Comparison of the influence of intralumenal irrigation solutions on free flap survival.

Heparin is commonly included in the irrigation solution used during microvascular surgery. Evidence has accumulated to indicate a beneficial effect of heparin on anastomotic patency, implying that its topical use is critical to success even in routine microvascular repairs. This investigation compared heparin and urokinase as additives to the irrigation solution (Ringer's lactate) used during rat groin free flap replantation. A newly trained microsurgeon performed all surgical procedures to lower the possible success rate through microsurgical inexperience and, thus, to create a stronger challenge for the topical irrigant. Solutions were administered on a blinded, randomized basis. Vessel patency and flap survival were followed for 7 days. No statistically significant differences were found between any of the treatment groups: patency and survival rates of 67% for heparin, 57% for urokinase, and 73% for controls (vehicle only). The flap failures that occurred may have been attributable to undetected technical errors due to the microsurgical inexperience of the surgeon. In a separate series, an experienced microsurgeon achieved 93% success using vehicle without additives for irrigation. These results suggest that topical heparin or urokinase is not essential for achieving high levels of success during microvascular surgery.