A PROSPECTIVE-STUDY OF MICROVASCULAR FREE-FLAP SURGERY AND OUTCOME

Over a 6-month period, 23 members of the International Microvascular R esearch Group participated in a prospective survey of their microvascu lar free-flap practice. Data were recorded with each case for 60 varia bles covering patient characteristics, surgical technique, pharmacolog ic treatment, and postoperative outcome. A total of 493 free flaps wer e reported with a representative demographic distribution for age, sex , indications for surgery, risk factors, flap type, surgical technique , and pharmacologic intervention. Mixed effects logistic regression mo deling was used to determine predictors of flap failure and associated complications. The overall incidence of flap failure was 4.1 percent (20 of 493). Reconstruction of an irradiated recipient site and the us e of a skin-grafted muscle flap were the only statistically significan t predictors of flap failure, with increased odds of failure of 4.2 (p = 0.01) and 11.1 (p = 0.03), respectively. A postoperative thrombosis requiring re-exploration surgery occurred in 9.9 percent of the flaps . The incidence of this complication was significantly higher when the flap was transferred to a chronic wound and when vein grafts were nee ded, with increased odds of failure of 2.9 (p = 0.02) and 2.5 (p = 0.0 2), respectively. There was a lower incidence of postoperative thrombo sis when rectus/transverse rectus abdominis muscle (TRAM) flaps were u sed, where odds of failure decreased by 0.36 (p = 0.04), and when subc utaneous heparin was administered in the postoperative period, where o dds decreased by 0.27 (p = 0.04). There was an overall 69-percent salv age rate for flaps identified with a postoperative thrombosis. Intraop erative thrombosis occurred in 41 cases (8.3 percent) and was observed more frequently in myocutaneous flaps or when vein grafts were needed (5.5 and 5.0 greater odds, respectively; p < 0.001) but was not assoc iated with higher flap failure (2 of 41 cases; 4.9-percent failure rat e). The incidence of a hematoma and/or hemorrhage was increased in obe se patients and when vein grafts were needed [2.7 (p = 0.02) and 2.6 ( p = 0.03) greater odds, respectively], whereas this complication was s ignificantly decreased in muscle flaps (myocutaneous or skin-grafted m uscle), in tobacco users, when a heparinized solution was used for gen eral wound irrigation, and when the attending surgeon performed the ar terial anastomosis (in contrast to the resident or fellow on staff) (p < 0.05 for each factor). With the multivariable analysis, many factor s were found not to have a significant effect on flap outcome, includi ng the recipient site (e.g., head/neck, breast, lower limb, etc.); ind ications for surgery (trauma, cancer, etc.); flap transfer in extremes of age, smokers, or diabetics; arterial anastomosis with an end-to-en d versus end-to-side technique; irrigation of the vessel without or wi th heparin added to the irrigation solution; and a wide spectrum of an tithrombotic drug therapies. These results present a current baseline for free-flap surgery to which future advances and improvements in tec hnique and practice may be compared.