Cushion layers

[Puma]

Hi people, after 30+ years on being in Chair my ischms severely hinder the amount of time I can spend in my Chair, ChatGPT suggested putting foam or gel underneath my Roho for more immersion and better pressure relief, has anybody successfully done this or tried it?
Thanks for your knowledge

[Burgerman]

I started getting this problem 10 years back. Tried everything and only roho and getting off chair 1 hour (bed) daily at 5pm. And a chair with tilt/recline/legs helped...
Even that became problematic and I now spend up to half the year stuck on a bed.

[LROBBINS]

The suggestion from ChatGPT is not worth the electrons used to compose it and send it to you.

Burgerman's suggestion of tilt for weight shifting is a good one, though, as in his case, not always effective.

The Roho, adjusted properly, is a good cushion choice, but there are some others now that you might consider. The one that Rachi had used for about a year (before her death in June) was the Starlock https://www.etac.com/products/seating/wheelchair-cushions/starlock/ (distributed in North America by Quickee). It comes in various air finger heights up to 5" and has an ingenious system of interconnections that allows molding each finger to fit and locking them in place and re-modelling it all pretty easily. Seated height is always the same, but the taller the fingers the greater the immersion. There is a downloadable user manual and quick start guide.

[Puma]

Yes, I have the starlock 5” cell, in theory it should work, but it does not because the air does not move at all once it is locked off even when it is not locked off the air does not flow from cell to cell like the Roho, I have a tilt in space on my chair which I use all the time, Roho used to do a 5 inch cell but they stopped making them about 10 years ago, when I used tilt my cleft suffers!!! It is a shame we cannot invent an FES system to go on our arse cheeks to build the muscle back up, in the early 90s I sat on a coach seat all the way to Lourdes with no problems!!!! Ffs

[martin007]

Please, excuse my ignorance.
What is the problem and what is its cause?

[Puma]

Due to paralysis and muscle waste, I have lost all the padding off my buttocks which protect your pelvis and ischms from pressure when sat in my chair, currently limited to 3 hours a day, I know this is better than some, but just trying to look for any other ideas. Would BM not be suitable for the Ease cushion? It is in America.

[martin007]

Spinal cord injury?

[Puma]

Yes in 1993

[Burgerman]

Ditto 97.

[Burgerman]

Yes, I have the starlock 5” cell, in theory it should work, but it does not because the air does not move at all once it is locked off even when it is not locked off the air does not flow from cell to cell like the Roho,

But it should lock it in place thats the point of it. I use a quadra roho so once seated and hand gap checks then I turn the valve that locks it into 4 quarters.

Why does it need to do this?
You likely dont want a physics lesson so I will keep it simple. PLEASE read this as its important that you understand it. This IS the simple short version even though its a book.

The sores are caused by skin pressure against the cushion stopping the blood (providing oxygen to the cells) when the capilliaries get squished flat under the skin.
Gravity is 1G. Your mass doesent change. And you sit on your ass... So that mass squashing those capilliaries, always remains the same. If you had no bones and were a "blob", that pressure would be exactly the same across the whole seat/ass bit of you that was touching. Thats great! But sadly we have structure and bones. That basically leaves 3 "hard" points under you that are at a higher pressure than the rest of you. The more of that muscle and fat on your backside retreats and atrophies then the greater the pressure is on those 3 points.
I am saying this as a preliminary as many here dont have this issue. And think a good cushion is about comfort. I know that you already know this stuff. This part wasnt for you!

********************

Now for the important stuff you might not fully appreciate.

With a FOAM cushion the further something pushes into it the more pressure it exerts (or the harder it has to press...)
So that if you press your finger into a foam cushion, (or anything with foam), it goes deeper only if you push harder. And with foam it does this at a rising rate. So you may need to press only 1lb with a finger to move that foam by 1 inch. But to move it in by 2 inches, needs 4 times that force. So 4lb... This is important!!! In order to push it another further 1 inch, that now needs 16lb... Its generally close to a "square" law. That means any bits of YOU that push into that foam the deepest or support the most weight, see by FAR the most skin pressure.

Now...
If you were to lay down on a flat hard surface. Most of you will not touch the ground. Maybe only 10% of your body surface supports ALL of your weight. So small area on back of head, a patch on your spine/shoulders, heels and your buttocks. These have enormous pressure. The rest of you, non! And is why we need a mattress and not a hard floor or it hurts!

