After Institutional review Board approval, series of cases posted for free fibular reconstruction after tumor excision during 2 years (2016 and 2017) was recorded prospectively. Cases operated by same surgeon were included in study to avoid confounding bias. Patients included were ASA I to II patients posted electively for head and reconstructive surgery.

Premedication and induction protocol was followed uniformly for all cases for general anaesthesia induction (Standardized for all cases). Maintenance of anaesthesia was done by O2 + N2O + Isoflurane (1 MAC) along with fentanyl and Atracurium (1:1) infusion @12 to 14 ml/h. Lungs were ventilated with tidal volume 6–8 ml/kg + respiratory rate of 12–14/min and airway pressure targeted to P max of 15–25 cm of H2O. Ventilation parameters were managed by respective anesthesiologist according to EtCO2 values so as to get PaCO2 between 35 and 45 mmHg. Record of preoperative parameters like age, weight, height, history of smoking, diabetes, American Society of Anaesthesiologist Physical Status Classification (ASA-PS) was done.

Ringer lactate was used as a fluid of choice for maintenance and. Assessment of blood loss was done by calculating approximately from suction bottles and soaked sponges. Blood transfusion was given if hemoglobin drops less than 7 g/dl. Intraoperative record of vitals, along with temperature, urine output and lactate levels in arterial blood gas analysis (ABG) were noted over 24 h every 2 hourly. Criteria included was lactate rise more than 2 mmol/L (values more than 5 mmol/L as severe) along with continuous rise over hours of surgery till 24 h. Other ABG parameters like pH, base excess/deficit, blood sugar, and hemoglobin were also recorded 2 hourly for 24 h. In the same way total fluids used and duration of surgery, use of Microspan (dextrans used to improve flap perfusion) was recorded. Flap re-exploration in 24 h was taken as criteria for flap failure. The patients were renamed into two groups—Group F includes all the patients with flap failure, requiring re-exploration and Group N includes all the patients with a successful flap with no re-exploration in 24 h.

Sample size is the number of similar tumor cases collected in two years operated by same surgeon (2016 and 2017). This is the reason we did not mention separately The Statistical software namely SPSS 18.0, and R environment ver.3.2.2 were used for the analysis of the data. Results on continuous measurements are presented on mean ± SD (min–max) and results on categorical measurements are presented in number (%). Significance is assessed at 5% level of significance. Student’s t test (two tailed, dependent) has been used to find the significance of study parameters on continuous scale with in each group. Student’s t test (two tailed, independent) has been used to find the significance of study parameters on continuous scale between two groups (inter group analysis) on metric parameters.