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​Novel Support Surface Based on Smart Material to Alleviate Pressure Ulcer Formation During the Rehabilitaion of Immobile​​
​Research Programmes Precision Rehabilitation​
​Clinical PI Dr WONG Chin Jung
Consultant, Department of Rehabilitation Medicine
Tan Tock Seng Hospital
​Technical PI Dr CHIAM Keng Hwee
Principal Investigator, Bioinformatics Institute, Agency for Science, Technology and Research

Pressure ulcers or bed sores are defined as areas of localised damage to the skin, muscle and underlying tissue, caused by unrelieved pressure, shear or friction, usually over bony prominences. They are more likely to occur in those who are bedridden, immobile, neurologically compromised, or paralysed, such as individuals with spinal cord injuries. In addition, they are also likely to develop in the elderly and those with chronic illnesses, poor nutrition, low skin elasticity, or healing potential. They can occur in the home setting, in long term care facilities such as nursing homes, in rehabilitation centres, or in acute care hospital facilities, thus spanning the whole rehabilitation continuum of care. They are a significant cause of morbidity, mortality and prolonged hospital stay with increased complications such as infections, osteomyelitis and other complications, and have also been associated with a four-fold increase in the risk of death among elderly with pressure ulcers. Globally, they resulted in 29,000 documented deaths in 2013, up from 14,000 deaths in 1990.

Therefore, the management of pressure ulcers is a serious problem in the entire gamut of healthcare system ranging from the acutely critically ill to the elderly and immobile in rehabilitation units, nursing homes and long term facilities. Importantly, even after the patients have been discharged from the hospital and are rehabilitating at home, they are still susceptible to pressure ulcer formation due to their long term lying on the bed at home.

As a result of this long period of immobility whether at home or in the hospital, parts of the patient’s skin and the soft tissue surrounding those skin are constantly being pressed down onto the support surface under the patient’s own weight. This pressure that is applied to the skin and surrounding soft tissues, particularly over a bony prominence such as the shoulders, sacrum and heels, distorts the skin and tissues. Furthermore, tensile and shear stresses can also occur within the tissues near bony prominences. These patients cannot sense or respond to these signals and do not move spontaneously. As a result, the skin and soft tissues can be subjected to prolonged and unrelieved pressures. (In alert patients, the effects of continuous pressure usually signal frequent small body movements to relieve the load and restore tissue perfusion.) Skin that has been subjected to potentially damaging levels of pressure initially manifests as an area of redness --- reactive hyperaemia --- that returns to normal if short lived. More prolonged ischaemia can cause blood cells to aggregate and block capillaries, perpetuating the ischaemia. Capillary walls can also become damaged, allowing red blood cells and fluid to leak into surrounding tissues.

To the individual, having a pressure ulcer increases the chances of further medical complications, especially sepsis, cellulitis, bone and joint infections such as osteomyelitis  which can be life threatening. For those who were previously not totally immobile, having a pressure ulcer with enforced immobility and bodily reaction to wound would lead to increased likelihood of muscle wasting, increased infections of the urinary tract, pneumonia and other complications. The immobile patient also requires increased medical and nursing care and, because absolutely no pressure should be on the pressure sore after it has developed, requires more vigilant care in turning and avoiding pressure at the skin break. A chronic wound that does not heal would also potentially increase the risk of cancer of the chronic wound. 


Most pressure ulcers can be prevented. Currently, pressure sore prevention strategies include the following:

  1. Identifying patients at risk of pressure ulcer development, and
  2. Implementing interventions that protect patients against external pressure, shear and frictional forces.

For example, patients with high risk assessment, especially those with immobility or requiring increased assistance, would require very vigilant nursing care, such as 2-hourly turning to relieve excessive pressure. However, even the most vigilant nursing care may fail to prevent pressure ulcers in the most high risk individuals.

There is thus a need to make use of advanced technologies to help address this problem. In particular, there has been increased research in the last few years to develop specialised support surfaces such as mattresses and overlays to relieve, reduce, and redistribute pressure at high risk areas such as the bony prominences. A recent Cochrane Review on support surfaces for pressure ulcer prevention showed that foam alternatives to standard hospital foam mattresses reduce the incidence of pressure ulcers in people at risk and that pressure-relieving overlays on the operating table reduce postoperative pressure ulcer incidence. Therefore, the importance of developing a novel support surface to alleviate pressure ulcer formation is crucial to reduce chances of developing pressure ulcers.

At present, pressure ulcer formation is being prevented by having nurses physically turn over and reposition the patient’s body every 2 hours. This 2-hourly turning schedule is implemented as usual standards in most hospitals. However, a study by Knox and colleagues demonstrated that subjects developed redness and skin temperature increased over their trochanters and sacral areas after one hour and two hours of being immobile, respectively. They concluded that a period of one and a half hours between turning may be more appropriate than the traditional 2 hours. This adds to the workload of caregivers and the manpower burden of hospitals.

Similarly, at home, the rehabilitating patients will have to rely on family members or domestic caregivers to carry out the 2-hourly turning schedule. Furthermore, these        2-hourly episodes have to be carried out even throughout the night. For many families, this is obviously an impractical arrangement, leading to a reduction of sleep quantity and quality, as well as overall quality of life. Thus, there is a need to make use of advanced technologies to reduce the manpower burden in the hospitals and at home, spanning the whole rehabilitation continuum of care.

We propose to develop a support surface which can redistribute pressure over bony prominences by using smart elastomers whose rigidity is dynamically sensed and tuned. We will conduct a clinical trial to assess tolerabililty, comfort, usability and to analyse pressure over time for high risk areas in immobile patients.

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