So a handful of your body parts see huge pressures, and the rest sees non.

Its important to get this bit.
Now imagine you are floating in a swimming pool. And relax. You ALMOST submerge in it. If you hold your breath and relax you JUST float on your back. BECAUSE of the large DEPTH of submersion, an awful lot of your skin contacts the water. Your weight is still the same. So the skin sees much less pressure.
And because the pressure is spread evenly through the water, (its easy to press your finger into that water further unlike that foam).*** you have almost exactly the same AND a now very low pressure supporting you across a huge area of your body. ***
The parts that are the deepest (heels, ass, back of head etc) do not have more pressure pushing back than any other part of your body. REMEMBER the greater the surface area in contact with that water the lower that pressure actually is. Same mass, more area!

So... A ROHO allows a very similar effect as that water but using low pressure trapped air. But here is the important but. IMMERSION. A cushion that allows you to sink into it deeper allows greater immersion. So you WANT a cusion thats slightly wider and deeper than you would normally use by maybe an inch all around. And you want JUST enough air to prevent your ass touching the base. And no more. You need to sink into that cushion to benefit from the IMMERSION that actually puts more of your skin area in contact. So around the sides of your legs etc.

So why do I WANT this air to be locked in place? Because once you sit in the chair and adjust pressures correctly, you will be as immersed as possible. Thats important. NOW lock it! If you dont, and you roll along a street at an angle laterally then YOU will sink on one side, and rise on the other as the air moves around. Now the lower side is bottomed out when your mass leaning on it pushed it away. You can prevent that by having more air. Now you lost the biggest advantage of the roho - its deep floatation capabilities that stop you getting a new sore.

I have a tilt in space on my chair which I use all the time, Roho used to do a 5 inch cell but they stopped making them about 10 years ago,

Greater submersion = lower pressures if the cushion size is large enough to sink ito it rather than sitting on top of all the cells. Shame they dont still make them.

when I used tilt my cleft suffers!!! It is a shame we cannot invent an FES system to go on our arse cheeks to build the muscle back up, in the early 90s I sat on a coach seat all the way to Lourdes with no problems!!!! Ffs

You want extra depth?
Get a custom cover made. The bottom of those cushions is very floppy and flexible. So just then add a 1 .5 inch thick SOFT polyurehane foam layer UNDER the RoHo. Now you can have the full 4 inch immersion depth, no need to worry about bottoming out.
And you can even cut the foam away under that roho below your cleft and your coccx and ischeals.

I am about to do this myself.

I suppose you already know that RECLINE and tilt as well as leg elevation all reduces pressure on your backside and moves it to the backrest and the legrest - if you do all 3 things at once (regularly).

[Puma]

thank you for your explanation,
I used to have a 5” dual valve (front/back) Star cushion which was like a Roho but when he Etac bought Star they stopped making them, these cushions let me Immerse more than the Roho, sadly the rubber has gone thin and loses air too fast for me to sit on it!!
I have also found that the Roho cover you get with the cushion is too tight and this causes cradling which marks my cleft, how I get away is I keep the cushion zipped up when I am getting on it (Hoist) then unzip the cover when I am seated in place..

Please will you keep us posted on how the polyurehane foam gets on, i’m going to try this too!
It is a shame that is not a cushion that is zero pressure!!

[Burgerman]

The only way to get zero pressure would be in orbit or free fall.

[Puma]

Could it be done with magnets?

[martin007]

The only way to get zero pressure would be in orbit or free fall.

You can add a vertical wind tunnel.

Could it be done with magnets?

Your body isn't magnetic...

[Puma]

I know your body is not magnetic, but you could wear pants or something with magnets on, it was just a crazy thought I had in my head!!
I am just looking at foam on the web, is there any particular websites that are any good?

[Burgerman]

But the pants that would lift you and then be the cause of the very same pressure...


The wind tunnel could potentially be made to work if you dont mind a 200mph wind all day long! But if it pushes on your ass then it too causes pressure... It would need to lift you from the sides only. So maybe 300mph? You would go deaf. Take hundreds of horsepower. And drive you insane.

Of course living on mars or the moon would help enotmously. Go Elon!

[Burgerman]

Foam, ebay.


If you find that an air cushion at super low pressure still causes issues then a cushion made from relatively hard foam. But SHAPED carefully in a way that it supports your mass evenly over a wide/ large surface area, with certain bits literally missing can do the same job better.

