 20mm or less remains - pressure is low enough that it does not close off the capilliaries in your skin even at the deepest parts. JUST. A fraction too much air in a roho and thats not the case. Its very critical to a couple of mmHg. So be sure you are sat very deeply into the cushion. This is the reason I bought that pressure monitor attached to the pump. I can get around 1 to 2 mmHg below that critical point. With around 10 to 15mm remaining before bottoming out. This magical pressure where no skin damage occurs is around 27mmhg. Anything below that and you are curing a sore. And not making it worse. This isnt possible with any other type of cushion.

Also theres this. Which is from gooserider,

One of the things I have heard about Roho's is that it is absolutely critical that the size of the cushion match the size of the butt that is sat upon it...

If the cushion is bigger than the butt, all the air moves to the un-sat-on cells and the sitter bottoms out unless very high pressures are used...

If the cushion is smaller than the butt there is no place for the air to go, so you end up w/ higher pressures in the cushion, while the excess butt droops over the edges...

The cushion needs a 'Goldilocks' style fit that is "just right"....

ex-Gooserider


Which is absolutely true. The little gauge I use shows this when experimenting on my two 19 inch x 20.5 cushions with my petite (small bum) female freind, and my somewhat well built relation. When at that 15mm hand gap point, they both need MORE pressure than I do. Meaning above that 27mmHg point.
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