Comparison of the Effect of Low and High Fraction of Inspired Oxygen on Postoperative Surgical Field Infection and Pulmonary Complications in Patients Undergoing Supratentorial Craniotomy

The aim of the study is to compare effects of high 0.8 FiO2 and low 0.4 FiO2 in patients are undergoing supratentorial craniotomy surgery primarily on postoperative surgical wound infection and secondarily on postoperative pulmonary complications.

The study will be performed prospectively in patient are undergoing elective supratentorial craniotomy with supine position at Istanbul university Cerrahpasa Medical School Department of Neurosurgery operating room. ASA class I-III 80 patients will be included the study. Exclusion criteria are obstructive or restrictive lung disease, chest wall deformity, congestive heart failure, liver or kidney failure, postoperatively non-cooperative and unconsciousness, preoperative fever and infection history, serious malnutrition( plasma albumin level < 3 g/dl, WBC <2500/mm3 or weight loss more than 20% in 3 months),and diabetes mellitus.

The gender, age, height, weight, BMI, smoking history and systemically illness of patients will be recorded. Patients will be randomized with closed envelop technique and divided in 2 groups. All patients will be monitored ECG, heart rate, invasive blood pressure , FiO2,pulse oximetry (SpO2) and end tidal carbon dioxide . Propofol (2 mg kg-1), remifentanyl (0.15 µ kg-1), rocuronium (0.6 mg kg-1) will be used for induction in both groups. Anesthesia maintenance will be provided with sevoflurane (1 MAC), remifentanyl (0.05-0.1 µ kg-1 dk-1) and rocuronium (0.3 mg kg-1 sa-1) . Patients will be intubated orotracheally and ventilated with volume control mode ( tidal volume 8 mL/kg, respiratory frequency will be adjusted between 9-12/minutes to hold PaCO2 between 33-35 mmHg ,inspiration/expiration ratio ½,PEEP:5 cmH2O ). Peroperative analgesia will be provided with remifentanyl infusion. Ondansetron 8 mg for antiemesis and tramadol 100 mg for postoperative analgesia will be administered intravenously 30 minutes before extubation. Duration of surgery and non-invasive cerebral oxygen saturation (SctO2) using bilateral frontal electrodes will be recorded. At the end of the surgery, sugammadex 2mg kg-1 will be administered for decurarization in all groups. Patients will be transferred to the recovery room in postoperative period and 15L/min and 4L/min oxygen will be given to 0.8 FiO2 group and other group, respectively.

Wound healing will be evaluated every day in terms of surgical wound infection occurrence for postoperative 14 days with ASEPSIS classification. Surgical wound infection will be considered in patients who score 20 or more on daily basis. The patients who are discharged will be reached by phone. Pneumonia, atelectasis, respiratory failure, hospital and intensive care unit stay will be recorded for postoperative 14 days. *CDC criteria will be used to diagnose pneumonia. Respiratory insufficiency is diagnosed by SpO2 fall below 90% despite oxygen treatment and mechanical ventilation need. If pulmonary complication develops ,findings will be recorded with chest radiography or tomography when necessary.

• ASA: american society of anaesthesiology
• WBC:white blood cell
• PEEP: positive end expiratory pressure
• CDC: centers for disease control and prevention