Look at the image below. The BASE part is hard shaped closed cell foam moulded to fit you. With a section then removed where your sores or high pressure bones are. This then has very soft foam, in that "gap". Its got rounded edges around that hole. So that there is no sudden transition from pressure to no pressure as that alone can cause issues if not designed right.
The white bit is a medium hard foam shaped to sit on tip.

You actually dont have to fit that centre dark "plug" bit at all. It then allows more airflow so no sweating/damp issues. The SHAPED outer part fully supports you. Even the corners take your weight.

This needs to be sculpted or formed with poyurethane foam, cut out, and then a mould made to build the thing from closed cell strong foam. So it can be a slikked DIY job. But its not easy.

[Burgerman]

More.

This lower fairly solid closed cell sculpted part alone supports you completely. With no pressure on the coccx, ischeals etc. That is a better solution than any gel, air or other cushion.

That white pad is more for "comfort" and is a simple bit of 2 inch foam in a bag.

This is what we both really need.

[Burgerman]

I may be able to get these, sunrise are now a dealer.
Sizes:

https://ridedesigns.com/wp-content/uplo ... ions_0.pdf

If you suffer issues with sores, you will really want to read this:
https://www.sunrisedice.com/asset-bank/ ... 111727.pdf

I am currently abou to order one! First I will see if WCS will supply one!

[Puma]

I am going to be curious on how you get on with this, I did enquire about a bespoke one being made, Wheelchair Services offered to pay but they said you have to sit in exactly the same position every single time and when you are hosted with different people getting exactly the right position is a little bit tricky ! I am going to drive the foam!!

[Burgerman]

In the case of that particular cushion it can be bought off the shelf.
It outperforms gel and air because the parts that are subject to damage like your isheals are basically in fresh air almost unloaded.
The perimeter of that cushion supports you even/especialy at the corners instead. And so now positioning isnt at all critical. And it automatically puts you into the same position as you sort of sink into rather than on it to the correct place as you decend. Theres no option!

Take a look at the pics carefully. Look at the black very tough closed cell moulded base. Imagine sitting on that.
There IS acustom made version too, if you want that. And a way to scan this yourself. Take a careful look at the manufacturers site.

Over the counter cushion ready to use.
https://ridedesigns.com/wheelchair-cush ... a-cushion/
Thats the one I am suggesting. And will try and get.

There are others.
https://ridedesigns.com/wheelchair-cushions/

[Puma]

I am going to see if I can get pressure tested on one of them, I was always led to believe that air is the best pressure relieving, I know it states problem areas can have zero pressure or very little but it is how much pressure will be on the other areas?? keep us posted, I am so going to have a go with this foam!!

[Puma]

I have heard people who work at the spinal unit recommending this cushion. I do not know if it would be any good for us.
https://kentmobility.co.uk/product/pro- ... o-inserto/

[Burgerman]

>>>I am going to see if I can get pressure tested on one of them, I was always led to believe that air is the best pressure relieving,

But you need to press that air cell down. With your weight ncreasing the pressure in the cushion.

I know it states problem areas can have zero pressure or very little but it is how much pressure will be on the other areas?? keep us posted, I am so going to have a go with this foam!!

More pressure. Where you dont get high peak pressures (no sticky out bones) anyway, so no sores. But air gives the most even pressure. But its a pressure non the less. Determined by your mass and the area it supports. Also note that this air does not support the corners. So increased pressure elsewhere.

On any normal cushion there is pressure on all of the flat surface. But even air has a depth pressure increase gradient. So that means the deeper the immersion of your 3 pressure points is the greater the pressure. (But it is a lesser gradient than a normal flat foam cushion). But that means the pressure is still at the greatest on the Isheals. (The two red dots on your map) And it always will be.

With the specially shaped hard closed cell foam cushion that supports you around the sides and in the corners, thats all reversed. The higher pressure is everywhere else and not in that centre hole. The slightly increased pressure is now in the places where you dont get sores easily (no bones/protrusions). And peak pressures are normally on the ischeals but now thats reduced or removed depending on configuration.

The other thing is heat/damp. This cushion has a groove underneath that connects to that hole, the place where your ischeals live. So its ventilated and kept dry by air pumping in and out as you bounce about on our streets too. I think heat is a major cause of breakdows as it seems way worse in summer.