---
title: "Hospital bed mattress guide: foam, alternating pressure and low air loss"
url: https://www.kelingmed.com/blog/pressure-relief-mattress-guide/
published: 2026-07-17
updated: 2026-10-19
author: Keling Medical export team
---

# Hospital bed mattress guide: foam, alternating pressure and low air loss

Choose the right hospital bed mattress: foam vs alternating pressure vs low air loss, overlays vs replacements, sizing, covers, cleaning and what to specify.

## Key points

- A hospital bed mattress is a clinical support surface: foam suits most low-risk patients, while alternating pressure and low air loss air mattresses are used for patients at higher risk of pressure injuries.
- Alternating pressure mattresses inflate and deflate cells in a cycle to shift load; low air loss mattresses let air flow through the surface to control heat and moisture.
- An overlay sits on top of an existing mattress and is cheaper, but it raises the patient and reduces effective side rail height.
- The mattress must match the bed platform size and be tested with the rails, otherwise gaps can create an entrapment risk.
- A damaged or worn cover lets fluids into the core, so covers need regular inspection and replacement.


A hospital bed mattress is a clinical support surface, not just bedding. Foam mattresses suit most patients who can change position themselves; alternating pressure and low air loss air mattresses are used for patients at higher risk of pressure injuries. The right choice depends on risk assessment, bed size, rails, cleaning and the care setting.

This guide compares the main types of medical mattress, explains alternating pressure vs low air loss, and lists what to check when buying or replacing them. It is educational and aimed at buyers, nurses and biomedical teams; the choice of surface for an individual patient belongs to the clinical team.

## Why the hospital bed mattress matters

The mattress decides how body weight is spread across the skin. When pressure, often combined with shear and moisture, stays on bony areas such as the sacrum, heels and hips, it can damage tissue and cause pressure injuries, also called pressure ulcers or bed sores.

A support surface works in two ways. It **redistributes pressure**, either by letting the body sink in (immersion) and wrap around (envelopment), or by moving load from one area to another. It can also **manage microclimate**, the heat and moisture at the skin.

The US National Pressure Injury Advisory Panel groups surfaces into **reactive** ones, which change load only when the patient moves (foam, gel, static air), and **active** ones, which change load with a power source even when the patient is still (alternating pressure).

## Types of medical mattress compared

Each type has a place. The table gives a quick comparison.

| Type | How it works | Typical use | Trade-offs |
|---|---|---|---|
| Standard foam | Single-density foam in a cover | Low-risk, mobile patients; general wards | Bottoms out over time; limited pressure relief |
| High-specification foam | Multi-layer or viscoelastic foam | Low to moderate risk; first-line in many hospitals | Warmer than air; heavier |
| Static air / bubble pad | Air cells at constant pressure | Low to moderate risk; overlays | Needs correct inflation |
| Alternating pressure (APM) | Cells inflate and deflate in cycle | Higher-risk, immobile patients | Pump noise, power needed, some find motion uncomfortable |
| Low air loss (LAL) | Air escapes through surface | Moisture and heat management | Needs compatible linen and continuous power |
| Combined APM + LAL | Both functions in one system | High-risk ICU and long-stay patients | Highest cost and maintenance |

### Hospital bed foam mattress

Foam is the default medical bed mattress for most wards. It needs no power, is quiet and gives a stable surface for sitting and transfers. Keling's [KL-P001 Mattress](https://www.kelingmed.com/products/hospital-beds/kl-p001-mattress/) is made in a 190 × 90 cm size with five thicknesses from 60 to 150 mm and a choice of fills, including high-density sponge and a PU cover. The [KL-P002 Mattress](https://www.kelingmed.com/products/hospital-beds/kl-p002-mattress/) is a three-section mattress that folds with the bed's backrest and knee sections.

A firm hospital bed mattress makes transfers easier, but a surface that is too firm concentrates pressure. Memory foam and multi-layer foams improve comfort and immersion but retain more heat.

## How an alternating pressure mattress works

An alternating pressure mattress has rows of air cells connected to a pump. The pump inflates one set of cells while the other deflates, then reverses, so that each area of skin is periodically offloaded. A cycle typically takes several minutes, and many pumps let staff set the cycle time and the pressure for the patient's weight.

