The medical records of patients who had undergone a free flap reconstruction after radical resection of oral cancer between January 2009 and December 2013 at the study hospital in China were reviewed retrospectively. Of the 1550 patients who underwent free flap reconstructions, 71 were explored for suspected flap compromise caused by postoperative thrombosis. Patient demographic data, clinicopathological data of the tumour, details of the free flaps, and operative findings were assessed, and the medical records were analyzed to identify the reasons for intervention and the outcomes. Of the 71 flaps in crisis, 47 (66.2%) were salvaged. Free flap failure was 6.2-times more likely to develop in patients undergoing surgical exploration after 72 h (95% confidence interval 2.090–18.197, P = 0.001). Of the 19 flaps identified as subject to delayed exploration, 14 failed and three had partial necrosis. Free flap failure was 3.4-times more likely to develop in patients with perforator flaps (95% confidence interval 1.222–9.719, P = 0.019). The early detection of free flap failure is critical to flap salvage. The salvage success rate decreases significantly at >72 h after the initial operation. It appears to be more difficult to salvage a perforator flap.
Microvascular free tissue transfer has become the gold standard for the reconstruction of head and neck defects after tumour resection. Free flap success rates in most high volume centres are reported to be in excess of 95%. Free flap failure can lead to functional and cosmetic morbidity, additional salvage surgery, a prolonged hospital stay, increased costs, and delayed adjuvant therapy such as radiotherapy. Vascular thrombosis remains the primary cause of flap failure, with clinical manifestations in skin colour, texture, temperature, and capillary refill. Thus, the early detection of flap compromise via careful monitoring and appropriate surgical exploration could lead to significant improvements in overall success rates. Salvage success rates range from 33% to 95%. The aim of this study was to examine the factors that may influence the success of flap salvage, such as the type of flap, operative findings at the time of salvage and exploration in relation to the time since surgery, and any delay between clinical signs and salvage surgery being performed. It is hoped that the results of this study will be helpful for clinical applications of microvascular free tissue transfer.
Patients and methods
The medical records of patients who had undergone a free flap reconstruction after radical resection of oral cancer between January 2009 and December 2013 in the Department of Oral and Maxillofacial–Head and Neck Oncology of the study hospital were reviewed retrospectively. A total of 1595 free flap reconstructions were performed in 1550 patients. Patient demographic data, clinicopathological data of the tumour, details of the free flaps, and operative findings were assessed. A patient aged over 60 years was defined as elderly. In assessing health status, diabetes, hypertension, and peripheral vascular disease were considered as systemic disease. The patient’s history of radiation therapy and chemotherapy was also recorded.
Free flap crisis included infection, arterial and venous thrombosis, and other necroses with an unknown aetiology. The medical records were analyzed to identify the reasons for intervention and the outcomes. The flap chart was studied to determine the length of time that had elapsed before the flap compromise was recorded. Details of the time at which the exploratory operation was started, the duration of the operation, and the volume of blood lost were obtained from the anaesthetic records. For arterial thrombosis, cases in which the time interval between the discovery of clinical signs by the surgeon and return to the operating room to deal with the problem was more than 6 h were defined as delayed exploration; for venous thrombosis, this interval was more than 4 h.
Of the 1550 patients, 71 were explored for suspected flap compromise. These 71 flaps were divided into salvaged flaps without necrosis, salvaged flaps with partial necrosis, and flap failure, according to the outcome. Salvaged flaps with partial necrosis included skin paddle necrosis of fibula and anterolateral thigh flaps, distal partial necrosis of latissimus dorsi myocutaneous flaps, and skin exfoliation of radial forearm free flaps. Flaps were monitored hourly for the first 24 h, every 2 h for the next two postoperative days, and every 4 h thereafter until day 7 after surgery.
The statistical analysis was performed with commercially available SPSS software (v. 13; SPSS Inc., Chicago, IL, USA). Logistic regression was used to identify risk factors associated with free flap failure. A P -value of <0.05 was considered statistically significant. Factors found to be statistically significant on univariate analysis were entered into a multivariate logistic regression model to adjust for the effects of all other variables in the equation.
Of the 1550 patients identified, 71 returned to the operating room for further exploration of a suspected flap compromise; 37 were male and 34 were female, and they ranged in age from 16 to 82 years (median 51 years). The most common diagnosis was squamous cell carcinoma (51/71). The overwhelming majority of patients had a one-stage operation (68/71). The defects were located in the tongue (20/71), mandible (16/71), cheek (11/71), skull base (7/71), maxilla (7/71), middle face skin (3/71), floor of the mouth (3/71), lip (2/71), and oropharynx (2/71). The average hospital stay was 29.1 days (range 15–129 days), which was significantly longer than the stay of the cases without surgical exploration (20.0 days).
