Radical breast cancer surgery is still the main procedure for breast tumor treatment, and due to its large and extensive invasion, flap necrosis has been one of the prominent complications of this procedure, with a necrosis rate of 10%-60% reported abroad [1] and 51%-57% reported in China [2], once it occurs, it will prolong the wound healing time and hospitalization time of patients, increase the psychological burden of patients, increase the economic cost, and delay the postoperative adjuvant radiotherapy and chemotherapy, and affect the effect of comprehensive treatment. From May 2000 to November 2006, a total of 337 cases of radical mastectomy were performed in our hospital. Due to the effective measures taken during and after surgery, good clinical results were achieved. Breast lumps were the main manifestation. The masses were >5 cm in diameter in 91 cases, 2~5 cm in 207 cases, and <2 cm in 39 cases, of which 21 cases had skin invasion or were fixed to the chest wall, and the rest had good mobility. There were 303 cases of longitudinal shuttle incision and 34 cases of transverse shuttle incision. International TNM staging: T1N0M0 44 cases, T1N1M 0 25 cases, T2N0M0 17 cases, T2N1M 0 136 cases, T3N0M0 8 cases, T3N1M 0 83 cases, T3N2M 0 4 cases, T4N1M 0 9 cases, T4N2M 0 11 cases, including 257 cases of ductal carcinoma, 66 cases of lobular carcinoma, 12 cases of Paget's disease, and 2 cases of inflammatory breast cancer In this group, the biopsies of anterior lymph nodes were taken. In this group, 184 cases of anterior lymph node biopsy were taken, of which 162 cases were positive. Patey's modified radical surgery was performed in 96 cases, and Halsted's standard radical surgery was performed in 241 cases. 1.2 Methods ① Reasonable design of surgical incision: according to the size and location quadrant of the mass, longitudinal or transverse incision was selected before surgery, the extent of skin excision was estimated, whether there was tension during suturing, and the preparation of skin grafting was done. ②Decide whether the surgical approach is Patey-type modified radical surgery or Halsted-type standard radical surgery according to the tumor stage, the metastasis of the anterior lymph nodes and axillary lymph nodes [3,4], the general condition of the patient before surgery and whether there are conditions for radiotherapy and chemotherapy. (3) Free flap protection and reasonable thickness: the surgical cutting edge is generally >3 cm from the tumor margin [5], and after cutting the skin and subcutaneous tissue, instead of using vascular forceps or tissue forceps to clamp the skin edge for traction, the intracutaneous multi-point suture is used for traction to reduce the damage to the blood vessels and tissues of the skin edge; when freeing the flap, the scalpel is used to sharply cut and free along the subcutaneous gap within 8 cm from the cutting edge, and the preserved The subcutaneous fat layer is slightly thinner, about 0.3 cm, on the near side of the incision margin and slightly thicker, about 0.5-1.0 cm, on the far side of the incision margin, to protect the subcutaneous vascular network. ④Tight hemostasis of the wound and routine ligation of the lymphatic vessels from the upper limb to the axilla to prevent the formation of postoperative lymphatic fistula and subcutaneous effusion. ⑤Ensure unobstructed drainage: before the flap is sutured, multi-lateral rubber drainage tubes with diameters of 0.8 cm and 0.5 cm are placed along the surgical wound edge of the lateral latissimus dorsi muscle and the medial wound edge of the sternal margin, respectively, and are poked at the lower edge of the rib arch and the lowermost end of the incision for extracutaneous fixation and connected to the central negative pressure suction. (6) Reduce flap tension and do not forcefully suture the flap: If the tumor is large and more skin is removed, the flap should be free to the posterior edge of the latissimus dorsi muscle and the contralateral chest wall as much as possible, so that the flap can be kept tension-free when suturing. If the flap suture tension is slightly large, a mesh-type staggered reduction incision parallel to the cut edge, 1~2 cm long and 4~5 cm spacing around the flap can be made on the distal flap more than 5 cm from the skin edge, and the wound is covered with petroleum jelly gauze to prevent its air leakage, this method has both better reduction effect and drainage of the trauma cavity; if the tension is large, a simultaneous skin grafting is performed. (7) Correct dressing of the wound: the wound of the chest wall surgical area is dressed with gauze pad followed by moderate pressure dressing, which