Mukaihara K et al. – This randomized controlled study measured changes in cerebral blood flow caused by thoracotomy incision made under general anesthesia (GA) and investigated the effect of GA supplementation with paravertebral block (PVB) on these changes using near–infrared spectroscopy (NIRS). The results of the study demonstrated that changes in concentration of cerebral oxygenated hemoglobin (O2Hb) concentration were detected by NIRS immediately following surgical incision under GA, but not in the presence of PNB. The authors also concluded that NIRS can be used for monitoring surgical pain, and PVB inhibited changes in oxygenation caused by incision–provoked pain.

Methods

• Patients (N = 34) undergoing elective thoracotomy were randomized to only GA and GA combined with PVB (GA + PVB) into 2 groups receiving only GA, or GA combined with PVB (GA + PVB), respectively.

Results

• The GA group revealed significantly higher changes in cerebral O2Hb in the hemisphere, which was contralateral to the side of surgery when the incision was made and 2 minutes following incision versus the ipsilateral side.
• On the other hand, similar changes in cerebral O2Hb were not reported at any time point in the GA + PVB group.
• However, changes in cerebral total hemoglobin (total Hb) was significantly higher than changes in cerebral O2Hb in the contralateral hemisphere in the GA group at the start of surgery.