Effects of ultrasound-guided stellate ganglion block on the balance of the supply and demand of cerebral oxygen during permissive hypercapnia in patients undergoing shoulder arthroscopy in beach chair position

Abstract

Objective: To investigate the effects of ultrasound-guided stellate ganglion block (SGB) on the supply and demand balance of cerebral oxygen in patients with permissive hypercapnia (PHC) undergoing shoulder arthroscopy in a beach chair position (BCP).

Method: In this prospective study, a total of 86 patients who had shoulder arthroscopy were enrolled and divided into the stellate ganglion block group (SG group, n=43) and the control group (CN group, n=43) using a random number table method. Ultrasound-guided SGB was performed on patients' operation side at the 6th cervical vertebra (C6) anterior transverse tubercle level. Patients in the SG group were injected with 6ml mixture of 0.25% ropivacaine hydrochloride and 1% lidocaine hydrochloride, and those in the CN group with an equal amount of 0.9% normal saline (NS). The patients of both groups were placed in BCP for shoulder arthroscopy, and rapid induction of endotracheal intubation was performed for assisted or mechanical ventilation. Ventilation strategy was adjusted to gradually increase pulmonary end-tidal CO₂ (P_ETCO₂) during surgery. The rSO₂ levels of patients in both groups were recorded 10 min after being placed in supine position in the operation room (T0), 10 min after SGB (T1), 10 min after anesthesia induction in supine position (T2), 10 min after anesthesia induction in beach chair position (T3), 30 min after P_ETCO₂ was stabilized at 35 to 40 mmHg (T4) during surgery, and 30 min after P_ETCO₂ was stabilized at 45 to 50 mmHg (T5), respectively. The cerebral oxygen metabolic measures, including saturation of jugular bulb venous oxygen (SjvO₂), difference in artery-jugular venous oxygen content (DajvO₂) and cerebral oxygen extraction rate (CERO₂) of patients in the two groups at the time point mentioned above were compared. Hemodynamic parameters including arterial carbon dioxide partial pressure (PaCO₂), mean arterial pressure (MAP), heart rate (HR) and Saturation of Pulse Oxygen (SpO₂) were recorded. Cerebral desaturation episodes, nausea, vomiting and the use of vasoactive drugs during surgery were also recorded. The Mini-Mental State Examination score (MMSE) was recorded 1 day before and after surgery.

Results: There was no significant difference in the comparison of SjvO₂, Da-jvO₂, CERO₂, PaCO₂, MAP, HR and SpO₂ between the two groups at T0-T5 (P>0.05); no significant differences were found in intra-group comparison of SjvO₂, Da-jvO₂, CERO₂ at T0-T4 (P>0.05); the level of SjvO₂ at T5 was higher than that at T4, and the levels of Da-jvO₂ and CERO₂ at T5 were markedly lower than those at T4 (P<0.05). No significant differences were found in the inter-group comparison of MAP, HR and SpO₂ at T0-T5 (P>0.05), while PaCO₂ was significantly higher at T4 than that at T5 (P<0.05). The rSO₂ levels of patients in both groups significantly decreased at T3, as compared with those at T0 (P<0.05); the rSO₂ levels markedly increased at T5 than those at T4 (P<0.05); and the rSO₂ levels showed more significant increase in SGB group than those in the CN group as the level of P_ETCO₂ rose.

Conclusion: Permissive hypercapnia resulting from proper ventilation can significantly increase the rSO₂ levels in patients who undergo shoulder arthroscopy in BCP, the effect of which was enhanced by SGB on patients' operation side to maintain well-balanced demand and supply of cerebral oxygen. (China Clinical Trial Registry, registration number ChiCTR2000033385, https://www.chictr.org.cn).

Keywords: SGB; permissive hypercapnia; rSO2; shoulder arthroscopy in BCP.