Two construction styles are common:

- **Bubble-cell pads**, a grid of small cells, usually used as an alternating pressure pad on top of an existing mattress
- **Tubular cell mattresses**, with larger cross-bed cells, usually deeper and used as a replacement mattress

Keling's [KL-P003 Air Mattress](https://www.kelingmed.com/products/hospital-beds/kl-p003-air-mattress/) is a bubble-cell air mattress with an electric pump, and the [KL-P004 Air Mattress](https://www.kelingmed.com/products/hospital-beds/kl-p004-air-mattress/) uses tubular air cells with a pump that has a digital control panel.

## Low air loss mattress vs alternating pressure mattress

The difference is what each one controls. Alternating pressure moves load; low air loss manages the skin environment.

A **low air loss mattress for hospital bed** use has small perforations or a breathable top layer through which air escapes continuously. The airflow carries away heat and moisture, which matters for patients who sweat heavily or have continence issues. A low air loss surface can be static or alternating.

| Question | Alternating pressure | Low air loss |
|---|---|---|
| Main purpose | Periodically offload skin | Control heat and moisture |
| Powered | Yes | Yes |
| Motion felt by patient | Yes, slow cycling | Usually little |
| Linen | Standard sheet, not tucked tight | Breathable linen; avoid multiple layers |
| Best for | Immobile, high-risk patients | Moisture, heat, high-risk skin |

A low air loss alternating pressure mattress combines both. These systems are common in ICUs and for long-stay patients with existing pressure injuries.

## Overlay or replacement mattress?

An **overlay** sits on top of the existing mattress; a **replacement** takes its place on the bed platform.

Overlays, such as an alternating pressure pad for hospital bed use or an air mattress topper, are cheaper, lighter and easy to deploy at home. Their drawback is height: adding 60–100 mm on top of the mattress raises the patient relative to the side rails.

Replacement air mattresses are deeper, give more consistent support and keep the surface at a predictable height. They usually cost more and need storage when not in use.

## Rails, sizing and entrapment

Any change of mattress changes the bed system. A thicker or softer surface lowers the effective height of the side rails and can open a gap between rail and mattress edge.

IEC 60601-2-52 and guidance based on it call for the rail top to sit at least 220 mm above the uncompressed mattress on adult medical beds. Check this with the air mattress fully inflated, and use extra-height rails if necessary. The [hospital bed rails guide](https://www.kelingmed.com/blog/hospital-bed-rails-guide/) covers the full set of gap limits.

Size matters equally. The mattress must cover the platform with no side or end gaps. Standard hospital mattress sizes are summarized in [hospital bed dimensions](https://www.kelingmed.com/blog/hospital-bed-dimensions/).

### Bariatric hospital bed mattress

A bariatric mattress must match the wider platform of a bariatric bed and carry the higher load without bottoming out. Air systems need a pump rated for the patient weight. Do not put a standard-width mattress on a wider frame.

## Covers, cleaning and infection control

The cover protects the core and is the part that touches the patient. Most hospital covers are fluid-resistant, vapor-permeable PU-coated fabric with welded or protected seams and a zip flap.

Regulators including the US FDA have warned that worn or damaged covers can let body fluids into the mattress core, creating an infection risk. Good practice:

1. **Inspect covers** at every patient change, including the underside and zip.
2. **Unzip and check the core** periodically for staining or damp.
3. **Clean with agents** listed in the manufacturer's instructions; harsh chemicals degrade coatings.
4. **Replace covers and cores** that fail inspection; keep spare covers in stock.
5. **Service pumps** as part of planned maintenance, including filters, hoses and alarms where fitted.

For fire safety, many European buyers specify mattress ignition testing to EN 597-1 and EN 597-2. Ask which tests apply to your market.

## Hospital bed mattress replacement: when and how

Mattresses wear out long before bed frames. Foam slowly loses its height and resilience, especially in the seat section where load is highest, and a mattress that has "bottomed out" no longer redistributes pressure even if it looks intact.

