ObjectiveTo investigate the effect of ultrasound-guided stellate ganglion block (SGB) on improvement of cerebral oxygen supply-demand balance in patients with permissible hypercapnia through real-time monitoring of intraoperative changes in cerebral oxygen saturation (rSO₂) during beach chair shoulder arthroscopic surgery.

MethodsA total of 86 patients undergoing elective shoulder arthroscopic surgery were randomly divided into an SGB group and a control group (CN group) using a random number table method, with 43 patients in each group.Both groups underwent ultrasound-guided SGB surgery at the level of the C6 transverse tubercle on the surgical side.The SGB group was injected with a mixture of 0.25%ropivacaine hydrochloride and 1%lidocaine hydrochloride in 6 mL, while the CN group was injected with an equal volume of 0.9%sodium chloride solution.Both groups underwent rapid induction tracheal intubation and mechanical assisted breathing after tracheal intubation.Later, the operation was performed in the beach chair position, and the ventilation strategy was adjusted during the operation to gradually increase P_ETCO₂.The rSO₂ levels of patients in each group at 10 minutes after entering the room (T₀), 10 minutes after SGB (T₁), lie flat for 10 minutes after induction (T₂), 10 minutes of beach chair position after induction (T₃), 30 minutes after stabilization of P_ETCO₂ 35-40 mmHg levels at the beginning of surgery (T₄), and 30 minutes after stabilization of P_ETCO₂ 45-50 mmHg levels at the beginning of surgery (T₅) were recorded.The occurrence of cerebral desaturation events (CDE) during surgery, the occurrence of nausea and vomiting, and the use of vasoactive drugs were recorded.

ResultsAt T₃-T₅, the rSO₂ on the surgical side of the SGB group was higher than that of the CN group (P < 0.05 to P < 0.01).There was no statistically significant difference in non-surgical rSO₂ between the two groups (P > 0.05).Compared at different time points within the SGB and CN groups, there was a statistically significant difference in the changes in rSO₂ between the surgical and non-surgical sides over time (P < 0.01).There was no statistically significant difference in the scores of the simplified mental state examination, incidence of postoperative nausea and vomiting, and incidence of CDE between the two groups of patients on the first day before surgery and the first day after surgery (P > 0.05).

ConclusionsThe decrease in rSO₂ levels caused by beach chair position during shoulder arthroscopic surgery can be effectively improved by adjusting the permissible hypercapnia after ventilation, and this improvement can be more effectively reflected in the effect of SGB on the surgical side.