Ischemia and reperfusion may be important in the pathogenesis of pressure u
lcers. On the basis of this hypothesis, the effects of intermittent pressur
e and the anti-free radical agents allopurinol and deferoxamine were studie
d in a pig model in which a pressure of 150 mmHg was applied intermittently
to the scapulae. Cutaneous blood flow, transcutaneous oxygen tension, skin
and muscle damage, and muscle levels of adenosine triphosphate were quanti
fied. A control group of pigs (n = 6) was untreated, the allopurinol group
(n = 6) received oral allopurinol beginning 2 days before the experiment, a
nd the deferoxamine group (n = 6) received an intramuscular injection of de
feroxamine 2 hours before the experiment. Pressure (150 mmHg) was applied t
o the scapulae for 210 minutes, and it was relieved for 30 minutes. This 4-
hour cycle was repeated continuously for 48 hours, and it resulted in press
ure injuries in all animals. Allopurinol and deferoxamine improved cutaneou
s brood flow and tissue oxygenation, but only deferoxamine could significan
tly reduce cutaneous and skeletal muscle necrosis (p < 0.001). This study s
uggests a future role for anti-free radical agents in the reduction of pres
sure-induced injury.