Topical Vasodilators in Microsurgery: What Is the Evidence?

Background Topical vasodilators are frequently used during free tissue transfer to prevent and treat vasospasm and microvascular thrombosis. A variety of agents have been studied and are available, yet most microsurgeons select an agent based on anecdotal evidence or personal training. Our aim was to review the literature on topical vasodilators so microsurgeons can make more informed decisions about which agent to use. Methods A systemic review of the literature was performed on PubMed, EMBASE, and Google Scholar using keywords "topical vasodilator," "antispasmodic," "vasospasm," "free flaps," and "microsurgery." Studies were included if they provided a comparative quantitative assessment of topical vasodilators and were written in English. In vitro, in vivo, and clinical studies were included. Results A total of 15 studies were identified and included in our analysis. The three most common classes of topical vasodilator include local anesthetics, phosphodiesterase inhibitors, and calcium channel blockers (CCBs). Of the most commonly used topical vasodilators, CCBs (nifedipine and verapamil) were most effective followed by papaverine and lidocaine. Conclusion The most effective topical vasodilators appear to be CCBs including nifedipine, nicardipine, and verapamil. Evidence suggests that these agents are more effective than papaverine and lidocaine solutions that are commonly used. Future research should directly compare individual CCBs to assess the most effective agent. Studies to date have focused on vessels other than those used by microsurgeons, and therefore further studies specific to these vessels are warranted.