The Effect of Oxygen Administration on Regional Cerebral Oxygen Saturation after Stellate Ganglion Block on the Non-Blocked Side

Abstract

Background: Stellate ganglion block (SGB) causes sympathetic denervation of the head, neck, and upper extremities. In some studies, it has been reported that cerebral blood flow on the nonblocked side decreases after SGB, so when performing an SGB for pain management of the head, neck, and arm, the increased risk of cerebral ischemia should be considered. Objectives: To examine the influence of administration of oxygen via nasal cannula after SGB on regional cerebral oxygen saturation (rSO2) of the non-blocked and blocked sides using nearinfrared spectroscopy (NIRS). Study Design: Prospective observational study. Setting: Outpatient department for interventional pain management at Yonsei University College of Medicine, Seoul, Korea Methods: Thirty-eight patients with disease entities in the head, neck, and upper extremity and 3 volunteers were studied. SGB was performed with 10 mL of 1% lidocaine using an anterior paratracheal approach at the C6 transverse process level. A successful block was determined based on the appearance of Horner syndrome at 15 minutes after SGB. Oxygen was supplied at a rate of 5 L/min via nasal cannula starting 15 minutes after SGB. rSO2, blood pressure (BP), and heart rate (HR) were obtained at 5-minute intervals for 30 minutes using NIRS, a non-invasive blood pressure manometer, an electrocardiogram, and a pulse oximetry. Results: On the non-blocked side, when compared to the baseline values, there were significant decreases in the rSO2 (P < 0.001) and after administration of oxygen, there were significant increases of the rSO2 compared to the rSO2 at 15 minutes (P < 0.001). The lowest rSO2 at 15 minutes on the non-blocked side recovered to greater than the baseline value 5 minutes after starting oxygen administration. On the blocked side, when compared to the baseline values, there were significant increases at all time points (P < 0.001) and after administration of oxygen there were significant increases compared to the rSO2 at 15 minutes (P < 0.001). The rSO2 on the blocked side and the non-blocked side were significantly different at 15 minutes (P = 0.015). After oxygen administration, there were no significant differences of rSO2 between the 2 sides. Limitations: This study is limited by its sample size and observational design. It is difficult to precisely define the importance of the effect of SGB and oxygen administration on rSO2 change as we did not examine how the intensity of the nerve block changed with the passage of time. Conclusion: SGB leads to decreased cerebral blood flow of the non-blocked hemisphere, and oxygen administration seems to be a simple method to compensate for this response. Clinical Trial: NCT01532713. IRB No.: 4-2011-0358. Key words: Brain ischemia, cerebrovascular circulation, nerve block, oximetry, oxygen, regional blood flow, spectroscopy, near-infrared, stellate ganglion