TIMING RELATIONSHIPS FOR SECONDARY ISCHEMIA IN RODENTS - THE EFFECT OF VENOUS OBSTRUCTION

In a previous study, 1 timing relationships were studied for flaps sub jected to secondary ischemia by total pedicle interruption. In the cur rent paper, using a rodent epigastric flap, a similar study for flaps subjected to secondary ischemia by venous obstruction was performed. T hese conditions were designed to mimic a venous thrombosis following f lap transfer, as would be performed clinically. In Experiment 1, the t ime interval between primary and secondary ischemia was varied. When t he interval was 72 hr, flaps with secondary ischemia had similar survi val to those with primary ischemia. However, when the time interval wa s 24 hr, flap survival after secondary ischemia was significantly wors e than after primary ischemia (p < 0.01). In Experiment 2, the duratio n of primary ischemia was varied (15 min, 30 min or 1.5 hr), prior to a fixed interval between primary and secondary ischemia and 5 hr of se condary ischemia. These conditions produced significantly more necrosi s than 5 hr of primary ischemia. Thus, even short periods of primary i schemia may have detrimental effects on flap survival after a subseque nt period of secondary ischemia. This may have important clinical rami fications.