mainly serves to keep the skin flap and chest wall relatively fixed. ⑧ Intraoperatively and postoperatively, if the flap blood supply is found to be poor, vasodilator drugs should be used. 2 Results One stage healing 284 cases, 53 cases of flap necrosis occurred (accounting for 15.7%). Among them, the width of necrosis was <2.0 cm in 29 cases, 2.0-5.0 cm in 21 cases, and >5.0 cm in 3 cases. For necrosis of the incision margins with a width of 5 cm or less, the wounds were mostly healed within 3-4 weeks postoperatively by local wound dressing and trimming, and topical application of moist burn cream and Beefeater to promote tissue repair and epithelial regeneration. For flap necrosis >5 cm in width, the flap was healed with skin grafting when the granulation tissue was fresh. 3 Discussion 3.1 Causes of flap necrosis after radical breast cancer surgery have various reasons. (1) Excessive skin excision and excessive flap suture tension: the tumor is large or invades the skin, resulting in excessive skin excision and the skin on both sides has to be pulled together and sutured with the help of tissue forceps, resulting in excessive tension in the incision and causing the flap blood flow obstruction and even necrosis. Improper use of electric knife: the power of electric knife is too large, and the contact time with the tissue is too long, which can produce high temperature in the local area and burn the skin, resulting in the liquefaction and necrosis of subcutaneous fat, the formation of thrombus in the subcutaneous blood vessels, and finally the ischemia and even necrosis of the flap. This situation is mostly related to the decreasing cutting ability caused by the repeated use of disposable electric knife, aging of the machine, and poor contact of the connection point, etc. Sometimes even increasing the power of the electric knife cannot improve the cutting ability of the electric knife, but will aggravate the burning of the flap. ③ Subcutaneous effusion: the drainage tube is blocked by blood clots, poor drainage, or premature extraction, drainage is not exhausted, etc. are likely to occur after extraction and then effusion, effusion to flap floating, ischemia and necrosis. ④Inappropriate flap free level, uneven flap thickness, flap separation is too large: flap free too thick can cause fat liquefaction necrosis and subcutaneous fluid formation, affecting the flap blood flow. Too thin can easily destroy the dense vascular network in the dermis, which also affects flap blood flow. According to Halsted surgery, the incision should be more than 5 cm from the mass, and the separation of subcutaneous fat should be more than 4~5 cm, sometimes the separation range is too large, which can lead to ischemic necrosis of the flap. ⑤ Postoperative activities are too early and too much: early shoulder joint activities are too early and too much, which can produce relative movement between the flap and the trauma, making it difficult to form and establish the vascular collateral circulation between the flap and the chest wall quickly and effectively, affecting the blood flow of the flap and the healing and fixation with the chest wall. (6) Intraoperative clamping of the skin edge, contusion caused by pulling the flap and prolonged operation time, and prolonged exposure of the wound are also causes of flap necrosis. (7) Inappropriate chest wall bandage fixation: In order to prevent the formation of postoperative subcutaneous fluid, the traditional method uses a chest wall bandage with pressure and axillary gauze ball filling to keep the flap tightly attached to the chest wall to promote healing. However, due to factors such as patients’ different body types, fat and thin, and different chest wall conditions, if the postoperative pressure bandage is too tight, it will not only affect the patient’s breathing, but also affect the blood flow of the flap, and may deflate the drainage tube, causing subcutaneous fluid separation and poor drainage, resulting in subcutaneous fluid accumulation and flap necrosis formation. 