Signs that a hospital bed mattress replacement is due:

- Visible dips or a seat area that feels thinner than the rest
- The hand test: with the patient's weight simulated, you can feel the platform through the foam
- Stains or damp inside the core, or a cover that is torn, cracked or no longer zips closed
- Air cells that leak, pumps that alarm repeatedly or cannot hold set pressure

Replace like for like in size, and re-check side rail height if the new mattress is thicker than the old one. Keep a register of mattress age and inspection results alongside the bed's maintenance record.

## Mattress for hospital bed at home

At home, the best hospital bed mattress for home use is usually a good foam mattress for people who can move themselves, and an air mattress or overlay for people who are bedbound. Consider pump noise in a bedroom, the power supply, and whether a caregiver can manage settings and alarms.

Patients and families should follow the advice of their nurse or clinician on the surface, and ask how often to reposition and check skin. The [home-care hospital beds guide](https://www.kelingmed.com/blog/home-care-hospital-beds/) covers the rest of the home setup.

## What to specify when buying medical mattresses

For tenders and replacement programs, put these points in writing:

- **Type:** foam, high-spec foam, alternating, low air loss or combined
- **Size and thickness** to match each bed model's platform
- **Patient weight range** for the mattress and pump
- **Cover material,** seam construction, zip protection and cleaning agents
- **Pump features:** cycle time, pressure settings, alarms, CPR deflation, power failure behavior
- **Electrical safety testing** of the pump to IEC 60601-1
- **Fire testing** required in your market
- **Spare covers, cells and pumps,** and expected service life

Order mattresses with the beds so sizes match exactly; Keling supplies foam and air mattresses alongside its [KL-BC101 Electric Hospital Bed](https://www.kelingmed.com/products/hospital-beds/kl-bc101-electric-hospital-bed/) ICU bed and ward beds. Ask for the documents that apply to the model and destination country.

## Next steps

Match the surface to the patient's risk, the mattress to the bed platform and rails, and the cover to your cleaning protocol. Browse Keling's [hospital beds and mattresses](https://www.kelingmed.com/products/hospital-beds/), or send your bed models and quantities through the [quote form](https://www.kelingmed.com/contact/#rfq) for matched mattress options.


## FAQ

### What is the best mattress for a hospital bed?

The best mattress depends on the patient's pressure injury risk. A good foam mattress suits most patients who can move themselves. Patients who are immobile, at high risk or already have pressure injuries are usually placed on an alternating pressure or low air loss air mattress. The clinical team should choose the surface after a risk assessment.

### What is the difference between a low air loss mattress and an alternating pressure mattress?

An alternating pressure mattress periodically inflates and deflates rows of air cells so that no area carries load for long. A low air loss mattress lets a small, constant flow of air escape through the surface to keep skin cooler and drier. Many modern air mattresses combine both functions.

### Do air mattresses help with bed sores?

Air mattresses are one part of pressure injury prevention and care. Alternating pressure and low air loss surfaces redistribute pressure and manage skin microclimate, which helps at-risk patients. They do not replace repositioning, skin checks, nutrition and continence care, so patients and caregivers should follow their clinician's plan.

### What size mattress fits a hospital bed?

Most adult hospital beds take a mattress of about 36 x 80 inches in North America, or about 900 x 1900-2000 mm elsewhere. Always use the size the bed manufacturer lists for the platform, since a mattress that is too small leaves gaps beside the rails.

### How often should a hospital bed mattress be replaced?

Replace a mattress when the foam has lost its support, the cover is torn or stained inside, or an air mattress no longer holds pressure. Check covers and cores at least at every patient change and as part of planned maintenance. Many facilities budget for replacement within a few years of heavy use.

### Can I put an alternating pressure pad on a home hospital bed?

Yes, alternating pressure pads and overlays are designed to sit on an existing mattress, including home-care beds. Check that the overlay fits the mattress size, that the pump can be mounted on the footboard, and that the side rails still rise well above the inflated surface.

### Is a firm hospital bed mattress better for back pain?

A firm mattress gives stable support for sitting up and transfers, but too firm a surface concentrates pressure on bony areas. Medium-firm foam or a high-specification foam often balances support and comfort. People with back pain should ask their clinician which surface suits their condition.