Changes on Blood Perfusion and Histological Structures of Sacral Skin in Rat by Externally Applied Pressure

We aimed to investigate the changes on blood perfusion and histological structures of sacral skin in rat by externally applied pressure. Sixty-four Sprague-Dawley rats were used. Pressure was applied to the sacral skin by a pressure column using a pressure delivery system and blood perfusion was monitored by a laser doppler flowmeter. Changes in blood perfusion were monitored before, during the application of pressure ranged from 9 mmHg to 468 mmHg for duration of 30 seconds by increment of 10 g of force. Macroscopic and histological changes were evaluated following pressure application ranged from 30 mmHg to 140 mmHg for duration of from 30 minutes to 5 hours. Blood perfusion decreased nonlinearly with increasing pressure and approached to 4.2 perfusion unit(PU) at 37 similar to 47 mmHg and maintained constantly with a pressure of 468 mmHg and following pressure release, reactive hyperemia was occurred. There was a marked change in the appearance of pressed skin as compared to normal skin. Histological changes were developed following pressure application of 100 mmHg for 30 minutes or more and45 mmHg for I hour or more. The pressure application of 45 mmHg for 3 consecutive 2 hour duration each made the apoptosis of the epidermis, dermis and skin appendage. Our findings are suggestive that position change per 2 hours is not enough for the prevention of pressure ulcer. Therefore, interval of position change should be reduced or pressure at body-bed interface should be reduced below 45 mmHg by specially made air mattress.