Prostanoid derivatives in experimental flap delay with formic acid.

The physiological changes that allow increased flap survival after flap delay have never been clearly defined. Inflammation has been postulated as a critical factor in flap delay and prostaglandins are known to be mediators of the inflammatory response. To evaluate the role of prostanoid derivatives in experimental flap delay, 0.2% formic acid was injected under the outline of modified McFarlane flaps in 20 rats and saline was injected under the flap outline in 20 control rats. Two weeks later the flaps were raised on all the rats. Average flap survival one week after flap elevation was 65.5% after formic acid delay and 42.9% after saline delay. Biopsies were taken from the flaps both during the delay period and after flap elevation. The specimens were stained for PGE2, PGF2 alpha and thromboxane. Changes noted in the levels of these prostanoid derivatives suggest that they may indeed mediate flap delay.