It is usually possible to prevent bedsores from developing or worsening. In 1989, the NPUAP set a goal that pressure sores be reduced by 50% by 2000. Because of the varying ways in which the number of cases were recorded during this timeframe, the NPUAP is finding it difficult to analyze accurate incident accounts. However even with the diversity of recording methods and the difficulties in comparing data, small group data indicates that progress has been made with the standardization of guidelines and care. All patients recovering from illness or surgery or confined to a bed or wheelchair long-term should be inspected regularly; they should be bathed or should shower every day using warm water and mild soap; and patients should avoid cold or dry air. Bedridden patients who are either mentally unaware or physically unable to turn themselves, must be repositioned regularly by caregivers at least once every two hours while awake. People who use a wheelchair should be encouraged to shift their weight every 10 or 15 minutes, or be repositioned by caregivers at least once an hour. It is important to lift, rather than to drag, a person being repositioned. Bony parts of the body should not be massaged. Even slight friction can remove the weakened top layer of skin and damage blood vessels beneath it. If the patient is bedridden, sensitive body parts can be protected by: sheepskin pads special cushions placed on top of a mattress a water-filled mattress a variable-pressure mattress with individually inflatable sections to redistribute pressure Pillows or foam wedges can prevent a bedridden patient's ankles from irritating each other, and pillows placed under the legs from mid-calf to ankle can raise the heels off the bed. Raising the head of the bed slightly and briefly can provide relief, but raising the head of the bed more than 30 degrees can cause the patient to slide, thereby causing damage to skin and tiny blood vessels. A person who uses a wheelchair should be encouraged to sit up as straight as possible. Pillows behind the head and between the legs can help prevent bedsores, as can a special cushion placed on the chair seat. Donutshaped cushions should not be used because they restrict blood flow and cause tissues to swell. Special support surfaces are manufactured and readily available for care in medical facilities or at home, including: air-filled mattresses and cushions, low-air loss beds, and air-fluidized beds. These devices give adequate support while reducing pressure on vulnerable skin. They have been shown to exert less pressure on the skin of compromised patients than do regular mattresses. Patients using these devices and beds must still be repositioned every two hours.