The relationship between prostaglandin E1 applied area and flap survival rate

Using a silicone gel sheet continuous drug delivery system containing Prostaglandin E1 (PGE1), the relationship between flap survival rate and the site of drug application was studied. Skin flaps measuring 2 x 9 cm were raised on the dorsum of rats, and divided into 3 areas. Area 1 was within 3 cm of the flap tip, area 2 was between 3-6 cm from the flap tip including the critical zone, and area 3 was the portion within 4 cm of the flap base. Further, area 4 was a strip of skin around the flap, 1 cm in width. Compared to the control group, a significant increase in flap survival rate was seen only when PGE1 was administered to area 2 (p < 0.01, t-test). Specimens injected with dye intravascularly showed an increase in the number of thick vessels in area 3, when PGE1 was applied only to area 3. However, when PGE1 was applied to area 2, there was no significant vascular increase in area 3. Instead, an extensive network of fine vessels was observed in area 2.