Contralateral cerebral hemoglobin oxygen saturation changes in patients undergoing thoracotomy with general anesthesia with or without paravertebral block: a randomized controlled trial

Purpose Perioperative analgesia during thoracotomy is often achieved by combining paravertebral block (PVB) with general anesthesia (GA). Functional near-infrared spectroscopy (NIRS) can detect changes in cerebral oxygenation resulting from nociceptive stimuli in the awake state or under sedation. We used NIRS to measure changes in cerebral blood flow provoked by thoracotomy incision made under GA and determine how these changes were influenced by supplementation of GA with PVB. Methods Thirty-four patients undergoing elective thoracotomy were enrolled. Patients were randomly assigned to a group receiving only GA, or GA combined with PVB (GA + PVB). Changes in cerebral oxygenated hemoglobin (ΔO 2 Hb), deoxygenated-Hb (ΔHHb), and total-Hb (ΔtotalHb) were evaluated by NIRS as surgery began. Results In the GA group, ΔO 2 Hb was significantly higher in the hemisphere contralateral to the side of surgery when the incision was made and 2 min after incision compared with the ipsilateral side (start of surgery, P