The forgotten line in a bed tender: hospital mattresses and pressure injury prevention
Most bed tenders specify the frame in detail and the mattress in three words. How to assess risk, when foam is enough and when it is not, what a cover has to survive, and how to write a mattress specification that is enforceable.
Read a hospital bed tender and count the words. The frame gets a page: motor count, height range, side rail type, castor diameter, CPR release, load rating. The mattress gets a line, often just the phrase with mattress, occasionally a thickness in millimetres. The frame will be inspected on delivery by three people. The mattress will be whatever the lowest bid could supply with the money left over, and it is the part of the bed that is in contact with the patient twenty-four hours a day.
The frame gets inspected on delivery. The mattress gets inspected when a patient develops a sore.: Vvon installation team
Pressure injury is a mechanical problem
Tissue over a bony prominence is damaged by sustained loading, and two mechanisms are at work that need different answers. Pressure, meaning perpendicular load, occludes capillaries and starves the tissue underneath. Shear, meaning tissue layers sliding against each other when a patient slips down a raised backrest, tears the vessels that were already compromised. A support surface can reduce pressure. Almost nothing reduces shear except positioning discipline, a low friction cover, and not leaving a patient sitting at a steep backrest angle for six hours.
The sites that fail are predictable: sacrum, heels, ischial tuberosities in a seated patient, greater trochanters when side lying, and the occiput in children and in anyone nursed flat. Heels are the site most often missed, because a surface designed to redistribute load under the sacrum does not necessarily offload a heel. Heels usually need a separate answer, meaning a pillow under the calf that lifts the heel clear or a purpose made offloading device.
Assess the patient before choosing the surface
The surface follows from the risk assessment, not from the ward it is going into. Structured tools such as the Braden and Waterlow scales exist to make that judgement consistent between staff and between shifts, and either is better than clinical impression, provided it is repeated rather than filled in once on admission and filed. What these tools measure is straightforward.
Mobility. Can the patient reposition themselves, and do they actually do it. Someone who shifts every few minutes without thinking about it is at low risk regardless of everything else on the chart.
Sensory perception. Spinal injury, sedation, dense stroke and diabetic neuropathy remove the discomfort signal that would otherwise prompt movement. In practice this is the strongest single predictor on the list, and diabetes is common enough in Bangladesh that it should be an explicit prompt in the assessment.
Moisture. Incontinence and sweat macerate skin and lower the load it will tolerate. In a ward in June, with intermittent air conditioning, this is not a minor factor.
Nutrition and perfusion. Low albumin, anaemia, dehydration and vasopressor support all reduce tissue tolerance, which is why a patient can deteriorate on a surface that was adequate last week.
Existing skin damage. A patient with an existing injury needs a surface chosen to offload that specific site. The assessment includes turning the patient and looking, heels included, rather than asking whether anyone has noticed anything.
Matching the surface to the patient
Patient
Reasonable surface
What actually decides it
Mobile, repositions independently, short stay
High specification foam
Comfort and cleanability. A powered surface adds cost and noise for no clinical benefit
Limited mobility, repositioned by staff on a schedule
High specification foam, layered or castellated, with good immersion
Whether the turning schedule is genuinely kept at night as well as during the day
Immobile, sedated or ventilated, or cannot be turned
Alternating pressure surface, or a high specification reactive surface if turning is truly reliable
Staffing at night. Be honest about this rather than optimistic
Existing injury over the sacrum
Alternating pressure, with the affected area offloaded, plus a written repositioning plan
The surface does not heal the injury. Offloading, nutrition and wound care do
Bariatric
Bariatric rated surface on a bariatric frame, widths matched
The rated load of frame and surface together, plus the width of the lift and the doorways
Seated in a chair for long periods
A pressure redistributing cushion, bought separately
A bed surface does nothing for a patient who spends the day in a chair, which is a gap in most tenders
Reactive foam surfaces
A reactive surface redistributes load by letting the body sink in and spreading contact over a larger area. That is what foam does, and good foam does it well enough for most ward patients. The properties that matter are density, hardness, thickness and construction. A layered or castellated foam with a softer top layer over a firmer support layer immerses the patient without bottoming out. A single slab of the cheap open cell foam sold locally as hospital mattress compresses permanently within months, and once it has bottomed out under the sacrum it is worse than no mattress at all, because it now concentrates load exactly where you did not want it.