3.2 Prevention of flap necrosis In view of the above causes of flap necrosis, we take the following preventive and control measures: (1) Good design of surgical incision and reduction of flap tension: the choice of skin incision during surgery should be based on the principles of treatment, and the pike or semilunar incision in different directions should be used according to the different quadrants where the mass is located, so that the cutting edge is more than 3 cm from the tumor edge, and the flap should be free to the posterior edge of the latissimus dorsi muscle and the contralateral chest wall as far as possible. The flap should be free to the posterior border of the latissimus dorsi muscle and the contralateral chest wall as far as possible, and the flap should be kept tension-free when suturing. If the tension of the flap is too great, it is difficult to close it, and it is necessary to perform one phase of skin grafting; if the tension of the flap suture is slightly greater, a mesh-type staggered incision can be made on the distal flap more than 5cm away from the skin edge to reduce the tension, and this method was adopted in 23 cases with satisfactory results. (2) Ligation of important lymphatic vessels to prevent the formation of subcutaneous fluid: subcutaneous fluid can cause the flap to float, the flap and chest wall cannot be closely attached, and the collateral circulation of their mutual vessels cannot be formed and established quickly and effectively, thus affecting the blood flow of the flap. The lymphatic ducts of the deep mammary gland and the upper abdomen, especially the main lymphatic ducts, should be carefully and thoroughly ligated. This can avoid the formation of lymphatic fistula or at least reduce the amount of lymphatic fluid leakage. At the same time, spraying with medical bioprotein gel in the axilla, subclavian area, parasternal bone and rib arch is also helpful to promote the closure of lymphatic ducts. (3) Intraoperative attention to flap protection: flaps beyond 3 cm from the cut edge rely on the surrounding vascular network to provide blood flow [6], which usually has a good blood supply and is not susceptible to necrosis, whereas flaps within 3 cm from the cut edge are mainly viable by adhering to the chest wall and establishing new blood flow, which has a poor blood supply and is susceptible to necrosis. Therefore, when freeing the flap, the flap within 8 cm from the skin edge was free with a blade between the skin and the superficial fascial layer, so that the flap near the cutting edge side was slightly thinner and the distant cutting edge side was slightly thicker, while the flap beyond 8 cm was separated with an electric knife, which caused less damage to the small subcutaneous vascular network and had little effect on the blood supply of the flap, and effectively prevented the flap from fat liquefaction and necrosis. At the same time, the skin edge is traction by intra-dermal multi-point sutures to reduce the damage to the blood vessels and tissues at the skin edge. (4) Correct and skilled use of the electric knife: the performance and connection of the electric knife should be checked before surgery, the power should be less than 30W, the cutting should be rapid and effective, and the contact time with the tissue should be as short as possible. If used improperly, it may burn the skin and cause subcutaneous fat liquefaction necrosis, subcutaneous vascular thrombosis, or even lead to skin flap ischemia or even necrosis. (5) The chest wall wound dressing should be fixed properly, mainly to keep the flap relatively fixed to the chest wall and reduce the formation of dead space. (6) The main points of drainage tube selection and placement [7]: the diameter of the selected drainage tube should be large enough and have a certain toughness and hardness, and multiple lateral holes should be cross-cut in the walking part of the drainage tube flap, and then one should be placed in the axilla, along the lateral surgical wound edge of the latissimus dorsi muscle, and one along the medial wound edge of the sternal border, respectively, at the lower edge of the rib arch, and another hole should be poked at the lowermost end of the incision to lead to extracutaneous fixation, taking into account the comprehensive drainage of the axilla, parasternal, and rib arch. (7) Proper flap suturing (7) Reasonable flap suturing: When suturing the flap, the sutures should be spaced 2 cm apart and 0.5 cm from the skin edge, so as to be as sparse as possible and not to leak; the tightness should be appropriate, so that the skin edge is close together. If the flap is abundant at the time of suturing, the skin margin can be cut off by about 0.5 cm to reduce the chance of necrosis. During the operation, the gas and fluid under the flap should be completely removed, and the gauze pad should be used to press the flap from the sternal side, so that the residual gas and fluid can be driven to the axilla and sucked out by the drainage tube, and a negative pressure drainage device should be connected under the premise of ensuring negative pressure. (8) Establish a smooth and effective continuous negative pressure drainage [8]: The author uses “active, continuous low negative pressure, central suction drainage with a circuit” by