An integrated theory of the no-reflow phenomenon and the beneficial effectof vascular washout on no-reflow

Objectives: No-reflow is failure of perfusion in free tissue transfer despi te adequate arterial inflow. The objectives of this study were to construct a theory of interactive mechanisms of the no-reflow phenomenon and to dete rmine whether preischemic vascular washout could increase flap ischemia tol erance. Study Design: The evidence for the role of various mechanisms in th e development of no-reflow is re; viewed, and an integrated network propose d. A rat-groin free flap model is used to test preischemic vascular washout with normal saline, heparinized normal saline, lactated Ringer's solution, Tis-U-Sol, and Viaspan, Methods: The mean ischemia tolerance of this flap without any therapeutic intervention was first determined, using 22 animals . An additional 50 animals were used to compare with the control group the ischemia tolerance of Baps washed out with the above fluids before their is chemic period. Results: The critical ischemia time 50 (time after which hal f of the flaps are expected to survive and half, die) of the untreated flap is 23.4 hours in this model (P <.05). Flaps washed out with normal saline or lactated Ringer's solution have significantly worse ischemia tolerance ( P <.0001), Flaps washed out with Tis-U-Sol or Viaspan behave similarly to t he control group (P >.57), Flaps receiving preischemic washout with heparin ized normal saline (4,000 units/L) had a significantly better outcome than the control group (P <.027), Conclusions: Preischemic washout with normal s aline, lactated Ringer's solution, or heparinized Tis-U-Sol is detrimental for flap survival after ischemia, Tis-U-Sol- and Viaspan-treated flaps do h ave ischemia tolerance similar to the control group, and flaps washed out w ith heparinized normal saline have a survival advantage in this model.