The effects of protective lung ventilation on regional cerebral oxygen saturation in intracranial tumor operation during dura opening：study protocol for a randomized controlled trial.

Abstract

Objective: To investigate the effects of protective lung ventilation on regional cerebral oxygen saturation during dura opening, that is from Ta (after dura opening) to Tb (before dura closing), in patients undergoing intracranial tumor surgery. Methods: This is a randomized, controlled trial which will be carried out at the second affiliated hospital of Soochow University. Fifty-four patients undergoing intracranial tumor surgery will be randomly allocated to the control group (C group) or the protective lung ventilation group (P group). In the C group, tidal volume (VT) will be set at 8 ml/kg of predicted body weight, but positive end-expiratory pressure (PEEP) and recruitment maneuvers will not be used. In the P group, VT will be set at 6 ml/kg of predicted body weight combined with individualized PEEP during dura opening, while in other periods of general anesthesia, VT will be set at 8 ml/kg of predicted body weight. Regional cerebral oxygen saturation (rSO2), partial pressure of oxygen (PaO2) and carbon dioxide (PaCO2), oxygenation index (OI), lactic acid level (Lac) in arterial blood, and mean arterial pressure (MAP) will be compared before anesthesia (T0), before dura opening (T1), after dura closing (T2) and 24 h after surgery (T3). Lung ultrasound scores (LUS) will be performed at T0 and T3. The degree of brain relaxation at T1 and T2 will be evaluated by the surgeon using the brain relaxation scale. Amount of vasoactive drugs used and blood loss will be recorded during surgery. The duration of operation and reoperation rate will be recorded.The primary outcome of this study is the changes in rSO2 within 24 hours postoperatively. Discussion: This study aims to determine whether protective lung ventilation during dura opening can improve regional cerebral oxygen saturation and the state of pulmonary ventilation in patients undergoing intracranial tumor surgery, and to investigate whether this strategy does not affect the degree of brain tissue swelling and the reoperation rate after operation. If our results are positive, this study will show that protective lung ventilation during dura opening can be used effectively and safely in neurosurgical patients undergoing craniotomy for tumor resection. Trial registration: chictr.org.cn, ID: ChiCTR1900025632. Registered on 3 September 2019. Study protocol version3.0. Keywords: Randomized controlled trial, Regional cerebral oxygen saturation, Lung ultrasound, Brain relaxation, Craniotomy