How to Choose the Right Size and Shape Donut Pillow for Bed Sores?

Do not use ring-shaped cushions for a pressure sore — US patient guidance says their edges cut blood flow and can create new wounds. Choose a fitted pressure-redistributing cushion instead.

An open center looks like relief. That is the whole selling point of the shape, and it is also the trap: MedlinePlus warns that donut- and ring-shaped cushions can reduce blood flow and cause pressure sores rather than heal them. So the honest answer to sizing a ring cushion is that no clinical body publishes a size chart for one. What follows is what to buy instead, how it should fit, and how often the person using it needs to shift position.

Why Ring and Donut Shapes Cause Harm

A donut cushion removes pressure from the center and dumps it onto the rim, which is exactly the wrong trade. The NPIAP/EPUAP/PPPIA seating guideline describes ring cushions as creating high-pressure edges that may damage tissue, impair circulation, and cause edema.

Two things go wrong at once. Blood supply to the skin over the sitting bones drops, and the tissue pressed against the inner edge of the ring swells. A wound sitting over that edge gets squeezed from a new direction.

Marketing claims that a hole “increases blood flow” have no clinical backing. Skip any product that leans on that promise.

What to Look For In A Pressure-Relief Cushion

Ask a clinician, wound-care nurse, or physical therapist to pick the support surface, because the right one depends on wound location, stage, mobility, body size, and whether the person is in bed or in a wheelchair. MedlinePlus is direct about this: cushion choice follows the wound and the seating position.

Whatever you end up considering, judge it on these points:

• Full seating support. The cushion must cover the entire sitting area and fit the chair or wheelchair securely, not perch on top of the seat rails.
• Immersion or off-loading. The surface should let the body sink in and spread weight, or deliberately shift load away from the wound. A central cutout does neither.
• Pelvic stability. A cushion that lets the pelvis tilt or slide can push a wound against a hard edge.
• No wound-to-hard-edge contact. Nothing the wound rests against should be firm.
• Daily inspection. Air, foam, and gel-cell cushions need checking every day for flattened cells or other defects that turn into pressure points.

If the person cannot reposition themselves, alternating-pressure equipment is worth raising with the care team — evidence supports considering it, and alternating-pressure cushions may help chair- or wheelchair-bound patients who cannot perform pressure relief on their own.

For heel risk, the shape question flips. A heel-support device, or a pillow or foam pad that runs along the lower leg and lifts the heel completely clear, works — as long as it does not press on the Achilles tendon or the vein behind the knee. Ordinary pillows should not go directly under a heel or other bony point, since the limb sinks and vessels can narrow.

Memory foam deserves a second look before you buy. It feels soft, but it holds heat and moisture, and damp skin breaks down faster.

If you want to see which specific cushions hold up best in practice, our guide to the best donut pillows for bed sores compares the tested options side by side.

Does Repositioning Matter More Than The Cushion?

Yes — always. A support surface lowers risk, but it never replaces the schedule. People in bed should be moved roughly every two hours. Wheelchair users need pressure relief far more often, about every 15 minutes.

That is a lean-and-lift or a push-up out of the seat, not a wiggle.

Two care habits matter alongside it. Do not massage skin over or near a pressure injury — MedlinePlus says massage can cause further damage. Get medical care promptly for blisters or an open wound, and contact a clinician immediately for foul odor, pus, surrounding redness or tenderness, warmth, swelling, or fever.

Getting the Fit Right For One Person

Size is prescribed, not shopped off a chart. No authoritative source publishes a universal donut-pillow opening diameter, thickness, or body-weight formula, because the shape is not recommended for pressure-injury care in the first place.

What the NPIAP/EPUAP/PPPIA guideline emphasizes instead is pressure redistribution plus clinical assessment. A cushion gets fitted to the person’s body dimensions and existing seating system, then checked so pelvic stability holds and no wound touches a firm edge. That sizing session is also where the care team decides between immersion, off-loading, and alternating pressure for this particular wound.

And avoid the assumption that a wider opening is safer. The hazard lives in the ring’s perimeter pressure, not just in what sits at the center.