Ask the supplier for density and hardness figures and put them in the specification. If the supplier cannot state them, you have your answer about the mattress.
Active and alternating pressure surfaces
An alternating pressure mattress inflates and deflates cells in sequence so that no site carries load continuously. It is the answer for a patient who cannot be turned, or where a turning schedule is not reliably achievable overnight. Buying one commits the hospital to several things that are easy to overlook at tender stage.
A pump that runs continuously. In a ward with load-shedding, the pump goes on the generator circuit or the patient loses the therapy for the duration of the cut. Ask what happens to the mattress when power fails, and specify either a static mode or non return valves that hold the mattress inflated rather than letting it settle under the patient.
A pump that can be repaired here. The pump is the part that fails. An imported pump with no local spares is a mattress permanently out of service, sitting in a store room next to the wheelchairs with flat tyres.
A CPR rapid deflation valve, positioned where it can be found and pulled in seconds, with staff who have been shown where it is. A patient on an inflated mattress cannot be compressed effectively.
Individually replaceable cells. Cells puncture. If they cannot be replaced one at a time, a single puncture writes off the whole mattress.
Patient tolerance. Some patients dislike the movement and will not stay on the surface. A therapy the patient rejects is not a therapy.
The cover fails before the foam does
Every hospital mattress in service fails through its cover, and the cover is asked to do four contradictory things at once: keep fluid out, let vapour through so that skin under the patient does not macerate, allow a low friction slide so shear is reduced, and survive chlorine cleaning several times a week.
Welded seams, not stitched. A stitched seam is a row of holes. Fluid reaches the foam through it and the mattress is then contaminated and impossible to clean, whatever the outside looks like.
Vapour permeable. A fully impermeable cover traps sweat under the patient. In a humid climate with intermittent air conditioning, that is the difference between intact skin and macerated skin over a week.
A flap over the zip, where a zip is used at all, because an exposed zip wicks fluid straight into the foam.
Two way stretch. A cover that will not stretch stops the foam beneath conforming to the patient, which is called hammocking and it defeats the surface you paid for. It is also why a replacement cover has to be the correct size, not the nearest size available.
Stated chemical compatibility. Ask which disinfectants the cover is rated for and at what dilution. Plenty of covers survive detergent and fail against the chlorine concentrations used after a soiled bed, which is precisely when they get used.
Fitting the surface to the bed
A mattress and a bed frame are one system, and mismatching them undermines both.
Dimensions. The mattress must match the platform. Narrower than the platform leaves a gap at the side rail, which is an entrapment risk. Wider than the platform means it bulges and the side rail no longer sits where it was designed to sit. Side rail geometry under IEC 60601-2-52 is defined against a mattress of a given size, so the two are specified together or not properly specified at all.
Thickness against rail height. A thicker mattress reduces the effective rail height above the sleeping surface. Substituting a thicker mattress into an existing frame can quietly convert a compliant rail into a non compliant one without anyone deciding to do it.
Articulation. A mattress on a profiling bed has to bend where the platform bends. A single stiff slab on a four section bed lifts away from the platform and slides the patient down the bed, creating exactly the shear the surface was bought to reduce.
Retention. Straps, a lip or a friction base, so the mattress stays put during lateral tilt or Trendelenburg. On an ICU bed with lateral tilt this is not optional.
Writing a mattress specification that can be enforced
Mattresses are bad because the specification is unenforceable. A small number of stated, checkable requirements fixes that, and every one of them can be verified on delivery by someone with a tape measure and the paperwork.
State finished dimensions and tolerance, referenced to the bed platform being supplied in the same order.
State foam density and hardness, by layer if the mattress is layered, and require a material certificate at delivery.
State the cover requirements: welded seams, vapour permeable, two way stretch, the disinfectants it must tolerate, and the zip arrangement.
State the fire performance requirement you intend to hold the supplier to, and check it against the submitted documentation rather than assuming it was met.
Require an approved sample before bulk delivery, and keep that sample. It is the reference the delivered stock is checked against, and without it a dispute is unwinnable.
Specify covers as a consumable spare in the same order, in a quantity that reflects the fact that they will be replaced several times before the foam is.
Require the mattress to be quoted as a separate priced line, so that it cannot be silently downgraded to protect the margin on the frame.