Pressure of less than 25 % the pressure of a normal mattress can lead to bedsores. Complete muscle necrosis was demonstrated at 100 mmHg (13 kPa) for 6 h and pressures of 70 mm Hg (9 kPa) for 2 h resulted in pathologic changes within muscle and lower pressures of 35 mmHg (5 kPa) for 4 h resulted in no changes [9].