Forty-seven of the 71 flaps were salvaged from flap crisis (66.2%). The radial forearm flap (40.0%, 622/1595), anterolateral thigh flap (28.2%, 450/1595), and fibula flap (21.8%, 348/1595) were the most common types of free flap transfer. In this study, surgical exploration of the radial forearm flap and fibula flap was more reliable than that for the anterolateral thigh flap, with significantly higher salvage success rates ( Tables 1 and 2 ). Venous crisis occurred in 42 flaps within 7 days after surgery; this was characterized by a dark and purple colour, swelling in the flap or neck, a dark exudate, and bleeding at the flap margin.
|Type of flap||Flaps in crisis||Number salvaged (partial necrosis after salvage operation)||Failed||Flaps in database||Crisis proportion in database (%)||Failure proportion in database (%)|
|Defect site||Flaps in crisis||Number salvaged (partial necrosis after salvage operation)||Failed||Flaps in database||Crisis proportion in database (%)||Failure proportion in database (%)|
|Skull base||7||4 (3)||3||69||10.1||4.3|
|Middle face skin||3||3 (0)||0||56||5.4||0|
|Floor of the mouth||3||2 (0)||1||120||2.5||0.8|
Venous thrombosis was observed in 28 of 42 flaps; the presenting symptoms were a pale or dull colour, no bleeding at the flap margin, no bleeding on acupuncture, and flaccid on palpation. Within 12 h after the operation, 10 flaps had been salvaged, including two cases with partial necrosis. The success rate of surgical exploration within 72 h was much higher than that after 72 h. Nineteen flaps were identified as having been subject to delayed exploration, of which 14 failed and three had partial necrosis ( Table 3 ).
|Salvaged flap without necrosis||Partial necrosis after salvage operation||Failure|
|Venous crisis performance||Arterial crisis performance||Venous crisis performance||Arterial crisis performance||Venous crisis performance||Arterial crisis performance|
|Delay for exploration||1 (24 h)||1 (24 h)||1 (48 h)||2 (48 h, 72 h)||7 (4 h ×2; 24 h ×3; 6 days; 14 days)||7 (4 h; 2 days ×2; 3 days; 4 days; 6 days; 17 days)|
During surgical exploration, venous thrombosis was observed in 28 flaps, arterial thrombosis in 13 flaps, and complete venous and arterial thrombosis in 13 flaps, probably due to late exploration such that it could not be differentiated whether the thrombosis originated from the vein or artery. In addition, there were 14 flaps without vascular thrombosis, but with clinical signs of flap crisis. This could be due to a number of factors, such as vascular stenosis caused by improper ligation, anastomotic leakage, too large a skin paddle flap, external pressure on the vascular pedicle (i.e., too tight bandaging and negative pressure drainage tube), and vascular stenosis induced by an infection at the surgical site ( Table 4 ).
|Venous thrombosis||Arterial thrombosis||Arterial and venous thrombosis||No thrombosis formation||No confirmed reason|
|Flap design or harvest||Dissection error||Vein was compressed||Infection|
|Salvaged flaps without necrosis||21||7||1||2||1||3||2||1|
|Partial necrosis after salvage operation||1||1||0||4||1||1||0||1|
The 71 free flaps that underwent surgical exploration were included in the logistic regression model to identify risk factors associated with flap failure. A perforator flap, delayed exploration, and surgical exploration at >72 h were found to be significantly associated with flap failure after surgical exploration.
All three of these predictors remained significant in the multivariate logistic regression model. Free flap failure was 3.4-times more likely to occur for patients with a perforator flap (95% confidence interval (CI) 1.222–9.719, P = 0.019), 11.8-times more likely for those subjected to delayed exploration (95% CI 3.430–40.322, P < 0.0001), and 6.2-times more likely for those undergoing surgical exploration after 72 h (95% CI 2.090–18.197, P = 0.001). Other variables such as sex, preoperative irradiation, age over 60 years, duration of surgery, volume of blood lost, systemic disease, preoperative chemotherapy, external jugular vein (EJV) or internal jugular vein (IJV) system at the recipient site, and facial or other recipient arteries for which data were also collected, revealed no statistical predictive strength in the regression analysis ( Table 5 ).
|Factors||No. of cases||No. of flap failure explorations||OR (95% CI)||P -value|
|Age, years||<60||42||15||1.0 (ref.)|
|Systemic disease||No||57||17||1.0 (ref.)|
|Duration of surgery||≤10 h||34||12||1.0 (ref.)|
|>10 h||37||12||0.880 (0.329–2.354)||0.799|
|Blood loss||<800 ml||39||13||1.0 (ref.)|
|≥800 ml||32||11||1.048 (0.390–2.813)||0.926|
|Primary/recurrent tumour||Primary tumour||46||17||1.0 (ref.)|
|Recurrent tumour||25||7||0.663 (0.230–1.912)||0.447|
|Recipient vein||IJV system||38||13||1.0 (ref.)|
|Recipient artery||Facial artery||40||15||1.0 (ref.)|
|Other artery||25||6||0.526 (0.172–1.611)||0.261|
|Perforator flap||No||46||11||1.0 (ref.)|
|Delay for exploration||No||52||10||1.0 (ref.)|
|Exploration time||≤72 h||46||9||1.0 (ref.)|
|>72 h||25||15||6.167 (2.090–18.197)||0.001|