connecting the two drainage tubes to the central suction device with a Y-type tee, and micro-opening the cut-off adjustment knob of the central suction device and adjusting its size, so that the entire drainage line forms A circuit, active, continuous, low negative pressure suction drainage. This method ensures that the drainage tube is open and effective and that the trauma surface is continuously and adequately drained, and that the flap, when tightly attached to the chest wall, facilitates the establishment of the intervening capillary network and closure of the trauma cavity. The only requirement is that the internal diameter of all connecting catheters should be large enough to prevent collapse or blockage of the drainage tube and result in poor drainage, which affects the drainage effect. At the same time, when replacing the drainage device after surgery, the drainage tube should be clamped closed with a vascular clamp first to prevent air ingress, which makes the potential cavity under the flap always maintain a negative pressure state and the flap tighten against the chest wall, which helps to prevent flap necrosis. This method was used to drain 232 cases in the latter part of the group with satisfactory results. (9) Braking and functional exercise of the affected limb: 3~5 d after surgery, the affected limb should be braked internally and the upper arm should be tightly attached to the chest wall, which makes the flap relatively fixed with the trauma surface, facilitates the establishment of blood flow connection between the flap and the chest wall, prevents the flap from freeing and promotes the closure of the trauma cavity. Therefore, functional exercise of the affected limb in the early stage should not be abducted, and should be limited to fist clenching and finger flexion on the first day after surgery, and the wrist and elbow joints should be properly flexed only when the upper arm is tightly attached to the chest wall. (10) Timely detection and treatment of subcutaneous effusion: if the effusion appears when the drainage tube is not removed, the fluid can be pushed to the drainage tube and discharged; if the effusion appears after the drainage tube is removed, if it is a small amount of limited effusion, it can be aspirated with a coarse needle puncture and wrapped with pressure; if the amount of effusion is large and the puncture and aspiration is ineffective, the tube should be repositioned at a low local level with negative pressure drainage and wrapped with pressure, and it will be cured. (11) Drainage tube removal time and removal time: We determine the time of drainage tube removal by 24 h drainage flow of less than 10 ml for 2 consecutive days with no signs of fluid accumulation under the flap. Usually, the parasternal drainage tube was removed first, and then the axillary drainage tube was finally removed according to the standard. After removal of the tube, the local pressure bandage should still be appropriately applied to prevent fluid accumulation in the tunnel; for patients with combined diabetes mellitus, hypoproteinemia due to liver and kidney insufficiency or large tension of the incision during suturing, the stitch removal time should be appropriately extended to avoid wound dehiscence. (12) If the flap is found to be purple in color intraoperatively or postoperatively, suggesting poor blood circulation, intravenous vasodilating drugs should be injected [9], such as danshen injection, low-molecular dextran, and pulsatilla injection, to dilate small blood vessels and improve microcirculation, which can avoid flap necrosis in some cases.3.3 Treatment of flap necrosis For cases with a necrotic width of 5.0 cm or less at the cut edge, after drug exchange treatment, when the necrotic border is After the border of necrosis is clear, the necrotic flap can be trimmed, which is required to cut until the skin edge is bleeding, and the wound surface can be dressed with moist burn cream and sprayed with drugs that promote tissue repair and epithelial regeneration, which generally do not require skin implantation and can be crusted over and healed within 3-4 weeks. For cases of necrotic skin flap with larger area, dark black appearance and moving feeling when touched, as long as there is no sign of infection, scab can be cut and implantation can be given early, if there is a combination of infection, antibiotic gauze such as gentamicin and metronidazole can be applied to the wound surface by wet dressing, diligent change of medicine to keep the wound surface dry and systemic anti-infection treatment, and then implantation can be performed after infection control and fresh granulation tissue.